Sarcopenia, a complex and debilitating condition characterized by progressive deterioration of skeletal muscle, is the primary cause of age-associated disability and significantly impacts healthspan in elderly patients. Despite its prevalence among the aging population, the underlying molecular mechanisms are still under investigation. The NLRP3 inflammasome is crucial in the innate immune response and has a significant impact on diseases related to inflammation and aging. Here, we investigated the expression of the NLRP3 inflammasome pathway and pro-inflammatory cytokines in skeletal muscle and peripheral blood of dependent and independent patients who underwent hip surgery. Patients were categorized into independent and dependent individuals based on their Barthel Index. The expression of NLRP3 inflammasome components was significantly upregulated in sarcopenic muscle from dependent patients, accompanied by higher levels of Caspase-1, IL-1β and IL-6. Among older dependent individuals with sarcopenia, there was a significant increase in the MYH3/MYH2 ratio, indicating a transcriptional shift in expression from mature to developmental myosin isoforms. Creatine kinase levels and senescence markers were also higher in dependent patients, altogether resembling dystrophic diseases and indicating muscle degeneration. In summary, we present evidence for the involvement of the NLRP3/ASC/NEK7/Caspase-1 inflammasome pathway with activation of pro-inflammatory SASP in the outcome of sarcopenia in the elderly.

Cleft lip and palate (CLP) is a well-known congenital defect in dogs, characterized by abnormal communication between the oral and nasal cavities. Its incidence rate is high and affects all dog breeds. The etiology of CLP is thought to be multifactorial, caused by both genetic and environmental factors. In this study, four puppies out of seven from a single litter of Staffordshire Bull Terrier dogs with craniofacial abnormalities were anatomically and genetically examined. Classical anatomical preparation, dyed-latex-injection of the arterial vessels, and cone-beam computed tomography were used. The puppies showed variations in their observable abnormalities: three of them had a complete cleft of the palate on both sides, while one puppy had a cleft on the right side only. Cytogenetic analysis showed a normal diploid chromosome number (2n = 78,XX or 78,XY) in the studied animals. Known genomic variants of CLP were examined in the ADAMTS20, DLX6, and MYH3 genes, but no mutations were identified. Further studies are needed to identify the breed-specific genetic variants associated with canine CLP.

Fatty acid (FA) composition is one of the most important parameters for the assessment of meat quality in pigs. The FA composition in pork can also affect human health. Our aim was to identify quantitative trait loci (QTLs) and positional candidate genes affecting the FA profile of the longissimus dorsi muscle in a large F2 intercross between Landrace and Korean native pigs comprising 1105 F2 progeny by genome-wide association studies (GWAS) and post-GWAS high-resolution mapping analyses. We performed GWAS using the PorcineSNP60K BeadChip and a linear mixed model. Four genome-wide significant QTL regions in SSC8, SSC12, SSC14, and SSC16 were detected (p < 2.53 × 10-7). Several co-localizations of QTLs in SSC12 for oleic acid, linoleic acid, arachidonic acid, monounsaturated FAs, polyunsaturated FAs, and the polyunsaturated/saturated FA ratio were observed. To refine the QTL region in SSC12, a linkage and linkage disequilibrium analysis was applied and could narrow down the critical region to a 0.749 Mb region. Of the genes in this region, GAS7, MYH2, and MYH3 were identified as strong novel candidate genes based on further conditional association analyses. These findings provide a novel insight into the genetic basis of FA composition in pork and could contribute to the improvement of pork quality.

Multiple pterygium syndrome (MPS) is a genetically heterogeneous rare form of arthrogryposis multiplex congenita characterized by joint contractures and webbing or pterygia, as well as distinctive facial features related to diminished fetal movement. It is divided into prenatally lethal (LMPS, MIM253290) and nonlethal (Escobar variant MPS, MIM 265000) types. Developmental spine deformities are common, may present early and progress rapidly, requiring regular fo llow-up and orthopedic management.
Retrospective chart review and prospective data collection were conducted at three hospital centers. Molecular diagnosis was confirmed with whole exome or whole genome sequencing.
This case series describes the clinical features and scoliosis treatment on 12 patients from 11 unrelated families. A molecular diagnosis was confirmed in seven; two with MYH3 variants and five with CHRNG. Scoliosis was present in all but our youngest patient. The remaining 11 patients spanned the spectrum between mild (curve ≤ 25°) and malignant scoliosis (≥50° curve before 4 years of age); the two patients with MYH3 mutations presented with malignant scoliosis. Bracing and serial spine casting appear to be beneficial for a few years; non-fusion spinal instrumentation may be needed to modulate more severe curves during growth and spontaneous spine fusions may occur in those cases.
Molecular diagnosis and careful monitoring of the spine is needed in children with MPS.

