Integrated analysis of long non-coding RNAs (lncRNAs) and mRNA expression profiles identifies lncRNA PRKG1-AS1 playing important roles in skeletal muscle aging

Epigenetics of Skeletal Muscle Atrophy

Skeletal muscle atrophy, characterized by diminished muscle strength and mass, arises from various causes, including malnutrition, aging, nerve damage, and disease-related secondary atrophy. Aging markedly escalates the prevalence of sarcopenia. Concurrently, the incidence of muscle atrophy significantly rises among patients with chronic ailments such as heart failure, diabetes, and chronic obstructive pulmonary disease (COPD). Epigenetics plays a pivotal role in skeletal muscle atrophy. Aging elevates methylation levels in the promoter regions of specific genes within muscle tissues. This aberrant methylation is similarly observed in conditions like diabetes, neurological disorders, and cardiovascular diseases. This study aims to explore the relationship between epigenetics and skeletal muscle atrophy, thereby enhancing the understanding of its pathogenesis and uncovering novel therapeutic strategies.

Lacticaseibacillus paracasei LC86 mitigates age-related muscle wasting and cognitive impairment in SAMP8 mice through gut microbiota modulation and the regulation of serum inflammatory factors

Purpose

Chronic inflammation contributes to the decline in muscle strength and cognitive abilities associated with aging. This study aims to clarify the effects of oral administration of Lacticaseibacillus paracasei LC86 on these age-related declines, as well as its impact on the composition of gut microbiota.

Methods

Senescence-accelerated mouse prone 8 (SAMP8) mice received a 12 week regimen of LC86 (1 × 109 CFU/day). Muscle strength was assessed through forelimb grip strength and four-limb hanging tests. Cognitive function was evaluated through behavioral performance tests, and changes in gut microbiota were analyzed.

Results

Administration of LC86 significantly enhanced muscle strength, demonstrated by increased grip strength and higher glycogen content in the gastrocnemius muscle (p = 0.041, p = 0.017, and p = 0.000, respectively). Behavioral tests suggested that LC86 mitigated age-related cognitive decline. Furthermore, there was a significant decrease in serum pro-inflammatory cytokines, such as IL-6, TNF-α, and MCP-1 (p = 0.002, p = 0.000, and p = 0.005, respectively), and an elevation in the anti-inflammatory cytokine IL-10 level (p = 0.000). An increase in hepatic antioxidant capacity was observed. Significant changes in the gut microbiota composition were noted, including increased populations of Bifidobacterium and Lactobacillus and decreased levels of Escherichia/Shigella and Bacteroides.

Conclusion

The findings suggest that LC86 supplementation mitigates muscle weakness and cognitive impairment in aging SAMP8 mice, potentially through the modulation of inflammation and gut microbiota composition. LC86 emerges as a promising candidate for ameliorating the decline of muscular and cognitive functions associated with aging.

The role of non-coding RNAs in muscle aging: regulatory mechanisms and therapeutic potential

Muscle aging is a complex physiological process that leads to the progressive decline in muscle mass and function, contributing to debilitating conditions in the elderly such as sarcopenia. In recent years, non-coding RNAs (ncRNAs) have been increasingly recognized as major regulators of muscle aging and related cellular processes. Here, we comprehensively review the emerging role of ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in the regulation of muscle aging. We also discuss how targeting these ncRNAs can be explored for the development of novel interventions to combat age-related muscle decline. The insights provided in this review offer a promising avenue for future research and therapeutic strategies aimed at improving muscle health during aging.

lncRNA GPRC5D-AS1 as a ceRNA inhibits skeletal muscle aging by regulating miR-520d-5p

