Search Results (63)

Down feathers and contour feathers are two distinct feather types with vastly different structures and functions coexisting in the same individual. However, the molecular mechanism underlying these differences remains unclear. In this study, skin tissue containing intact feather follicles was collected from four anatomically defined regions of healthy Beijing ducks (Anas platyrhynchos domesticus) for transcriptomic sequencing: the breast and abdomen, which generate down feathers, and the wingtips and rump, which produce contour feathers. To mitigate bias arising from site-specific effects, we established paired comparisons between contour feathers and down feathers across different regions. Across all comparisons, 36 core differentially expressed genes (DEGs) were consistently identified. These encompassed nine HOX family transcription factors across three paralogous clusters, ZIC family members (ZIC1 and ZIC4), WNT4, TBX4, BMP5, cytoskeletal and sarcomeric genes (MYOZ2, ACTN2, DES, SMPX), extracellular matrix regulators (ASPN, MGP, FMOD), and lipid metabolism-related genes (MOGAT2, PNPLA2), among others. Pathway enrichment analysis revealed that transcriptomic variations in different feather follicles involve gene modules functioning in positional identity, cytoskeletal organization, extracellular matrix remodeling and lipid metabolism, with potential neuroendocrine modulation. The transcriptomic dataset established here facilitates future studies on the molecular mechanisms of feather differentiation and offers a reference for molecular breeding to enhance down feather yield and quality of Beijing ducks. Full article

Background: Cardiac hypertrophy, a major feature of heart failure, is closely linked to metabolic remodeling and energy deficiency. Lysine lactylation (Kla), a recently discovered post-translational modification (PTM), has been implicated in various cellular processes. However, its specific role in cardiac hypertrophy remains poorly understood. Methods: We conducted quantitative proteomics and Kla PTM analysis on left ventricular tissues from both sham-operated and aortic banding-induced hypertrophic mouse hearts. Protein samples were extracted, enriched for lactylation, and subjected to mass spectrometry. Bioinformatic analyses were performed to uncover pathways and protein–protein interactions (PPI) related to Kla-modified proteins. Results: Our lactylome analysis identified 159 Kla-modified sites across 80 proteins, with 72 proteins exhibiting elevated Kla levels, particularly in mitochondrial and sarcomeric proteins. Pathway enrichment analysis highlighted significant involvement of fatty acid metabolism, the tricarboxylic acid (TCA) cycle, and cardiomyopathy-related pathways, underscoring the role of Kla in energy metabolism and cardiac remodeling. PPI analysis further revealed the central role of metabolic and structural proteins in the hypertrophic response. Conclusions: Our study provides the comprehensive analysis of Kla in cardiac hypertrophy, revealing its significant role in modulating proteins involved in mitochondrial energy metabolism and sarcomeric structure. Our findings provide a comprehensive overview of the lactylation landscape in cardiac hypertrophy and reveal extensive lactylation changes in proteins associated with mitochondrial metabolism and sarcomeric organization. These observations suggest a potential link between Kla and cardiac hypertrophy, which warrants further functional investigation. Full article

The landscape of human cardiac biology was transformed by the discovery that adult somatic cells can be reprogrammed into induced pluripotent stem cells, enabling patient-specific disease modeling, drug testing, and regenerative strategies without the prior ethical or biological constraints. Subsequent advances in directed differentiation made the generation of human iPSC-derived cardiac myocytes reliable and scalable. Despite this progress, a central limitation has remained: these cells are developmentally immature, resembling fetal cardiac myocytes in structure, metabolism, and function. This immaturity restricts their utility for modeling adult-onset disease, predicting drug responses, and achieving clinical translation. Maturation is now understood as a multifactorial symphony, requiring coordinated molecular, structural, and environmental inputs rather than single interventions. As a result, the field is shifting toward integrative approaches that incorporate 3D architecture, multicellular systems, and biomimetic environments to better replicate native cardiac tissue. While fully adult-like myocardium remains an ongoing goal, advances in bioengineering and system-level design are narrowing the gap, with success increasingly defined by the generation of functional cardiac tissue rather than isolated cell maturity. Full article

