Muscle fibers are the main component of skeletal muscle and undergo maturation through the formation of myotubes.  During early development, a population of skeletal muscle satellite cells (SSCs) proliferate into myoblasts.  The myoblasts then undergo further differentiation and fusion events, leading to the development of myotubes.  However, the mechanisms involved in the transition from SSCs to myotube formation remain unclear.  In this study, we characterized changes in the proteomic and transcriptomic expression profiles of SSCs, myoblasts (differentiation for 2 d) and myotubes (differentiation for 10 d).  Proteomic analysis identified SLMAP and STOM as potentially associated with myotube formation.  In addition, some different changes in MyoD, MyoG, Myosin7 and Desmin occurred after silencing SLMAP and STOM, suggesting that they may affect changes in the myogenic marker.  GO analysis indicated that the differentiation and migration factors SVIL, ENSCHIG00000026624 (AQP1) and SERPINE1 enhanced the transition from SSCs to myoblasts, accompanied by changes in the apoptotic balance.  In the myoblast vs. myotube group, candidates related to cell adhesion and signal transduction were highly expressed in the myotubes.  Additionally, CCN2, TGFB1, MYL2 and MYL4 were identified as hub-candidates in this group.  These data enhance our existing understanding of myotube formation during early development and repair.

MicroRNA (miRNA) has vital regulatory effects on the proliferation, differentiation and secretion of ovarian granulosa cells, but the role of miR-99a-5p in goat ovarian granulosa cells (GCs) is unclear.  Both miR-99a-5p and Frizzled-5 (FZD5) were found to be expressed in GCs in goat ovaries via fluorescence in situ hybridization and immunohistochemistry, respectively, and FZD5 was verified (P<0.001) as a target gene of miR-99a-5p by double luciferase reporter gene experiments.  Furthermore, FZD5 mRNA and protein expression were both found to be regulated (P<0.05) by miR-99a-5p in GCs.  Moreover, the overexpression of miR-99a-5p or knockdown of FZD5 suppressed (P<0.05) estradiol and progesterone secretion from the GCs, as determined by ELISA.  In summary, miR-99a-5p inhibits target gene FZD5 expression and estradiol and progesterone synthesis in GCs.  Our study thus provides seminal data and new insights into the regulatory mechanisms of follicular development in the goat and other animals.

Skin and hair pigmentation in animals involve intricate regulatory processes. Circular RNA-microRNA (circRNA-miRNA) networks play vital roles in various biological processes, although their involvement in pigmentation has been underexplored. This study focused on circKIF27 expression, which differs significantly in melanocytes isolated from white and brown Boer coat-colored skin, yet its function remains unclear. Here, we investigated the roles of circKIF27 in melanocytes. In situ hybridization assays demonstrated that circKIF27 is expressed in the cytoplasm of melanocytes. qRT-PCR results revealed differential expression levels of circKIF27 in various tissues of male and female goats. Functional analysis showed that circKIF27 overexpression in melanocytes significantly reduces melanin production (P<0.01) and inhibits cell proliferation (P<0.0001). Bioinformatics analysis identified a putative miR-129-5p binding site on circKIF27, and luciferase reporter assays confirmed their interaction. Overexpression of miR-129-5p in melanocytes enhances melanin production (P<0.01) and promotes cell proliferation (P<0.05). Further analysis revealed that TGIF2 possesses two potential miR-129-5p binding sites, and miR-129-5p overexpression in melanocytes significantly inhibits TGIF2 expression (P<0.0001), suggesting a targeted regulatory relationship between these two molecules. Silencing TGIF2 expression via siRNA-TGIF2 transfection leads to increased melanocyte proliferation (P<0.0001) and increased melanin production (P<0.01). These findings highlight the involvement of the circRNA-miRNA network in pigmentation, offering new insights into the molecular mechanisms underlying pigmentation and guiding animal hair color breeding strategies.