Gene Summary

Gene:CHAT; choline O-acetyltransferase
Summary:This gene encodes an enzyme which catalyzes the biosynthesis of the neurotransmitter acetylcholine. This gene product is a characteristic feature of cholinergic neurons, and changes in these neurons may explain some of the symptoms of Alzheimer's disease. Polymorphisms in this gene have been associated with Alzheimer's disease and mild cognitive impairment. Mutations in this gene are associated with congenital myasthenic syndrome associated with episodic apnea. Multiple transcript variants encoding different isoforms have been found for this gene, and some of these variants have been shown to encode more than one isoform. [provided by RefSeq, May 2010]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:choline O-acetyltransferase
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Latest Publications: CHAT (cancer-related)

Chat V, Ferguson R, Simpson D, et al.
Autoimmune genetic risk variants as germline biomarkers of response to melanoma immune-checkpoint inhibition.
Cancer Immunol Immunother. 2019; 68(6):897-905 [PubMed] Article available free on PMC after 01/06/2020 Related Publications
Immune-checkpoint inhibition (ICI) treatments improve outcomes for metastatic melanoma; however, > 60% of treated patients do not respond to ICI. Current biomarkers do not reliably explain ICI resistance. Given the link between ICI and autoimmunity, we investigated if genetic susceptibility to autoimmunity modulates ICI efficacy. In 436 patients with metastatic melanoma receiving single line ICI or combination treatment, we tested 25 SNPs, associated with > 2 autoimmune diseases in recent genome-wide association studies, for modulation of ICI efficacy. We found that rs17388568-a risk variant for allergy, colitis and type 1 diabetes-was associated with increased anti-PD-1 response, with significance surpassing multiple testing adjustments (OR 0.26; 95% CI 0.12-0.53; p = 0.0002). This variant maps to a locus of established immune-related genes: IL2 and IL21. Our study provides first evidence that autoimmune genetic susceptibility may modulate ICI efficacy, suggesting that systematic testing of autoimmune risk loci could reveal personalized biomarkers of ICI response.

Lauzon MA, Drevelle O, Faucheux N
Peptides derived from the knuckle epitope of BMP-9 induce the cholinergic differentiation and inactivate GSk3beta in human SH-SY5Y neuroblastoma cells.
Sci Rep. 2017; 7(1):4695 [PubMed] Article available free on PMC after 01/06/2020 Related Publications
The incidence of brain degenerative disorders like Alzheimer's disease (AD) will increase as the world population ages. While there is presently no known cure for AD and current treatments having only a transient effect, an increasing number of publications indicate that growth factors (GF) may be used to treat AD. GFs like the bone morphogenetic proteins (BMPs), especially BMP-9, affect many aspects of AD. However, BMP-9 is a big protein that cannot readily cross the blood-brain barrier. We have therefore studied the effects of two small peptides derived from BMP-9 (pBMP-9 and SpBMP-9). We investigated their capacity to differentiate SH-SY5Y human neuroblastoma cells into neurons with or without retinoic acid (RA). Both peptides induced Smad 1/5 phosphorylation and their nuclear translocation. They increased the number and length of neurites and the expression of neuronal markers MAP-2, NeuN and NSE better than did BMP-9. They also promoted differentiation to the cholinergic phenotype more actively than BMP-9, SpBMP-9 being the most effective as shown by increases in intracellular acetylcholine, ChAT and VAchT. Finally, both peptides activated the PI3K/Akt pathway and inhibited GSK3beta, a current AD therapeutic target. BMP-9-derived peptides, especially SpBMP-9, with or without RA, are promising molecules that warrant further investigation.

Chen CP, Wang LK, Chern SR, et al.
Prenatal diagnosis of partial monosomy 5p (5p15.1→pter) and partial trisomy 7p (7p15.2→pter) associated with cystic hygroma, abnormal skull development, and ventriculomegaly.
Taiwan J Obstet Gynecol. 2016; 55(4):591-5 [PubMed] Related Publications
OBJECTIVE: Prenatal diagnosis of concomitant chromosome 5p deletion syndrome and chromosome 7p duplication syndrome in a fetus with abnormal prenatal ultrasound is presented.
CASE REPORT: A 34-year-old woman was referred for amniocentesis at 22 weeks of gestation because of an irregular-shaped skull, bilateral ventriculomegaly, and nuchal cystic hygroma. Amniocentesis revealed a derivative chromosome 5 with a distal 5p deletion and an addendum of an extra unknown chromosomal segment at the breakpoint of 5p. Cytogenetic analysis of parental bloods revealed a karyotype of 46, XX, t(5;7)(p15.1;p15.2) in the mother and a karyotype of 46,XY in the father. The karyotype of the fetus was 46, XX, der(5) t(5;7)(p15.1;p15.2)mat consistent with partial monosomy 5p (5p15.1→pter) and partial trisomy 7p (7p15.2→pter). A malformed fetus was subsequently delivered with an irregular-shaped skull, a large anterior fontanelle, brachycephaly, hypertelorism, a high and prominent forehead, a large nuchal cystic hygroma, large low-set ears, a short and flattened nose, and micrognathia. Array comparative genomic hybridization analysis of the placenta revealed the result of arr 5p15.33p15.1 (22,179-18,133,327)×1.0, 7p22.3p15.2 (54,215-25,551,540)×3.0, indicating an 18.11-Mb deletion of 5p (5p15.33-p15.1) and a 22.5-Mb duplication of 7p (7p22.3-p15.2). Cord blood sampling revealed a karyotype of 46, XX, der(5)t(5;7) (p15.1;p15.2)mat.
CONCLUSION: Fetuses with 5p deletion syndrome and 7p duplication syndrome may present ventriculomegaly, abnormal skull development, and cystic hygroma on prenatal ultrasound.

