Martins-Green M, Bissell M J
Cell and Molecular Biology Division, Lawrence Berkeley Laboratory, Berkeley, California 94720.
J Cell Biol. 1990 Mar;110(3):581-95. doi: 10.1083/jcb.110.3.581.
The avian gene 9E3/CEF-4, a member of the superfamily of genes that includes KC and gro, is expressed abundantly in exponentially growing cultures of chick embryo fibroblasts (CEFs) and at high levels in CEFs transformed with Rous sarcoma virus (RSV). The product of this gene is a secreted protein that has homologies and structural similarities to inflammatory mediators. The function of 9E3 is obscure and its expression in vivo has not yet been investigated. We studied by in situ hybridization and RNA blots the pattern of 9E3 mRNA distribution in the wings of normal, wounded, and RSV-infected newly hatched chicks. We found that the message for 9E3 is high in specific tissues in normal wings; whereas connective tissue, tendon, and bone express the gene, muscle fibers, endothelium, epidermis, and bone marrow do not. The distribution coincides with that of interstitial collagen. Wounding results in marked elevation of the mRNA within the granulation tissue formed during healing and in adjacent tissues, especially those showing neovascularization. Similar elevation of mRNA occurs immediately adjacent to RSV tumors but, surprisingly, the tumor tissue itself shows no detectable levels of this message. Cells explanted from the tumors and grown in culture also show no expression of 9E3, in marked contrast to the very high level found in similarly cultured RSV-transformed CEFs. These results show that there are intrinsic differences between transformed embryonic cells in tissue culture and RSV target cells in the hatched chick. However, the expression of the gene in the periphery of tumors leaves open the possibility that 9E3 may still be involved in RSV carcinogenesis. The abundant expression of 9E3 in normal tissues indicates that the product of this gene plays a normal physiological role in tissues growing by cell division, perhaps as a growth regulator. The elevated expression of 9E3 in areas of neovascularization, makes it possible that the product of this gene could act as an angiogenic factor. Finally, expression in conjunction with high collagen levels and in wounded tissues may point to a role in wound response and/or repair, possibly via alteration of extracellular matrix.
禽类基因9E3/CEF-4是包括KC和gro在内的基因超家族的成员，在鸡胚成纤维细胞（CEF）的指数生长培养物中大量表达，在用劳氏肉瘤病毒（RSV）转化的CEF中也高水平表达。该基因的产物是一种分泌蛋白，与炎症介质具有同源性和结构相似性。9E3的功能尚不清楚，其在体内的表达尚未得到研究。我们通过原位杂交和RNA印迹研究了正常、受伤和RSV感染的新孵出小鸡翅膀中9E3 mRNA的分布模式。我们发现，正常翅膀的特定组织中9E3的信息含量很高；结缔组织、肌腱和骨骼表达该基因，而肌纤维、内皮、表皮和骨髓则不表达。这种分布与间质胶原的分布一致。受伤导致愈合过程中形成的肉芽组织及相邻组织（尤其是那些显示新生血管形成的组织）中的mRNA显著升高。紧邻RSV肿瘤处也出现类似的mRNA升高，但令人惊讶的是，肿瘤组织本身未检测到该信息的水平。从肿瘤中移出并在培养中生长的细胞也不表达9E3，这与在类似培养的RSV转化的CEF中发现的非常高水平形成鲜明对比。这些结果表明，组织培养中的转化胚胎细胞与孵出小鸡中的RSV靶细胞之间存在内在差异。然而，该基因在肿瘤周边的表达使得9E3仍可能参与RSV致癌作用成为可能。9E3在正常组织中的大量表达表明该基因的产物在通过细胞分裂生长的组织中发挥正常的生理作用，也许作为一种生长调节因子。9E3在新生血管形成区域的表达升高，使得该基因的产物有可能作为一种血管生成因子发挥作用。最后，与高胶原水平和受伤组织一起表达可能表明其在伤口反应和/或修复中起作用，可能是通过改变细胞外基质。
