Majack R A
Department of Pediatrics, University of Colorado Health Sciences Center, Denver 80262.
J Clin Invest. 1995 Feb;95(2):464-8. doi: 10.1172/JCI117686.
Vascular smooth muscle cells (SMC) isolated from embyronic and early fetal (e13-e18) rat aortas exhibit an "embryonic growth phenotype" in culture (Cook, C. L., M. C. M. Weiser, P. E. Schwartz, C. L. Jones, and R. A. Majack. 1994. Circ. Res. 74:189-196). Cells in this growth phenotype exhibit autonomous, serum-independent replication, in contrast to SMC in the "adult" growth phenotype, whose proliferation in culture is dependent on exogenous mitogens. To determine which of these two phenotypes is genetically dominant, heterokaryons were constructed between adult and embryonic (day e17) rat aortic SMC. The fused cells were maintained in serum-free medium for 3 d, then were labeled with bromodeoxyuridine (BrdU) for an additional 24 h. Under these conditions, parental e17 SMC exhibited a high rate of self-driven DNA synthesis (73-85% BrdU-positive cells), while parental adult SMC showed minimal replication (13-21% BrdU-positive cells). Homokaryons of parental cells exhibited parental growth phenotypes and showed the expected mitogenic response when stimulated with serum. Heterokaryons between e17 and adult SMC exhibited a nonautonomous growth phenotype; the "adult" growth phenotype was calculated to be dominant in > 89% of all true heterokaryons. The data suggest that adult SMC express molecules capable of genetically extinguishing or otherwise inhibiting the autonomous replication of embryonic SMC.
从胚胎期和胎儿早期（e13 - e18）大鼠主动脉分离出的血管平滑肌细胞（SMC）在培养中表现出“胚胎生长表型”（库克，C.L.，M.C.M.韦泽，P.E.施瓦茨，C.L.琼斯，和R.A.马杰克。1994年。《循环研究》74:189 - 196）。与“成年”生长表型的SMC不同，处于这种生长表型的细胞表现出自主的、不依赖血清的复制，后者在培养中的增殖依赖于外源性有丝分裂原。为了确定这两种表型中哪一种在遗传上占主导地位，构建了成年和胚胎期（e17天）大鼠主动脉SMC之间的异核体。将融合细胞在无血清培养基中培养3天，然后用溴脱氧尿苷（BrdU）再标记24小时。在这些条件下，亲代e17 SMC表现出高的自我驱动DNA合成速率（73 - 85%的BrdU阳性细胞），而亲代成年SMC显示出最小的复制（13 - 21%的BrdU阳性细胞）。亲代细胞的同核体表现出亲代生长表型，并在受到血清刺激时显示出预期的有丝分裂反应。e17和成年SMC之间的异核体表现出非自主生长表型；计算得出“成年”生长表型在所有真正的异核体中占主导地位的比例> 89%。数据表明成年SMC表达能够在遗传上消除或以其他方式抑制胚胎SMC自主复制的分子。