Shi Y, Chen Q, Huang Y, et al.
Function and clinical implications of short-chain fatty acids in patients with mixed refractory constipation.
Colorectal Dis. 2016; 18(8):803-10 [PubMed] Related Publications
AIM: The present study was designed to investigate the function and clinical implications of stool short-chain fatty acids (SCFAs) in patients with mixed refractory constipation.
METHOD: Ascending colon specimens obtained from 30 patients with ascending colon cancer were regarded as the control group. Ascending colon specimens obtained from patients with mixed refractory constipation were regarded as the experimental group and were divided into three subgroups, according to Wexner scores [A constipation scoring system to simplify evaluation and management of constipated patients. Dis Colon Rectum 1996; 39: 681-5] of 16-20, 21-25 and 26-30, with 30 patients in each group. The stool SCFAs were extracted and quantitatively analysed using gas chromatography-mass spectrometry (GC-MS). The expression of G protein-coupled receptor 43 (GPR43) and of choline acetyltransferase (ChAT) were detected by immunofluorescence, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting of colon samples.
RESULTS: The levels of acetate, propionate and butyrate were significantly lower in the experimental group than in the control group (P < 0.05). Compared with the control group, the densitometric quantification and mean density of GPR43 and ChAT proteins, and expression of GPR43 and CHAT genes, were significantly decreased in the patients with mixed refractory constipation (P < 0.05).
CONCLUSION: In the patients with mixed refractory constipation, the levels of stool SCFAs, including acetate, propionate and butyrate, as well as the levels of GPR43 and ChAT expressed in the colon, which were all negatively correlated with the Wexner score, were decreased and may be associated with the pathogenesis of mixed refractory constipation.

Wang L, Zhi X, Zhang Q, et al.
Muscarinic receptor M3 mediates cell proliferation induced by acetylcholine and contributes to apoptosis in gastric cancer.
Tumour Biol. 2016; 37(2):2105-17 [PubMed] Related Publications
The muscarinic receptor M3 is an acetylcholine receptor that regulates the activity of numerous fundamental central and peripheral nervous system functions. Recent studies have identified the activation of the M3 receptor in several cancers; however, the role of M3 in human gastric cancer (GC) remains largely unknown. In this study, we demonstrated that the M3 receptor was overexpressed in human GC tissues and was correlated with the cancer stage and with lymph node metastasis. In vitro, the M3 receptor enhanced the proliferation induced by acetylcholine in human GC cells, whereas the knockdown of M3 by a small hairpin RNA (shRNA) inhibited cell proliferation. Furthermore, M3 knockdown caused G2/M phase cell cycle arrest and induced apoptosis in human GC cells. In vivo, M3 knockdown suppressed tumorigenesis and promoted apoptosis in GC xenografts. In addition, we also detected the secretion of acetylcholine (ACh) by human GC cells and observed the co-expression of the M3 receptor and choline acetyltransferase (ChAT), the enzyme necessary for acetylcholine synthesis, in human GC tissues and cells. Taken together, our findings support an oncogenic role for the M3 receptor in gastric cancer, suggesting that M3 antagonists may serve as potential adjuvants to GC therapies. Further study of the underlying molecular mechanism could also lead to the identification of novel therapeutic targets for improved treatment of GC.

Wang N, Yao M, Xu J, et al.
Autocrine Activation of CHRM3 Promotes Prostate Cancer Growth and Castration Resistance via CaM/CaMKK-Mediated Phosphorylation of Akt.
Clin Cancer Res. 2015; 21(20):4676-85 [PubMed] Related Publications
PURPOSE: Although a previous study reported nerve ending-derived acetylcholine promoted prostate cancer invasion and metastasis by regulating the microenvironment of cancer cells, the present study aims to determine whether there is autocrine cholinergic signaling in prostate epithelial cells that promotes prostate cancer growth and castration resistance.
EXPERIMENTAL DESIGN: In this study, IHC was performed to detect protein expression in mouse prostate tissue sections and human prostate cancer tissue sections. Subcutaneously and orthotopically xenografted tumor models were established to evaluate the functions of autocrine cholinergic signaling in regulating prostate cancer growth and castration resistance. Western blotting analysis was performed to assess the autocrine cholinergic signaling-induced signaling pathway.
RESULTS: We found the expression of choline acetyltransferase (ChAT), the secretion of acetylcholine and the expression of CHRM3 in prostate epithelial cells, supporting the presence of autocrine cholinergic signaling in the prostate epithelium. In addition, we found that CHRM3 was upregulated in clinical prostate cancer tissues compared with adjacent non-cancer tissues. Overexpression of CHRM3 or activation of CHRM3 by carbachol promoted cell proliferation, migration, and castration resistance. On the contrary, blockading CHRM3 by shRNA or treatment with darifenacin inhibited prostate cancer growth and castration resistance both in vitro and in vivo. Furthermore, we found that autocrine cholinergic signaling caused calmodulin/calmodulin-dependent protein kinase kinase (CaM/CaMKK)-mediated phosphorylation of Akt.
CONCLUSIONS: These findings suggest that blockade of CHRM3 may represent a novel adjuvant therapy for castration-resistant prostate cancer.

