New insights on the biology of myelin basic protein gene: the neural-immune connection.

In the past 6 years, our conception of the major myelin protein genes has begun to change significantly because of recent findings documenting the existence of new exons encoding other products of these genes. A decade ago the myelin basic protein (MBP) and proteolipid protein (PLP) genes were thought to be expressed solely in myelin-forming cells, and their products were thought to be structural components of myelin. Since then, abundant evidence has been gathered identifying the presence of products of these genes in nonmyelinating cell types including both the immune and the nervous systems. Furthermore, within the nervous system, products of these genes have been identified in neurons and embryonic cells, clearly indicating that these myelin protein genes have additional functions in a number of cell types that are unrelated to myelination. In this brief communication, we review the recent literature that has resulted in this revision of our understanding of the MBP gene structure, products and expression.