Shabana A H, Amar L, Oboeuf M, Martin N, Forest N
Laboratoire de Biologie-Odontologie, Institut Biomédical des Cordeliers, Paris, France.
Tissue Cell. 1996 Oct;28(5):537-45. doi: 10.1016/s0040-8166(96)80056-5.
Cytoplasmic desmosomes (CD) are classically found in dyskeratotic cells of many epithelial tumors. Their significance and mechanism of formation remain largely speculative. Recently, we have reported the induction of these structures in rat keratinocytes following a brief treatment with acrylamide, and proposed that protein kinase inhibition may be implicated in their formation. In the present study, we show that protein kinase inhibitor H-7 in the presence of EGF is able to induce CD in rat keratinocytes within half an hour. In serum free medium containing 20 ng/ml of EGF, desmosomal structures at different stages of assembly were obtained using H-7 at concentrations ranging between 20 and 80 microM. No such structures were found at lower concentrations. The plaque diameters were significantly small in comparison with plasma membrane plaques. EGF induced plakoglobin positive membrane invaginations and in the presence of H-7, desmosomal plaques assembled on these membranes as either half desmosomes or as symmetric ones. The present results implicate protein kinase inhibition in CD formation and suggest that EGF provides tubular membrane structures in the cytoplasm on which desmosomes may assemble.
细胞质桥粒（CD）经典地存在于许多上皮肿瘤的角化不良细胞中。它们的意义和形成机制在很大程度上仍属推测。最近，我们报道了用丙烯酰胺短暂处理大鼠角质形成细胞后可诱导这些结构的形成，并提出蛋白激酶抑制可能与它们的形成有关。在本研究中，我们表明在表皮生长因子（EGF）存在的情况下，蛋白激酶抑制剂H-7能够在半小时内诱导大鼠角质形成细胞中形成CD。在含有20 ng/ml EGF的无血清培养基中，使用浓度在20至80 microM之间的H-7可获得处于不同组装阶段的桥粒结构。在较低浓度下未发现此类结构。与质膜斑块相比，斑块直径明显较小。EGF诱导了桥粒斑蛋白阳性的膜内陷，并且在H-7存在的情况下，桥粒斑块在这些膜上组装成半桥粒或对称桥粒。目前的结果表明蛋白激酶抑制与CD的形成有关，并表明EGF在细胞质中提供了桥粒可能组装于其上的管状膜结构。
