Asundi V K, Dreher K L
Sigfried and Janet Weis Center for Research, Geisinger Clinic, Danville, PA.
Eur J Cell Biol. 1992 Dec;59(2):314-21.
Two overlapping clones containing sequences homologous to bovine, human and chicken decorin have been recovered from poly A+ RNA isolated from rat vascular smooth muscle cells (VSMC) using cDNA cloning and reverse transcription-polymerase chain reaction (PCR) methodologies. Results of nucleotide sequence analysis performed on these clones demonstrated that they encode the complete mature rat decorin protein expressed by VSMC. Within the coding region, rat decorin exhibits 76% nucleotide sequence homology to human and bovine decorin, and 69% homologous to chicken decorin indicating a significant level of conservation among these species. This level of conservation among species was also maintained at the protein level with rat decorin being 77% homologous to its human, bovine and chicken homologues. As previously observed its human homologue, rat decorin, is made up of seven, tandem, leucine-rich repeat sequences. Furthermore, within the core of these repeats was the consensus protein sequence NKISK which has been proposed to be the fibronectin binding region of decorin (G. Schmidt et al., Biochem. J. 280, 411-414 (1991)). The vast majority of amino acid substitutions within rat decorin were of the conservative type. The highest frequency of amino acid substitutions were found to be localized within a hypervariable region located near the amino terminus of the decorin core protein. Unlike rat biglycan, rat decorin mRNA levels were found to increase significantly in density-arrested VSMC cultures. In contrast to rat biglycan gene expression, no quantitative differences in rat decorin mRNA levels were observed between proliferating VSMC and VSMC made quiescent through serum depletion. Finally, specific extracellular matrix (ECM) proteins were able to regulate the expression of decorin at the mRNA level in a slightly different manner than previously observed for biglycan.
利用cDNA克隆和逆转录-聚合酶链反应（PCR）方法，从大鼠血管平滑肌细胞（VSMC）分离的多聚腺苷酸加尾RNA中获得了两个重叠克隆，其包含与牛、人和鸡核心蛋白聚糖同源的序列。对这些克隆进行的核苷酸序列分析结果表明，它们编码VSMC表达的完整成熟大鼠核心蛋白聚糖蛋白。在编码区内，大鼠核心蛋白聚糖与人和牛核心蛋白聚糖的核苷酸序列同源性为76%，与鸡核心蛋白聚糖的同源性为69%，表明这些物种之间存在显著的保守水平。物种间的这种保守水平在蛋白质水平上也得以维持，大鼠核心蛋白聚糖与其人、牛和鸡的同源物的同源性为77%。如先前在其人同源物中观察到的那样，大鼠核心蛋白聚糖由七个串联的富含亮氨酸的重复序列组成。此外，在这些重复序列的核心区域是共有蛋白序列NKISK，该序列被认为是核心蛋白聚糖的纤连蛋白结合区域（G. Schmidt等人，《生物化学杂志》280，411 - 414（1991））。大鼠核心蛋白聚糖内的绝大多数氨基酸替换属于保守类型。发现氨基酸替换的最高频率位于核心蛋白聚糖核心蛋白氨基末端附近的一个高变区内。与大鼠双糖链蛋白聚糖不同，在密度抑制的VSMC培养物中，大鼠核心蛋白聚糖mRNA水平显著增加。与大鼠双糖链蛋白聚糖基因表达相反，在增殖的VSMC和通过血清饥饿使其静止的VSMC之间，未观察到大鼠核心蛋白聚糖mRNA水平的定量差异。最后，特定的细胞外基质（ECM）蛋白能够以一种与先前观察到的双糖链蛋白聚糖略有不同的方式在mRNA水平上调节核心蛋白聚糖的表达。
