Alibardi Lorenzo, Toni Mattia
Dipartimento di Biologia evoluzionistica sperimentale, University of Bologna, Italy.
J Exp Zool A Comp Exp Biol. 2005 Oct 1;303(10):845-60. doi: 10.1002/jez.a.213.
The keratin cytoskeleton of the wound epidermis of lizard limb (which does not regenerate) and tail (which regenerates) hase been studied by qualitative ultrastructural, immunocytochemical, and immunoblotting methods. The process of re-epithelialization is much shorter in the tail than in the limb. In the latter, a massive tissue destruction of bones, and the shrinkage of the old skin over the stump surface, delay wound closure, maintain inflammation, reduce blastemal cell population, resulting in inhibition of regeneration. The expression of special wound keratins found in the newt epidermis (W6) or mammalian epidermis (K6, K16, and K17) is present in the epidermis of both tail and limb of the lizard. These keratins are not immunolocalized in the migrating epithelium or normal (resting) epidermis but only after it has formed the thick wound epithelium, made of lacunar cells. The latter are proliferating keratinocytes produced during the cyclical renewal or regeneration of lizard epidermis. W6-immunolabeled proteic bands mainly at 45-47 kDa are detected by immunoblotting in normal, regenerating, and scarring epidermis of the tail and limb. Immunolabeled proteic bands at 52, 62-67 kDa (with K6), at 44-47, 60, 65 kDa (with K16), and at 44-47 kDa (with K17) were detected in normal and regenerating epidermis. It is suggested that: (1) these keratins constitute normal epidermis, especially where the lacunar layer is still differentiating; (2) the wound epidermis is similar in the limb and tail in terms of morphology and keratin content; (3) the W6 antigen is similar to that of the newt, and is associated with tonofilaments; (4) lizard K6 and K17 have molecular weights similar to mammalian keratins; (5) K16 shows some isoforms or degradative products with different molecular weight from those of mammals; (6) K17 increases in wound keratinocytes and localizes over sparse filaments or small bundles of short filaments, not over tonofilaments joined to desmosomes; and (7) failure of limb regeneration in lizards may not depend on the wound reaction of keratinocytes.
运用定性超微结构、免疫细胞化学和免疫印迹方法，对蜥蜴肢体（不能再生）和尾巴（能够再生）伤口表皮的角蛋白细胞骨架进行了研究。尾巴重新上皮化的过程比肢体要短得多。在肢体中，骨骼的大量组织破坏以及残端表面旧皮肤的收缩，延迟了伤口闭合，维持了炎症，减少了芽基细胞数量，从而抑制了再生。在蝾螈表皮（W6）或哺乳动物表皮（K6、K16和K17）中发现的特殊伤口角蛋白的表达，在蜥蜴的尾巴和肢体表皮中均有出现。这些角蛋白在迁移上皮或正常（静止）表皮中没有免疫定位，而是在由腔隙细胞构成的厚伤口上皮形成后才出现。腔隙细胞是蜥蜴表皮周期性更新或再生过程中产生的增殖角质形成细胞。通过免疫印迹在尾巴和肢体的正常、再生和瘢痕形成表皮中检测到主要位于45 - 47 kDa的W6免疫标记蛋白条带。在正常和再生表皮中检测到52、62 - 67 kDa（与K6相关）、44 - 47、60、65 kDa（与K16相关）以及44 - 47 kDa（与K17相关）的免疫标记蛋白条带。研究表明：（1）这些角蛋白构成正常表皮，尤其是在腔隙层仍在分化的部位；（2）肢体和尾巴的伤口表皮在形态和角蛋白含量方面相似；（3）W6抗原与蝾螈的相似，且与张力丝相关；（4）蜥蜴的K6和K17分子量与哺乳动物角蛋白相似；（5）K16显示出一些与哺乳动物不同分子量的异构体或降解产物；（6）K17在伤口角质形成细胞中增加，并定位于稀疏的细丝或短细丝小束上，而非连接到桥粒的张力丝上；（7）蜥蜴肢体再生失败可能不取决于角质形成细胞的伤口反应。
