Mesodermal cell determination and differentiation

Many in vitro systems have been designed to study the processes governing cell determination and differentiation during development. Mammalian culture systems have been particularly helpful in elucidating the mechanisms regulating gene expression during differentiation in cells of mesodermal origin, namely, myoblasts, preadipocytes, and chondroblasts. Studies have shown that particular cis-acting sequences and trans-acting factors are important in determining tissue-specific and developmental gene expression in these systems. The role of growth factors, oncogenes, and other agents during differentiation has also been examined. Recently four putative muscle determination genes have been isolated and are being characterized. These studies have been useful in postulating models of how development proceeds in vivo and how differentiation and transformation to a neoplastic phenotype may be related.