Huang Z, Rui J, Li X, et al.
Use of ¹¹C-Choline positron emission tomography/computed tomography to investigate the mechanism of choline metabolism in lung cancer.
Mol Med Rep. 2015; 11(5):3285-90 [PubMed] Article available free on PMC after 01/06/2020 Related Publications
The present study was conducted to investigate the 11C‑Choline metabolic mechanism and examine the association between 11C‑Choline metabolism and uptake in different pathological types of lung cancer. A total of 18 tumor specimens and corresponding normal lung tissues were collected from patients who were diagnosed with lung cancer using 11C‑Choline positron emission tomography (PET)/computed tomography (CT) imaging between January 2007 and December 2008 at the Medical Imaging Center of the Provincial Hospital Affiliated to Shandong University. The diagnosis was further confirmed pathologically following surgery. Reverse transcription polymerase chain reaction and western blotting were used to investigate the expression of choline acetyltransferase (ChAT) and choline kinase α (ChoK) in lung cancer tissue and normal lung tissue. The 11C‑Choline PET/CT data were analyzed visually and semiquantitatively. Compared with the expression in the normal lung tissues, the mRNA and protein expression of ChAT and ChoK increased in nine and 14 of the 18 lung tumors, respectively. A total of eight of the 18 tumors exhibited significantly increased expression, while three exhibited no expression of ChoK and ChAT. All lung cancer lesions were visualized with 11C‑Choline PET/CT imaging. The phosphorylation and acetylation pathways of choline metabolism may be important in 11C‑Choline uptake and metabolism in different pathological types of lung cancer.

Zhang L, Ramchandren R, Papenhausen P, et al.
Transformed aggressive γδ-variant T-cell large granular lymphocytic leukemia with acquired copy neutral loss of heterozygosity at 17q11.2q25.3 and additional aberrations.
Eur J Haematol. 2014; 93(3):260-4 [PubMed] Related Publications
T-cell large granular lymphocytic leukemia (T-LGLL) is a rare indolent lymphoproliferative disorder characterized by cytopenias, splenomegaly, and various degrees of T-cell lymphocytosis, due to a clonal expansion of CD8-positive cytotoxic T-cells. Phenotypic variants of T-LGLL include CD4(+) /CD8(-) T-cells, with dual CD4(-) /CD8(-) /γδ(+) T-cells being even rarer. Cytogenetic abnormalities in T-LGLL have rarely been reported, and there is scientific debate regarding the existence of aggressive or transformed variants of T-LGLL. We report a patient with T-LGLL, γδ variant, with nearly 20-year-long duration of cytopenias before transformation to an unusual clinical scenario, manifesting with marked lymphocytosis >100 × 10(9) /L and infiltration of lymph nodes, tonsils, and subcutaneous tissue. Single-nucleotide polymorphism assays revealed acquired copy neutral loss of heterozygosity at 17q and deletion of 3p21.31, in addition to trisomy 5, monosomy X, and monosomy 21. These genetic abnormalities provided a better understanding of the molecular nature and the potentiality of disease transformation.

