Miller D F, Rogers B T, Kalkbrenner A, Hamilton B, Holtzman S L, Kaufman T
Department of Biology, Howard Hughes Medical Institute, Indiana University, Bloomington, IN 47405, USA.
Mech Dev. 2001 Apr;102(1-2):3-16. doi: 10.1016/s0925-4773(01)00301-x.
Cross-regulation of Homeotic Complex (Hox) genes by ectopic Hox proteins during the embryonic development of Drosophila melanogaster was examined using Gal4 directed transcriptional regulation. The expression patterns of the endogenous Hox genes were analyzed to identify cross-regulation while ectopic expression patterns and timing were altered using different Gal4 drivers. We provide evidence for tissue specific interactions between various Hox genes and demonstrate the induction of endodermal labial (lab) by ectopically expressed Ultrabithorax outside the visceral mesoderm (VMS). Similarly, activation and repression of Hox genes in the VMS from outside tissues seems to be mediated by decapentaplegic (dpp) gene activation. Additionally, we find that proboscipedia (pb) is activated in the epidermis by ectopically driven Sex combs reduced (Scr) and Deformed (Dfd); however, mesodermal pb expression is repressed by ectopic Scr in this tissue. Mutant analyses demonstrate that Scr and Dfd regulate pb in their normal domains of expression during embryogenesis. Ectopic Ultrabithorax and Abdominal-A repress only lab and Scr in the central nervous system (CNS) in a timing dependent manner; otherwise, overlapping expression in the CNS in tolerated. A summary of Hox gene cross-regulation by ectopically driven Hox proteins is tabulated for embryogenesis.
利用Gal4定向转录调控，研究了异位Hox蛋白在黑腹果蝇胚胎发育过程中对同源异型复合体（Hox）基因的交叉调控。分析内源性Hox基因的表达模式以确定交叉调控，同时使用不同的Gal4驱动子改变异位表达模式和时间。我们提供了各种Hox基因之间组织特异性相互作用的证据，并证明在内脏中胚层（VMS）之外异位表达的超双胸（Ultrabithorax）可诱导内胚层唇（lab）基因的表达。同样，来自外部组织的VMS中Hox基因的激活和抑制似乎是由五体不全（dpp）基因的激活介导的。此外，我们发现异位驱动的性梳减少（Scr）和变形（Dfd）可在表皮中激活触须足（pb）基因；然而，在该组织中，中胚层pb基因的表达会被异位的Scr抑制。突变分析表明，Scr和Dfd在胚胎发育过程中在其正常表达域中调控pb基因。异位的超双胸和腹部-A仅以时间依赖性方式在中枢神经系统（CNS）中抑制lab和Scr；否则，CNS中的重叠表达是可耐受的。列出了异位驱动的Hox蛋白对Hox基因交叉调控在胚胎发育过程中的总结。
