Yan R T, Wang S Z
Department of Ophthalmology, University of Alabama at Birmingham School of Medicine 35233, USA.
J Neurobiol. 1998 Mar;34(4):319-28.
The initiation of cellular differentiation in the vertebrate central nervous system is a cascade of regulated gene expression events involving both intrinsic and extrinsic factors. Currently, the molecular events underlying the developmental transition from the cessation of cell proliferation to the onset of cell differentiation during neurogenesis are still poorly understood. We have identified a gene, tenp, which is likely to play a role during the transition. tenp mRNA was detected in the developing retina and brain, but not in the heart, kidney, or liver. Anatomically, cells expressing tenp formed a narrow strip at the boundary between the ventricular zone (consisting of proliferating cells) and the intermediate zone (occupied by postmitotic, differentiating cells). Further analysis showed that they were bromodeoxyuridine negative and thus postmitotic, yet without apparent differentiation such as the expression of microtubule-associated protein (MAP2) and neurofilament (NF68). When expressed in chicken embryonic fibroblast cells through transfection, Tenp protein was immunodetected in membrane fractions, implying that Tenp might be a membrane protein as predicted by a computer analysis of its primary sequence. Our data suggested that tenp might be involved in an early neurogenic event that existed transiently after terminal mitosis, yet before the overt differentiation of neural precursor cells.
脊椎动物中枢神经系统中细胞分化的起始是一系列受调控的基因表达事件，涉及内在和外在因素。目前，对于神经发生过程中从细胞增殖停止到细胞分化开始这一发育转变背后的分子事件仍知之甚少。我们鉴定出了一个基因tenp，它可能在这一转变过程中发挥作用。tenp mRNA在发育中的视网膜和大脑中被检测到，但在心脏、肾脏或肝脏中未被检测到。从解剖学角度来看，表达tenp的细胞在脑室区（由增殖细胞组成）和中间区（被有丝分裂后、正在分化的细胞占据）之间的边界处形成一条狭窄的带。进一步分析表明，它们溴脱氧尿苷阴性，因此是有丝分裂后细胞，但没有明显的分化，如微管相关蛋白（MAP2）和神经丝（NF68）的表达。当通过转染在鸡胚成纤维细胞中表达时，Tenp蛋白在膜组分中被免疫检测到，这意味着Tenp可能是一种膜蛋白，正如对其一级序列进行计算机分析所预测的那样。我们的数据表明，tenp可能参与了一个早期神经发生事件，该事件在终末有丝分裂后短暂存在，但在神经前体细胞明显分化之前。
