Basic helix-loop-helix proteins and the timing of oligodendrocyte differentiation.
Basic helix-loop-helix proteins and the timing of oligodendrocyte differentiation.
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作者：
T. Kondo;M. Raff
少突胶质前体细胞中的细胞内计时器被认为有助于控制其分化的时间。我们在这里发现，在这些细胞中，编码神经特异性bHLH蛋白的Hes5和Mash1基因的表达分别随着时间的推移而减少和增加，如果这些蛋白是计时器的一部分。我们发现，在纯化的前体细胞中，Hes5的强制表达强烈抑制甲状腺激素受体蛋白TR()1的正常增加，这被认为是定时机制的一部分；它还能强烈抑制丝裂原停用或甲状腺激素治疗诱导的分化。相比之下，Mash1的强制表达在一定程度上加速了TR(β)1蛋白的增加。这些发现提示Hes5和Mash1可能是前体细胞中细胞内在计时器的一部分。
An intracellular timer in oligodendrocyte precursor cells is thought to help control the timing of their differentiation. We show here that the expression of the Hes5 and Mash1 genes, which encode neural-specific bHLH proteins, decrease and increase, respectively, in these cells with a time course expected if the proteins are part of the timer. We show that enforced expression of Hes5 in purified precursor cells strongly inhibits the normal increase in the thyroid hormone receptor protein TR()1, which is thought to be part of the timing mechanism; it also strongly inhibits the differentiation induced by either mitogen withdrawal or thyroid hormone treatment. Enforced expression of Mash1, by contrast, somewhat accelerates the increase in TR(beta)1 protein. These findings suggest that Hes5 and Mash1 may be part of the cell-intrinsic timer in the precursor cells.