Sarcopenia induced by muscle aging is associated with negative outcomes in a variety of diseases. Long non-coding RNAs are a class of RNAs longer than 200 nucleotides with lower protein coding potential. An increasing number of studies have shown that lncRNAs play a vital role in skeletal muscle development. According to our previous research, lncRNA GPRC5D-AS1 is selected in the present study as the target gene to further study its effect on skeletal muscle aging in a dexamethasone-induced human muscle atrophy cell model. As a result, GPRC5D-AS1 functions as a ceRNA of miR-520d-5p to repress cell apoptosis and regulate the expression of muscle regulatory factors, including MyoD, MyoG, Mef2c and Myf5, thus accelerating myoblast proliferation and differentiation, facilitating development of skeletal muscle. In conclusion, lncRNA GPRC5D-AS1 could be a novel therapeutic target for treating sarcopenia.

Advances in research on cell models for skeletal muscle atrophy

Skeletal muscle, the largest organ in the human body, plays a crucial role in supporting and defending the body and is essential for movement. It also participates in regulating the processes of protein synthesis and degradation. Inhibition of protein synthesis and activation of degradation metabolism can both lead to the development of skeletal muscle atrophy, a pathological condition characterized by a decrease in muscle mass and fiber size. Many physiological and pathological conditions can cause a decline in muscle mass, but the underlying mechanisms of its pathogenesis remain incompletely understood, and the selection of treatment strategies and efficacy evaluations vary. Moreover, the early symptoms of this condition are often not apparent, making it easily overlooked in clinical practice. Therefore, it is necessary to develop and use cell models to understand the etiology and influencing factors of skeletal muscle atrophy. In this review, we summarize the methods used to construct skeletal muscle cell models, including hormone, inflammation, cachexia, genetic engineering, drug, and physicochemical models. We also analyze, compare, and evaluate the various construction and assessment methods.

Pathogenic mycoplasmas of humans regulate the long noncoding RNAs in epithelial cells

Non-coding RNAs (ncRNAs), specifically long ncRNAs (lncRNAs), regulate cellular processes by affecting gene expression at the transcriptional, post-transcriptional, and epigenetic levels. Emerging evidence indicates that pathogenic microbes dysregulate the expression of host lncRNAs to suppress cellular defense mechanisms and promote survival. To understand whether the pathogenic human mycoplasmas dysregulate host lncRNAs, we infected HeLa cells with Mycoplasma genitalium (Mg) and Mycoplasma penumoniae (Mp) and assessed the expression of lncRNAs by directional RNA-seq analysis. HeLa cells infected with these species showed up-and-down regulation of lncRNAs expression, indicating that both species can modulate host lncRNAs. However, the number of upregulated (200 for Mg and 112 for Mp) and downregulated lncRNAs (30 for Mg and 62 for Mp) differ widely between these two species. GREAT analysis of the noncoding regions associated with differentially expressed lncRNAs showed that Mg and Mp regulate a discrete set of lncRNA plausibly related to transcription, metabolism, and inflammation. Further, signaling network analysis of the differentially regulated lncRNAs exhibited diverse pathways such as neurodegeneration, NOD-like receptor signaling, MAPK signaling, p53 signaling, and PI3K signaling, suggesting that both species primarily target signaling mechanisms. Overall, the study's results suggest that Mg and Mp modulate lncRNAs to promote their survival within the host but in distinct manners.

Identification and Functional Prediction of Long Non-Coding RNA in Longissimus Dorsi Muscle of Queshan Black and Large White Pigs

