Goldstein S, Moerman E J, Baxter R C
Department of Medicine, University of Arkansas for Medical Sciences, Little Rock.
J Cell Physiol. 1993 Aug;156(2):294-302. doi: 10.1002/jcp.1041560211.
We have found that insulin-like growth factor binding protein-3 (IGFBP-3) accumulates to higher levels in medium conditioned by a strain of normal fibroblasts at late passage (LP) and a strain derived from subjects with Werner syndrome (WS) of premature aging, compared to medium conditioned by the same normal cells at early passage (EP) (Goldstein et al., Proc. Natl. Acad. Sci. USA, 88:9680-9684, 1991). To explore the generality of this phenomenon with respect to chronological age of donor (in vivo aging) and LP (in vitro senescence) we assayed IGFBP-3 in medium conditioned by 18 normal fibroblast strains at EP and LP and two WS strains at the midpoint of their curtailed replicative lifespans and assessed IGFBP-3 mRNA levels in cells by Northern analysis. The lowest accumulations of IGFBP-3 were found in medium conditioned by fetal cells with progressively increasing amounts postnatally; direct correlations between IGFBP-3 levels and donor age were seen in EP cells 3 days after subculture (during logarithmic growth) r = 0.80, P < 0.001, and 7 days after subculture (at confluence) r = 0.77, P < 0.001. With two exceptions, conditioned medium of cell strains accumulated more IGFBP-3 at LP; IGFBP-3 levels correlated with chronological age after 3 days, r = 0.50, P = 0.05, and after 7 days, r = 0.75, P < 0.001. IGFBP-3 content of WS culture medium fell within the range of LP normal cells. Cumulative IGFBP-3 levels were inversely proportional to the thymidine labeling index, a measure of proliferative vigor. With some exceptions IGFBP-3 mRNA levels were commensurate with the amount of IGFBP-3 accumulated in the medium, suggesting that distal translational and posttranslational mechanisms also regulate IGFBP-3 production in some strains. The trend toward augmented IGFBP-3 output of fibroblasts as a direct function of chronological age and in vitro senescence and as an inverse function of proliferative vigor is consistent with the known inhibitory effect of excess IGFBP-3 on IGF-mediated DNA synthesis and the reduced regenerative potential that is evident during biological aging in vivo.
我们发现，与早期传代（EP）的同一正常细胞所条件培养的培养基相比，胰岛素样生长因子结合蛋白3（IGFBP - 3）在晚期传代（LP）的正常成纤维细胞株以及源自早衰的沃纳综合征（WS）患者的细胞株所条件培养的培养基中积累到更高水平（Goldstein等人，《美国国家科学院院刊》，88:9680 - 9684，1991）。为了探究这种现象在供体实际年龄（体内衰老）和传代次数（体外衰老）方面的普遍性，我们检测了18个正常成纤维细胞株在EP和LP时以及两个WS细胞株在其缩短的复制寿命中点时所条件培养的培养基中的IGFBP - 3，并通过Northern分析评估了细胞中的IGFBP - 3 mRNA水平。在胎儿细胞所条件培养的培养基中发现IGFBP - 3的积累量最低，出生后逐渐增加；在传代后3天（对数生长期），EP细胞中IGFBP - 3水平与供体年龄呈直接相关，r = 0.80，P < 0.001，传代后7天（汇合时），r = 0.77，P < 0.001。除两个例外情况外，细胞株的条件培养基在LP时积累了更多的IGFBP - 3；传代后3天，IGFBP - 3水平与实际年龄相关，r = 0.50，P = 0.05，传代后7天，r = 0.75，P < 0.001。WS培养基中的IGFBP - 3含量落在LP正常细胞的范围内。累积的IGFBP - 3水平与胸苷标记指数成反比，胸苷标记指数是增殖活力的一种衡量指标。除一些例外情况外，IGFBP - 3 mRNA水平与培养基中积累的IGFBP - 3量相当，这表明在某些细胞株中，远端翻译和翻译后机制也调节IGFBP - 3的产生。成纤维细胞中IGFBP - 3输出量随实际年龄和体外衰老而增加、随增殖活力而降低的趋势，与已知的过量IGFBP - 3对IGF介导的DNA合成的抑制作用以及体内生物衰老过程中明显降低的再生潜力是一致的。