Inazu M, Yamada T, Kubota N, Yamanaka T
Functional expression of choline transporter-like protein 1 (CTL1) in small cell lung carcinoma cells: a target molecule for lung cancer therapy.
Pharmacol Res. 2013; 76:119-31 [PubMed] Related Publications
Choline is essential for the synthesis of the major membrane phospholipid phosphatidylcholine and the neurotransmitter acetylcholine (ACh). Elevated levels of choline and up-regulated choline kinase activity have been detected in cancer cells. Thus, the intracellular accumulation of choline through choline transporters is the rate-limiting step in phospholipid metabolism and a prerequisite for cancer cell proliferation. However, the uptake system for choline and the functional expression of choline transporters in lung cancer cells are poorly understood. We examined the molecular and functional characterization of choline uptake in the small cell lung carcinoma cell line NCI-H69. Choline uptake was saturable and mediated by a single transport system. Interestingly, removal of Na(+) from the uptake buffer strongly enhanced choline uptake. This increase in choline uptake under the Na(+)-free conditions was inhibited by dimethylamiloride (DMA), a Na(+)/H(+) exchanger (NHE) inhibitor. Various organic cations and the choline analog hemicholinium-3 (HC-3) inhibited the choline uptake and cell viability. A correlation analysis of the potencies of organic cations for the inhibition of choline uptake and cell viability showed a strong correlation (R=0.8077). RT-PCR revealed that choline transporter-like protein 1 (CTL1) mRNA and NHE1 are mainly expressed. HC-3 and CTL1 siRNA inhibited choline uptake and cell viability, and increased caspase-3/7 activity. The conversion of choline to ACh was confirmed, and this conversion was enhanced under Na(+)-free conditions, which in turn was sensitive to HC-3. These results indicate that choline uptake through CTL1 is used for ACh synthesis. Both an acetylcholinesterase inhibitor (eserine) and a butyrylcholinesterase inhibitor (ethopropazine) increased cell proliferation, and these effects were inhibited by 4-DAMP, a mAChR3 antagonist. We conclude that NCI-H69 cells express the choline transporter CTL1 which uses a directed H(+) gradient as a driving force, and its transport functions in co-operation with NHE1. This system primarily supplies choline for the synthesis of ACh and secretes ACh to act as an autocrine/paracrine growth factor, and the functional inhibition of CTL1 could promote apoptotic cell death. Identification of this new CTL1-mediated choline transport system provides a potential new target for therapeutic intervention.

Parnell EA, Calleja-Macias IE, Kalantari M, et al.
Muscarinic cholinergic signaling in cervical cancer cells affects cell motility via ERK1/2 signaling.
Life Sci. 2012; 91(21-22):1093-8 [PubMed] Related Publications
AIMS: The etiology of cervical cancer depends primarily on infection with human papillomaviruses, but tobacco smoking is the most important behavioral risk factor for this cancer. Therefore, we have previously confirmed involvement of nicotinic acetylcholine receptors (nAChRs) in cervical cancer biology. In order to comprehensively evaluate the role of cholinergic signaling in cervical cells, we have addressed additional participation of muscarinic acetylcholine receptors (mAChRs).
MAIN METHODS: We have studied the expression of mAChRs and cholinergic system components by reverse transcription PCR and Western blots, the motility of cervical cancer cells in cell culture, and the signaling from mAChRs via the ERK1/2 signaling pathway.
KEY FINDINGS: The cervical cancer cells HeLa, SiHa and CaSki express four of the five mAChRs, M1, M3, M4, and M5, and the acetylcholine (ACh) synthesizing and degrading enzymes choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), and vesicular ACh transporter (VAChT). mAChR-dependent signaling induces cervical cell motility, which requires ERK1/2 activation, and could be abrogated by mAChR antagonists.
SIGNIFICANCE: The epidemiological finding that tobacco smoke raises the prevalence of cervical cancer has led to analysis of the cholinergic signaling in cervical biology and carcinogenesis. Cervical cancer cells express several nAChRs and mAChRs, whose activation leads to changes of cellular properties such as increased motility and proliferation that favor a carcinogenic phenotype. The signaling involves intracellular phosphorylation cascades including ERK1/2.

Hughes L, Phelps C
"The bigger the network the bigger the bowl of cherries...": exploring the acceptability of, and preferences for, an ongoing support network for known BRCA 1 and BRCA 2 mutation carriers.
J Genet Couns. 2010; 19(5):487-96 [PubMed] Related Publications
There is increasing evidence to suggest that the ongoing information and support needs of BRCA gene mutation carriers are not being met. This qualitative study investigated preferences for an on-going support network for mutation carriers in Wales, UK. Seventeen female BRCA1/2 mutation carriers participated in focus groups which explored their current and on-going information and psychological support needs. The interviews were transcribed and thematically analysed. The results reflected a diversity of experiences and support needs. The majority of participants felt they and their families would benefit from an on-going 'support network' which should incorporate information-provision alongside elements of a traditional support group alongside, internet-based support such as web-based chat forums, matching schemes and professionally led workshops. Some degree of professional input into any such initiative was believed to be important. This study has informed the development of an appropriate support network based on a hub and spoke model to help carriers and their families adapt to living and coping with their genetic risk.

Wu X, Rauch TA, Zhong X, et al.
CpG island hypermethylation in human astrocytomas.
Cancer Res. 2010; 70(7):2718-27 [PubMed] Article available free on PMC after 01/06/2020 Related Publications
Astrocytomas are common and lethal human brain tumors. We have analyzed the methylation status of over 28,000 CpG islands and 18,000 promoters in normal human brain and in astrocytomas of various grades using the methylated CpG island recovery assay. We identified 6,000 to 7,000 methylated CpG islands in normal human brain. Approximately 5% of the promoter-associated CpG islands in the normal brain are methylated. Promoter CpG island methylation is inversely correlated whereas intragenic methylation is directly correlated with gene expression levels in brain tissue. In astrocytomas, several hundred CpG islands undergo specific hypermethylation relative to normal brain with 428 methylation peaks common to more than 25% of the tumors. Genes involved in brain development and neuronal differentiation, such as BMP4, POU4F3, GDNF, OTX2, NEFM, CNTN4, OTP, SIM1, FYN, EN1, CHAT, GSX2, NKX6-1, PAX6, RAX, and DLX2, were strongly enriched among genes frequently methylated in tumors. There was an overrepresentation of homeobox genes and 31% of the most commonly methylated genes represent targets of the Polycomb complex. We identified several chromosomal loci in which many (sometimes more than 20) consecutive CpG islands were hypermethylated in tumors. Seven such loci were near homeobox genes, including the HOXC and HOXD clusters, and the BARHL2, DLX1, and PITX2 genes. Two other clusters of hypermethylated islands were at sequences of recent gene duplication events. Our analysis offers mechanistic insights into brain neoplasia suggesting that methylation of the genes involved in neuronal differentiation, in cooperation with other oncogenic events, may shift the balance from regulated differentiation towards gliomagenesis.

