TCAP Gene Research Articles

AAV-based TCAP delivery rescues mitochondria dislocation in limb-girdle muscular dystrophy R7.

Limb-girdle muscular dystrophy R7 is a rare genetic disease caused by homozygous or compound heterozygous variants in the titin-cap (TCAP) gene that results in the absence of the protein telethonin. The primary pathological features of limb-girdle muscular dystrophy R7 are fiber size variation, nuclear centralization, and abnormal mitochondrial distribution. The mechanisms underlying this disease are unclear, and there is currently no specific treatment for limb-girdle muscular dystrophy R7. This study established a Tcap-deficient mouse model to explore the disease mechanism of mitochondria dislocation and potential therapeutic strategies. We use methods such as proteomics, immunofluorescence, histopathological staining, and western blotting to explore the mechanism of mitochondrial dislocation. Moreover, in the quest for a prospective therapeutic intervention for this disorder, the adeno-associated virus serotype 2/9 was employed to deliver the Tcap gene into the muscles of these mice, facilitating preclinical experimentation. After 2 months and 7 months, the muscular phenotype was evaluated and selected mice were humanely euthanized for subsequent molecular and histological analysis. The phenotype of Tcap-/- mice mimicked that observed in individuals diagnosed with limb-girdle muscular dystrophy R7. This study elucidated the mechanism of mitochondrial dislocation in limb-girdle muscular dystrophy R7. Through our in vitro experiments, we discovered that telethonin aids in preserving the integrity of desmin by preventing truncation at the N-terminus. Additionally, telethonin combined with desmin and colocalized at the Z-disc. Research has shown that the Tcap gene plays a crucial role in controlling the desmin cytoskeleton organization. The absence of telethonin leads to a collapsed desmin cytoskeleton. This causes disorganization of the mitochondrial network, leading to mitochondrial dysfunction. In addition, the study investigated the efficacy of adeno-associated virus (AAV)-mediated Tcap replacement in Tcap-/- mice. By intramuscular delivery of AAV, we observed dramatic improvements in muscle phenotype, muscle pathology, CK levels, muscle magnetic resonance imaging, mitochondrial network organization, and mitochondrial function. The results of this study demonstrated that telethonin deficiency led to desmin cytoskeleton collapse that caused mitochondrial dislocation. AAV-mediated replacement therapy could be a promising safe and efficient treatment option for limb-girdle muscular dystrophy R7. The study highlights the potential of AAV-mediated replacement therapy for specific types of limb-girdle muscular dystrophy.

Tcap deficiency impedes striated muscle function and heart regeneration with elevated ROS and autophagy

Telethonin/titin-cap (TCAP) encodes a Z-disc protein that plays important roles in sarcomere/T-tubule interactions, stretch-sensing and signaling. Mutations in TCAP are associated with muscular dystrophy and cardiomyopathy; however, the complete etiology and its roles in myocardial infarction and regeneration are not fully understood. Here, we generated tcap gene knockout zebrafish with CRISPR/Cas9 technology and observed muscular dystrophy-like phenotypes and abnormal mitochondria in skeletal muscles. The stretch-sensing ability was inhibited in tcap‐/‐ mutants. Moreover, Tcap deficiency led to alterations in cardiac morphology and function as well as increases in reactive oxygen species (ROS) and mitophagy. In addition, the cardiac regeneration and cardiomyocyte proliferation ability of tcap‐/‐ mutants were impaired, but these impairments could be rescued by supplementation with ROS scavengers or autophagy inhibitors. Overall, our study demonstrates the essential roles of Tcap in striated muscle function and heart regeneration. Additionally, elevations in ROS and autophagy may account for the phenotypes resulting from Tcap deficiency and could serve as novel therapeutic targets for muscular dystrophy and cardiomyopathy.

