Published online before print May 1, 2008, doi: 10.1161/CIRCRESAHA.107.167783
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© 2008 American Heart Association, Inc.
Clinical Research |
A Missense Mutation in the CHRM2 Gene Is Associated With Familial Dilated Cardiomyopathy
From the Heart Center (L.Z., H.Y., L.C., G.M., X.Y., L.W., J.L., X.L., S.W., Z.Z.), Department of Medicine, Capital Medical University, ChaoYang Hospital, Beijing; Fu Wai Hospital (A.H., L.L.), Chinese Academy of Sciences/Peking Union Medical College, Beijing; Department of Physiology (R.Z.), Shanxi Medical University, Taiyuan; and National Laboratory of Medical Molecular Biology (Y.S.), Institute of Basic Medical Sciences, Chinese Academy of Sciences/Peking Union Medical College, Beijing, China.
Correspondence to Lin Zhang, MD, PhD, Professor and Chairman, Department of Medicine Capital Medical University Chao-Yang Hospital 8# Gong-Ti South Road, Beijing 100020, China. E-mail linzhangpeking{at}yahoo.com.cn
 |
Abstract |
|---|
 Top Abstract IntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Circulating autoantibodies against the M2-muscarinic acetylcholine receptor (CHRM2) have been detected in patients with dilated cardiomyopathy (DCM). However, it has yet to be determined whether the pathogenesis of familial DCM may be linked to the genetic variability of the CHRM2 gene. The coding regions of the CHRM2 gene were examined by direct DNA sequencing. Plasma concentrations of autoantibodies against CHRM2 were determined by ELISA in 7 unrelated DCM families. Linkage analysis demonstrated cosegregation of the microsatellite markers, D7S509 and D7S495 that flank the CHRM2 gene, with the familial form of DCM. A novel missense mutation (C722G) replacing cysteine with tryptophane (Cys176Trp) was identified in the CHRM2 gene in all affected members but was absent in unaffected members. Additionally, 139 sporadic DCM patients and 450 normal volunteers were screened for the same mutation, but none were identified. Among the 12 affected members with familial DCM, 5 patients had died suddenly and 7 experienced ventricular arrhythmia, atrioventricular conduction block, and heart failure. All mutation carriers were positive for autoantibodies against CHRM2. Survival analysis disclosed that prognosis in patients who were mutation carriers with familial DCM was poorer than that seen in patients who were noncarriers with sporadic DCM ((P<0.05). We have identified a novel missense mutation (C722G) in the CHRM2 gene associated with familial DCM. We also show that this variant correlates with the presence of autoantibodies against CHRM2. Patients with C722G mutation have more progressive disease, characterized by sudden death, arrhythmia, and heart failure.
Key Words: autoimmune • genetic • heart failure • sudden death
|
Introduction |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Muscarinic acetylcholine receptors (CHRM) belong to the G protein–coupled receptor family and contain 5 subtypes (M1 to M5). The M2 receptor (CHRM2) is primarily expressed in the heart (human and other mammalian species), and its activation results in negative chronotropic and inotropic effects by inhibiting adenylyl cyclase, decreasing intracellular cAMP,1,2 and reducing L-type Ca2+ current.3 It has been reported that the density of cardiac CHRM2 is significantly higher in patients with CHF as compared to normal controls.4
Autoimmune-mediated myocardial damage has been generally accepted to be the major mechanism causing dilated cardiomyopathy (DCM).5 Circulating autoantibodies against CHRM2 (anti-CHRM2) are present in 38% to 48% of patients with DCM.6 Previous studies from our group and others have demonstrated that anti-CHRM2 display "agonistic activity" against their target receptor and result in myocardial injury and cardiac dysfunction.7 Another study found that anti-CHRM2 alters the sinus node function, suggesting that this electrophysiological action may be responsible for arrhythmias in both patients with DCM and idiopathic atrial fibrillation.8
Moreover, we have previously demonstrated that anti-CHRM2–positive sera obtained from DCM patients have similar effects as those exerted by the CHRM2 agonist carbachol. Specifically, in cardiac myocytes isolated from guinea pigs, anti-CHRM2–positive sera decreases peak intensity and density of L-type Ca2+ and exerts significant negative inotropic effects. These effects are completely blocked by the CHRM2 antagonist, atropine.9 Collectively, these clinical and experimental evidence suggest that overproduction of anti-CHRM2 may play an important role in the development of DCM. However, the mechanisms responsible for this pathological autoantibody production remain unknown.
