A post-middle-age crisis for CD47 and THBS1 that turns into a vicious cycle

The long noncoding RNA lncMPD2 inhibits myogenesis by targeting the miR-34a-5p/THBS1 axis

Long noncoding RNAs (lncRNAs) participate in regulating skeletal muscle development. However, little is known about their role in regulating chicken myogenesis. In this study, we identified a novel lncRNA, lncMPD2, through transcriptome sequencing of chicken myoblasts at different developmental stages. Functionally, gain- and loss-of-function experiments showed that lncMPD2 inhibited myoblast proliferation and differentiation. Mechanistically, lncMPD2 directly bound to miR-34a-5p, and miR-34a-5p promoted myoblasts proliferation and differentiation and inhibited the mRNA and protein expression of its target gene THBS1. THBS1 inhibited myoblast proliferation and differentiation in vitro and delayed muscle regeneration in vivo. Furthermore, rescue experiments showed that lncMPD2 counteracted the inhibitory effects of miR-34a-5p on THBS1 and myogenesis-related gene mRNA and protein expression. In conclusion, lncMPD2 regulates the miR-34a-5p/THBS1 axis to inhibit the proliferation and differentiation of myoblasts and skeletal muscle regeneration. This study provides more insight into the molecular regulatory network of skeletal muscle development, identifying novel potential biomarkers for improving chicken quality and increasing chicken yield. In addition, this study provides a potential goal for breeding strategies that minimize muscle damage in chickens.

Integrin β1-rich extracellular vesicles of kidney recruit Fn1+ macrophages to aggravate ischemia-reperfusion-induced inflammation

Ischemia-reperfusion injury-induced (IRI-induced) acute kidney injury is accompanied by mononuclear phagocyte (MP) invasion and inflammation. However, systematic analysis of extracellular vesicle-carried (EV-carried) proteins mediating intercellular crosstalk in the IRI microenvironment is still lacking. Multiomics analysis combining single-cell RNA-Seq data of kidney and protein profiling of kidney-EV was used to elucidate the intercellular communication between proximal tubular cells (PTs) and MP. Targeted adhesion and migration of various MPs were caused by the secretion of multiple chemokines as well as integrin β1-rich EV by ischemic-damaged PTs after IRI. These recruited MPs, especially Fn1+ macrophagocyte, amplified the surviving PT's inflammatory response by secreting the inflammatory factors TNF-α, MCP-1, and thrombospondin 1 (THBS-1), which could interact with integrin β1 to promote more MP adhesion and interact with surviving PT to further promote the secretion of IL-1β. However, GW4869 reduced MP infiltration and maintained a moderate inflammatory level likely by blocking EV secretion. Our findings establish the molecular bases by which chemokines and kidney-EV mediate PT-MP crosstalk in early IRI and provide insights into systematic intercellular communication.

CRIPTO-based micro-heterogeneity of mouse muscle satellite cells enables adaptive response to regenerative microenvironment

Skeletal muscle repair relies on heterogeneous populations of satellite cells (SCs). The mechanisms that regulate SC homeostasis and state transition during activation are currently unknown. Here, we investigated the emerging role of non-genetic micro-heterogeneity, i.e., intrinsic cell-to-cell variability of a population, in this process. We demonstrate that micro-heterogeneity of the membrane protein CRIPTO in mouse-activated SCs (ASCs) identifies metastable cell states that allow a rapid response of the population to environmental changes. Mechanistically, CRIPTO micro-heterogeneity is generated and maintained through a process of intracellular trafficking coupled with active shedding of CRIPTO from the plasma membrane. Irreversible perturbation of CRIPTO micro-heterogeneity affects the balance of proliferation, self-renewal, and myogenic commitment in ASCs, resulting in increased self-renewal in vivo. Our findings demonstrate that CRIPTO micro-heterogeneity regulates the adaptative response of ASCs to microenvironmental changes, providing insights into the role of intrinsic heterogeneity in preserving stem cell population diversity during tissue repair.