PDF(Pubmed)
Abstract：
Fibrillin microfibrils play a critical role in the formation of elastic fibers, tissue/organ development, and cardiopulmonary function. These microfibrils not only provide structural support and flexibility to tissues, but they also regulate growth factor signaling through a plethora of microfibril-binding proteins in the extracellular space. Mutations in fibrillins are associated with human diseases affecting cardiovascular, pulmonary, skeletal, and ocular systems. Fibrillins consist of up to 47 epidermal growth factor-like repeats, of which more than half are modified by protein O-glucosyltransferase 2 (POGLUT2) and/or POGLUT3. Loss of these modifications reduces secretion of N-terminal fibrillin constructs overexpressed in vitro. Here, we investigated the role of POGLUT2 and POGLUT3 in vivo using a Poglut2/3 double knockout (DKO) mouse model. Blocking O-glucosylation caused neonatal death with skeletal, pulmonary, and eye defects reminiscent of fibrillin/elastin mutations. Proteomic analyses of DKO dermal fibroblast medium and extracellular matrix provided evidence that fibrillins were more sensitive to loss of O-glucose compared to other POGLUT2/3 substrates. This conclusion was supported by immunofluorescent analyses of late gestation DKO lungs where FBN levels were reduced and microfibrils appeared fragmented in the pulmonary arteries and veins, bronchioles, and developing saccules. Defects in fibrillin microfibrils likely contributed to impaired elastic fiber formation and histological changes observed in DKO lung blood vessels, bronchioles, and saccules. Collectively, these results highlight the importance of POGLUT2/3-mediated O-glucosylation in vivo and open the possibility that O-glucose modifications on fibrillin influence microfibril assembly and or protein interactions in the ECM environment.
摘要：
纤溶蛋白微纤维在弹性纤维的形成中起着至关重要的作用,组织/器官发育，和心肺功能。这些微纤维不仅为组织提供结构支持和灵活性，但它们也通过细胞外空间中过多的微纤维结合蛋白调节生长因子信号。原纤维蛋白的突变与影响心血管的人类疾病有关，肺,骨骼，和眼部系统。纤维蛋白由多达47个表皮生长因子（EGF）样重复组成，其中一半以上被蛋白质O-葡糖基转移酶2(POGLUT2)和/或POGLUT3修饰。这些修饰的丧失减少了在体外过表达的N-末端纤丝蛋白构建体的分泌。这里,我们使用Poglut2/3双敲除（DKO）小鼠模型研究了POGLUT2和POGLUT3在体内的作用。阻断O-糖基化导致新生儿骨骼死亡，肺,和眼睛缺陷让人联想到纤丝蛋白/弹性蛋白突变。DKO真皮成纤维细胞培养基和细胞外基质的蛋白质组学分析提供了与其他POGLUT2/3底物相比，原纤维蛋白对O-葡萄糖损失更敏感的证据。这一结论得到了晚期妊娠DKO肺的免疫荧光分析的支持，其中FBN水平降低，并且在肺动脉和静脉中出现微纤维碎片，细支气管,和发育囊。纤丝蛋白微纤维的缺陷可能导致DKO肺血管中观察到的弹性纤维形成受损和组织学变化，细支气管,和囊。总的来说，这些结果强调了POGLUT2/3介导的体内O-糖基化的重要性,并揭示了纤丝蛋白上的O-葡萄糖修饰在ECM环境中影响微纤丝组装和/或蛋白质相互作用的可能性.