It has been reported that 20% to 40% of DCM cases are familial, with a predominance of autosomal-dominant inheritance pattern.10–18 A few novel loci have been mapped on the chromosome 7, including 7q22.3-31.119 and 7q12.1-7q21,20 and these loci have been correlated with familial DCM. Previous linkage studies have shown that the markers D7S471 and D7S501 cosegregate with the disease-containing mutation that causes DCM. Collectively, evidence to date indicates that genetic factors play an important role in the etiology of DCM. However, the mechanism by which genetic variations may result in cardiac damage remains to be determined.
Autoantibodies have been shown to correlate with genetic mutations,21 and the presence of autoantibodies and autoimmunity have been reported to correlate with specific variations in DCM.22–24 Indeed, currently available clinical results suggest that overproduction of autoimmune antibody against CHRM2 may be related to genetic variations on chromosome 7. However, there is a lack of direct evidence to support this notion.
The purpose of this study is to determine whether genetic variations may underlie the familial form of DCM. Because production of anti-CHRM2 has been shown to result in cardiac injury, and genetic variations on chromosome 7 have been linked to DCM, we hypothesized that variations in the encoding regions of the CHRM2 gene may provide a link between genetic variation, autoantibody production, and cardiac injury in patients with familial DCM.
|
Patients and Methods |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Clinical Evaluation and Study Cases
A diagnosis of DCM was made in accordance with the criteria established by the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Classification of Cardiomyopathy.25 The familial DCM patients and all sporadic DCM patients were evaluated by collecting a detailed clinical history, physical examination, 12-lead ECG, 24-hour ambulatory ECG, chest radiography, and transthoracic echocardiography (M-mode, 3D, and Doppler). The diagnostic criteria for DCM were defined as an ejection fraction <50% and/or left ventricular shortening fraction <28% by echocardiography analysis, regional fractional shortening on M-mode analysis, or both in the presence of a left ventricular internal diastolic diameter
2.7 cm/m2 of body surface area.26 The disease status of deceased individuals was based on a review of medical records. The study protocol was approved by the Ethics Committees of the Beijing Chao Yang Hospital and conformed to the Declaration of Helsinki. All participants gave written informed consent. All patients in this study were of Han (Chinese) descent from the Northern part of China. Secondary causes of DCM, including coronary heart disease, myocarditis, hypertension, and valvular heart disease, were carefully excluded from the present study. Diagnostic criteria for familial DCM is as described above.27
Mutation Detection
Blood samples were collected into tubes containing EDTA to allow for DNA extraction. DNA was extracted subsequently according to the standard procedure. Using the sequence of CHRM2 from GenBank (accession no. M16404), 6 sets of primers were designed to amplify the entire coding region of the gene according to its published genomic DNA sequence from nucleotide 195 to 1595 (see the expanded Materials and Methods section, available at http://circres.ahajournals.org). The PCR products were sequenced directly in an ABI3700 DNA sequencer (Applied Biosystems). The sequence alignment was performed by BLAST analysis through the National Center for Biotechnology Information (http://www.ncbi.nlm.nih. gov/blast). These sequences were also examined manually.
ELISA-Based Screening for Autoantibodies Against CHRM2
Autoantibody against M2-muscarinic acetylcholine receptor (anti-CHRM2) has been detected in the sera of patients with dilated cardiomyopathy and has received increased attention in recent years. CHRM2 contains 3 extracellular loops and 3 cytoplasmic loops. The second extracellular (E2) loop (residues 168 to 192, V-R-T-V-E-D-G-E-C-Y-I-Q-F-F-S-N-A-A-V-T-F-G-T-A-I-) acts as an autoimmune target. Synthetic peptides corresponding to the E2 loop were used as antigens in an ELISA-based screening for anti-CHRM2 in the sera of all subjects in the study. The shadow above demonstrates the recognized region of autoantibody.28 The ELISA immunoassay was performed according to the method described by Fu et al.6
Linkage Analysis
Two-point linkage analysis was performed using the MLINK program of the linkage software package version 5.10 to explore whether familial DCM correlated with the variation of CHRM2. We modeled the disease as an AD inheritance with 100% penetrance, with a uniform distribution for the allele frequencies. Six short-tandem-repeat polymorphisms flanking the CHRM2 gene were used, as well as fluorescence-labeled forward primers (Table I in the online data supplement, linkage in family DCM to markers at 7q31-35 of CHRM2 gene). The PCR products were separated in an ABI3700 DNA sequencer (Applied Biosystems). Data collection and genotyping were conducted by ABI Prism GeneMapper version 3.0 software.
