Insect cytokine, growth-blocking peptide, is a primary regulator of melanin-synthesis enzymes in armyworm larval cuticle
Insect cytokine, growth-blocking peptide, is a primary regulator of melanin-synthesis enzymes in armyworm larval cuticle
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DOI：
10.1111/j.1742-4658.2007.05724.x
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发表时间：
2007-04-01
期刊：
影响因子：
5.4
通讯作者：
Hayakawa, Yoichi
中科院分区：
文献类型：
--
作者：
Ninomiya, Yosuke;Hayakawa, Yoichi
大多数昆虫幼虫的表皮具有多种黑色素模式，这些模式在昆虫与其生物和非生物环境的相互作用中起作用。粘虫的幼虫有黑色和白色条纹纵向沿着身体轴。在最后一次幼虫蜕皮后，通过增加线条之间的对比度来强调这种模式。我们以前已经表明，3，4-二羟基-L-苯丙氨酸（多巴）脱羧酶（DDC）在蜕皮期间被激活，其转录的优先增强下的黑色条纹的表皮细胞。这项研究表明，酪氨酸羟化酶（TH）的表达与DDC同步激活。此外，DDC和TH转录的增强是由于细胞质Ca 2+的增加，这是由昆虫细胞因子生长阻断肽（GBP）诱导的。两种酶的基因表达增强诱导的钙离子载体A23187的取代，并完全阻断EGTA。黑条表皮细胞胞浆Ca ~（2+）浓度升高，而白色表皮细胞胞浆Ca ~（2+）浓度升高，提示黑条表皮细胞内Ca ~（2+）浓度的差异导致DDC和TH基因的特异性表达。根据白色条纹下表皮细胞含有丰富的主要由尿酸组成的颗粒，尿酸可以与Ca 2+形成复合物，从而降低其游离浓度的事实，我们讨论了尿酸以及GBP导致表皮细胞内细胞质Ca 2+差异的可能性。
The cuticles of most insect larvae have a variety of melanin patterns that function in the insects' interactions with their biotic and abiotic environments. Larvae of the armyworm Pseudaletia separata have black and white stripes running longitudinally along the body axis. This pattern is emphasized after the last larval molt by an increase in the contrast between the lines. We have previously shown that 3,4-dihydroxy-L-phenylalanine (Dopa) decarboxylase (DDC) is activated during the molt period by preferential enhancement of its transcription in the epidermal cells beneath the black stripes. This study demonstrated that tyrosine hydroxylase (TH) expression is activated synchronously with DDC. Furthermore, enhancement of DDC and TH transcription is due to an increase in cyotoplasmic Ca2+, which is induced by the insect cytokine, growth-blocking peptide (GBP). Enhanced gene expression for both enzymes was induced by substitution of the calcium ionophore A23187, and completely blocked by EGTA. A GBP-induced increase in cytoplasmic Ca2+ was seen in epidermal cells under the black stripes but not those beneath the white stripes, suggesting that a difference in Ca2+ concentration in stripe cells leads to the specific expression of DDC and TH genes. Based on the fact that epidermal cells beneath the white stripes contain abundant granules composed mainly of uric acid, which can form a complex with Ca2+ and hence decrease its free concentration, we discuss the possibility that uric acid, as well as GBP, contributes to the difference in cytoplasmic Ca2+ within the epidermal cells.