Long non-coding RNA (lncRNA) participates in the regulation of various biological processes, but its function and characteristics in intramuscular fat (IMF) deposition in different breeds of pigs have not been fully understood. IMF content is one of the important factors affecting pork quality. In the present study, the differentially expressed lncRNAs (DE lncRNAs) and their target genes were screened by comparing Queshan Black (QS) and Large White (LW) pigs based on RNA-seq. The results displayed 55 DE lncRNAs between QS and LW, 29 upregulated and 26 downregulated, with 172 co-located target genes, and 6203 co-expressed target genes. The results of GO and KEGG analysis showed that the target genes of DE lncRNAs were involved in multiple pathways related to lipogenesis and lipid metabolism, such as the lipid biosynthetic process, protein phosphorylation, activation of MAPK activity, and the Jak-STAT signaling pathway. By constructing regulatory networks, lincRNA-ZFP42-ACTC1, lincRNA-AMY2-STAT1, and/or lincRNA-AMY2/miR-204/STAT1 were sieved, and the results indicate that lncRNA could participate in IMF deposition through direct regulation or ceRNA. These findings provide a basis for analyzing the molecular mechanism of IMF deposition in pigs and lay a foundation for developing and utilizing high-quality resources of local pig breeds.

Multiple myeloma, a quintessential malignant disease of aging: a geroscience perspective on pathogenesis and treatment

Multiple myeloma (MM) is an incurable plasma cell malignancy, which is predominantly a disease of older adults (the median age at diagnosis is 70 years). The slow progression from asymptomatic stages and the late-onset of MM suggest fundamental differences compared to many other hematopoietic system-related malignancies. The concept discussed in this review is that age-related changes at the level of terminally differentiated plasma cells act as the main risk factors for the development of MM. Epigenetic and genetic changes that characterize both MM development and normal aging are highlighted. The relationships between cellular aging processes, genetic mosaicism in plasma cells, and risk for MM and the stochastic processes contributing to clonal selection and expansion of mutated plasma cells are investigated. In line with the DNA damage accumulation theory of aging, in this review, the evolution of monoclonal gammopathy to symptomatic MM is considered. Therapeutic consequences of age-dependent comorbidities that lead to frailty and have fundamental influence on treatment outcome are described. The importance of considering geriatric states when planning the life-long treatment course of an elderly MM patient in order to achieve maximal therapeutic benefit is emphasized.

seRNA PAM controls skeletal muscle satellite cell proliferation and aging through trans regulation of Timp2 expression synergistically with Ddx5

Muscle satellite cells (SCs) are responsible for muscle homeostasis and regeneration and lncRNAs play important roles in regulating SC activities. Here, in this study, we identify PAM (Pax7 Associated Muscle lncRNA) that is induced in activated/proliferating SCs upon injury to promote SC proliferation as myoblast cells. PAM is generated from a myoblast-specific super-enhancer (SE); as a seRNA it binds with a number of target genomic loci predominantly in trans. Further studies demonstrate that it interacts with Ddx5 to tether PAM SE to its inter-chromosomal targets Timp2 and Vim to activate the gene expression. Lastly, we show that PAM expression is increased in aging SCs, which leads to enhanced inter-chromosomal interaction and target genes upregulation. Altogether, our findings identify PAM as a previously unknown lncRNA that regulates both SC proliferation and aging through its trans gene regulatory activity.

The Functional Role of Long Non-Coding RNA in Myogenesis and Skeletal Muscle Atrophy

Skeletal muscle is a pivotal organ in humans that maintains locomotion and homeostasis. Muscle atrophy caused by sarcopenia and cachexia, which results in reduced muscle mass and impaired skeletal muscle function, is a serious health condition that decreases life longevity in humans. Recent studies have revealed the molecular mechanisms by which long non-coding RNAs (lncRNAs) regulate skeletal muscle mass and function through transcriptional regulation, fiber-type switching, and skeletal muscle cell proliferation. In addition, lncRNAs function as natural inhibitors of microRNAs and induce muscle hypertrophy or atrophy. Intriguingly, muscle atrophy modifies the expression of thousands of lncRNAs. Therefore, although their exact functions have not yet been fully elucidated, various novel lncRNAs associated with muscle atrophy have been identified. Here, we comprehensively review recent knowledge on the regulatory roles of lncRNAs in skeletal muscle atrophy. In addition, we discuss the issues and possibilities of targeting lncRNAs as a treatment for skeletal muscle atrophy and muscle wasting disorders in humans.