Kim HS, Park H, Lim JH, et al.
Morphometric evaluation of oesophageal wall in patients with nutcracker oesophagus and ineffective oesophageal motility.
Neurogastroenterol Motil. 2008; 20(8):869-76 [PubMed] Related Publications
The pathogenesis of nutcracker oesophagus (NE) and ineffective oesophageal motility (IEM) is unclear. Damage to the enteric nervous system or smooth muscle can cause oesophageal dysmotility. We tested the hypothesis that NE and IEM are associated with abnormal muscular or neural constituents of the oesophageal wall. Oesophageal manometry was performed in patients prior to total gastrectomy for gastric cancer. The oesophageal manometries were categorized as normal (n = 7), NE (n = 13), or IEM (n = 5). Histologic examination of oesophageal tissue obtained during surgery was performed after haematoxylin and eosin (H&E) and trichrome staining. Oesophageal innervation was examined after immunostaining for protein gene product-9.5 (PGP-9.5), choline acetyltransferase (ChAT) and neuronal nitric oxide synthase (nNOS). There were no significant differences in inner circular smooth muscle thickness or degree of fibrosis among the three groups. Severe muscle fibre loss was found in four of five patients with IEM. The density of PGP-9.5-reactive neural structures was not different among the three groups. The density of ChAT immunostaining in the myenteric plexus (MP) was significantly greater in patients with NE (P < 0.05) and the density of nNOS immunostaining in the circular muscle (CM) was significantly greater in IEM patients (P < 0.05). The ChAT/nNOS ratio in both MP and CM was significantly greater in NE patients. NE may result from an imbalance between the excitatory and inhibitory innervation of the oesophagus, because more than normal numbers of ChAT-positive myenteric neurones are seen in NE. Myopathy and/or increased number of nNOS neurones may contribute to the hypocontractile motor activity of IEM.

Near RI, Zhang Y, Makkinje A, et al.
AND-34/BCAR3 differs from other NSP homologs in induction of anti-estrogen resistance, cyclin D1 promoter activation and altered breast cancer cell morphology.
J Cell Physiol. 2007; 212(3):655-65 [PubMed] Article available free on PMC after 01/06/2020 Related Publications
Over-expression of AND-34/BCAR3/NSP2 (BCAR3) or its binding-partner p130Cas/BCAR1 generates anti-estrogen resistance in human breast cancer lines. Here, we have compared BCAR3 to two related homologs, NSP1 and NSP3/CHAT/SHEP, with regards to expression, anti-estrogen resistance, and signaling. BCAR3 is expressed at higher levels in ERalpha-negative, mesenchymal, than in ERalpha-positive, epithelial, breast cancer cell lines. Characterization of "intermediate" epithelial-like cell lines with variable ER-alpha expression reveals that BCAR3 expression correlates with both mesenchymal and ERalpha-negative phenotypes. Levels of the BCAR3/p130Cas complex correlate more strongly with the ERalpha-negative, mesenchymal phenotype than levels of either protein alone. NSP1 and NSP3 are expressed at lower levels than BCAR3 and without correlation to ERalpha/mesenchymal status. Among NSP-transfectants, only BCAR3 transfectants induce anti-estrogen resistance and augment transcription of cyclin D1 promoter constructs. Over-expression of all homologs results in activation of Rac, Cdc42 and Akt, suggesting that these signals are insufficient to induce anti-estrogen resistance. BCAR3 but not NSP1 nor NSP3 transfectants show altered morphology, transitioning from polygonal cell groups to rounded, single cells with numerous blebs. Whereas stable over-expression of BCAR3 in MCF-7 cells does not lead to classic epithelial-to-mesenchymal transition, it does result in down-regulation of cadherin-mediated adhesion and augmentation of fibronectin expression. These studies suggest that BCAR's ability to induce anti-estrogen resistance is greater than that of other NSP homologs and may result from altered interaction of breast cancer cells with each other and the extracellular matrix.