Data Analysis
The influence of CHRM2 genotype on the occurrence of DCM was determined by analyzing contingency tables using Fisher’s exact test, with the results reported as odds ratios. Categorical data were presented as mean values±SEM or percentages. A positive score of anti-CHRM2 was defined as a ratio (sample OD–blank OD/negative contrast OD–blank OD) of 2.1. Survival analysis was estimated by the Kaplan–Meier method over a 3-year period. In all cases, a value of P<0.05 was considered as statistically significant. Analyses were performed with the GraphPad 4.0 software package (San Diego, Calif).
|
Results |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Clinical Data and Characteristics
We screened the CHRM2 gene for DNA sequence variation in 7 unrelated DCM families, 139 unrelated patients with sporadic DCM, and 450 normal individuals by direct sequencing analysis. Twelve patients were identified who had the same missense mutation in the CHRM2 gene, and, interestingly, they all belong to the same DCM family. We found that different phenotypes showed different clinical characteristics. Specifically, the age of DCM onset was considerably younger in patients with the C722G allele as compared with sporadic DCM. In contrast, patients with sporadic DCM had worse left ventricular end diastolic diameter, systolic diameter, ejection fraction, and heart function when compared to mutation carriers in the DCM family (Table 1).
|
Mutation Screening
A missense mutation, C722G (Figure 1), which results in conversion of amino acid 176 (GenBank accession no. NM_001006630) from cysteine to tryptophane (Cys176Trp), was identified in 12 affected members in a DCM family. No mutation was identified in the CHRM2 gene in the unaffected family members, the other 6 unrelated DCM families, the 139 sporadic DCM cases, or 450 healthy controls. These results demonstrate that the C722G substitution in the CHRM2 gene is a mutation associated with DCM, rather than rare polymorphism. In contrast, a mutation screen performed on several other previously characterized cardiovascular genes, such as the β1- and β2-adrenoceptors genes, the angiotensin II type 1 receptor gene and the angiotensin-converting enzyme gene, was negative.
|
G transition at nucleotide 722 of CHRM2 gene; the transition results in the Cys176Trp mutation.These data indicate that the CHRM2 gene influences the onset age of DCM in patients who are C722G carriers of familial DCM. The patients with sporadic DCM had lower level of cardiac function than patients who were C722G carriers. However, the phenotype present in the family is notable for an autosomal dominant pattern of inheritance of the mixed DCM, which is notable for the presence of sudden death and severe arrhythmia (Table 2). These observations suggest that the C722G genotype may be an important prognostic indicator in the clinical evaluation of patients with familial DCM.
|
Pedigree and Linkage Analysis
The DCM family consists of 49 members spanning 6 generations (Figure 2). Of these individuals, 25 were available for blood collection and clinical evaluation. Review of the family history and medical records revealed that 5 affected individuals (III:1, III:3, III:5, IV:17 and V: 10) had died suddenly or had diagnosed heart failure before the cohort could be identified as being predisposed to DCM. Twelve members carried the C722G mutation (Table 2), in which 5 members (IV:1, IV:11, IV:13, V:1, and V:12) died suddenly and developed CHF, whereas IV:3, IV:7, V:2, V:7, V:8, V:16, and VI:1 experienced either arrhythmia or heart failure (supplemental Figures I through III, representative ECG findings and cardiac arrhythmias). All other members of the family were free of any symptoms associated with arrhythmia and heart failure.
|
, affected males; 
, affected females; 
, normal males; 
, normal females; slashed symbols, deceased individuals; arrow, proband; +, presence of mutation; –, absence of mutation;, 
individuals who died suddenly or heart failure; ?, unknown clinical status and without DNA samples.
