Site-Specific IGFBP-1 Hyper-Phosphorylation in Fetal Growth Restriction: Clinical and Functional Relevance
Site-Specific IGFBP-1 Hyper-Phosphorylation in Fetal Growth Restriction: Clinical and Functional Relevance
复制标题
DOI：
10.1021/pr900987n
复制
发表时间：
2010-04-01
影响因子：
4.4
通讯作者：
Gupta, Madhulika B.
中科院分区：
文献类型：
--
作者：
Abu Shehab, Majida;Khosravi, Javad;Gupta, Madhulika B.
磷酸化增强了IGFBP-1与IGF-I的结合，从而限制了IGF-I的生物利用度，这可能是胎儿生长中的重要因素。我们在这项研究中的目标是确定特定部位的IGFBP-1磷酸化的变化是否是胎儿生长受限所独有的。为了建立联系，我们比较了FGR(N=10)和对照组(N=12)羊水中IGFBP-1的磷酸化(位点和程度)。胎龄儿血清丝氨酸磷酸化IGFBP-1浓度与出生体重呈负相关(P=0.049)。LC-MS/MS分析显示，FGR和对照组的所有四个先前发现的磷酸化位点(Ser98、Ser101、Ser119和Ser169)都是共同的。FGR组和对照组的相对磷酸肽强度(LC-MS)分别是Ser101的4倍(P=0.026)、Ser98/Ser101的7倍(P=0.02)和Ser169的23倍(P=0.002)。初步Biaccore数据显示，在FGR中，IGFBP-1/IGF-I的缔合常数是FGR的4倍，解离常数是IGFBP-1/IGF-I的1.7倍。IGFBP-1与IGF-I结合的结构模型表明，所有的磷酸化位点都位于IGFBP-1序列的相对移动区。残基Ser98、Ser101和Ser169靠近参与IGF-I结合的结构区，因此可能与IGF-I直接接触。另一方面，残基Ser119位于连接IGFBP-1的N-末端和C-末端结构域的非结构化连接子的中间。该模型与Ser98、Ser101和Ser169残基可以直接与IGF-I相互作用的假设一致，因此这些位点的磷酸化可能改变IGF-I的相互作用。我们认为，IGFBP-1磷酸化的位点特异性增加限制了IGF-I的生物利用度，这直接促进了FGR的发展。这项研究阐明了IGFBP-1的高磷酸化在FGR中的潜在作用，并为用更大的样本量证实这些发现提供了基础。
Phosphorylation enhances IGFBP-1 binding to IGF-I, thereby limiting the bioavailability of IGF-I that may be important in fetal growth. Our goal in this study was to determine whether changes in site-specific IGFBP-1 phosphorylation were unique to fetal growth restriction. To establish a link, we compared IGFBP-1 phosphorylation (sites and degree) in amniotic fluid from FGR (N = 10) and controls (N = 12). The concentration of serine phosphorylated IGFBP-1 showed a negative correlation with birth weight in FGR (P = 0.049). LC-MS/MS analysis revealed all four previously identified phosphorylation sites (Ser98, Ser101, Ser119, and Ser169) to be common to FGR and control groups. Relative phosphopeptide intensities (LC-MS) between FGR and controls demonstrated 4-fold higher intensity for Ser101 (P = 0.026), 7-fold for Ser98/Ser101 (P = 0.02), and 23-fold for Ser169 (P = 0.002) in the FGR group. Preliminary BIAcore data revealed 4-fold higher association and 1.7-fold lower dissociation constants for IGFBP-1/IGF-I in FGR. A structural model of IGFBP-1 bound to IGF-I indicates that all the phosphorylation sites are on relatively mobile regions of the IGFBP-1 sequence. Residues Ser98, Ser101, and Ser169 are close to structured regions that are involved in IGF-I binding and, therefore, could potentially make direct contact with IGF-I. On the other hand, residue Ser119 is in the middle of the unstructured linker that connects the N- and C-terminal domains of IGFBP-1. The model is consistent with the assumption that residues Ser98, Ser101, and Ser169 could directly interact with IGF-I, and therefore phosphorylation at these sites could change IGF-I interactions. We suggest that site-specific increase in IGFBP-1 phosphorylation limits IGF-I bioavailability, which directly contributes to the development of FGR. This study delineates the potential role of higher phosphorylation of IGFBP-1 in FGR and provides the basis to substantiate these findings with larger sample size.