Spreading of embryologically distinct urothelial cells is inhibited by SPARC.
Spreading of embryologically distinct urothelial cells is inhibited by SPARC.
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SPARC 抑制胚胎学上不同的尿路上皮细胞的扩散。
DOI：
10.1002/jcp.20140
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
Bassuk,JamesA
中科院分区：
文献类型：
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作者：
Hudson,AmberE;Feng,WaldoC;Delostrinos,CatherineF;Carmean,Nicole;Bassuk,JamesA
分泌蛋白（secreted protein acid and rich in半胱氨酸，SPARC）的AON表位是人类SPARC在多种人类细胞类型中表达的保守基序。通过使用识别该表位的单克隆抗体，发现移行上皮将SPARC的表达限制在基底上和中间层。这种细胞内表达是通过定位于基底上细胞和中间细胞的顶质膜的免疫反应信号来定义的。在体外实验中，显示出基底上细胞特征的细胞亚群——细胞周期静止、大细胞体积和多核——保留了SPARC向基底上细胞顶质膜的极化。相比之下，体内移行上皮的基底层和体外循环细胞没有表现出这种顶端染色模式，相反，免疫组织化学分析显示，SPARC多肽被隔离在尿路上皮细胞质和/或细胞核内。从尿路上皮细胞中洗脱可溶性蛋白和DNA，发现SPARC存在于核基质中，并且SPARC与核基质Ki‐67抗原共定位。重组SPARC以浓度和时间依赖的方式抑制新镀细胞的扩散，通过四舍五入实验证明并量化了rSPARC的活性。在来自内胚层（膀胱）和中胚层（输尿管）的尿路上皮细胞中观察到扩散的抑制。这两层的尿路上皮细胞有显著的统计学差异。中胚层细胞从rSPARC的抑制作用中恢复得更慢，因此在第6小时，内胚层细胞的扩散明显增加，如四舍五入指数（RI）所示。这些实验为SPARC的基质细胞运输提供了新的见解，并表明细胞内和细胞外定位模式影响移行上皮的发育、稳态和分化。©2004 Wiley‐Liss, Inc。
The AON epitope of secreted protein acidic and rich in cysteine (SPARC) is a conserved motif expressed by human SPARC in a variety of human cell types. Through the use of a monoclonal antibody that recognizes this epitope, transitional epithelium was found to restrict expression of SPARC to the suprabasal and intermediate layer. Such intracellular expression was defined by immunoreactive signals that localized to the apical plasma membranes of suprabasal and intermediate cells. Polarization of SPARC to apical plasma membranes of suprabasal cells was retained in vitro by a subpopulation of cells that exhibited characteristics of suprabasal cells—cell‐cycle quiescence, large cell volumes, and multiple nuclei. In contrast, the basal layer of transitional epithelium in vivo and cycling cells in vitro did not exhibit this apical staining pattern, but instead sequestered the SPARC polypeptide within urothelial cytoplasm and/or nuclei, as revealed by immunohistochemical analysis. Elution of soluble proteins and DNA from urothelial cells revealed the presence of SPARC within the nuclear matrix—and that SPARC colocalized with the nuclear matrix Ki‐67 antigen. rSPARC activity was demonstrated and quantified with a rounding assay whereby the spreading of freshly plated cells was inhibited by recombinant SPARC in a concentration‐ and time‐dependent manner. Inhibition of spreading was observed in urothelial cells derived from endoderm (bladder) and mesoderm (ureter) germ layers. Statistically significant differences were seen between urothelial cells from these two layers. Mesodermal cells recovered more slowly from the inhibitory effects of rSPARC, such that at hour 6 endodermal cells underwent significantly more spreading, as shown by a rounding index (RI). These experiments provide new insights about the matricellular trafficking of SPARC and suggest that intra‐ and extra‐cellular localization patterns influence the development, homeostasis, and differentiation of transitional epithelium. © 2004 Wiley‐Liss, Inc.