Mason PJ, Bessler M
Heterozygous telomerase deficiency in mouse and man: when less is definitely not more.
Cell Cycle. 2004; 3(9):1127-9 [PubMed] Related Publications
Telomerase, whose core components are a reverse transcriptase (TERT) and an integral RNA (TERC) maintains telomere ends. In somatic cells in the absence of telomerase telomeres get shorter leading to replicative cell senescence. In cancer cells abundant telomerase is present and cells do not senesce. Hence levels of telomerase may be crucial in regulating senescence and the transition to the neoplastic state. Heterozygous TERC mutations in man have been shown to underlie the rare inherited skin and bone marrow failure condition dyskeratosis congenita and a number of patients initially classified as idiopathic aplastic anemia have also been found to be mutated in one allele of the TERC gene. Families in which TERC mutations are segregating show disease anticipation, the severity of the disease increasing in successive generations due to decreasing telomere length. These data, along with biochemical analysis of mutated Terc and studies of Terc deficient mice show that in man and mouse haploinsufficiency for TERC leads to inability to correctly maintain telomeres, and highlights the importance of finely controlled telomerase levels in striking a balance between the processes of aging and cancer. Here we review several scenarios in which telomerase levels are disturbed, in human diseases or following genetic manipulation in mice.

Nagai A, Suzuki Y, Baek SY, et al.
Generation and characterization of human hybrid neurons produced between embryonic CNS neurons and neuroblastoma cells.
Neurobiol Dis. 2002; 11(1):184-98 [PubMed] Related Publications
A human hybrid neuronal cell line A1 has been generated by somatic fusion between a human fetal cerebral neuron and a human neuroblastoma cell, and RT-PCR, immunochemical, and electrophysiological studies of the hybrid cells indicated that the cells express faithfully of morphological, immunochemical, physiological, and genetic features of human cerebral neurons. A1 hybrid neurons express neuron-specific markers such as neurofilament-L (NF-L), NF-M, NF-H, MAP-2, and beta tubulin III. A1 human hybrid neurons express messages for various cytokines and cytokine receptors which are similar to parental human CNS neurons and different from the other parental cell line, SK-SH-SY5Y neuroblastoma. A1 hybrid neurons also express messages for choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD), indicating that they could differentiate into various subsets of neuronal types. Whole-cell patch clamp experiments showed that A1 hybrid neurons expressed Na+ currents, which were completely blocked by tetrodotoxin. In addition, depolarizing and hyperpolarizing voltage clamp steps evoked respective outward and inward K+ currents in these cells. When A1 hybrid neurons were exposed to beta amyloid for 72 hr, there was three-fold increase in TUNEL positive cells over controls, indicating that beta amyloid is neurotoxic to A1 hybrid neurons. The present study indicates that the A1 human hybrid neuronal cell line should serve as a valuable in vitro model for studies of biology, physiology, and pathology of human neurons in health and disease.

Robert I, Quirin-Stricker C
A novel untranslated 'exon H' of the human choline acetyltransferase gene in placenta.
J Neurochem. 2001; 79(1):9-16 [PubMed] Related Publications
To investigate the existence of 5'-region(s) of human choline acetyltransferase (hChAT) mRNA in placenta we analyzed the presence or absence of ChAT 5'-untranslated regions (UTR) in human neuronal and non-neuronal cells. Total RNA from human spinal cord, placenta, cultured choriocarcinoma JEG-3 and neuroblastoma CHP126 and MC-IXC cells was reverse transcribed and used for polymerase chain reaction amplification (RT-PCR). We used a sense primer located in the 5'-flanking region, in the previously defined intronic sequence and an anti-sense primer located in the common coding exon 2 of the hChAT gene. An amplified product of 567 bp in size was obtained only in human placenta and in JEG-3 cells whereas it was absent in spinal cord, CHP126 and MC-IXC cells. It was designated 'H-type' of ChAT mRNA. Whereas CHP126 produced the R- and N-type of ChAT mRNAs, no transcript of the N-and R-type was detected in JEG-3 and human placenta. In addition, CHP126 and JEG-3 cells and placenta showed the expression of the M-type of ChAT mRNA. The identity of the amplified 567 bp product (H-type) was confirmed by Southern hybridization and sequencing. The nucleotide sequence of the amplified fragment in placenta revealed the existence of a previously unknown type of ChAT mRNA produced by alternative splicing. Using primer extension we further determined the transcription initiation site of the H-type hChAT mRNA in placenta. These results demonstrate the expression of a novel ChAT mRNA isoform in human placenta in addition to the M-type. These data may be possibly explained by the presence of a placenta specific promoter in the ChAT gene, which might be the proximal promoter P1.