Improving meat quality has become the main goal of modern pig breeding. Intramuscular fat content (IMF) is an important trait influencing meat quality of livestock, but the molecular mechanism behind this trait is still unclear. Recently, Cho et al. reported the discovery of the first causal mutation affecting IMF and red flesh color (a*) in pigs, namely XM_013981330.2:g.-1805_-1810del, a 6-bp deletion variant in the porcine MYH3 promoter region. The objective of this study was to reassess the causality of this mutation for its potential commercial application. By Sanger sequencing, we firstly identified several new variants (including a 4-bp deletion) at or near the 6-bp deletion site, which formed four haplotypes in multiple breeds. Unexpectedly, the 6-bp deletion allele, previously determined as the MYH3 Q allele because of its significantly positive effect on IMF and a*, was found not only in Chinese indigenous breeds, but also in four western commercial breeds with relatively lower IMF levels, including Duroc, Large White, Landrace and Pietrain. More surprisingly, we found that the MYH3 Q allele and the haplotypes harboring it had no significant effects on IMF, marbling and color score in three large-scale divergent pig populations: the heterogeneous F6 and F7 pigs and commercial crossbred Duroc × (Landrace × Yorkshire) pigs. Transient transfection analysis in porcine satellite cells showed that the 6-bp deletion variants had a negligible effect on transcription of reporter gene, but could attenuate the MRF (myogenesis regulatory factors)-induced increase in luciferase activity of the MYH3 promoter vector. The MYH3 protein level in muscle did not differ significantly among the haplotype groups. Therefore, our results cannot support the causal relationship between the 6-bp deletion in MYH3 and IMF trait, suggesting that the causal mutation for the IMF QTL on SSC12 needs to be further identified.

Gene expression is one of the main factors to influence meat quality by modulating fatty acid metabolism, composition, and deposition rates in muscle tissue. This study aimed to explore the transcriptomics of the Longissimus lumborum muscle in two local pig breeds with distinct genetic background using next-generation sequencing technology and Real-Time qPCR. RNA-seq yielded 49 differentially expressed genes between breeds, 34 overexpressed in the Alentejano (AL) and 15 in the Bísaro (BI) breed. Specific slow type myosin heavy chain components were associated with AL (MYH7) and BI (MYH3) pigs, while an overexpression of MAP3K14 in AL may be associated with their lower loin proportion, induced insulin resistance, and increased inflammatory response via NFkB activation. Overexpression of RUFY1 in AL pigs may explain the higher intramuscular (IMF) content via higher GLUT4 recruitment and consequently higher glucose uptake that can be stored as fat. Several candidate genes for lipid metabolism, excluded in the RNA-seq analysis due to low counts, such as ACLY, ADIPOQ, ELOVL6, LEP and ME1 were identified by qPCR as main gene factors defining the processes that influence meat composition and quality. These results agree with the fatter profile of the AL pig breed and adiponectin resistance can be postulated as responsible for the overexpression of MAP3K14\'s coding product NIK, failing to restore insulin sensitivity.

The multiple pterygium syndromes (MPS) are rare disorders with disease severity ranging from lethal to milder forms. The nonlethal Escobar variant MPS (EVMPS) is characterized by multiple pterygia and arthrogryposis, as well as various additional features including congenital anomalies. The genetic etiology of EVMPS is heterogeneous and the diagnosis has been based either on the detection of pathogenic CHRNG variants (~23% of patients), or suggestive clinical features. We describe four patients with a clinical suspicion of EVMPS who manifested with multiple pterygia, mild flexion contractures of several joints, and vertebral anomalies. We revealed recessively inherited MYH3 variants as the underlying cause in all patients: two novel variants, c.1053C>G, p.(Tyr351Ter) and c.3102+5G>C, as compound heterozygous with the hypomorphic MYH3 variant c.-9+1G>A. Recessive MYH3 variants have been previously associated with spondylocarpotarsal synostosis syndrome. Our findings now highlight multiple pterygia as an important feature in patients with recessive MYH3 variants. Based on all patients with recessive MYH3 variants reported up to date, we consider that this disease entity should be designated as \"Contractures, pterygia, and variable skeletal fusions syndrome 1B,\" as recently suggested by OMIM. Our findings underline the importance of analyzing MYH3 in the differential diagnosis of EVMPS, particularly as the hypomorphic MYH3 variant might remain undetected by routine exome sequencing.