Linkage analysis was performed to investigate the correlation of CHRM2 and familial DCM. Logarithm of the odds score of 4.62 and 4.43 (
=0) was achieved at the D7S509 and D7S495 loci, respectively, that flank the CHRM2 gene and cosegregate with familial DCM. Taken together, these data provide strong evidence of linkage to the CHRM2 gene with the familial form of DCM.
Effect of CHRM2 Genotype on Anti-CHRM2
Interestingly, all of the C722G mutation carriers were positive for anti-CHRM2, a significantly higher rate than that seen in sporadic DCM (100% versus 45.4%, P<0.01). The rate of occurrence of this mutation was also significantly higher than what has been reported in the normal individuals (100% versus 9.1%, P<0.001). Likewise, the geometric mean titers were significantly higher than in nonmutation carriers with sporadic DCM, as well as the normal individuals (Figure 3). These results demonstrate that the mutation of CHRM2 gene is highly correlated to the presence of anti-CHRM2. We speculate that the immunoreactions induced by this missense mutation are an important causative factor but that there may be additional factors involved yet to be determined.
|
Survival Analysis
Kaplan–Meier survival analysis was performed using 3-year survival data (Figure 4). There were 5 deaths in 12 subjects with C722G mutation from the DCM family, in which 4 patients died suddenly and 1 patient succumbed to rapid atrial fibrillation and heart failure. Ambulatory ECG monitoring showed that the mutation carriers experienced severe arrhythmia, ventricular tachycardia, rapid atrial fibrillation, or first or second degree atrioventricular conduction block (Table 2). These study results suggest that the mutation carriers have a significantly poorer prognosis than noncarriers (P<0.001, 5 deaths in 12 cases versus 27 deaths in 139 cases).
|
2=4.863, P=0.027, 95% confidence interval of ratio 1.197 to 21.21).
Analyses of Other DCM Cases
There were 10 patients with familial DCM from whom we obtained DNA samples. These patients were in the other 6 unrelated DCM families. We reviewed their medical records and observed that these patients have progressive disease characterized by progressive cardiac enlargement and end-stage heart failure, which resulted in 1 patient undergoing heart transplantation. This patient is alive and well at the time of publication. Only ECG records could be obtained, which showed arrhythmia in patients with sporadic DCM. However, because Holter data were unavailable, it is not sufficient to report these results.
|
Discussion |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Evidence and Prognosis for a Disease-Associated Mutation
In the present study, we identified and reported a novel Cys176Trp conversion at amino acid site 176 of the CHRM2 gene in the affected members of a 6-generation DCM family. This family has progressive DCM manifested by sudden death, arrhythmias, and heart failure. The altered DNA sequence is considered a disease-associated mutation of familial DCM rather than a polymorphism for several reasons. Firstly, the C722G mutation is present in all affected family members but is absent in the unaffected family members, the 139 unrelated patients with sporadic DCM, or the 450 normal volunteers. Secondly, the CHRM2 gene variant (C722G) is a DCM-associated mutation and the transition is shown to cosegregate with familial DCM, in which the mutation replaces a highly conserved amino acid. Thirdly, all of the C722G mutation carriers are positive for anti-CHRM2 and have the Cys176Trp substitution in the protein product. Fourthly, the age of onset of DCM in mutation carriers is significantly younger than in noncarriers. Lastly, it is of importance that the mortality in patients with the C722G mutation was significantly higher than the mortality rate observed in the noncarriers during the 3-year follow up. Because we cannot exclude the possibility that this DNA variant is in linkage disequilibrium with the DNA variant that is actually pathogenic, additional studies using transgenic animals are being designed to address the possible "causality" of the mutation.
The Cys176Trp Altering the Binding of Autoantibodies Against CHRM2
The CHRM2 gene is located at the 7q31-7q35. The transcribed mRNA product of the CHRM2 gene corresponds to nucleotides 195 to 1595 of the genomic sequence and codes for a 466 amino acid. Structural analysis indicates that CHRM2 contains 7 transmembrane domains, 3 extracellular loops (E1, E2 and E3), 3 intracellular loops (C1, C2 and C3), an extracellular amino terminus, and an intracellular carboxyl terminus.29–31
The second extracellular loop (E2) and the sequence of human muscarinic receptor subtypes (HM1 to HM4) share less homology (maximum 50%), but the E2 sequence of CHRM2 is conserved in various mammalian species, including Homo sapiens, Bos taurus, Mus musculus, Sus scrofa, Rattus norvegicus, and Pan troglodytes. Exposures to synthesized peptides based on the amino acid sequence of CHRM2 with the use of immune rabbits as antigens was observed to correlate with rise in the titer of autoantibodies against M2 receptors.32 It was predicted that the E2 sequence may serve as an antigen in an autoimmune reaction. The CHRM2 bears both an orthosteric and an allosteric binding site. Site-directed mutagenesis of the cysteine residue located in the E2 loop could lead to alternation of ligand binding. The missense mutation Cys176Trp identified in this study may alter the autoantibody binding to CHRM2,33 and studies are underway to confirm this.