Unveiling polymorphism and protein structure prediction insights in diacylglycerol O-acyltransferase 1 and telethonin genes of Egyptian buffalo

BackgroundThe Egyptian buffalo has a sizable impact on Egypt's agricultural sector and food supply. It is regarded as the main dairy animal and an important source of red meat. This study aimed to detect the polymorphisms of the DGAT1 and TCAP genes and assess the potential impact of the discovered nsSNPs on the stability of the tertiary structure polypeptides of selected genes in Egyptian buffalo.MethodsAllele identification was made by the restriction fragment length polymorphism (RFLP), and the single nucleotide polymorphisms (SNPs) were recognized by sequencing the purified PCR products. Protein translation indicated the synonymous and non-synonymous SNPs, and the peptides' 3D tertiary structure of selected genes, as well as the effect of amino acid substitution on the protein structure, was performed using bioinformatics tools.ResultsAnalysis of the data revealed that an nsSNP was detected in a tested region of the DGAT1 gene and caused an amino acid substitution in a polypeptide that was predicted to be neutral and located in the coiled part of the protein. The analysis of the TCAP gene showed four nsSNPs that caused four substitutions located in the α-helix region. Protein prediction analysis showed that the amino acid substitutions in DGAT1 and TCAP were non-conserved with low sensitivity to variation. The non-conservative amino acid substitutions result in amino acids with new properties different from the original amino acid that change the protein's structure and function.ConclusionWe can infer that the DGAT1 and TCAP genes' SNPs may affect meat-related traits and may improve meat quality.

Single-centre experience with autosomal recessive limb-girdle muscular dystrophy: case series and literature review.

Limb-girdle muscular dystrophy (LGMD) is a group of myopathies that lead to progressive muscle weakness, predominantly involving the shoulder and pelvic girdles; it has a heterogeneous genetic etiology, with variation in the prevalence of subtypes according to the ethnic backgrounds and geographic origins of the populations. The aim of the present study was to analyze a series of patients with autosomal recessive LGMD (LGMD-R) to contribute to a better characterization of the disease and to find the relative proportion of the different subtypes in a Southern Brazil cohort. The sample population consisted of 36 patients with LGMD-R. A 9-gene targeted next-generation sequencing panel revealed variants in 23 patients with LGMD (64%), and it identified calpainopathy (LGMD-R1) in 26%, dysferlinopathy (LGMD-R2) in 26%, sarcoglycanopathies (LGMD-R3-R5) in 13%, telethoninopathy (LGMD-R7) in 18%, dystroglicanopathy (LGMD-R9) in 13%, and anoctaminopathy (LGMD-R12) in 4% of the patients. In these 23 patients with LGMD, there were 27 different disease-related variants in the ANO5, CAPN3, DYSF, FKRP, SGCA, SGCB, SGCG, and TCAP genes. There were different causal variants in different exons of these genes, except for the TCAP gene, for which all patients carried the p.Gln53* variant, and the FKRP gene, which showed recurrence of the p.Leu276Ile variant. We analyzed the phenotypic, genotypic and muscle immunohistochemical features of this Southern Brazilian cohort.

TCAP gene is not a common cause of cardiomyopathy in Iranian patients

BackgroundHypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are the most frequent cardiomyopathies that cause acute heart failure and sudden cardiac death. Previous genetic reports have shown that pathogenic variants of genes encoding Z-disc components such as telethonin protein (TCAP) are the primary cause of DCM and HCM.MethodsThis study was the first investigation on the TCAP gene among the Iranian cardiomyopathies population wherein the TCAP gene was analyzed in 40 unrelated patients (17 females and 23 males) who were clinically diagnosed with HCM and DCM. In addition, we conducted a thorough review of all published articles and the databases that were the first to report novel pathogenic or likely pathogenic variants the in TCAP gene.ResultsIn the cohort of this study, we identified only one intronic variant c.111-42G > A in one of the HCM patients that were predicted as polymorphism by in-silico analysis. Moreover, a total of 44 variants were reported for the TCAP gene in the literature where a majority of mutations were found to be missense. Pathogenic mutations in TCAP may cause diseases including limb-girdle muscular dystrophy 2G (LGMD-2G), DCM, HCM, intestinal pseudo-obstruction, and telethonin deficiency. However, a large number of affected patients were clinically diagnosed with limb-girdle 2G compared to other presenting phenotypes.DiscussionThese findings suggest that the TCAP gene pathogenic mutations might not be a common cause of cardiomyopathies among Iranian patients. These gene disease-causing mutations may cause various manifestations, but it has a high prevalence among LGMD-2G, HCM, and DCM patients.

Unique Clinical, Radiological and Histopathological Characteristics of a Southeast Asian Cohort of Patients with Limb-Girdle Muscular Dystrophy 2G/LGMD-R7-Telethonin-Related.

