Riehle Michael A, Fan Yongliang, Cao Chun, Brown Mark R
Forbes 410, PO Box 210036, Department of Entomology, University of Arizona, Tucson, AZ 85721-0036, USA.
Peptides. 2006 Nov;27(11):2547-60. doi: 10.1016/j.peptides.2006.07.016. Epub 2006 Aug 24.
Insulin-like peptides are key regulators of metabolism, reproduction, and senescence in higher eukaryotic organisms. Here we present the identification, expression, and tissue localization of eight genes encoding insulin-like peptides (ILPs) in the yellow fever mosquito, Aedes aegypti. All eight ILPs share the conserved features of the insulin superfamily as prepropeptides consisting of contiguous signal, B, C, and A peptides. However, one of the ILPs has a truncated C peptide and a carboxy terminal extension, features consistent with insulin growth factors. Transcripts for five of the ILPs occurred predominantly in the heads (brains) of larval, pupal, and adult mosquitoes. Transcripts of two other genes, one of which was the putative insulin growth factor, were present in the head, thorax and abdomens of all stages. The final ILP was predominantly expressed in abdomen. Results from immunocytochemistry with two different ILP antisera showed cellular localizations in the nervous system and midgut that corroborated the existence of these expression patterns. Three of the ILP genes are so closely linked that only the 5' region of the first ILP gene likely suffices as a promoter, indicating that these genes form a eukaryotic operon. The nearly identical expression pattern of these three ILPs supported this idea. Finally, the phylogenetic relationship of ILPs from three dipteran species, Ae. aegypti, the African malaria mosquito (Anopheles gambiae), and Drosophila melanogaster is presented as a step towards understanding the structural and functional diversity of insect ILPs.
胰岛素样肽是高等真核生物新陈代谢、繁殖和衰老的关键调节因子。在此，我们展示了在黄热病蚊子埃及伊蚊中编码胰岛素样肽（ILP）的八个基因的鉴定、表达及组织定位。所有八个ILP作为前原肽都具有胰岛素超家族的保守特征，由连续的信号肽、B肽、C肽和A肽组成。然而，其中一个ILP具有截短的C肽和羧基末端延伸，这些特征与胰岛素生长因子一致。五个ILP的转录本主要出现在幼虫、蛹和成年蚊子的头部（脑）。另外两个基因的转录本，其中一个是假定的胰岛素生长因子，在所有发育阶段的头部、胸部和腹部均有表达。最后一个ILP主要在腹部表达。用两种不同的ILP抗血清进行免疫细胞化学的结果显示，在神经系统和中肠中的细胞定位证实了这些表达模式的存在。三个ILP基因紧密相连，以至于只有第一个ILP基因的5'区域可能足以作为启动子，这表明这些基因形成了一个真核操纵子。这三个ILP几乎相同的表达模式支持了这一观点。最后，展示了来自三种双翅目物种埃及伊蚊、非洲疟蚊（冈比亚按蚊）和黑腹果蝇的ILP的系统发育关系，作为理解昆虫ILP结构和功能多样性的一步。