Possible Pathogenesis of DCM in Mutation Carriers
The mutation in the E2 loop may function by altering the structure of either the orthosteric or allosteric binding site on cardiomyocytes. The substitution of cysteine destroyed the disulfide bond formation of the molecules, subsequently reducing the E2 loop flexibility and affecting the binding of autoantibodies against CHRM2 (anti-CHRM2).34 The autoantibodies, behaving like an agonist, could induce desensitization and/or downregulation of the receptors, leading to autonomic disturbances in DCM patients. Anti-CHRM2 can also behave as a positive allosteric modulator. We, therefore, presume that the mutation Cys176Trp alters allosteric binding sites such that agonists may not be able to bind to CHRM2 normally, therefore failing to protect the heart by boosting the parasympathetic system. However, the exact molecular mechanisms by which the C722G mutation contributes to familial DCM requires further investigation.
Possible Pathogenesis of Arrhythmia in Mutation Carriers
In this study, all of the C722G mutation carriers are positive for anti-CHRM2. Medei et al reported that the anti-CHRM2 have proarrhythmic effects.35 It was proved that electrophysiological effects of these autoantibodies can indicate altered activity of ion channels. Experimental evidence demonstrated that G protein–regulated inwardly rectifying K+ channels can operate as dynamic integrators of 
-adrenergic and cholinergic signals in atrial myocytes. The autoantibodies combine allosteric binding sites. These channels are then activated by direct interactions with β
subunits of the inhibitory G proteins and efficiently translate CHRM2 activation into membrane hyperpolarization.36 The CHRM2 activation shortens action potential duration and effective refractory period in myocardial cells, which may result in arrhythmia.37
Our previous study has shown that anti-CHRM2 decreases the stimulated L-type Ca2+ current and appears to have a negative inotropic effect in cardiac myocytes (supplemental Figure IV, the effects of anti-CHRM2 on L-type current is comparable to that of Carb). We therefore postulate that the alteration of CHRM2 gene may play an important role in the immune response associated with DCM, and may be related to slow arrhythmia or conduction block. However, the exact molecular mechanisms by which the C722G mutation contributes to arrhythmia in familial DCM remains to be further elucidated.
Recent studies have mapped inherited and dilated cardiomyopathy to different loci on chromosome 7. These subjects have similar phenotypic characteristics to that of familial DCM, and we have attributed to the CHRM2 gene, which resides on 7q31-7q35, including heart failure and sudden cardiac death occurring at relatively young ages. Thus, the present study suggests that the C722G mutation in the CHRM2 gene may be a novel disease mutation and may provide insights into novel pathophysiological mechanism of cardiac dilation and arrhythmia beyond the familial form of the disease.
Limitations
There is an important limitation with regard to the results of the anti-CHRM2. We were unable to completely explain why 46% patients with sporadic DCM were positive for anti-CHRM2. Therefore, these results have to be considered as a conjecture that the immunoreactions induced by a gene mutation may be 1 of several important causative factors. We intend to further explore the biological mechanism of the presence of anti-CHRM2 in sporadic DCM patients, including the possibility that a different mutation may be present in the gene and or a different splice variant of the gene may account for these other cases.
|
Conclusions |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
Our study demonstrates that the CHRM2 gene plays an important role in the alteration of cardiac structure and function and suggests that the C722G mutation substitution in the CHRM2 gene may be a pathogenic mutation and not a benign polymorphism. In addition, we have observed that the patients who carry the C722G mutation have progressive disease characterized by sudden death, severe arrhythmia, and heart failure. To our knowledge, this is the first report linking a mutation in the CHRM2 gene to familial DCM and correlating this mutation with immunologic mechanisms.
|
Acknowledgments |
|---|
We are grateful to the families, sporadic DCM patients, and control subjects for participation in the study. We also thank Drs Keith LePage, Xiuzhen Yan, Guodong Liang, Jue Ye, Zhiqing Zhao, Bai Xiao, Sanderson John, Xinliang Ma, and Hakon Hakonarson for advice and technical assistance.
