Agrawal N, Kango M, Mishra A, Sinha P
Drosophila Stock Center, School of Life Sciences, Devi Ahilya Vishwavidyalaya, Indore, India.
Dev Biol. 1995 Nov;172(1):218-29. doi: 10.1006/dbio.1995.0017.
Homozygosity for lethal(2)giant larvae (lgl), a mutation in a tumor suppressor gene of Drosophila, induces neoplasia of the imaginal discs. To explore the developmental capacities of lgl mutant cells, we have investigated their growth and differentiation in genetic mosaics. Adult wings mosaic for lgl displayed abnormal growth and differentiation of the lgl mutant and neighboring wild-type cells, suggesting aberrant cell-cell interactions during development. lgl mutant clones also straddled the anteroposterior boundary of the wing imaginal disc, apparently due to failure of the cells of the anterior and the posterior compartment to segregate at the boundary. To further test if anteroposterior compartmentalization takes place in the neoplastic imaginal discs of lgl mutant larvae, we studied the expression of an engrailed (en)-specific lacZ reporter gene during progressive stages of their tumorous growth. Our results show that en is activated in the posterior compartments of the neoplastic imaginal discs. However, during later stages of tumorous overgrowth, the en-expressing and nonexpressing cells appear to show extensive intermixing. These observations suggest that neoplastic transformation of imaginal discs involves loss of their normal cell-cell interactions and signaling.
致死性（2）巨幼虫（lgl）基因纯合子，该基因是果蝇肿瘤抑制基因的一种突变，可诱导成虫盘形成肿瘤。为了探究lgl突变细胞的发育能力，我们研究了它们在遗传嵌合体中的生长和分化情况。lgl基因镶嵌的成年翅膀显示出lgl突变细胞和邻近野生型细胞的异常生长和分化，这表明在发育过程中细胞间相互作用异常。lgl突变克隆也跨越了翅膀成虫盘的前后边界，这显然是由于前后区室的细胞在边界处未能分离所致。为了进一步测试在lgl突变幼虫的肿瘤性成虫盘中是否发生前后区室化，我们研究了在其肿瘤生长的不同阶段一种特定于engrailed（en）的lacZ报告基因的表达情况。我们的结果表明，en在肿瘤性成虫盘的后区室中被激活。然而，在肿瘤过度生长的后期阶段，表达en和不表达en的细胞似乎出现了广泛的混合。这些观察结果表明，成虫盘的肿瘤转化涉及正常细胞间相互作用和信号传导的丧失。