We describe a cohort of five patients with limb-girdle muscular dystrophy (LGMD) 2G/LGMD-R7 in a South-east Asian cohort. LGMD2G/LGMD-R7-telethonin-related is caused by mutations in the TCAP gene that encodes for telethonin. We identified consecutive patients with LGMD2G/LGMD-R7-telethonin-related, diagnosed at the National Neuroscience Institute (NNI) and National University Hospital (NUH) between January 2000 and June 2021. At onset, three patients presented with proximal lower limb weakness, one patient presented with Achilles tendon contractures, and one patient presented with delayed gross motor milestones. At last follow up, three patients had a limb girdle pattern of muscle weakness and two had a facioscapular humeral pattern of weakness. Whole body muscle MRI performed for one patient with a facioscapular-humeral pattern of weakness showed a pattern of muscle atrophy similar to facioscapular-humeral dystrophy. One patient had histological features consistent with myofibrillar myopathy; electron microscopy confirmed the disruption of myofibrillar architecture. One patients also had reduced staining to telethonin antibody on immunohistochemistry. We report the unique clinical and histological features of a Southeast Asian cohort of five patients with LGMD2G/LGMD-R7-telethonin-related muscular dystrophy and further expand its clinical and histopathological spectrum.

P.172 AAV-mediated strategy for TCAP gene correction as a new treatment for LGMDR7/LGMD2G dystrophy

P.172 AAV-mediated strategy for TCAP gene correction as a new treatment for LGMDR7/LGMD2G dystrophy

Differential gene expression profile by RNA sequencing study of elderly osteoporotic hip fracture patients with sarcopenia.

BackgroundThe purpose of this study was to report the RNA sequencing profile according to the presence or absence of sarcopenia in elderly patients with osteoporotic hip fracture. Therefore, an important genetic factor candidate for sarcopenia causing hip fracture in elderly with osteoporosis has been identified.MethodsThe patient group involved subjects over 65 years who had undergone hip fracture surgery. Among 323 hip fracture (HF) patients identified from May 2017 to December 2019, 162 HF patients (90 non-sarcopenia and 72 sarcopenia groups), excluding subjects with high energy trauma and non-osteoporosis, were finally included in the analysis. For RNA sequencing, each patient with hand grip strength (HGS) values in the top 10% were enrolled in the control group and with the bottom 10% in the patient group. After excluding patients with poor tissue quality, 6 patients and 5 patients were selected for sarcopenia and non-sarcopenia groups, respectively. For qPCR validation, each patient with HGS values in the top 20% and bottom 20% was enrolled in the control and patient groups, respectively. After excluding patients with poor tissue quality, 12 patients and 12 patients were enrolled in the sarcopenia and non-sarcopenia groups, respectively. Sarcopenia was defined according to the Asia Working Group for Sarcopenia (AWGS) criteria for low muscle strength (hand grip strength below 18 ​kg in women and 28 ​kg in men) and low muscle mass (SMI below 5.4 ​kg/m2 in women and 7.0 ​kg/m2 in men). The libraries were prepared for 100 bp paired-end sequencing using TruSeq Stranded mRNA Sample Preparation Kit (Illumina, CA, USA). The gene expression counts were supplied to Deseq2 to extract possible gene sets as differentially expressed genes (DEG) that discriminate between sarcopenia and non-sarcopenia groups that were carefully assigned by clinical observation. For the classification of the candidate genes from DEG analysis, we used the public databases; gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Quantitative real-time PCR was performed for validation.ResultsSamples collected were subjected to RNAseq using the Illumina platform. A total of 11 samples from both sarcopenia and non-sarcopenia groups were sequenced. Fifteen genes (RUNX 1, NGFR, CH3L1, BCL3, PLA2G2A, MYBPH, TEP1, SEMA6B, CSPG4, ACSL5, SLC25A3, NDUFB5, CYC1, ACAT1, and TCAP) were identified as differentially expressed genes (DEG) in both the groups.In the qPCR results, the expression levels of SLC25A3 and TCAP gene in the OS group were significantly lower than in the non-OS groups whereas an increase in RUNX1 mRNA level was observed in the OS samples (p ​< ​0.05).ConclusionsIn summary, this study detected gene expression difference according to the presence or absence of sarcopenia in elderly osteoporosis female patients with hip fracture. We have also identified 15 important genes (RUNX 1, NGFR, CH3L1, BCL3, PLA2G2A, MYBPH, TEP1, SEMA6B, CSPG4, ACSL5, SLC25A3, NDUFB5, CYC1, ACAT1, TCAP), a few GO categories and biological pathways that may be associated with the osteosarcopenia. Our study may provide effective means for the prevention, diagnosis and treatment sarcopenia in elderly osteoporosis female patients.The Translational potential of this articleThese findings provide a novel insight into the effects of aging on the response in women with postmenopausal osteoporosis. Further studies are underway to identify the specific signalling pathways involved. These results reveal potential therapeutic targets that could aid the regenerative capacity of aging skeletal muscle.