Sources of Funding
This project was supported by grants and contracts from the China Science & Technology Committee, China (grant 2002BA711A07).
Disclosures
None.
|
Footnotes |
|---|
*These authors contributed equally to this work.
Original received February 5, 2007; resubmission received November 13, 2007; revised resubmission received April 10, 2008; accepted April 23, 2008.
|
References |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsDiscussionConclusionsReferences |
|---|
1. Brodde OE, Michel MC. Adrenergic and muscarinic receptors in the human heart. Pharmacol Rev. 1999; 51: 651–690.
2. Fenech AG, Ebejer MJ, Felice AE, Ellul-Micallef R, Hall IP. Mutation screening of the muscarinic M(2) and M(3) receptor genes in normal and asthmatic subjects. Br J Pharmacol. 2001; 133: 43–48.[CrossRef][Medline] [Order article via Infotrieve]
3. Nascimento JH, Salle L, Hoebeke J, Argibay J, Peineau N. cGMP-mediated inhibition of cardiac L-type Ca(2+) current by a monoclonal antibody against the M(2) ACh receptor 1. Am J Physiol Cell Physiol. 2001; 281: C1251–C1258.
4. Le GD, Cohen-Solal A, Delforge J, Delahaye N, Syrota A, Merlet P. Increased myocardial muscarinic receptor density in idiopathic dilated cardiomyopathy: an in vivo PET study. Circulation. 1997; 96: 3416–3422.
5. Caforio AL, Daliento L, Angelini A, Bottaro S, Vinci A, Dequal G, Tona F, Iliceto S, Thiene G, McKenna WJ. Autoimmune myocarditis and dilated cardiomyopathy: focus on cardiac autoantibodies. Lupus. 2005; 14: 652–655.
6. Fu LX, Magnusson Y, Bergh CH, Liljeqvist JA, Waagstein F, Hjalmarson A, Hoebeke J. Localization of a functional autoimmune epitope on the muscarinic acetylcholine receptor-2 in patients with idiopathic dilated cardiomyopathy. J Clin Invest. 1993; 91: 1964–1968.[Medline] [Order article via Infotrieve]
7. Fu ML, Hoebeke J, Matsui S, Matoba M, Magnusson Y, Hedner T, Herlitz H, Hjalmarson A. Autoantibodies against cardiac G-protein-coupled receptors define different populations with cardiomyopathies but not with hypertension. Clin Immunol Immunopathol. 1994; 72: 15–20.[CrossRef][Medline] [Order article via Infotrieve]
8. Baba A, Yoshikawa T, Fukuda Y, Sugiyama T, Shimada M, Akaishi M, Tsuchimoto K, Ogawa S, Fu M. Autoantibodies against M2-muscarinic acetylcholine receptors: new upstream targets in atrial fibrillation in patients with dilated cardiomyopathy 1. Eur Heart J. 2004; 25: 1108–1115.
9. Zhang L, Hu D, Shi X, Li J, Zeng W, Xu L, Cui L. Autoantibodies against the myocardium beta 1-adrenergic and M2-muscarinic receptors in patients with heart failure. Zhonghua Nei Ke Za Zhi. 2001; 40: 445–447.[Medline] [Order article via Infotrieve]
10. Olson TM, Illenberger S, Kishimoto NY, Huttelmaier S, Keating MT, Jockusch BM. Metavinculin mutations alter actin interaction in dilated cardiomyopathy. Circulation. 2002; 105: 431–437.