Fetal skeletal muscle development involves coordinated interactions among myogenic, stromal, vascular, and immune compartments, yet the cellular and molecular programs guiding tissue maturation remain incompletely understood. To address this, we generated a high-resolution single-cell atlas of fetal female goat skeletal muscle and performed trajectory analysis, transcription factor activity profiling, and intercellular communication mapping. Unsupervised clustering identified RUNX2 mesenchymal progenitors, fibro-adipogenic progenitors (FAPs), myofibroblasts, endothelial cells, macrophages, differentiating myocytes, and mature skeletal muscle fibers, revealing a heterogeneous ecosystem in which stromal populations support myogenic progression and vascular and immune cells contribute to tissue organization. Pseudotime analysis traced a maturation continuum from differentiation-competent myocytes to contractile fibers, marked by sequential activation of extracellular matrix remodeling, cytoskeletal stabilization, and sarcomere assembly. KEGG and GO enrichment highlighted stage-specific engagement of ErbB, Hedgehog, and Hippo signaling, as well as cell cycle and ubiquitin-mediated proteolysis pathways, linking proliferation, differentiation, and structural maturation. Transcription factor profiling revealed early-stage proliferative and morphogenetically permissive states driven by E2F4/5, HMGA2, and HAND2, transitioning to late-stage differentiation, ECM remodeling, and tissue stabilization orchestrated by CEBPB, CREB3L1, ELK1, and E2F2. Cell–cell communication analysis showed a developmental redistribution of signaling authority, from ECM-driven, progenitor-centered networks to modular, structurally stabilized interactions. These findings define the cellular, transcriptional, and signaling framework orchestrating fetal skeletal muscle maturation. Full article

Background/Objectives: Patient-derived mesenchymal stem cells (MSCs) represent a promising avenue for myocardial regeneration, yet therapeutic application remains limited by inconsistent differentiation capacity and the absence of standardized cardiogenic induction protocols. This study demonstrates a proof-of-concept for guiding patient-specific bone marrow MSCs toward a functional cardiomyocyte phenotype using paracrine signals from differentiating iPSC-derived cardiomyocytes (iPSC-CMs). Materials and Methods: MSCs were maintained in conditioned medium from a concurrent, validated iPSC-CM differentiation protocol, with evaluation via immunocytochemistry, optical mapping, and whole-cell patch-clamp recordings. Results: Differentiated MSCs acquired organized sarcomeric architecture with cross-striations and displayed spontaneous calcium oscillations with decay kinetics matching source iPSC-CMs (CaT50 ≈ 283 ms vs. 301 ms). In co-culture, MSC-derived cells exhibited synchronized calcium dynamics with iPSC-CMs, confirming functional coupling, while patch-clamp detected hallmark cardiac ion currents (INa, ICa,L, and IKv). Morphologically, MSC-CMs displayed more mature, elongated rod-like shapes. Conclusions: Although current densities indicate partial immaturity, their reproducible detection validates successful cardiomyogenic commitment. This “parallel differentiation” platform eliminates donor-specific protocol tuning, providing a streamlined, paracrine-mediated approach to generate autologous cardiomyocyte-like cells for disease modeling, pharmacological testing, and future regenerative applications. Full article

Background/Objectives: Variants of MYPN, encoding a sarcomeric protein myopalladin, are associated with different types of cardiomyopathies and myopathies. However, the molecular mechanisms of MYPN-associated pathologies are still poorly understood. Methods: In this study, we generated induced pluripotent stem cells (iPSCs) from a hypertrophic cardiomyopathy patient carrying a novel p.N989I (c.2966A>T) variant of MYPN and used iPSC-derived cardiomyocytes to examine the impact of the variant on biophysical characteristics and transcriptomic profile. Results: No significant changes in parameters of calcium transients, sodium current and action potential were found in iPSC-derived cardiomyocytes with the p.N989I (c.2966A>T) variant of MYPN compared to non-isogenic cells from an unrelated healthy donor. At the transcriptomic level, MYPN-N989I cardiomyocytes demonstrated an upregulation of genes linked to cell cycle, mitotic spindle, microtubule cytoskeleton organization, and myogenic program genes. Downregulation of sarcomeric, Z-disc- and cell junction-associated genes, as well as genes involved in ATP synthesis, oxidative phosphorylation, and the SRF-signaling pathway, was also revealed. Conclusions: Our data suggest that the p.N989I (c.2966A>T) variant of MYPN plays a dual role in hypertrophic cardiomyopathy pathogenesis, disrupting not only sarcomeric and cytoskeletal organization but also the regulation of the muscle gene program. Full article

