Role of cyclophilin B in prolactin signal transduction and nuclear retrotranslocation.
Role of cyclophilin B in prolactin signal transduction and nuclear retrotranslocation.
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DOI：
10.1210/mend.14.8.0508
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发表时间：
2000-08
影响因子：
--
通讯作者：
M. Rycyzyn;Sean C. Reilly;Kerri O’Malley;C. Clevenger
中科院分区：
文献类型：
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作者：
M. Rycyzyn;Sean C. Reilly;Kerri O’Malley;C. Clevenger
PRL的多效性作用是乳腺生长、分化和体外淋巴细胞增殖所必需的。该配体的近端作用由其细胞表面受体通过相关网络介导。然而，催乳素的作用也与这种激素的内化和转运到细胞核中有关。为了阐明这种逆转录易位的机制，进行酵母双杂交筛选，并揭示了PRL和亲环素B（CypB）之间的相互作用。CypB是在内质网、细胞外空间和细胞核中发现的肽基脯氨酰异构酶（PPI）。CypB和PRL之间的相互作用，随后证实在体外和体内通过使用重组蛋白和免疫共沉淀研究。CypB的外源性添加增强3 H-胸苷掺入的PRL依赖性细胞系高达18倍。CypB本身无促有丝分裂作用，不增强GH或其他白细胞介素的作用。CypB没有改变PRL受体（PRLr）对其配体的亲和力，也没有增加PRLr相关的Jak 2或Stat 5a的磷酸化。然而，CypB对PRL作用的增强伴随着PRL核转位的急剧增加。CypB突变体，称为CypB-NT，产生缺乏野生型N-末端核定位序列。虽然CypB-NT表现出与野生型CypB相当的PRL结合和PPI活性水平，但它不能介导PRL的核转位或增强PRL驱动的增殖。这些研究揭示CypB作为促进催乳激素的核逆向转运和作用的重要伴侣。
The pleiotropic actions of PRL are necessary for mammary growth and differentiation and in vitro lymphoid proliferation. The proximal action of this ligand is mediated by its cell surface receptor via associated networks. PRL action, however, is also associated with the internalization and translocation of this hormone into the nucleus. To delineate the mechanism of this retrotranslocation, a yeast two-hybrid screen was performed and revealed an interaction between PRL and cyclophilin B (CypB). CypB is a peptidyl prolyl isomerase (PPI) found in the endoplasmic reticulum, extracellular space, and nucleus. The interaction between CypB and PRL was subsequently confirmed in vitro and in vivo through the use of recombinant proteins and coimmunoprecipitation studies. The exogenous addition of CypB potentiated the 3H-thymidine incorporation of PRL-dependent cell lines up to 18-fold. CypB by itself was nonmitogenic and did not potentiate the action of GH or other interleukins. CypB did not alter the affinity of the PRL receptor (PRLr) for its ligand, or increase the phosphorylation of PRLr-associated Jak2 or Stat5a. The potentiation of PRL-action by CypB, however, was accompanied by a dramatic increase in the nuclear retrotranslocation of PRL. A CypB mutant, termed CypB-NT, was generated that lacked the wild-type N-terminal nuclear localization sequence. Although CypB-NT demonstrated levels of PRL binding and PPI activity equivalent to wild-type CypB, it was incapable of mediating the nuclear retrotranslocation of PRL or enhancing PRL-driven proliferation. These studies reveal CypB as an important chaperone facilitating the nuclear retrotransport and action of the lactogenic hormones.