Type IIA procollagen in development of the human intervertebral disc: regulated expression of the NH(2)-propeptide by enzymic processing reveals a unique developmental pathway.
Type IIA procollagen in development of the human intervertebral disc: regulated expression of the NH(2)-propeptide by enzymic processing reveals a unique developmental pathway.
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人类椎间盘发育中的 IIA 型前胶原：通过酶处理调节 NH(2)-前肽的表达揭示了独特的发育途径。
DOI：
10.1002/dvdy.1115
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Sandell,LJ
中科院分区：
文献类型：
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作者：
Zhu,Y;McAlinden,A;Sandell,LJ
II型胶原可以通过前体mRNA的选择性剪接产生的两种形式合成。IIA型前胶原在NH 2前肽（外显子2）中含有富含半胱氨酸的结构域，由前软骨和非软骨上皮细胞和间充质细胞产生，而IIB型前胶原不含富含半胱氨酸的结构域，是软骨细胞的特征。缺乏II型胶原蛋白的小鼠不能发育椎间盘。我们以前已经表明，人类椎间盘和脊索合成主要是IIA型前胶原。因此，我们研究了人类椎间盘发育早期IIA型前胶原的分布。通过放射性原位杂交和荧光免疫组织化学的过程中，我们本地化的mRNA和蛋白质的IIA型前胶原，I型胶原，和III型胶原在胎儿椎间盘标本从第42天（胚胎期17）到第101天（14.5周）的妊娠。使用针对IIA型前胶原的三个不同结构域的抗体：NH 2-前肽、纤维结构域和COOH-前肽。椎间盘发育的最早阶段（42天，第17期）的特征在于致密区（椎间区域）中I型和III型胶原的弥漫性合成以及椎间盘周围软骨细胞祖细胞合成IIA型前胶原。脊索细胞合成并沉积于脊索鞘内。到第54天（第22阶段），发育中的椎间盘明显分为三个区域：1。外环，其特征在于I型和III型胶原的合成和沉积; 2.）内环，其特征在于含有NH 2-前肽但不含COOH-前肽的IIA型胶原（pN-前胶原）的合成和沉积;和3.）脊索细胞合成和沉积所有三种纤维状胶原。在胎儿发育的后期（72-101天），在内环细胞中观察到IIA型前胶原加工的变化：即使这些细胞继续合成IIA型前胶原，它们也仅将加工的纤维结构域沉积到细胞外基质（ECM）中，而NH 2-前肽被去除。这一发现表明，在内环细胞中IIA型前胶原NH 2-前肽的加工中存在发育调节的变化。这一机制与先前显示的通过前体mRNA的选择性剪接对NH 2-前肽的富含半胱氨酸结构域的发育调节相反。虽然内环的细胞已被确定为软骨细胞，基于其形状和特征性ECM成分的合成，它们似乎代表了一个独特的发育途径，其特征在于IIA型前胶原的合成和差异加工。这种发育模式可能对椎间盘再生很重要。© 2001 Wiley利斯公司
Type II collagen can be synthesized in two forms generated by alternative splicing of the precursor mRNA. Type IIA procollagen, which contains a cysteine‐rich domain in the NH2‐propeptide (exon 2), is produced by precartilage and noncartilage epithelial and mesenchymal cells, and type IIB procollagen, without the cysteine‐rich domain, is characteristic of chondrocytes. Mice lacking type II collagen fail to develop intervertebral discs. We have previously shown that the human intervertebral disc and notochord synthesize primarily the type IIA form of procollagen. Therefore, we investigated the distribution of type IIA procollagen during early disc development in humans. By processes of radioactive in situ hybridization and fluorescence immunohistochemistry, we localized mRNA and protein of type IIA procollagen, type I collagen, and type III collagen in fetal intervertebral disc specimens ranging from day 42 (embryonic stage 17) to day 101 (week 14.5) of gestation. Antibodies to the three distinct domains of type IIA procollagen: the NH2‐propeptide, the fibrillar domain, and the COOH‐propeptide were used. The earliest stage of developing intervertebral disc (42 days, stage 17) was characterized by diffuse synthesis of types I and III collagens in the dense zone (intervertebral area) and synthesis of type IIA procollagen by the chondrocyte progenitor cells surrounding the disc. The notochord cells synthesized and deposited into the notochordal sheath all three fibrillar collagens. By 54 days (stage 22), the developing disc was clearly divided into three regions: 1.) the outer annulus, characterized by synthesis and deposition of types I and III collagens; 2.) the inner annulus, characterized by synthesis and deposition of type IIA collagen containing the NH2‐propeptide but devoid of the COOH‐propeptide (pN‐procollagen); and 3.) the notochord, the cells of which synthesized and deposited of all three fibrillar collagens. In later stages of fetal development (72–101 days), a change in type IIA procollagen processing was observed in the cells of the inner annulus: even though these cells continued to synthesize type IIA procollagen, they deposited into the extracellular matrix (ECM) only the processed fibrillar domain, with the NH2‐propeptide removed. This finding indicates that there is a developmentally regulated change in the processing of type IIA procollagen NH2‐propeptide in the cells of the inner annulus. This mechanism is in contrast to previously shown developmental regulation of the cysteine‐rich domain of the NH2‐propeptide by alternative splicing of the precursor mRNA. Although the cells of the inner annulus have been identified as chondrocytes, based on their shape and synthesis of characteristic ECM components, they appear to represent a distinct developmental pathway characterized by their synthesis and differential processing of type IIA procollagen. This developmental pattern may prove important for disc regeneration. © 2001 Wiley‐Liss, Inc.