11. Olson TM, Kishimoto NY, Whitby FG, Michels VV. Mutations that alter the surface charge of alpha-tropomyosin are associated with dilated cardiomyopathy. J Mol Cell Cardiol. 2001; 33: 723–732.[CrossRef][Medline] [Order article via Infotrieve]
12. Gerull B, Gramlich M, Atherton J, McNabb M, Trombitas K, Sasse-Klaassen S, Seidman JG, Seidman C, Granzier H, Labeit S, Frenneaux M, Thierfelder L. Mutations of TTN, encoding the giant muscle filament titin, cause familial dilated cardiomyopathy. Nat Genet. 2002; 30: 201–204.[CrossRef][Medline] [Order article via Infotrieve]
13. Schonberger J, Levy H, Grunig E, Sangwatanaroj S, Fatkin D, MacRae C, Stacker H, Halpin C, Eavey R, Philbin EF, Katus H, Seidman JG, Seidman CE. Dilated cardiomyopathy and sensorineural hearing loss: a heritable syndrome that maps to 6q23–24. Circulation. 2000; 101: 1812–1818.
14. Schmitt JP, Kamisago M, Asahi M, Li GH, Ahmad F, Mende U, Kranias EG, MacLennan DH, Seidman JG, Seidman CE. Dilated cardiomyopathy and heart failure caused by a mutation in phospholamban. Science. 2003; 299: 1410–1413.
15. Kamisago M, Sharma SD, DePalma SR, Solomon S, Sharma P, McDonough B, Smoot L, Mullen MP, Woolf PK, Wigle ED, Seidman JG, Seidman CE. Mutations in sarcomere protein genes as a cause of dilated cardiomyopathy. N Engl J Med. 2000; 343: 1688–1696.
16. Murphy RT, Mogensen J, Shaw A, Kubo T, Hughes S, McKenna WJ. Novel mutation in cardiac troponin I in recessive idiopathic dilated cardiomyopathy. Lancet. 2004; 363: 371–372.[CrossRef][Medline] [Order article via Infotrieve]
17. Arimura T, Hayashi T, Terada H, Lee SY, Zhou Q, Takahashi M, Ueda K, Nouchi T, Hohda S, Shibutani M, Hirose M, Chen J, Park JE, Yasunami M, Hayashi H, Kimura A. A Cypher/ZASP mutation associated with dilated cardiomyopathy alters the binding affinity to protein kinase C. J Biol Chem. 2004; 279: 6746–6752.
18. Bienengraeber M, Olson TM, Selivanov VA, Kathmann EC, O'Cochlain F, Gao F, Karger AB, Ballew JD, Hodgson DM, Zingman LV, Pang YP, Alekseev AE, Terzic A. ABCC9 mutations identified in human dilated cardiomyopathy disrupt catalytic KATP channel gating. Nat Genet. 2004; 36: 382–387.[CrossRef][Medline] [Order article via Infotrieve]
19. Schonberger J, Kuhler L, Martins E, Lindner TH, Silva-Cardoso J, Zimmer M. A novel locus for autosomal-dominant dilated cardiomyopathy maps to chromosome 7q22.3-31.1. Hum Genet. 2005; 118: 451–457.[CrossRef][Medline] [Order article via Infotrieve]
20. Song L, DePalma SR, Kharlap M, Zenovich AG, Cirino A, Mitchell R, McDonough B, Maron BJ, Seidman CE, Seidman JG, Ho CY. Novel locus for an inherited cardiomyopathy maps to chromosome 7. Circulation. 2006; 113: 2186–2192.
21. Angelopoulou K, Yu H, Bharaj B, Giai M, Diamandis EP. p53 gene mutation, tumor p53 protein overexpression, and serum p53 autoantibody generation in patients with breast cancer. Clin Biochem. 2000; 33: 53–62.[CrossRef][Medline] [Order article via Infotrieve]
22. Limas C, Limas CJ, Boudoulas H, Graber H, Bair R, Sparks L, Wooley CF. T-cell receptor gene polymorphisms in familial cardiomyopathy: correlation with anti-beta-receptor autoantibodies. Am Heart J. 1992; 124: 1258–1263.[CrossRef][Medline] [Order article via Infotrieve]
23. Limas C, Limas CJ, Boudoulas H, Bair R, Graber H, Sparks L, Wooley CF. Anti-beta-receptor antibodies in familial cardiomyopathy: correlation with HLA-DR and HLA-DQ gene polymorphisms. Am Heart J. 1994; 127: 382–386.[CrossRef][Medline] [Order article via Infotrieve]
24. Thiene G, Corrado D, Basso C. Cardiomyopathies: is it time for a molecular classification? Eur Heart J. 2004; 25: 1772–1775.
