Ferraris C, Cooklis M, Polakowska R R, Haake A R
Department of Dermatology, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
Exp Cell Res. 1997 Jul 10;234(1):37-46. doi: 10.1006/excr.1997.3601.
The dermal papilla (DP) consists of a discrete population of specialized fibroblasts that are important in the morphogenesis of the hair follicle in the embryo and in the control of the hair growth cycle in the adult. This mitotically quiescent and long-lived cell population expresses gene products that promote cell survival such as Bcl-2, and thus normally might be protected from apoptosis. We investigated whether cultured DP fibroblasts are able to undergo apoptosis by treatment with the protein kinase inhibitor staurosporine. Involvement of the PKC signaling pathway in DP fibroblast survival/death was investigated by inhibition (staurosporine and Bisindolylmaleimide (Bis) treatment) or activation (TPA; 12-O-tetradecanoylphorbol-13-acetate treatment) of PKC and characterization of DP-expressed PKC isoforms by RT-PCR. We determined that cultured DP fibroblasts undergo apoptosis, in a dose-related manner, when treated with staurosporine but not when treated with Bis, an inhibitor with narrow PKC isoform specificity. TPA confers partial and transient resistance to staurosporine-induced DP apoptosis. Staurosporine and Bis each induced G1 arrest, whereas TPA treatment of cultured DP resulted in increased entry into S-phase. The differential responses to individual inhibitors and activators of PKC may be related to the multiple PKC isoforms that DP fibroblasts express. Flow cytometric analysis indicates that the mechanism of staurosporine-induced apoptosis may be through decrease of Bcl-2 in treated DP cells or through modulation of cell cycle regulators. Correlation between sensitivity to induction of apoptosis and proliferation suggests that dermal papilla cells may normally be protected from apoptosis in vivo by their mitotically quiescent state.
真皮乳头（DP）由一群离散的特殊成纤维细胞组成，这些细胞在胚胎期毛囊的形态发生以及成年期毛发生长周期的控制中起着重要作用。这群有丝分裂静止且寿命较长的细胞表达促进细胞存活的基因产物，如Bcl-2，因此通常可能受到保护而免于凋亡。我们研究了培养的DP成纤维细胞在用蛋白激酶抑制剂星形孢菌素处理后是否能够发生凋亡。通过抑制（星形孢菌素和双吲哚马来酰胺（Bis）处理）或激活（佛波酯；12-O-十四烷酰佛波醇-13-乙酸酯处理）蛋白激酶C（PKC）以及通过逆转录聚合酶链反应（RT-PCR）对DP中表达的PKC同工型进行表征，研究了PKC信号通路在DP成纤维细胞存活/死亡中的作用。我们确定，培养的DP成纤维细胞在用星形孢菌素处理时会以剂量相关的方式发生凋亡，但在用Bis处理时不会，Bis是一种具有狭窄PKC同工型特异性的抑制剂。佛波酯赋予对星形孢菌素诱导的DP凋亡的部分和短暂抗性。星形孢菌素和Bis均诱导G1期阻滞，而用佛波酯处理培养的DP导致进入S期的细胞增加。对PKC的个别抑制剂和激活剂的不同反应可能与DP成纤维细胞表达的多种PKC同工型有关。流式细胞术分析表明，星形孢菌素诱导凋亡的机制可能是通过降低处理过的DP细胞中的Bcl-2或通过调节细胞周期调节因子。对凋亡诱导的敏感性与增殖之间的相关性表明，真皮乳头细胞在体内可能因其有丝分裂静止状态而通常受到保护免于凋亡。