Investigation of Mutations in Exon 12 Of β-MYH7, 16 Of MYBPC3 and 2 Of TCAP Gene in Dogs with Dilated Cardiomyopathy using PCR-SSCP Technique

Background: Dilated cardiomyopathy is the important myocardial disease and one of the most common cause of death in the medium to large size dog breeds worldwide. The disease is characterized by dilatation of cardiac chambers and thinning of walls leads to systolic failure. Mutations in some sarcomere genes leads to cardiomyopathy in humans. Sarcomere is an important multifunctional protein network involved in the signal reception and transduction. Mutations in β-MYH7, MYBPC3 and TCAP genes produce alterations in the morphology of heart (hypertrophy or dilatation). Methods: In this study twenty apparently healthy and twenty five dogs with dilated cardiomyopathy (DCM) were selected from patients reported or referred to University Veterinary Hospital and Teaching Veterinary Clinical Complex, Mannuthy (2015-2017) based on the clinical examination, radiographic, electrocardiographic, haematobiochemical and echocardiographic studies cardiac disorders (Dilated cardiomyopathy and hypertrophic cardiomyopathy) were confirmed. Result: In the present study we investigated genetic alterations of exon 12 of β-MYH7, 16 of MYBPC3 and 2 of TCAP gene in dogs by polymerase chain reaction -single stranded confirmation of polymorphism (PCR-SSCP). Polymerase chain reactions were analysed using acrylamide gel and samples with different pattern of bands were sequenced. Polymerase chain reaction-SSCP showed different migration of band pattern in the intron 1 of TCAP gene in one sample.

Identification of a novel titin-cap/telethonin mutation in a Portuguese family with hypertrophic cardiomyopathy

Introduction and objectivesHypertrophic cardiomyopathy (HCM) is a genetically and phenotypically heterogeneous disease; there is still a large proportion of patients with no identified disease-causing mutation. Although the majority of mutations are found in the MYH7 and MYBPC3 genes, mutations in Z-disk-associated proteins have also been linked to HCM. MethodsWe assessed a small family with HCM based on family history, physical examination, 12-lead ECG, echocardiogram and magnetic resonance imaging. After exclusion of mutations in eleven HCM disease genes, we performed direct sequencing of the TCAP gene encoding the Z-disk protein titin-cap (also known as telethonin). ResultsWe present a novel TCAP mutation in a small family affected by HCM. The identified p.C57W mutation showed a very low population frequency, as well as high conservation across species. All of the bioinformatic prediction tools used considered this mutation to be damaging/deleterious. Family members were screened for this new mutation and a co-segregation pattern was detected. Both affected members of this family presented with late-onset HCM, moderate asymmetric left ventricular hypertrophy, atrial fibrillation and heart failure with preserved ejection fraction and low risk of sudden cardiac death. ConclusionsWe present evidence supporting the classification of the TCAP p.C57W mutation, encoding the Z-disk protein titin-cap/telethonin as a new likely pathogenic variant of hypertrophic cardiomyopathy, with a specific phenotype in the family under analysis.

The Blood and Muscle Expression Pattern of the Equine TCAP Gene during the Race Track Training of Arabian Horses.

Simple SummaryThe highly selective breeding of horses results in a variety of fiber type compositions among the breeds. Moreover, fiber type composition is known to differ within and between muscles. Telethonin (TCAP) plays a significant role in myofibril assembly, muscle development, and functional regulation. Analysis performed by qPCR of the gluteus medius muscle and the whole blood of Arabian horses during the training schedule showed that the expression pattern of the TCAP gene differs between skeletal muscles and whole blood. The results of these studies are a base for further research focused on the identification of processes related to adaptation of exertion in horses.Horse musculature has been shaped through evolution by environmental and human factors, which has resulted in several extraordinary adaptations to physical effort. Skeletal muscle plasticity results from the response to mechanical stimulation causing hypertrophy, where sarcomeres increase the muscle’s cross-sectional area under the influence of contractile forces. The aim of the present study was the evaluation of transcript abundance of the telethonin (TCAP) gene, which is a part of the sarcomere macromolecular mechanosensory complex in the gluteus medius muscle, and the whole blood of Arabian horses during flat race training. The analysis, performed by quantitative PCR, showed an increase of TCAP transcripts in skeletal muscle. However, in whole blood, the transcript abundance decreased after the first stage of training and further increased after the second phase. The obtained results indicate a lack of similarity of TCAP gene expression in both tissues.

