de Velasco Begona, Erclik Ted, Shy Diana, Sclafani Joey, Lipshitz Howard, McInnes Roderick, Hartenstein Volker
Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA.
Dev Biol. 2007 Feb 1;302(1):309-23. doi: 10.1016/j.ydbio.2006.09.035. Epub 2006 Sep 26.
The central neuroendocrine system in the Drosophila brain includes two centers, the pars intercerebralis (PI) and pars lateralis (PL). The PI and PL contain neurosecretory cells (NSCs) which project their axons to the ring gland, a complex of peripheral endocrine glands flanking the aorta. We present here a developmental and genetic study of the PI and PL. The PI and PL are derived from adjacent neurectodermal placodes in the dorso-medial head. The placodes invaginate during late embryogenesis and become attached to the brain primordium. The PI placode and its derivatives express the homeobox gene Dchx1 and can be followed until the late pupal stage. NSCs labeled by the expression of Drosophila insulin-like peptide (Dilp), FMRF, and myomodulin form part of the Dchx1 expressing PI domain. NSCs of the PL can be followed throughout development by their expression of the adhesion molecule FasII. Decapentaplegic (Dpp), secreted along the dorsal midline of the early embryo, inhibits the formation of the PI and PL placodes; loss of the signal results in an unpaired, enlarged placodeal ectoderm. The other early activated signaling pathway, EGFR, is positively required for the maintenance of the PI placode. Of the dorso-medially expressed head gap genes, only tailless (tll) is required for the specification of the PI. Absence of the corpora cardiaca, the endocrine gland innervated by neurosecretory cells of the PI and PL, does not affect the formation of the PI/PL, indicating that inductive stimuli from their target tissue are not essential for early PI/PL development.
果蝇大脑中的中枢神经内分泌系统包括两个中心，即脑间部（PI）和外侧部（PL）。PI和PL含有神经分泌细胞（NSC），这些细胞的轴突投射到环腺，环腺是位于主动脉两侧的一组外周内分泌腺。我们在此展示了对PI和PL的发育和遗传学研究。PI和PL源自背内侧头部相邻的神经外胚层基板。这些基板在胚胎发育后期内陷，并附着于脑原基。PI基板及其衍生物表达同源框基因Dchx1，并且可以追踪到蛹期晚期。由果蝇胰岛素样肽（Dilp）、FMRF和肌动蛋白调节素的表达标记的神经分泌细胞构成了表达Dchx1的PI区域的一部分。PL的神经分泌细胞在整个发育过程中可通过其对黏附分子FasII的表达来追踪。沿着早期胚胎背中线分泌的骨形态发生蛋白（Dpp）抑制PI和PL基板的形成；信号缺失会导致一个不成对的、扩大的基板外胚层。另一个早期激活的信号通路，表皮生长因子受体（EGFR），对于维持PI基板是正向必需的。在背内侧表达的头部间隙基因中，只有无尾基因（tll）对于PI的特化是必需的。PI和PL的神经分泌细胞所支配的内分泌腺心侧体缺失，并不影响PI/PL的形成，这表明来自其靶组织的诱导刺激对于早期PI/PL发育并非必不可少。