At the dawn of the 20th century, seminal studies revealed that muscle fibers produce less heat and generate greater force during elongation than during shortening actions, laying the foundation for contemporary research on eccentric exercise. Today, eccentric exercise is widely used by athletes to enhance strength and by older adults to maintain functional capacity, yet it may cause muscle damage, particularly in unaccustomed muscles. Despite more than a century of investigation, the precise mechanisms of eccentric exercise-induced muscle damage remain incompletely resolved. Nevertheless, eccentric exercise serves as a valuable model for studying muscle injury and repair and adaptation. This review organizes current evidence into nine key themes: (1) eccentric exercise-induced muscle damage and flawed biomarkers, (2) satellite cell-mediated and alternative repair pathways, (3) high-force, low-cost contractions and metabolic impact, (4) repeated bout effect and protective adaptations, (5) architectural remodeling of fascicles, sarcomeres and tendon, (6) distinct neural control, proprioception, and cross-education adaptations, (7) mitochondrial, sarcoplasmic reticulum, and cytoskeletal stress remodeling, (8) connective tissue perturbation, remodeling, and joint stability, and (9) targeted, cautious use of antioxidant supplementation. Rather than offering a comprehensive overview, this review highlights pivotal experiments, concepts, and controversies within these themes to guide readers to the most impactful discoveries in eccentric exercise and muscle damage. Full article

The maturation of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) remains a major translational bottleneck in regenerative cardiac medicine, as current differentiation platforms yield electrophysiologically and metabolically immature phenotypes. This review explores emerging strategies to engineer “smart” biomaterial interfaces that actively instruct iPSC-CM maturation through synergistic biophysical and metabolic reprogramming. By integrating nanotopographical patterning, mechanoelectric coupling, and tunable substrate stiffness with metabolic interventions such as mitochondrial substrate optimization and fatty acid oxidation induction, the literature reveals consistent links between cell–matrix crosstalk, sarcomeric organization, calcium handling, and oxidative metabolism. Recent advances in bioactive scaffolds and extracellular vesicle (EV)-functionalized hydrogels are highlighted as platforms capable of approximating key features of the myocardium’s native electromechanical and bioenergetic environment. Across two- and three-dimensional culture systems, this review identifies recurring maturation patterns, persistent gaps in metric standardization and long-term phenotype stability, and ongoing limitations related to scalability and translational implementation. Collectively, the findings synthesized here indicate that convergence between biomaterial engineering and metabolic programming represents a critical design principle for advancing iPSC-CMs toward functionally mature, clinically relevant phenotypes. This integrated approach enhances the fidelity of iPSC-CMs for disease modeling, drug screening, and regenerative cardiac therapies. Full article

Hypertrophic cardiomyopathy (HCM) is a common and deadly cardiac disease characterized by enlarged myocytes, increased myocardial wall thickening, and fibrosis. A majority of HCM cases are associated with mutations in the β-myosin heavy chain (MYH7) converter domain locus, which leads to varied pathophysiological and clinical manifestations. Using base-editing technology, we generated mutant human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) harboring HCM-causing myosin converter domain mutations (MYH7 c.2167C>T [R723C]; MYH6 c.2173C>T [R725C]) to define HCM pathogenesis in vitro. In this study, we integrated transcriptomic analysis with phenotypic and molecular analyses to dissect the HCM disease mechanisms using MYH6/7 myosin mutants. Our KEGG analysis of bulk RNA-sequencing data revealed significant upregulation of transcripts associated with HCM in the mutant hiPSC-CMs. Further, in-depth transcriptomic analysis using Gene-Ontology (GO-term) analysis for biological process showed upregulation of several transcripts associated with heart development and disease. Notably, our analysis showed robust upregulation of cytoskeletal transcripts, including actin-cytoskeleton networks, sarcomere components, and other structural proteins in the mutant CMs. Furthermore, cellular and nuclear morphological analysis showed that the MYH6/7 mutation induced cellular hypertrophy and increased aspect ratio compared to the isogenic control. Immunostaining experiments showed marked sarcomere disorganization with lower sarcomeric order and higher dispersion in the mutant hiPSC-CMs, highlighting the remodeling of the myofibril arrangement. Notably, the MYH6/7 mutant showed reduced cortical F-actin expression and increased central F-actin expression compared to the isogenic control, confirming the cytoskeletal remodeling and sarcomeric organization during HCM pathogenesis. These pathological changes accumulated progressively over time, underscoring the chronic and evolving nature of HCM driven by the MYH6/7 mutations. Together, our findings provide critical insights into the cellular and molecular underpinnings of MYH6/7-mutation-associated disease. These findings offer valuable insights into HCM pathogenesis, aiding in future therapies. Full article