Limb girdle muscular dystrophy 2G in a religious minority of Bulgarian Muslims homozygous for the c.75G>A, p.Trp25X mutation

Mutations in TCAP gene cause autosomal recessive limb-girdle muscular dystrophy type 2G (LGMD2G), congenital muscular dystrophy and autosomal dominant dilated and hypertrophic cardiomyopathy. We studied 18 affected individuals from 12 pedigrees, belonging to a Bulgarian Muslim minority from the South-West of Bulgaria, homozygous for the c.75G>A, p.Trp25X mutation in TCAP gene. The heterozygous carrier rate of p.Trp25X among 100 newborns in this region was found to be 2%. The clinical features in the Bulgarian TCAP group include disease onset in the first to the third decade of life, proximal muscle weakness in the lower limbs, followed or accompanied by difficulties in ankle dorsiflexion and involvement of the proximal muscles of the upper limbs 5–9 years after the disease onset. Asymmetry between left and right was present in more than 20% of the affected. Respiratory and cardiac functions were not affected. On the MRI the muscles of the posterior pelvic area, thigh and anterior leg were predominantly affected, while sartorius, gracilis and biceps femoris muscles remained relatively spared.In conclusion, LGMD2G appears to be a common form among Bulgarian Muslims. Homozygosity for c.75G>A, p.Trp25X is associated with a homogeneous clinical presentation, but the clinical course and severity of the disease show inter- and intra-familial variation.

A new case of limb girdle muscular dystrophy 2G in a Greek patient, founder effect and review of the literature

Limb girdle muscular dystrophy (LGMD) type 2G is a rare form of muscle disease, described only in a few patients worldwide, caused by mutations in TCAP gene, encoding the protein telethonin. It is characterised by proximal limb muscle weakness associated with distal involvement of lower limbs, starting in the first or second decade of life.We describe the case of a 37-year-old woman of Greek origin, affected by disto-proximal lower limb weakness. No cardiac or respiratory involvement was detected. Muscle biopsy showed myopathic changes with type I fibre hypotrophy, cytoplasmic vacuoles, lipid overload, multiple central nuclei and fibre splittings; ultrastructural examination showed metabolic abnormalities. Next generation sequencing analysis detected a homozygous frameshift mutation in the TCAP gene (c.90_91del), previously described in one Turkish family. Immunostaining and Western blot analysis showed complete absence of telethonin. Interestingly, Single Nucleotide Polymorphism analysis of the 10 Mb genomic region containing the TCAP gene showed a shared homozygous haplotype of both the Greek and the Turkish patients, thus suggesting a possible founder effect of TCAP gene c.90_91del mutation in this part of the Mediterranean area.

P.151 - Limb girdle muscular dystrophy 2G in a religious minority of Bulgarian muslims homozygous for the c.75G>A, p.Trp25* TCAP mutation

Mutations in TCAP gene cause autosomal recessive limb-girdle muscular dystrophy type 2G (LGMD2G), congenital muscular dystrophy and dilated and hypertrophic cardiomyopathy. To describe the phenotypic spectrum of LGMD 2G in a genetically homogeneous group of patients, belonging to a religious minority of Bulgarian muslims. Sixteen affected individuals (11 male and 5 female) from 10 pedigrees underwent neurological examination, including manual muscle testing, electromyography (EMG), cardiac evaluation, ventillatory assessment, evaluation of serum creatine kinase levels (CK) and molecular-genetic testing. The pattern of muscle involvement in the lower limbs was assessed in 2 patients by 3T MRI. Fifteen of the affected were homozygous for the c.75G>A, p.Trp25*mutation, whereas one was compound heterozygous, carrying Glu132Val in exon 2 as second mutation. The mean age at onset was 17.94 ± 3.97 years, ranging between 10 and 25 years. The initial manifestations in 12 patients included proximal muscle weakness in the lower limbs, followed by difficulties in ankle dorsiflexion. In 4 of the affected the proximal and distal weakness in the legs occurred simultaneously. The proximal muscles of the upper limbs became involved 5–9 years after the disease onset. Scapular winging and lumbar hyperlordosis developed late in the course of the disease. Respiratory and cardiac functions were spared. On the MRI the muscles in all three compartments of the thigh and anterior leg ones were predominantly affected, while m. sartorius, gracilis remained relatively spared. Homozygosity for c.75G>A, p.Trp25*mutation is associated with a homogeneous clinical presentation in terms of pattern of muscle involvement. The clinical course and severity of the disease however show inter- and intra-familial variation despite the mutation homogeneity.

