Photoperiodic expression of two RALDH enzymes and the regulation of cell proliferation by retinoic acid in the rat hypothalamus
Photoperiodic expression of two RALDH enzymes and the regulation of cell proliferation by retinoic acid in the rat hypothalamus
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DOI：
10.1111/j.1471-4159.2012.07824.x
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发表时间：
2012-08-01
影响因子：
4.7
通讯作者：
McCaffery, Peter
中科院分区：
文献类型：
--
作者：
Shearer, Kirsty D.;Stooney, Patrick N.;McCaffery, Peter
神经化学杂志。（2012）122，789799。摘要维甲酸（RA）已被发现可调节下丘脑功能，但其确切作用部位尚不清楚。这项研究显示，在与下丘脑神经干细胞重叠的第三脑室的延伸细胞中，有视网膜醛脱氢酶（RALDH）的表达。使用器官型切片培养物检查RA对第三脑室内衬祖细胞增殖的影响。正如在神经发生的其他区域中所示，发现RA抑制增殖。大鼠下丘脑RALDH 1表达的动态研究表明，这种酶在光周期控制下的伸长细胞中，在长日照与短日照期间水平最高。与RA合成的这种转变平行，发现第三脑室中的细胞增殖在RA最高时的长时间内最低，这意味着RALDH 1合成的RA可能调节神经干细胞增殖。第二个RA合成酶，RALDH 2也存在于第三脑室内衬的伸长细胞中。与RALDH1相反，RALDH2随着光周期性变化几乎没有变化，但令人惊讶的是，该蛋白质在明显缺乏mRNA转录物的情况下存在，并且假设内吞伸展细胞可能从脑脊液（CSF）中吸收这种酶。
J. Neurochem. (2012) 122, 789799. Abstract Retinoic acid (RA) has been found to regulate hypothalamic function, but precisely where it acts is unknown. This study shows expression of retinaldehyde dehydrogenase (RALDH) enzymes in tanycytes that line the third ventricle in an area overlapping with the site of hypothalamic neural stem cells. The influence of RA was examined on the proliferation of progenitors lining the third ventricle using organotypic slice cultures. As has been shown in other regions of neurogenesis, RA was found to inhibit proliferation. Investigations of the dynamics of RALDH1 expression in the rat hypothalamus have shown that this enzyme is in tanycytes under photoperiodic control with highest levels during long versus short days. In parallel to this shift in RA synthesis, cell proliferation in the third ventricle was found to be lowest during long days when RA was highest, implying that RALDH1 synthesized RA may regulate neural stem cell proliferation. A second RA synthesizing enzyme, RALDH2 was also present in tanycytes lining the third ventricle. In contrast to RALDH1, RALDH2 showed little change with photoperiodicity, but surprisingly the protein was present in the apparent absence of mRNA transcript and it is hypothesized that the endocytic tanycytes may take this enzyme up from the cerebrospinal fluid (CSF).