The Sarco Endoplasmic Reticulum Ca²⁺-ATPase (SERCA) pumps cytosolic Ca²⁺ into the endoplasmic reticulum lumen (ER) to maintain cytosolic and ER Ca²⁺ levels under physiological conditions. Previous reports suggest that cellular Ca²⁺ homeostasis is compromised in Alzheimer’s Disease (AD) and that SERCA activity can modulate the phenotype of AD mouse models. Here, we used a C. elegans strain that overexpresses the most toxic human ß-amyloid peptide (Aß_(1-42)) in body-wall muscle cells to study the effects of SERCA (sca-1) silencing on Aß_(1-42)-induced body-wall muscle dysfunction. sca-1 knockdown reduced the percentage of paralyzed worms, improved locomotion in free-mobility assays, and restored pharynx pumping in Aß_(1-42)-overexpressing worms. At the cellular level, sca-1 silencing partially prevented Aß_(1-42)-induced exacerbated mitochondrial respiration and mitochondrial ROS production and restored mitochondrial organization around sarcomeres. sca-1 knockdown reduced the number and size of Aß_(1-42) aggregates in body–wall muscle cells and prevented the formation of Aß_(1-42) oligomers. Aß_(1-42) expression induced a slower kinetics of spontaneous cytosolic Ca²⁺ transients in muscle cells and sca-1 partially restored these changes. We propose that partial sca-1 loss of function prevents the toxicity associated with beta-amyloid accumulation by reducing the formation of Aß_(1-42) oligomers and improving mitochondrial function, in a mechanism that requires remodeling of cytosolic Ca²⁺ dynamics and partial ER Ca²⁺ depletion. Full article

Neonatal rodent cardiomyocytes (CMs) are a mainstay of in vitro cardiac research, yet their immature phenotype limits the study of key physiological processes such as excitation–contraction coupling (ECC) and sympathetic modulation. Here, we present a defined low-glucose, serum-free (LGSF) culture protocol that drives the structural and functional maturation of neonatal CMs and supports their integration into functional neuro-cardiac co-cultures. After 15 days in LGSF conditions, CMs exhibit elongated morphology, organized sarcomeres, polarized connexin-43, mitochondrial redistribution, and sarcoplasmic reticulum (SR) development, all closely resembling features of adult cells. These structural hallmarks were paralleled by enhanced Ca²⁺ handling, with increased SR contribution and reduced spontaneous activity, indicative of a mature ECC phenotype. When co-cultured with sympathetic neurons (SN), CMs established anatomically distinct neuro-cardiac junctions. Notably, nicotine stimulation triggered spatially restricted, reversible increases in CM Ca²⁺ transients, confined to varicosity-contacted cells. Pharmacological analysis revealed subtype-specific roles for β₁- and β₂-adrenergic receptors, and uncovered evidence of functional crosstalk between them. Our study defines a reproducible culture framework that advances CM maturation and enables the high-resolution interrogation of synaptic-like sympathetic modulation. This approach opens new avenues for mechanistic studies and drug testing in developmentally relevant neuro-cardiac systems. Full article

The hypertrophic cardiomyopathy (HCM) clinical phenotype includes sarcomeric HCM, which is the most common form of inherited cardiomyopathy with a population prevalence of 1:500, and phenocopies such as cardiac amyloidosis and Anderson–Fabry disease, which are considered rare diseases. Identification of cardiac and non-cardiac red flags in the context of multi-organ syndrome, multimodality imaging, including echocardiography, cardiac magnetic resonance, and genetic testing, has a central role in the diagnostic pathway. Identifying the specific disease underlying the hypertrophic phenotype is very important since many disease-modifying therapies are currently available, and phase 3 trials for new treatments have been completed or are ongoing. In particular, many chemotherapy agents (alkylating agents, proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies targeting clonal cells) allowing one to treat AL amyloidosis, transthyretin stabilizers (tafamidis and acoramidis), and gene silencers (patisiran and vutrisiran) are available in transthyretin cardiac amyloidosis, and enzyme replacement therapies (agalsidase-alpha, agalsidase-beta, and pegunigalsidase-alpha) or oral chaperone therapy (migalastat) can be used in Anderson–Fabry disease. In addition, the introduction of cardiac myosin inhibitors (mavacamten and aficamten) has deeply modified the treatment of hypertrophic obstructive cardiomyopathy. The aim of this review is to describe the new disease-modifying treatments available in HCM and phenocopies in light of current scientific evidence. Full article

