骨-肾矿物质与能量代谢的调节:PHEX、FGF23、DMP1、MEPE ASARM信号通路
Regulation of bone-renal mineral and energy metabolism: the PHEX, FGF23, DMP1, MEPE ASARM pathway.
作者信息
Rowe Peter S N
机构信息
Department of Internal Medicine, The Kidney Institute and Division of Nephrology-Hypertension, University of Kansas Medical Center, Kansas City, Kansas, USA.
出版信息
Crit Rev Eukaryot Gene Expr. 2012;22(1):61-86. doi: 10.1615/critreveukargeneexpr.v22.i1.50.
More than 300 million years ago, vertebrates emerged from the vast oceans to conquer gravity and the dry land. With this transition, new adaptations occurred that included ingenious changes in reproduction, waste secretion, and bone physiology. One new innovation, the egg shell, contained an ancestral protein (ovocleidin-116) that likely first appeared with the dinosaurs and was preserved through the theropod lineage in modern birds and reptiles. Ovocleidin-116 is an avian homolog of matrix extracellular phosphoglycoprotein (MEPE) and belongs to a group of proteins called short integrin-binding ligand-interacting glycoproteins (SIBLINGs). These proteins are all localized to a defined region on chromosome 5q in mice and chromosome 4q in humans. A unifying feature of SIBLING proteins is an acidic serine aspartate-rich MEPE-associated motif (ASARM). Recent research has shown that the ASARM motif and the released ASARM peptide have regulatory roles in mineralization (bone and teeth), phosphate regulation, vascularization, soft-tissue calcification, osteoclastogenesis, mechanotransduction, and fat energy metabolism. The MEPE ASARM motif and peptide are physiological substrates for PHEX, a zinc metalloendopeptidase. Defects in PHEX are responsible for X-linked hypophosphatemic rickets (HYP). There is evidence that PHEX interacts with another ASARM motif containing SIBLING protein, dentin matrix protein-1 (DMP1). DMP1 mutations cause bone and renal defects that are identical with the defects caused by a loss of PHEX function. This results in autosomal recessive hypophosphatemic rickets (ARHR). In both HYP and ARHR, increased FGF23 expression plays a major role in the disease and in autosomal dominant hypophosphatemic rickets (ADHR), FGF23 half-life is increased by activating mutations. ASARM peptide administration in vitro and in vivo also induces increased FGF23 expression. FGF23 is a member of the fibroblast growth factor (FGF) family of cytokines, which surfaced 500 million years ago with the boney fish (i.e., teleosts) that do not contain SIBLING proteins. In terrestrial vertebrates, FGF23, like SIBLING proteins, is expressed in the osteocyte. The boney fish, however, are an-osteocytic, so a physiological bone-renal link with FGF23 and the SIBLINGs was cemented when life ventured from the oceans to the land during the Triassic period, approximately 300 million years ago. This link has been revealed by recent research that indicates a competitive displacement of a PHEX-DMP1 interaction by an ASARM peptide that leads to increased FGF23 expression. This review discusses the new discoveries that reveal a novel PHEX, DMP1, MEPE, ASARM peptide, and FGF23 bone-renal pathway. This pathway impacts not only bone formation, bone-renal mineralization, and renal phosphate homeostasis but also energy metabolism. The study of this new pathway is relevant for developing therapies for several diseases: bone-teeth mineral loss disorders, renal osteodystrophy, chronic kidney disease and bone mineralization disorders (CKD-MBD), end-stage renal diseases, ectopic arterial-calcification, cardiovascular disease renal calcification, diabetes, and obesity.
3亿多年前,脊椎动物从浩瀚的海洋中脱颖而出,开始征服重力并踏上陆地。随着这种转变,出现了新的适应性变化,包括繁殖、废物分泌和骨骼生理方面的巧妙改变。一项新的创新是蛋壳,它含有一种祖传蛋白质(卵壳蛋白-116),这种蛋白质可能最早出现在恐龙身上,并通过兽脚亚目谱系在现代鸟类和爬行动物中得以保留。卵壳蛋白-116是基质细胞外磷酸糖蛋白(MEPE)的鸟类同源物,属于一类称为短整合素结合配体相互作用糖蛋白(SIBLINGs)的蛋白质。这些蛋白质在小鼠中均定位于5号染色体q臂上的一个特定区域,在人类中定位于4号染色体q臂上。SIBLING蛋白质的一个共同特征是富含酸性丝氨酸天冬氨酸的MEPE相关基序(ASARM)。最近的研究表明,ASARM基序和释放的ASARM肽在矿化(骨骼和牙齿)、磷酸盐调节、血管生成、软组织钙化、破骨细胞生成、机械转导和脂肪能量代谢中具有调节作用。MEPE ASARM基序和肽是锌金属内肽酶PHEX的生理底物。PHEX缺陷是X连锁低磷性佝偻病(HYP)的病因。有证据表明,PHEX与另一种含有ASARM基序的SIBLING蛋白质牙本质基质蛋白-1(DMP1)相互作用。DMP1突变会导致骨骼和肾脏缺陷,与PHEX功能丧失所导致的缺陷相同。这会导致常染色体隐性低磷性佝偻病(ARHR)。在HYP和ARHR中,FGF23表达增加在疾病中起主要作用,而在常染色体显性低磷性佝偻病(ADHR)中,激活突变会增加FGF23的半衰期。在体外和体内给予ASARM肽也会诱导FGF23表达增加。FGF23是细胞因子成纤维细胞生长因子(FGF)家族的成员,它在5亿年前随着不含SIBLING蛋白质的硬骨鱼(即硬骨鱼类)出现。在陆生脊椎动物中,FGF23与SIBLING蛋白质一样,在骨细胞中表达。然而,硬骨鱼没有骨细胞,所以大约在3亿年前的三叠纪时期,当生命从海洋向陆地演化时,FGF23与SIBLINGs之间的生理性骨-肾联系得以确立。最近的研究揭示了这种联系,即ASARM肽竞争性取代PHEX-DMP1相互作用,导致FGF23表达增加。本综述讨论了揭示新型PHEX、DMP1、MEPE、ASARM肽和FGF23骨-肾途径的新发现。这条途径不仅影响骨形成、骨-肾矿化和肾脏磷酸盐稳态,还影响能量代谢。对这条新途径的研究与开发多种疾病的治疗方法相关:骨-牙矿物质流失疾病、肾性骨营养不良、慢性肾脏病和骨矿化障碍(CKD-MBD)、终末期肾病、异位动脉钙化、心血管疾病肾钙化、糖尿病和肥胖症。