Lee TJ, Kim SJ, Park JH
Influence of the sequence variations of the HLA-DR promoters derived from human melanoma cell lines on nuclear protein binding and promoter activity.
Yonsei Med J. 2000; 41(5):593-9 [PubMed] Related Publications
In previous studies we reported that the expression of HLA-DR on melanoma cell lines was differentially modulated by IFN- gamma and that the transcription rate was responsible for this differential modulation. We have also reported the nucleotide sequence variations in the promoter region of HLA-DR genes, and proposed that differences in the promoter activity by the sequence variations of the HLA-DR promoters might contribute to such a differential transcriptional regulation at the promoter level. In this study, in order to assess whether the sequence variations of the HLA-DR promoters affect the factor binding and exert influence on the promoter activity, nuclear factor binding to our previous six HLA-DRA and fourteen HLA-DRB promoter clones was evaluated with the nuclear protein extracted from a B-lymphoblastoid cell line (BLCL), BH, together with the chloramphenicol acetyltransferase (CAT) reporter assay. In the HLA-DRA promoters, clone #35 containing one bp nucleotide sequence variation at the octamer binding site (OCT) (GATTTGC to GATCTGC) showed relatively weak factor binding. In the HLA-DRB promoters, clusters I, III, and IV of our previous HLA-DRB promoter homologues, containing one bp nucleotide sequence variation (GATTCG) in their Y boxes exhibited weak factor binding and CAT activity compared to other clusters (GATTGG) that showed strong factor binding and CAT activity. This data suggests chat the binding patterns of transcription factors influenced by the nucleotide sequence variations of the HLA-DR promoter could affect the promoter activity and the DNA sequence elements in the HLA-DR promoter could mediate transcriptional regulation.

Tanaka H, Shimojo M, Wu D, Hersh LB
Regulation of the cholinergic gene locus.
J Physiol Paris. 1998; 92(2):149-52 [PubMed] Related Publications
DNase I hypersensitive site mapping of the human cholinergic gene locus has been used to detect cholinergic specific potential regulatory sites. Analysis of mutant PC12 cell lines provides evidence that protein kinase A II is required and coordinately regulates basal expression of both the ChAT and VAChT genes.

Pinkel D, Segraves R, Sudar D, et al.
High resolution analysis of DNA copy number variation using comparative genomic hybridization to microarrays.
Nat Genet. 1998; 20(2):207-11 [PubMed] Related Publications
Gene dosage variations occur in many diseases. In cancer, deletions and copy number increases contribute to alterations in the expression of tumour-suppressor genes and oncogenes, respectively. Developmental abnormalities, such as Down, Prader Willi, Angelman and Cri du Chat syndromes, result from gain or loss of one copy of a chromosome or chromosomal region. Thus, detection and mapping of copy number abnormalities provide an approach for associating aberrations with disease phenotype and for localizing critical genes. Comparative genomic hybridization (CGH) was developed for genome-wide analysis of DNA sequence copy number in a single experiment. In CGH, differentially labelled total genomic DNA from a 'test' and a 'reference' cell population are cohybridized to normal metaphase chromosomes, using blocking DNA to suppress signals from repetitive sequences. The resulting ratio of the fluorescence intensities at a location on the 'cytogenetic map', provided by the chromosomes, is approximately proportional to the ratio of the copy numbers of the corresponding DNA sequences in the test and reference genomes. CGH has been broadly applied to human and mouse malignancies. The use of metaphase chromosomes, however, limits detection of events involving small regions (of less than 20 Mb) of the genome, resolution of closely spaced aberrations and linking ratio changes to genomic/genetic markers. Therefore, more laborious locus-by-locus techniques have been required for higher resolution studies. Hybridization to an array of mapped sequences instead of metaphase chromosomes could overcome the limitations of conventional CGH (ref. 6) if adequate performance could be achieved. Copy number would be related to the test/reference fluorescence ratio on the array targets, and genomic resolution could be determined by the map distance between the targets, or by the length of the cloned DNA segments. We describe here our implementation of array CGH. We demonstrate its ability to measure copy number with high precision in the human genome, and to analyse clinical specimens by obtaining new information on chromosome 20 aberrations in breast cancer.

Usami S, Matsubara A, Shinkawa H, et al.
Neuroactive substances in the human vestibular end organs.
Acta Otolaryngol Suppl. 1995; 520 Pt 1:160-3 [PubMed] Related Publications
In order to evaluate the involvement of neuroactive substances in the human vestibular periphery, the immunocytochemical distribution of substance P (SP), calcitonin gene-related peptide (CGRP), and choline acetyltransferase (ChAT) was examined. SP-like immunoreactivity (LI) was present around and beneath sensory hair cells, probably corresponding to their afferent nerve endings. SP-LI was found predominantly in subpopulations of the primary afferents distributed in the peripheral region of the end organs. ChAT-LI and CGRP-LI were found throughout as small puncta below the hair cell layer, probably corresponding to efferent endings. The present results indicate that these neuroactive substances, previously described in animals, are also distributed in the human vestibular periphery, and almost certainly contribute to human vestibular function.