G.P.280: Preserved expression of truncated telethonin in a patient with LGMD2G

Limb-girdle muscular dystrophy type 2G (LGMD2G) is a disorder caused by mutations in the TCAP gene that encodes for the striated muscle specific protein telethonin. LGMD2G is extremely rare and was initially identified in the Brazilian population. Recently, a small number of LGMD2G patients have been diagnosed in populations with diverse genetic backgrounds indicating a wider geographical distribution of this disorder. Here we describe a 49 year old male patient presenting a classical LGMD phenotype. He was born from non-consanguineous healthy parents of Indian descent. He had normal motor milestones but became noticeable slower in his early teens and presented scapular winging and Achilles tendon contractures. He eventually became wheelchair bound by age 47. There has been no cardiac involvement so far and the respiratory function is only mildly reduced with nocturnal hypoventilation. CK levels were 2541 iU/L. A muscle biopsy showed well preserved fascicular architecture with mild myopathic features. Immunohistochemistry with an antibody directed to the C-terminal portion of telethonin showed complete absence of labelling. However, an antibody directed against full-length telethonin showed some labelling on sections and a single band of ∼10 kDa on Western blot. Sequence analysis of the TCAP gene revealed a novel homozygous non-sense c.244C>T (p.Gln82X) mutation in exon 2, predicted to generate a truncated protein of molecular mass consistent with the Western blot findings. Double labelling for telethonin and filamin C showed overlap in a cross-striated pattern, consistent with the Z-disc localization of both proteins, indicating that the mutant telethonin is retained at the Z-disc. Our results suggest that the mutant protein is correctly incorporated in the sarcomere allowing sufficient binding to titin such that functional rather than structural defects may be the mechanism that leads to LGMD2G.

Polymorphisms in candidate genes and their association with carcass traits and meat quality in Nellore cattle

The objective of this work was to estimate the allele polymorphism frequencies of genes in Nellore cattle and associate them with meat quality and carcass traits. Six hundred males were genotyped for the following polymorphisms: DGAT1 (VNTR with 18 nucleotides at the promoter region); ANK1, a new polymorphism, identified and mapped here at the gene regulatory region NW_001494427.3; TCAP (AY428575.1:g.346G&gt;A); and MYOG (NW_001501985:g.511G&gt;C). In the association study, phenotype data of hot carcass weight, ribeye area, backfat thickness, percentage of intramuscular fat, shear force, myofibrillar fragmentation index, meat color (L*, a*, b*), and cooking losses were used. Allele B from the ANK1 gene was associated with greater redness (a*). Alleles 5R, 6R, and 7R from the DGAT1 VNTR gene were associated with increased intramuscular fat, reduced cooking losses and increased ribeye area, respectively. The single nucleotide polymorphism (SNP) of the TCAP gene was not polymorphic, and MYOG alleles were not associated with any of the evaluated characteristics. These results indicate that ANK1 and DGAT1 genes can be used in the selection of Nellore cattle for carcass and meat quality.

Molecular characterization, transcriptional regulation and association analysis with carcass traits of porcine TCAP gene

TCAP (also known as titin-cap or telethonin) is one of the titin interacting Z-disk proteins involved in the regulation and development of normal sarcomeric structure. In this study, we cloned the cDNA and promoter sequences of porcine TCAP gene, which contained a 504bp full-length coding region. Quantitative real-time PCR (qRT-PCR) analyses showed that porcine TCAP was highly expressed in the skeletal muscle, heart, and kidney. During postnatal muscle development, TCAP expression was down-regulated from 30days to 120days in Large White and Meishan pigs. One single nucleotide polymorphism c.334G>A in exon 2 of the TCAP gene was identified and detected by allele-specific primer-polymerase chain reaction (ASP-PCR). Association analysis revealed that the polymorphism had significant associations (P<0.05 and P<0.01) with some carcass traits. Analysis of the porcine TCAP promoter in different cell lines demonstrated that it is a muscle-specific promoter. In addition, we found that the porcine TCAP promoter can be activated by MyoD, MyoG and MEF2 in myotubes, which indicated that TCAP may play a role in the regulation of porcine skeletal muscle development. These findings provide useful information for the further investigation of the function of TCAP in porcine skeletal muscle.