25. Richardson P, McKenna W, Bristow M, Maisch B, Mautner B, O'Connell J, Olsen E, Thiene G, Goodwin J, Gyarfas I, Martin I, Nordet P. Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Definition and Classification of cardiomyopathies. Circulation. 1996; 93: 841–842.
26. Li D, Czernuszewicz GZ, Gonzalez O, Tapscott T, Karibe A, Durand JB, Brugada R, Hill R, Gregoritch JM, Anderson JL, Quinones M, Bachinski LL, Roberts R. Novel cardiac troponin T mutation as a cause of familial dilated cardiomyopathy. Circulation. 2001; 104: 2188–2193.
27. Mestroni L, Maisch B, McKenna WJ, Schwartz K, Charron P, Rocco C, Tesson F, Richter A, Wilke A, Komajda M. Guidelines for the study of familial dilated cardiomyopathies. Collaborative Research Group of the European Human and Capital Mobility Project on Familial Dilated Cardiomyopathy. Eur Heart J. 1999; 20: 93–102.
28. May LT, Avlani VA, Langmead CJ, Herdon HJ, Wood MD, Sexton PM, Christopoulos A. Structure-function studies of allosteric agonism at M2 muscarinic acetylcholine receptors. Mol Pharmacol. 2007; 72: 463–476.
29. Heitz F, Holzwarth JA, Gies JP, Pruss RM, Trumpp-Kallmeyer S, Hibert MF, Guenet C. Site-directed mutagenesis of the putative human muscarinic M2 receptor binding site. Eur J Pharmacol. 1999; 380: 183–195.[CrossRef][Medline] [Order article via Infotrieve]
30. Shi L, Javitch JA. The binding site of aminergic G protein-coupled receptors: the transmembrane segments and second extracellular loop. Annu Rev Pharmacol Toxicol. 2002; 42: 437–467.[CrossRef][Medline] [Order article via Infotrieve]
31. Fu ML. Anti-M2 muscarinic receptor autoantibodies and idiopathic dilated cardiomyopathy. Int J Cardiol. 1996; 54: 127–135.[CrossRef][Medline] [Order article via Infotrieve]
32. Fu ML, Schulze W, Wallukat G, Hjalmarson A, Hoebeke J. Functional epitope analysis of the second extracellular loop of the human heart muscarinic acetylcholine receptor. J Mol Cell Cardiol. 1995; 27: 427–436.[Medline] [Order article via Infotrieve]
33. Huang XP, Ellis J. Mutational disruption of a conserved disulfide bond in muscarinic acetylcholine receptors attenuates positive homotropic cooperativity between multiple allosteric sites and has subtype-dependent effects on the affinities of muscarinic allosteric ligands. Mol Pharmacol. 2007; 71: 759–768.
34. Avlani VA, Gregory KJ, Morton CJ, Parker MW, Sexton PM, Christopoulos A. Critical role for the second extracellular loop in the binding of both orthosteric and allosteric G protein-coupled receptor ligands. J Biol Chem. 2007; 282: 25677–25686.
35. Medei E, Pedrosa RC, Benchimol Barbosa PR, Costa PC, Hernández CC, Chaves EA, Linhares V, Masuda MO, Nascimento JH, Campos de Carvalho AC. Human antibodies with muscarinic activity modulate ventricular repolarization: basis for electrical disturbance. Int J Cardiol. 2007; 115: 373–380.[CrossRef][Medline] [Order article via Infotrieve]
36. Nikolov EN, Ivanova-Nikolova TT. Coordination of membrane excitability through a GIRK1 signaling complex in the atria. J Biol Chem. 2004; 279: 23630–23636.
37. Dobrev D, Graf E, Wettwer E, Himmel HM, Hala O, Doerfel C, Christ T, Schuler S, Ravens U. Molecular basis of downregulation of G-protein-coupled inward rectifying K(+) current (I(K,ACh) in chronic human atrial fibrillation: decrease in GIRK4 mRNA correlates with reduced I(K,ACh) and muscarinic receptor-mediated shortening of action potentials. Circulation. 2001; 104: 2551–2557.
This article has been cited by other articles:
 |
|
 |
|
  D. Rosskopf and M. C. Michel Pharmacogenomics of G Protein-Coupled Receptor Ligands in Cardiovascular Medicine Pharmacol. Rev., December 1, 2008; 60(4): 513 - 535. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||