Quirin-Stricker C, Nappey V, Simoni P, et al.
Trans-activation by thyroid hormone receptors of the 5' flanking region of the human ChAT gene.
Brain Res Mol Brain Res. 1994; 23(3):253-65 [PubMed] Related Publications
Fusion gene constructs containing the human choline acetyltransferase 5' flanking region are stimulated by thyroid hormone (T3) in neuronal NG108-15 and NE1-115 cells but not in non neuronal COS-1 and JEG-3 cells. To identify potential T3 receptor binding elements (T3RE), chimeric plasmids containing various lengths of the 5' end of the hChAT gene linked to the CAT reporter gene were assayed by transient transfections into NG108-15, NE1-115 and COS-1 cells. We show that regulation is T3 specific as estrogen, dexamethasone, dihydrotestosterone, all-trans-retinoic acid and 9-cis-retinoic acid have no effect. We localized several potential T3REs and characterized the most proximal T3RE (position 3280-3291) which contains two hexameric half-sites arranged as a direct repeat without a base pair spacer. An oligonucleotide containing this sequence confers T3 responsiveness to a heterologous promoter. The transcriptional response of this T3RE is markedly reduced after mutation of the first or second half-site indicating that both half-sites are required for a maximal T3 response. We have found that RAR alpha, RXR alpha and COUP-TF do not enhance T3 responsiveness and therefore they may not interact with T3R alpha in NG108-15 cells on this regulatory sequence. T3R monomer and dimer specific binding to the proximal T3RE is demonstrated by gel-retardation DNA binding assays and by methylation interference experiments. In COS-1 cells, T3R inhibits transcriptional activation by the transcription factor AP-1 whereas in NE1-115 cells T3R enhances AP-1 mediated activation in a T3 dependant fashion. It is likely that these effects involve protein-protein interactions. These results suggest that the T3 receptor can act as a positive transcriptional regulatory factor on the hChAT gene.

Inoue H, Baetge EE, Hersh LB
Enhancer containing unusual GC box-like sequences on the human choline acetyltransferase gene.
Brain Res Mol Brain Res. 1993; 20(4):299-304 [PubMed] Related Publications
The minimum requirement of an enhancer for the human choline acetyltransferase (ChAT) gene was analyzed by mutagenesis and protein-DNA interaction studies. A series of deletion and site-specific mutants were expressed transiently in a rat cholinergic neuroblastoma cell, NS20Y. The results revealed that the distal region between -970 and -941 base pairs (bp) from the transcription start site is essential for efficient transcription of the human ChAT gene. Two GC box-like sequences were located within this region, and they were shown to bind purified Sp1 transcription factor by footprinting and gel retardation analyses. This sequence, however, has an orientational effect and is located approximately 1000 bp from the transcription start site, unusual for the conventional GC box sequence. Furthermore, the sequence between these GC box-like sequences is shown to bind another novel trans-acting factor by gel retardation assay and to be necessary for efficient enhancer activity. On the other hand, gel retardation assays using a nuclear extract from Drosophila SL2 cells suggested that non-Sp1 trans-acting factors could also participate in the enhancing activity of this element. Taken together, the results demonstrate that two GC box-like sequences and another trans-acting factor-binding sequence located between -970 and -941 bp act coordinately and are essential for efficient transcription of this low expressed human ChAT gene.

Li YP, Baskin F, Davis R, Hersh LB
Cholinergic neuron-specific expression of the human choline acetyltransferase gene is controlled by silencer elements.
J Neurochem. 1993; 61(2):748-51 [PubMed] Related Publications
Choline acetyltransferase (ChAT) is specifically expressed in cholinergic neurons. To identify control mechanisms regulating the cell-specific expression of the gene encoding ChAT, transient expression of the luciferase gene driven by human ChAT gene 5'flanking sequences was compared in cholinergic and noncholinergic cell lines. Analysis of the gene indicated the presence of two regulatory elements with selective silencing activity. These elements, located between nucleotides -2043 to -3347 and nucleotides -3347 to -6550, act cooperatively to repress promoter activity > 10-fold in a human adrenergic neuroblastoma cell line, SHSY5Y, and a human osteosarcoma cell line, 143 TK-, while exhibiting less than a two-fold effect in cholinergic cell lines. Deletion of either nucleotides -2043 to -3347 or nucleotides -3348 to -6550 reduced cell-specific repression by approximately half. Such differential repression appears to be responsible for the selective expression of the ChAT component of the cholinergic phenotype.

Bausero P, Schmitt M, Toussaint JL, et al.
Identification and analysis of the human choline acetyltransferase gene promoter.
Neuroreport. 1993; 4(3):287-90 [PubMed] Related Publications
Choline acetyltransferase (ChAT) is the key enzyme responsible for the synthesis of the neurotransmitter acetylcholine and is reduced in various central neurodegenerative diseases. From a previously selected 12.6 kb human choline acetyltransferase (hChAT) genomic clone, we have identified and characterized a promoter region of 895 bp. Sequence analysis revealed the presence of a TATA-like box, a CAAT box and several putative regulatory responsive elements. Three transcription initiation sites were determined by primer extension analysis. The Northern blot of poly(A)+ RNA, showed a single band of 2300 Nt in the human nucleus accumbens and facial nucleus. By using transient transfections into NE-1-115 and COS-1 cells of the 5' flanking region of the hChAT gene we identified a sequence of 66 bp upstream of the transcription start site which confers responsiveness to proto-oncogenes c-Fos/c-Jun. These data suggest that the hChAT gene may be a physiological target of c-Fos/c-Jun and therefore may play a role in neuronal responses to various stimuli.

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