Promoter Characterization and Expression Pattern Analysis of Porcine TCAP Gene

Promoter Characterization and Expression Pattern Analysis of Porcine TCAP Gene

G.P.40 LGMD2G with clinical presentation of congenital muscular dystrophy: A rare phenotype

LGMD2G is a relatively rare and mild autosomal recessive form of progressive neuromuscular disorder with a wide spectrum of inter and intrafamilial clinical variability. The age at onset ranges from 9 to 15 years old and loss of ambulation is uncommon, or in the third or fourth decade of life. LGMD2G is caused by mutations in the TCAP gene, causing the deficiency of the sarcomeric protein telethonin in muscle of affected patients. Up to now, only a few families have been described, mainly in Brazil. In a recent screening for mutation in the TCAP gene, including 200 additional LGMD adult patients, we identified six new cases, confirming the rarity of the disease also in Brasil. All these patients carried the same c.157C>T (Q53X) homozygous missense mutation, identified in the first families, suggesting a common origin of this mutation. In addition,we studied a five years-old patient with clinical diagnosis of congenital muscular dystrophy. Immunohistochemical analysis for muscle protein excluded the deficiency of dystrophin, the four sarcoglycans, α2-laminin, dysferlin and calpain3 proteins. Surprisingly, telethonin analysis showed a total deficiency, both through immune fluorescence and western blot analyses. Sequencing of the TCAP gene identified the common c.157C>T mutation in a homozygous state in the patient and in heterozygosity in both non-consanguineous parents. This called our attention to the fact that the rarity of the disease could be due to the screening of the improper patients. Telethonin deficiency could be, in fact, the cause of more severe forms of muscular dystrophies. To test this hypothesis, we analyzed telethonin deficiency in the muscle of 118 patients with clinical diagnosis of congenital MD, from which we selected sixteen patients for gene sequencing. However, no alteration was found in any of them. Therefore, mutation in the TCAP gene is not a common cause of severe forms of MD. FAPESP-CEPID, CNPq-INCT, FINEP, ABDIM.

G.P.41 The identification of LGMD2G (TCAP) in Australia

The limb-girdle MDs (LGMDs) are characterised by predominant weakness and wasting of pelvic and shoulder girdle muscles with onset after two years of age. Recessive mutations in the TCAP gene (encoding telethonin), were first identified as the cause of LGMD2G in 2000. Only a handful of families have been reported to date. Here, we report the ninth family with LGMD2G. The proband (P1) is a 32year old male with an affected sister, five unaffected siblings and first-cousin parents of Chinese-Cambodian descent. P1 had slowly progressive muscle weakness since his late teenage years. On examination at 27years of age, he had bilateral Achilles contractures, mild calf hypertrophy, asymmetric scapular winging and normal facial strength except mild weakness of eye closure. There was moderate weakness of hip movements and knee extension and mild weakness of most other muscle groups, except hand and wrist movements. We performed genome-wide linkage analysis assuming autosomal recessive inheritance using Illumina 660WQ SNP platform and found positive LOD scores for the chromosomal region 17p11.2-q22, containing the TCAP gene, as well as regions on chromosomes 7, 16 and 18. Sanger sequencing of TCAP revealed a homozygous 8 base pair duplication (c.26_33dupAGGTGTCG) resulting in a frameshift and truncated protein (p.R12fsX31), predicted to abolish telethonin expression. Two other families of Chinese origin have been reported with the same homozygous mutation. A muscle MRI at 28years of age demonstrated widespread asymmetric fatty infiltration of lower limb muscles in a pattern similar to that reported in another LGMD2G patient by CT imaging. In conclusion, LGMD2G is rare, but exists outside Brazil and our identification of a third Asian LGMD2G family with the p.R12fsX31 mutation suggests this may be a population-specific mutation. Consistency in the pattern of muscle involvement on MRI or CT in two LGMD2G patients suggests this investigation may be a useful tool for diagnosis.