Cabrera-Socorro Alfredo, Pueyo Morlans Mercedes, Suarez Sola Maria Luisa, Gonzalez Delgado Francisco J, Castañeyra-Perdomo Agustin, Marin Maria C, Meyer Gundela
Department of Anatomy, Faculty of Medicine, University of La Laguna, 38071, La Laguna, Spain.
Eur J Neurosci. 2006 Apr;23(8):2109-18. doi: 10.1111/j.1460-9568.2006.04750.x.
p73, a homolog of the p53 tumor suppressor, codes for full-length transactivating (TA) and N-terminally truncated (DeltaN) isoforms, with pro- and anti-apoptotic activities, respectively. We examined the expression of the main p73 isoforms in adult human and mouse telencephalon and choroid plexus by immunohistochemistry on paraffin sections, and immunoblotting (IB) of tissue extracts and cerebrospinal fluid (CSF), using antibodies against different protein domains. Cortical neurons expressed TAp73 predominantly in the cytoplasm and DeltaNp73 mainly in the nucleus, with partial overlap in the cytoplasm. Highest expression was found in the hippocampus. IB showed an array of TAp73 variants in adult human cortex and hippocampus. IB of human choroid plexus and CSF using TAp73-specific antibodies revealed the presence of a approximately 90-kDa protein whose molecular weight was reduced after N-deglycosylation, suggesting that glycosylated TAp73 is exported into the CSF. In the mouse, high expression of TAp73 was also detected in the subcommissural organ (SCO), an ependymal gland absent in adult humans. TAp73 colocalized with anti-fibra-Reissner-antibody (AFRU), which is a marker of Reissner's fiber, the secreted SCO product. p73-deficient mice had generalized cortical hypoplasia and hydrocephalus; in addition, we observed a dramatic size reduction of the choroid plexus. However, the SCOs were apparently unaltered and continued to secrete Reissner's fiber. Our findings point to complex and widespread p73 activities in the maintenance of adult cortical neurons and in brain homeostasis. TAp73 in the CSF may play important roles in the maintenance of the adult ventricular wall as well as in the development of the proliferating neuroepithelium.
p73是p53肿瘤抑制因子的同源物，编码具有全长反式激活（TA）和N端截短（DeltaN）的异构体，分别具有促凋亡和抗凋亡活性。我们通过石蜡切片免疫组织化学以及组织提取物和脑脊液（CSF）的免疫印迹（IB），使用针对不同蛋白结构域的抗体，检测了成体人类和小鼠端脑及脉络丛中主要p73异构体的表达。皮质神经元中TAp73主要在细胞质中表达，DeltaNp73主要在细胞核中表达，在细胞质中有部分重叠。在海马体中表达最高。免疫印迹显示在成体人类皮质和海马体中有一系列TAp73变体。使用TAp73特异性抗体对人类脉络丛和脑脊液进行免疫印迹，发现存在一种约90 kDa的蛋白，其分子量在N-去糖基化后降低，表明糖基化的TAp73被分泌到脑脊液中。在小鼠中，在连合下器官（SCO）中也检测到TAp73的高表达，这是一种在成体人类中不存在的室管膜腺。TAp73与抗纤维-赖斯纳抗体（AFRU）共定位，AFRU是赖斯纳纤维（SCO分泌产物）的标志物。p73基因缺陷小鼠出现广泛性皮质发育不全和脑积水；此外，我们观察到脉络丛显著缩小。然而，SCOs明显未改变并继续分泌赖斯纳纤维。我们的研究结果表明，p73在维持成体皮质神经元和脑内稳态方面具有复杂而广泛的活性。脑脊液中的TAp73可能在维持成体脑室壁以及增殖神经上皮的发育中发挥重要作用。
