Evidence that the interaction between insulin-like growth factor (IGF)-II and IGF binding protein (IGFBP)-4 is essential for the action of the IGF-II-dependent IGFBP-4 protease.
Evidence that the interaction between insulin-like growth factor (IGF)-II and IGF binding protein (IGFBP)-4 is essential for the action of the IGF-II-dependent IGFBP-4 protease.
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有证据表明，胰岛素样生长因子 (IGF)-II 和 IGF 结合蛋白 (IGFBP)-4 之间的相互作用对于 IGF-II 依赖性 IGFBP-4 蛋白酶的作用至关重要。
DOI：
10.1006/abbi.2000.1872
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Mohan,S
中科院分区：
文献类型：
--
作者：
Qin,X;Byun,D;Lau,KH;Baylink,DJ;Mohan,S
多种类型的人类细胞，包括人类成骨细胞(HOBS)，产生一种IGFBP-4蛋白酶，在IGF-II存在的情况下分解IGFBP-4。最近，妊娠相关血浆蛋白(PAPP)-A被确定为人成纤维细胞产生的依赖于IGF-II的IGFBP-4蛋白。本研究试图确定IGF-II促进IGFBP-4蛋白降解的机制。加入PAPP-A抗体可阻断HOB条件培养液中IGFBP-4的蛋白分解活性，提示PAPP-A是HOB条件培养液中主要的IGFBP-4蛋白水解酶。IGFBP-4与IGF-II预先孵育，然后去除未结合的IGF-II，导致IGFBP-4蛋白降解，而不需要IGF-II的进一步存在。相反，从HOB CM或人妊娠血清中部分纯化的IGFBP-4蛋白酶与IGF-II预先孵育不会导致IGFBP-4蛋白分解，除非将IGF-II重新加入检测中。为了进一步证实IGFBP-4酶活性需要IGF-II和IGFBP-4之间的相互作用，我们通过删除IGF结合域中的Leu72-His74残基或含有IGF结合增强基序的Cys183-Glu237，制备了含有完整切割位点(Met135-Lys136)但缺乏IGF结合活性的IGFBP-4突变体。无论检测中是否存在IGF-II，IGFBP-4酶都不能切割这些IGFBP-4突变体。相反，具有正常IGF结合活性的His74被Ala取代的IGFBP-4突变体在IGF-II存在下被有效切割。综上所述，这些发现提供了强有力的证据，表明最佳的IGFBP-4蛋白降解需要IGF-II和IGFBP-4之间的相互作用，而不是IGF-II和IGFBP-4酶之间的直接相互作用。
A variety of human cell types, including human osteoblasts (hOBs), produce an IGFBP-4 protease, which cleaves IGFBP-4 in the presence of IGF-II. Recently, the pregnancy-associated plasma protein (PAPP)-A has been determined to be the IGF-II-dependent IGFBP-4 protease produced by human fibroblasts. This study sought to define the mechanism by which IGF-II enhances IGFBP-4 proteolysis. Addition of PAPP-A antibody blocked the IGFBP-4 proteolytic activity in hOB conditioned medium (CM), suggesting that PAPP-A is the major IGFBP-4 protease in hOB CM. Pre-incubation of IGFBP-4 with IGF-II, followed by removal of unbound IGF-II, led to IGFBP-4 proteolysis without further requirement of the presence of IGF-II in the reaction. In contrast, prior incubation of the partially purified IGFBP-4 protease from either hOB CM or human pregnancy serum with IGF-II did not lead to IGFBP-4 proteolysis unless IGF-II was re-added to the assays. To further confirm that the interaction between IGF-II and IGFBP-4 is required for IGFBP-4 protease activity, we prepared IGFBP-4 mutants, which contained the intact cleavage site (Met135–Lys136) but lacked the IGF binding activity, by deleting the residues Leu72–His74 in the IGF binding domain or Cys183–Glu237 that contained an IGF binding enhancing motif. The IGFBP-4 protease was unable to cleave these IGFBP-4 mutants, regardless of whether or not IGF-II was present in the assay. Conversely, an IGFBP-4 mutant with His74 replaced by an Ala, which exhibited normal IGF binding activity, was effectively cleaved in the presence of IGF-II. Taken together, these findings provided strong evidence that the interaction between IGF-II and IGFBP-4, rather than the direct interaction between IGF-II and IGFBP-4 protease, is required for optimal IGFBP-4 proteolysis.
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影响因子：
4.8
作者：
E. K. Neely;R. G. Rosenfeld
通讯作者：
E. K. Neely;R. G. Rosenfeld
影响因子：
4.8
作者：
J. Fowlkes;M. Freemark
通讯作者：
J. Fowlkes;M. Freemark
胰岛素样生长因子-I (IGF-I) 增强人蜕膜原代培养物条件培养基中 IGF 结合蛋白 4 的蛋白水解：独立于 IGF 受体结合。
影响因子：
4.8
作者：
Myers,SE;Cheung,PT;Handwerger,S;Chernausek,SD
通讯作者：
Chernausek,SD
人子宫内膜基质细胞培养物中胰岛素样生长因子结合蛋白 4 的调节：配体诱导蛋白水解的证据。
DOI：
10.1210/jcem.80.2.7531715
发表时间：
1995
期刊：
The Journal of clinical endocrinology and metabolism.
影响因子：
--
作者：
Irwin,JC;Dsupin,BA;Giudice,LC
通讯作者：
Giudice,LC
影响因子：
4.1
作者：
CANALIS, E
通讯作者：
CANALIS, E