Muscle satellite cells are usually at rest, and when externally stimulated or regulated, they can be further differentiated by cell fusion to form new myotubes and muscle fibers. WD repeat domain 13 (WDR13) is highly conserved in vertebrates. Studies have shown that mice lacking the Wdr13 gene develop mild obesity, hyperinsulinemia, and increased islet β cell proliferation. However, the role of WDR13 in bovine cells is unclear. Here, we investigated the effect of WDR13 on bovine skeletal muscle-derived satellite cells (MDSCs). We found that WDR13 was upregulated in bovine MDSCs using western blotting and immunofluorescence experiments. Moreover, activation and inhibition of WDR13 expression increased and decreased cell differentiation, respectively, suggesting that WDR13 promotes bovine MDSC differentiation. To further understand the mechanism of action of WDR13, we examined changes in the PI3K/AKT signaling pathway following WDR13 activation or inhibition. In addition, cells were treated with a phosphoinositide kinase 3 (PI3K) inhibitor, LY294004, to observe cell differentiation. The results showed that activation of WDR13 inhibited the PI3K/AKT signaling pathway and enhanced cell differentiation. These data suggest that WDR13 can promote the differentiation of bovine MDSCs by affecting the PI3K/AKT signaling pathway.

Spondylocarpotarsal synostosis syndrome (SCTS) is characterized by intervertebral fusions and fusion of the carpal and tarsal bones. Biallelic mutations in FLNB cause this condition in some families, whereas monoallelic variants in MYH3, encoding embryonic heavy chain myosin 3, have been implicated in dominantly inherited forms of the disorder. Here, five individuals without FLNB mutations from three families were hypothesized to be affected by recessive SCTS on account of sibling recurrence of the phenotype. Initial whole-exome sequencing (WES) showed that all five were heterozygous for one of two independent splice-site variants in MYH3. Despite evidence indicating that three of the five individuals shared two allelic haplotypes encompassing MYH3, no second variant could be located in the WES datasets. Subsequent genome sequencing of these three individuals demonstrated a variant altering a 5\' UTR splice donor site (rs557849165 in MYH3) not represented by exome-capture platforms. When the cohort was expanded to 16 SCTS-affected individuals without FLNB mutations, nine had truncating mutations transmitted by unaffected parents, and six inherited the rs557849165 variant in trans, an observation at odds with the population allele frequency for this variant. The rs557849165 variant disrupts splicing in the 5\' UTR but is still permissive of MYH3 translational initiation, albeit with reduced efficiency. Although some MYH3 variants cause dominant SCTS, these data indicate that others (notably truncating variants) do not, except in the context of compound heterozygosity for a second hypomorphic allele. These observations make genetic diagnosis challenging in the context of simplex presentations of the disorder.

Copy number variations (CNVs) have been recently recognized as another important genetic variability complementary to single nucleotide polymorphisms (SNPs). Compelling evidence has indicated that CNVs are responsible for phenotypic traits by changing the copy numbers of functional genes. Myosin heavy chain 3 (MYH3) gene is a critical regulatory factor in skeletal muscle development, and has been detected in the CNVs region by comparative genomic hybridization (CGH) array. This study was conducted to validate and detect the distribution of MYH3 copy numbers (relative to Angus cattle) in four Chinese cattle breeds (NY, QC, LX, and CY), and further to investigate the associations of the copy number changes with its transcriptional expression and cattle growth traits. Substantial genetic differences of MYH3 copy numbers were identified between NY and the other three breeds (P<0.01). The copy numbers of MYH3 gene presented the positive correlations with the transcript level of MYH3 gene in both fetal and adult skeletal muscles (P<0.05). Statistical analysis revealed that CNVs of MYH3 gene were significantly associated with growth traits of NY cattle, and the individuals with copy number gain showed better phenotypes than the loss and/or median groups (P<0.05). This study firstly attempted to establish the correlations between CNVs of candidate genes and growth traits, and our results suggested that the CNVs of MYH3 gene may be utilized as the potential markers for economic traits in selection breeding programs of Chinese cattle.