Castellot J J, Karnovsky M J, Spiegelman B M
Proc Natl Acad Sci U S A. 1980 Oct;77(10):6007-11. doi: 10.1073/pnas.77.10.6007.
3T3 cells that have undergone adipose differentiation in vitro secrete into the culture medium a potent growth stimulatory activity for bovine aortic endothelial cells. When medium containing 2% fetal calf serum, which does not support significant endothelial cell growth, is conditioned by 3T3-F442A adipocytes, the endothelial cells grow rapidly (doubling time, 24 hr) at a rate equal to the growth rate in 20% fetal calf serum. The potency of the conditioned medium is further shown by the fact that it can be diluted 1:5 with little apparent loss of activity and shows a half-maximal stimulation at 10 microliter/ml. Serum is not required for either the secretion of this mitogen by the adipocytes or its action on the endothelial cells, as shown by the fact that the latter are stimulated to divide in serum-free medium conditioned by the adipocytes. The growth stimulatory activity appears to be specific for vascular endothelial cells in that no other cell type examined, including vascular smooth muscle cells and pericytes, are significantly stimulated by medium conditioned by 3T3-F442A cells. Similarly, medium conditioned by no other cell type examined has more than 10% of the activity of medium conditioned by the adipocytes. The specificity and potency of the adipocyte-derived factor suggest that it may play a role in the vascularization of this tissue during development. Preliminary biochemical analysis indicates that the adipocyte factor is nondialyzable and is not inactivated by heat or proteases. The protease insensitivity distinguishes the adipocyte growth stimulatory activity from the low levels of activity secreted by fibroblasts and preadipocytes, suggesting that the adipocyte mitogen is a product specifically related to the differentiation process.
在体外经历脂肪分化的3T3细胞会向培养基中分泌一种对牛主动脉内皮细胞具有强大生长刺激活性的物质。当含有2%胎牛血清（这种血清不能支持内皮细胞显著生长）的培养基被3T3 - F442A脂肪细胞处理后，内皮细胞能快速生长（倍增时间为24小时），其生长速率与在20%胎牛血清中的生长速率相当。这种条件培养基的效力还体现在它可以被稀释1:5而活性几乎没有明显损失，并且在10微升/毫升时显示出半数最大刺激作用。脂肪细胞分泌这种有丝分裂原及其对内皮细胞的作用都不需要血清，这一点可由以下事实证明：在内皮细胞在由脂肪细胞处理过的无血清培养基中能被刺激分裂。这种生长刺激活性似乎对血管内皮细胞具有特异性，因为所检测的其他细胞类型，包括血管平滑肌细胞和周细胞，都不会被3T3 - F442A细胞处理过的培养基显著刺激。同样，所检测的其他细胞类型处理过的培养基的活性都不超过脂肪细胞处理过的培养基活性的10%。脂肪细胞衍生因子的特异性和效力表明它可能在该组织发育过程中的血管形成中发挥作用。初步生化分析表明，脂肪细胞因子不能透析，且不会被加热或蛋白酶灭活。蛋白酶不敏感性将脂肪细胞生长刺激活性与成纤维细胞和前脂肪细胞分泌的低水平活性区分开来，这表明脂肪细胞有丝分裂原是一种与分化过程特异性相关的产物。
