Thyroid hormone regulates the expression of the MAL proteolipid, a component of glycolipid-enriched membranes, in neonatal rat brain.

ABSTRACT

Detergent-insoluble glycosphingolipid-enriched membranes (DIGs) have been involved in the sorting and transport of specific proteins during oligodendrocyte maturation. The MAL (MAL, MVP17, VIP17) proteolipid, an integral membrane protein present in DIGs in mature oligodendrocytes, has been proposed as a component of the machinery for DIG-mediated transport in a restricted pattern of cell types including myelinating cells. We have previously shown that thyroid hormone regulates the expression of the myelin protein genes coordinately, and have suggested a major role for thyroid hormone in the control of oligodendrocytes generation. Here we show that the expression of the MAL gene is down-regulated by hypothyroidism and up-regulated by hyperthyroidism in myelinated regions of the brain. In contrast, adult-onset hypothyroidism has no effect on the steady-state levels of MAL mRNA. Taken together, our results show that MAL expression during oligodendrocyte maturation is modulated by thyroid hormone, suggesting that this hormone could play an important role in the myelin biogenesis during neonatal development.