Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
Front Biosci (Landmark Ed). 2011 Jun 1;16(8):2812-902. doi: 10.2741/3887.
Matrix vesicles (MVs) induce calcification during endochondral bone formation. Experimental methods for structural, compositional, and functional analysis of MVs are reviewed. MV proteins, enzymes, receptors, transporters, regulators, lipids and electrolytes are detailed. MV formation is considered from both structural and biochemical perspectives. Confocal imaging of Ca(2+) and H(+) were used to depict how living chondrocytes form MVs. Biochemical studies revealed that coordinated mitochondrial Ca(2+) and Pi metabolism produce MVs containing a nucleational complex (NC) of amorphous calcium phosphate, phosphatidylserine and annexin A5--all critical to the mechanism of mineral nucleation. Reconstitution of the NC and modeling with unilamellar vesicles reveal how the NC transforms into octacalcium phosphate, regulated by Mg(2+), Zn(2+) and annexin A5. Extravasation of intravesicular mineral is mediated by phospholipases and tissue-nonspecific alkaline phosphatase (TNAP). In the extravesicular matrix, hydroxyapatite crystal propagation is enhanced by cartilage collagens and TNAP, which destroys inhibitory PPi, and by metalloproteases that degrade proteoglycans. Other proteins also modulate mineral formation. Recent findings from single and multiple gene knockouts of TNAP, NPP1, ANK, PHOSPHO1, and Annexin A5 are reviewed.
基质小泡 (MVs) 在软骨内骨形成过程中诱导钙化。本文回顾了用于 MV 结构、组成和功能分析的实验方法。详细介绍了 MV 中的蛋白、酶、受体、转运蛋白、调节因子、脂质和电解质。从结构和生化两个角度考虑 MV 的形成。利用共聚焦成像观察 Ca(2+) 和 H(+)，描绘了活软骨细胞如何形成 MV。生化研究表明，协调的线粒体 Ca(2+) 和 Pi 代谢产生含有无定形磷酸钙、磷脂酰丝氨酸和 annexin A5 的核化复合物 (NC)，这对矿化核化机制至关重要。NC 的重建和单层囊泡模型表明，NC 如何在 Mg(2+)、Zn(2+) 和 annexin A5 的调节下转化为八钙磷酸盐。囊内矿物质的外渗由磷脂酶和组织非特异性碱性磷酸酶 (TNAP) 介导。在囊外基质中，软骨胶原和 TNAP 增强了羟基磷灰石晶体的传播，TNAP 破坏了抑制性的焦磷酸，金属蛋白酶降解蛋白聚糖。其他蛋白也调节矿化的形成。本文综述了 TNAP、NPP1、ANK、PHOSPHO1 和 annexin A5 的单基因和多基因敲除的最新发现。
