A head-to-toe dimerization has physiological relevance for ligand-induced inactivation of protein tyrosine receptor type Z
A head-to-toe dimerization has physiological relevance for ligand-induced inactivation of protein tyrosine receptor type Z
复制标题
DOI：
10.1074/jbc.ra119.007878
复制
发表时间：
2019-10-11
影响因子：
4.8
通讯作者：
Noda, Masaharu
中科院分区：
文献类型：
--
作者：
Fujikawa, Akihiro;Sugawara, Hajime;Noda, Masaharu
Z型蛋白酪氨酸磷酸酶（PTPRZ）受体（PTPRZ）有两种亚型，PTPRZ-A和-B，含有串联的胞内PTP-D1和-D2结构域，只有D1具有活性。多效营养因子（PTN）与细胞外PTPRZ区结合导致其PTPRZ活性失活，从而促进中枢神经系统中的少突胶质前体细胞（OPC）分化和髓鞘形成。然而，负责PTN诱导的PTPRZ失活的机制仍不清楚。我们在此报告，晶体结构的细胞内区域的PTPRZ（PTPRZ-ICR）显示？从头到脚？型二聚体构象，与D2掩蔽D1的催化位点。MS分析显示，PTPRZ-ICR蛋白在水溶液中保持单体-二聚体平衡，并且底物衍生的抑制肽或竞争性抑制剂（SCB 4380）以1：1的比例特异性结合单体形式。D2缺失（？D2）或二聚体界面突变（DDKK）破坏二聚体形成，但SCB 4380结合得以维持。类似于WT PTPRZ-B，单体偏置PTPRZ-B-？当在BHK-21细胞中共表达时，D2和PTPRZ-B-DDKK变体在Tyr-1105处有效地使p190 RhoGAP去磷酸化。这些变体的催化活性不被PTN处理抑制，但被细胞渗透性PTN抑制剂NAZ 2329抑制。值得注意的是，PTN治疗并没有提高原代培养的胶质细胞从OPC分化？D2或PTPase-inactive PTPRZ-B（CS）突变敲入小鼠。因此，我们的研究结果表明，PTN诱导的PTPRZ失活的结果从二聚体形成的细胞内串联PTP结构域在头到脚的配置，这是生理相关的OPC分化的控制在体内。
Protein-tyrosine phosphatase (PTPase) receptor type Z (PTPRZ) has two receptor isoforms, PTPRZ-A and -B, containing tandem intracellular PTP-D1 and -D2 domains, with only D1 being active. Pleiotrophin (PTN) binding to the extracellular PTPRZ region leads to inactivation of its PTPase activity, thereby facilitating oligodendrocyte precursor cell (OPC) differentiation and myelination in the central nervous system. However, the mechanisms responsible for PTN-induced PTPRZ inactivation remain unclear. We herein report that the crystal structure of the intracellular region of PTPRZ (PTPRZ-ICR) shows a ?head-to-toe?-type dimer conformation, with D2 masking the catalytic site of D1. MS analyses revealed that PTPRZ-ICR proteins remain in monomer-dimer equilibrium in aqueous solution and that a substrate-derived inhibitory peptide or competitive inhibitor (SCB4380) specifically bind to the monomer form in a 1:1 ratio. A D2 deletion (?D2) or dimer interface mutation (DDKK) disrupted dimer formation, but SCB4380 binding was maintained. Similar to WT PTPRZ-B, monomer-biased PTPRZ-B-?D2 and PTPRZ-B-DDKK variants efficiently dephosphorylated p190RhoGAP at Tyr-1105 when co-expressed in BHK-21 cells. The catalytic activities of these variants were not suppressed by PTN treatment, but were inhibited by the cell-permeable PTPase inhibitor NAZ2329. Of note, the PTN treatment did not enhance OPC differentiation in primary cultured glial cells from ?D2 or PTPase-inactive PTPRZ-B (CS) mutant knock-in mice. Our results thus indicate that PTN-induced PTPRZ inactivation results from dimer formation of the intracellular tandem PTP domains in a head-to-toe configuration, which is physiologically relevant to the control of OPC differentiation in vivo.