Sower Stacia A, Decatur Wayne A, Hausken Krist N, Marquis Timothy J, Barton Shannon L, Gargan James, Freamat Mihael, Wilmot Michael, Hollander Lian, Hall Jeffrey A, Nozaki Masumi, Shpilman Michal, Levavi-Sivan Berta
Center for Molecular and Comparative Endocrinology (C.A.S., W.A.D., K.N.H., T.J.M., S.L.B., J.G., M.F., M.W., J.A.H.), Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire 03824; Robert H. Smith Faculty of Agriculture, Food, and Environment (L.H., M.S., B.L.-S.), The Hebrew University of Jerusalem, Rehovot, Israel 76100; and Sado Marine Biological Station (M.N.), Niigata University, Tassha, Sado, Niigata 952-2135, Japan.
Endocrinology. 2015 Aug;156(8):3026-37. doi: 10.1210/en.2014-1797. Epub 2015 Jun 11.
The gnathostome (jawed vertebrates) classical pituitary glycoprotein hormones, FSH, LH, and TSH, consist of a common α-subunit (GpA1) and unique β-subunits (Gpβ1, -2, and -3), whereas a recently identified pituitary glycoprotein hormone, thyrostimulin, consists of GpA2 and GpB5. This paper reports the identification, expression, and function of an ancestral, nonclassical, pituitary heterodimeric glycoprotein hormone (GpH) consisting of the thyrostimulin A2 subunit with the classical β-subunit in the sea lamprey, Petromyzon marinus, a jawless basal vertebrate. Lamprey (l) GpA2, and lGpHβ were shown to form a heterodimer by coimmunoprecipitation of lGpA2 with FLAG-tagged lGpHβ after the overexpression in transiently transfected COS7 cells using a bipromoter vector. Dual-label fluorescent in situ hybridization and immunohistochemistry showed the coexpression of individual subunits in the proximal pars distalis of the pituitary. GnRH-III (1μΜ) significantly increased the expression of lGpHβ and lGpA2 in in vitro pituitary culture. Recombinant lamprey GpH was constructed by tethering the N terminal of lGpA2 to the C terminal of lGpHβ with a linker region composed of six histidine residues followed by three glycine-serine repeats. This recombinant lamprey GpH activated the lamprey glycoprotein hormone receptor I as measured by increased cAMP/luciferase activity. These data are the first to demonstrate a functional, unique glycoprotein heterodimer that is not found in any other vertebrate. These data suggest an intermediate stage of the structure-function of the gonadotropin/thyroid-stimulating hormone in a basal vertebrate, leading to the emergence of the highly specialized gonadotropin hormones and thyroid stimulating hormones in gnathostomes.
有颌脊椎动物（gnathostome）的经典垂体糖蛋白激素，即促卵泡激素（FSH）、促黄体生成素（LH）和促甲状腺激素（TSH），由一个共同的α亚基（GpA1）和独特的β亚基（Gpβ1、-2和-3）组成，而最近鉴定出的一种垂体糖蛋白激素——促甲状腺素，由GpA2和GpB5组成。本文报道了一种原始的、非经典的、垂体异源二聚体糖蛋白激素（GpH）的鉴定、表达及功能，该激素由七鳃鳗（一种无颌的基底脊椎动物，海七鳃鳗，Petromyzon marinus）的促甲状腺素A2亚基与经典β亚基组成。在瞬时转染的COS7细胞中使用双启动子载体过表达后，通过将带有FLAG标签的七鳃鳗lGpHβ与七鳃鳗lGpA2进行共免疫沉淀，结果显示七鳃鳗（l）GpA2和lGpHβ形成了异源二聚体。双标记荧光原位杂交和免疫组织化学显示，垂体远侧部近端的各个亚基共表达。GnRH-III（1μM）显著增加了体外垂体培养中lGpHβ和lGpA2的表达。通过用由六个组氨酸残基组成的连接区，随后是三个甘氨酸-丝氨酸重复序列，将lGpA2的N末端连接到lGpHβ的C末端，构建了重组七鳃鳗GpH。如通过增加的cAMP/荧光素酶活性所测定的，这种重组七鳃鳗GpH激活了七鳃鳗糖蛋白激素受体I。这些数据首次证明了一种功能性的、独特的糖蛋白异源二聚体，它在任何其他脊椎动物中都未发现。这些数据表明了基底脊椎动物中促性腺激素/促甲状腺激素结构-功能的一个中间阶段，导致了有颌脊椎动物中高度特化的促性腺激素和促甲状腺激素的出现。
