Monday, August 24, 2009

Activin RII and LSJL

LSJL upregulates Activin RII.

Immunohistochemical detection of activin A, follistatin, and activin receptors during fracture healing in the rat.

"Activins exert their cellular effects by way of activin type-I and type-II serine/threonine kinase receptors. Follistatin is an activin-binding protein that can suppress the biological effects of activins. In this study, the immunohistochemical expression of activin A, follistatin, and activin receptors was studied during fracture healing in the rat. Activin A was weakly detected in the periosteum near the fracture ends at an early stage but was absent in the chondrocytes around the fracture gap, where endochondral ossification took place. An antibody to follistatin stained osteogenic cells in the periosteum near the fracture ends; moderate and strong staining were observed in proliferating, mature, and hypertrophied chondrocytes at the sites of endochondral ossification. Levels of activin A and follistatin were high near the osteoblasts on the surface of the newly formed trabecular bone[The increase in FST in LSJL could be a result of new trabecular bone formation]. In addition, an intense localization of activin A was noted where multinucleated osteoclast-like cells were present. This study suggests that the activin-follistatin system may contribute to cellular events related to the formation and remodeling of bone during fracture healing. Activin type-I and type-II receptors were co-expressed in intramembranous and endochondral ossification sites[or it could be this]. The expression of activin type-I, type-II, and type-IIB receptors in the absence of activin A in the endochondral ossification suggests that other isoforms of activins may signal by way of these receptors."

"certain BMPs were shown to bind to activin receptors as well as to their own BMP receptors"

"In normal intact femurs of the rat, activin type-IB and type-II-but not type-I-receptors were weakly expressed in osteogenic cells at the periosteum; however, activin type-I and type-I1 receptors were not observed in osteocytes at the cortical bone."

Myostatin inhibition induces muscle fibre hypertrophy prior to satellite cell activation., states that Activin RII can inhibit Myostatin.

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