Skeletal myogenesis is a highly coordinated process that involves cell proliferation, differentiation and fusion controlled by a complex gene regulatory network. The microRNA gene cluster miR-17–92 has been shown to be related to this process; however, the exact role of each cluster member remains unclear. Here, we show that miR-17 and miR-20a could effectively promote the differentiation of both C2C12 myoblasts and primary bovine satellite cells. In contrast, miR-18a might play a negative role in C2C12 cell differentiation, while miR-19 and miR-92a had little influence. Transcriptome and target analyses revealed that miR-17 could act on Ccnd2, Jak1 and Rhoc genes that are critical for cell proliferation and/or fusion. Notably, the addition of miR-19 could reverse the lethal effect of miR-17 and could thus facilitate the maturation of myotubes. Furthermore, by co-injecting the lentiviral shRNAs of miR-17 and miR-19 into mouse tibialis anterior muscles, we demonstrated the wound healing abilities of the two miRNAs. Our findings indicate that in combination with miR-19, miR-17 is a potent inducer of skeletal muscle differentiation.Electronic supplementary materialThe online version of this article (10.1007/s00018-019-03165-7) contains supplementary material, which is available to authorized users.

Hematopoietic stem cell (HSC) aging is accompanied by hematopoietic reconstitution dysfunction, including loss of regenerative and engraftment ability, myeloid differentiation bias and elevated risks of hematopoietic malignancies. Gut microbiota, a key regulator of host health and immunity, has been recently reported to impact hematopoiesis. However, there is currently limited empirical evidence elucidating the direct impact of gut microbiome on aging hematopoiesis. In this study, we performed fecal microbiota transplantation (FMT) from young mice to aged mice and observed significant increment in lymphoid differentiation and decrease in myeloid differentiation in aged recipient mice. Further, FMT from young mice rejuvenated aged HSCs with enhanced short-term and long-term hematopoietic repopulation capacity. Mechanistically, single-cell RNA sequencing deciphered that FMT from young mice mitigated inflammatory signals, upregulated FoxO signaling pathway and promoted lymphoid differentiation of HSCs during aging. Finally, integrated microbiome and metabolome analyses uncovered that FMT reshaped gut microbiota construction and metabolite landscape, and Lachnospiraceae and tryptophan-associated metabolites promoted the recovery of hematopoiesis and rejuvenated aged HSCs. Together, our study highlights the paramount importance of the gut microbiota in HSC aging and provides insights into therapeutic strategies for aging-related hematologic disorders.

Chimeric antigen receptor (CAR) T cells are potent agents for recognizing and eliminating tumors, and have achieved remarkable success in the treatment of patients with refractory leukemia and lymphoma. However, dysfunction of T cells, including exhaustion, is an inevitable obstacle for persistent curative effects. Here, the authors initially found that calcium signaling is hyperactivated via sustained tonic signaling in CAR‐T cells. Next, it is revealed that the store‐operated calcium entry (SOCE) inhibitor BTP‐2, but not the calcium chelator BAPTA‐AM, markedly diminishes CAR‐T cell exhaustion and terminal differentiation of CAR‐T cells in both tonic signaling and tumor antigen exposure models. Furthermore, BTP‐2 pretreated CAR‐T cells show improved antitumor potency and prolonged survival in vivo. Mechanistically, transcriptome and metabolite analyses reveal that treatment with BTP‐2 significantly downregulate SOCE‐calcineurin‐nuclear factor of activated T‐cells (NFAT) and glycolysis pathways. Together, the results indicate that modulating the SOCE‐calcineurin‐NFAT pathway in CAR‐T cells renders them resistant to exhaustion, thereby yielding CAR products with enhanced antitumor potency.