Ghert M A, Qi W N, Erickson H P, Block J A, Scully S P
Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA.
Cell Struct Funct. 2001 Jun;26(3):179-87. doi: 10.1247/csf.26.179.
Tenascin-C is an oligomeric glycoprotein of the extracellular matrix that has been found to have both adhesive and anti-adhesive properties for cells. Recent elucidation of the two major TNC splice variants (320 kDa and 220 kDa) has shed light on the possibility of varying functions of the molecule based on its splicing pattern. Tenascin-C is prominently expressed in embryogenesis and in pathologic conditions such as tumorogenesis and wound healing. Fibronectin is a prominent adhesive molecule of the extracellular matrix that is often co-localized with tenascin-C in these processes. We studied the chondrosarcoma cell line JJ012 with enzyme-linked immunoabsorbance assays, cell attachment assays and antibody-blocking assays to determine the adhesive/anti-adhesive properties of the two major tenascin-C splice variants with respect to fibronectin and their effect on chondrosarcoma cell attachment. We found that the small tenascin-C splice variant (220 kDa) binds to fibronectin, whereas the large tenascin-C splice variant (320 kDa) does not. In addition, the small tenascin-C splice variant was found to decrease adhesion for cells when bound to fibronectin, but contributed to adhesion when bound to plastic in fibronectin-coated wells. Antibody blocking experiments confirmed that both the small tenascin-C splice variant and fibronectin contribute to cell adhesion when bound to plastic. The large tenascin-C splice variant did not promote specific cell attachment. We hypothesize that the biologic activity of tenascin-C is dependent on the tissue-specific splicing pattern. The smaller tenascin-C isoform likely plays a structural and adhesive role, whereas the larger isoform, preferentially expressed in malignant tissue, likely plays a role in cell egress and metastasis.
腱生蛋白-C是细胞外基质中的一种寡聚糖蛋白，已发现它对细胞具有黏附性和抗黏附性。最近对两种主要的腱生蛋白-C剪接变体（320 kDa和220 kDa）的阐释，揭示了该分子基于其剪接模式可能具有不同功能。腱生蛋白-C在胚胎发育以及肿瘤发生和伤口愈合等病理状况中显著表达。纤连蛋白是细胞外基质中一种突出的黏附分子，在这些过程中常与腱生蛋白-C共定位。我们通过酶联免疫吸附测定、细胞黏附测定和抗体阻断测定，研究了软骨肉瘤细胞系JJ012，以确定两种主要的腱生蛋白-C剪接变体相对于纤连蛋白的黏附/抗黏附特性及其对软骨肉瘤细胞黏附的影响。我们发现，小的腱生蛋白-C剪接变体（220 kDa）与纤连蛋白结合，而大的腱生蛋白-C剪接变体（320 kDa）则不结合。此外，发现小的腱生蛋白-C剪接变体与纤连蛋白结合时会降低细胞黏附，但在纤连蛋白包被的孔中与塑料结合时则有助于黏附。抗体阻断实验证实，小的腱生蛋白-C剪接变体和纤连蛋白与塑料结合时均有助于细胞黏附。大的腱生蛋白-C剪接变体不促进特异性细胞黏附。我们推测，腱生蛋白-C的生物学活性取决于组织特异性剪接模式。较小的腱生蛋白-C异构体可能发挥结构和黏附作用，而较大的异构体优先在恶性组织中表达，可能在细胞逸出和转移中发挥作用。