Recent studies on myogenic satellite cells (SCs) in Duchenne muscular dystrophy (DMD) documented altered division capacities and impaired regeneration potential of SCs in DMD patients and animal models. It remains unknown, however, if SC-intrinsic effects trigger these deficiencies at pre-contractile stages of myogenesis rather than resulting from the pathologic environment. In this study, we isolated SCs from a porcine DMD model and age-matched wild-type (WT) piglets for comprehensive analysis. Using immunofluorescence, differentiation assays, traction force microscopy (TFM), RNA-seq, and label-free proteomic measurements, SCs behavior was characterized, and molecular changes were investigated. TFM revealed significantly higher average traction forces in DMD than WT SCs (90.4 ± 10.5 Pa vs. 66.9 ± 8.9 Pa; p = 0.0018). We identified 1390 differentially expressed genes and 1261 proteins with altered abundance in DMD vs. WT SCs. Dysregulated pathways uncovered by gene ontology (GO) enrichment analysis included sarcomere organization, focal adhesion, and response to hypoxia. Multi-omics factor analysis (MOFA) integrating transcriptomic and proteomic data, identified five factors accounting for the observed variance with an overall higher contribution of the transcriptomic data. Our findings suggest that SC impairments result from their inherent genetic abnormality rather than from environmental influences. The observed biological changes are intrinsic and not reactive to the pathological surrounding of DMD muscle. Full article

Microgravity, defined by minimal gravitational forces, represents a unique environment that profoundly influences biological systems, including human cells. This review examines the effects of microgravity on biological processes and their implications for human health. Microgravity significantly impacts the immune system by disrupting key mechanisms, such as T cell activation, cytokine production, and macrophage differentiation, leading to increased susceptibility to infections. In cancer biology, it promotes the formation of spheroids in cancer stem cells and thyroid cancer cells, which closely mimic in vivo tumor dynamics, providing novel insights for oncology research. Additionally, microgravity enhances tissue regeneration by modulating critical pathways, including Hippo and PI3K-Akt, thereby improving stem cell differentiation into hematopoietic and cardiomyocyte lineages. At the organ level, microgravity induces notable changes in hepatic metabolism, endothelial function, and bone mechanotransduction, contributing to lipid dysregulation, vascular remodeling, and accelerated bone loss. Notably, cardiomyocytes derived from human pluripotent stem cells and cultured under microgravity exhibit enhanced mitochondrial biogenesis, improved calcium handling, and advanced structural maturation, including increased sarcomere length and nuclear eccentricity. These advancements enable the development of functional cardiomyocytes, presenting promising therapeutic opportunities for treating cardiac diseases, such as myocardial infarctions. These findings underscore the dual implications of microgravity for space medicine and terrestrial health. They highlight its potential to drive advances in regenerative therapies, oncology, and immunological interventions. Continued research into the biological effects of microgravity is essential for protecting astronaut health during prolonged space missions and fostering biomedical innovations with transformative applications on Earth. Full article

Limb–girdle muscular dystrophy R1 (LGMDR1) is characterized by progressive proximal muscle weakness due to mutations in the CAPN3 gene. Little is known about CAPN3’s function in muscle, but its loss results in aberrant sarcomere formation. Human muscle structure was analyzed in this study, with observations including integrin β1D isoform (ITGβ1D) mislocalization, a lack of Talin-1 (TLN1) in the sarcolemma and the irregular expression of focal adhesion kinase (FAK) in LGMDR1 muscles, suggesting a lack of integrin activation with an altered sarcolemma, extracellular matrix (ECM) assembly and signaling pathway deregulation, which may cause frailty in LGMDR1 muscle fibers. Additionally, altered nuclear morphology, centrosome distribution and microtubule organization have been found in muscle cells derived from LGMDR1 patients. Full article