ALPHA-5 INTEGRIN SUBUNIT EXPRESSION CHANGES DURING MYOGENESIS

Fibronectin and its cellular receptor, the alpha5beta1 integrin, are involved in the transmembrane signalling events that control muscle cell differentiation. In this study, the expression of the alpha5 integrin subunit was followed by reverse transcription-polymerase chain reaction (RT-PCR) to determine alterations during myogenesis. In studies of murine muscle, we found a 90% reduction in the level of the alpha5 integrin subunit mRNA during early postnatal development. Concurrently, the fibronectin alternative splicing pattern changed markedly in the EIIIB and V exons. In-vitro analyses of these molecules during myoblast differentiation revealed changes that followed trends similar to those observed in vivo, although of lesser magnitude. These observations imply an important role of fibronectin and the alpha5 integrin subunit in muscle development.