Boschi N M, Takeuchi K, Sterling C, Tank A W
Department of Pharmacology & Physiology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, United States.
Department of Pharmacology & Physiology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, United States; Department of Psychiatry, North Rias Hospital, Monzen 1-151-1, Kuji, Iwate 0280021, Japan.
Neuroscience. 2015 Feb 12;286:1-12. doi: 10.1016/j.neuroscience.2014.11.038. Epub 2014 Nov 26.
Polycytosine-binding proteins (PCBPs) are RNA-binding proteins that participate in post-transcriptional control pathways. Among the diverse functions of these proteins is the interaction with a 27 nucleotide pyrimidine-rich domain within the 3'UTR of tyrosine hydroxylase (TH) mRNA. Mutations to this domain result in decreased stability of TH mRNA and loss of cAMP-mediated activation of TH mRNA translation. PCBPs are hypothesized to play key roles in these regulatory mechanisms. In order to further test this hypothesis, we examined the tissue distribution of PCBPs in catecholaminergic cells. Initial studies demonstrated that proteins from catecholaminergic tissues bind to TH mRNA 3'UTR sequences and these proteins have an apparent Mr of ∼ 44 kDa, which is close to the molecular sizes for PCBPs. Fluorescent immunohistochemistry and confocal microscopy was used to analyze the distribution of PCBP isoforms in TH-positive cells of the rat midbrain, locus coeruleus, and adrenal gland. Our results suggest that: (1) PCBP2 is the predominant isoform in TH-positive cells of the rat midbrain; (2) PCBP3 is the predominant isoform in TH-positive cells of the locus coeruleus; and (3) PCBP1 is the predominant isoform in the adrenal medulla. The localization of PCBP proteins to TH-positive cells in these catecholaminergic tissues is consistent with the hypothesis that PCBPs play a role in the regulation of TH expression.
聚胞嘧啶结合蛋白（PCBP）是参与转录后调控途径的RNA结合蛋白。这些蛋白的多种功能之一是与酪氨酸羟化酶（TH）mRNA 3'非翻译区（UTR）内一个富含27个核苷酸的嘧啶结构域相互作用。该结构域的突变会导致TH mRNA稳定性降低以及cAMP介导的TH mRNA翻译激活丧失。据推测，PCBP在这些调控机制中起关键作用。为了进一步验证这一假设，我们研究了PCBP在儿茶酚胺能细胞中的组织分布。初步研究表明，来自儿茶酚胺能组织的蛋白与TH mRNA 3'UTR序列结合，这些蛋白的表观分子量约为44 kDa，与PCBP的分子大小相近。采用荧光免疫组织化学和共聚焦显微镜分析PCBP异构体在大鼠中脑、蓝斑和肾上腺TH阳性细胞中的分布。我们的结果表明：（1）PCBP2是大鼠中脑TH阳性细胞中的主要异构体；（2）PCBP3是蓝斑TH阳性细胞中的主要异构体；（3）PCBP1是肾上腺髓质中的主要异构体。这些儿茶酚胺能组织中PCBP蛋白在TH阳性细胞中的定位与PCBP在TH表达调控中起作用的假设一致。
