Bovine Myoblast Differentiation

Satellite cells are involved in postnatal myogenesis and in muscle hypertrophy. A better understanding of the mechanisms of myogenesis is useful to improve the muscle production in farm animals. Herein, we show the cytokine effects on the myogenesis in bovine myoblast cultures. Acidic fibroblast growth factors (aFGF) and interleukin 1 (IL-1) stimulated the cell proliferation, and insulin-1ike growth factor-I (IGF-I) stimulated to form multinucleated myotubes. Thus, it was possible to regulate the bovine myoblast differentiation by aFGF, IL-1 and/or IGF-I. Using the culture system, the expression of myosin heavy chain (MyHC) isoforms was detailed in bovine myoblasts during the differentiation. It was immunohistochemically confirmed that bovine myoblasts expressed β/slow-type MyHC (MyHC-slow), fast-type MyHC (MyHC-fast) and developmental-type MyHC (MyHC-dev) isoforms. Furthermore, the expression of fast 2a and β/slow MyHC mRNA was recognized in the cultures of bovine myoblasts. The results support the existence of bovine myoblast phenotypes that express differentially MyHC isoforms

Anterior Pituitary Progenitor Cells Express Costimulatory Molecule 4Ig-B7-H31

Abstract Stem/Progenitor cells in the postnatal pituitary gland are embedded in a marginal cell layer around Rathke’s pouch. However, the nature and behavior of anterior pituitary progenitor cells remain unclear. We established bovine anterior pituitary progenitor cell line (BAPC)-1 from the anterior pituitary gland, which expressed stem/progenitor cell-related genes and several inflammatory cytokines. To characterize and localize these pituitary progenitor cells, we produced a mAb (12B mAb) against BAPC-1. The 12B mAb recognized the 4Ig-B7-H3 molecule, which is a costimulatory molecule and negative regulator in T cell activation. WC1+ γδ T cells in young bovine PBMC express the 4Ig-B7-H3 molecule, but few or no 4Ig-B7-H3-immunoreactive cells are expressed in PBMC in adult cattle. The 12B-immunoreactive cells in the bovine anterior pituitary gland were localized around Rathke’s pouch and expressed IL-18 and MHC class II. However, the number of 12B-immunoreactive cells was lower in adult than in young cattle. BAPC-1 expressed IL-18 and MHC class II, and demonstrated phagocytotic activity. BAPC-1 also had the ability to promote CD25 expression in PBMC after 5 days of coculture, and blocking 4Ig-B7-H3 × 12B mAb enhanced their expression of CD25. In addition, the 12B-immunoreactive cells were observed around the pars tuberalis closely bordering the median eminence and in the blood vessels of the primary portal plexus in the anterior pituitary gland. These results suggest that an established BAPC-1 may originate from these progenitor cells, and that the progenitor cells with 4Ig-B7-H3 may play a critical role in the immunoendocrine network.</jats:p