Papp Helga, Czifra Gabriella, Lázár József, Gönczi Mónika, Csernoch Lászlo, Kovács Lászlo, Bíro Tamás
Department of Physiology, University of Debrecen, Medical Faculty, Hungary.
Exp Dermatol. 2003 Dec;12(6):811-24. doi: 10.1111/j.0906-6705.2003.00097.x.
Protein kinase C (PKC) isoforms play pivotal roles in the regulation of differentiation of normal human epidermal keratinocytes (NHEK). In this study, we investigated the participation of the PKC system in the proliferation and high cell density-induced differentiation of the human immortalized keratinocyte line HaCaT. HaCaT keratinocytes possessed a characteristic PKC isoform pattern (PKC alpha, beta, gamma, delta, epsilon, eta, theta, zeta), which altered during proliferation and differentiation. The GF109203X compound, a selective PKC inhibitor, suppressed the expressions of the lat (granular cell) differentiation markers involucrin (INV) and filaggrin (FIL), and the terminal marker keratinocyte-specific transglutaminase-1 (TG), but did not affect the level of the early (spinous cell) marker keratin 10 (K10) and cellular proliferation. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, inhibited proliferation, elevated intracellular calcium concentration, decreased the expression of K10, and increased the expressions of INV, FIL, and TG. These data indicate that the endogenous activation of PKC regulates the expressions of the late differentiation markers, and that the exogenous activation of PKC by PMA results in the induction of terminal differentiation. Because the cellular effects of PMA were accompanied by differential down-regulations of the sensitive PKC isoforms in proliferating and differentiating cultures, our findings argue for the differential roles of the existing PKC isoforms in the regulation of cellular proliferation and high cell density-induced differentiation of HaCaT cells.
蛋白激酶C（PKC）亚型在正常人表皮角质形成细胞（NHEK）分化的调控中起关键作用。在本研究中，我们调查了PKC系统在人永生化角质形成细胞系HaCaT的增殖和高细胞密度诱导分化中的参与情况。HaCaT角质形成细胞具有特征性的PKC亚型模式（PKCα、β、γ、δ、ε、η、θ、ζ），其在增殖和分化过程中发生改变。选择性PKC抑制剂GF109203X化合物抑制了晚期（颗粒细胞）分化标志物兜甲蛋白（INV）和丝聚蛋白（FIL）以及终末标志物角质形成细胞特异性转谷氨酰胺酶-1（TG）的表达，但不影响早期（棘状细胞）标志物角蛋白10（K10）的水平和细胞增殖。PKC激活剂佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA）抑制增殖，提高细胞内钙浓度，降低K10的表达，并增加INV、FIL和TG的表达。这些数据表明PKC的内源性激活调节晚期分化标志物的表达，并且PMA对PKC的外源性激活导致终末分化的诱导。由于PMA的细胞效应伴随着增殖和分化培养物中敏感PKC亚型的差异性下调，我们的研究结果支持现有PKC亚型在HaCaT细胞的细胞增殖调控和高细胞密度诱导分化中具有不同作用。
