Cellular dynamics of transforming growth factor beta-2 [TGF-beta [2]] in the postnatal developing rat muscles

ABSTRACT

Transforming growth factor beta-2 [TGF-beta2] is a multifunctional superfamily. TGF-beta2 has been found to be involved in multiple cellular functions including; cell growth, proliferation, differentiation and death. However, the specific function of muscle-derived TGF-beta2 has not been determined. The localization as well as the study of time course of muscle-derived TGF-beta2 is a crucial step towards understanding the role of TGF-beta in the postnatal developing skeletal muscle. Extensor digitorum longus muscles of Wistar rats at ages 0,2,4,7,13,16,19,21,42 and 90 postnatal days were used. The muscles were processed for double labeling immunohistochemistry and confocal examination. Anti-TGF-beta2 antibodies and alpha-bungarotoxin were used to localize TGF-beta 2 in the muscle fibers of the different age groups. The results showed that TGF-beta2 localizes at the mature neuromuscular junction [nmj] after being diffuse throughout the immature muscle cell. The time curse of muscle derived TGF-beta2 can be divided into 3 phases; the first plateau phase, second fluctuant phase and third plateau phase. The second phase demonstrated a sudden increase of muscle derived TGF-beta2 ratio at the nmj coinciding with the timing of synaptic eliminate on phenomenon of the muscle fibers