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果蝇马氏管中神经肽对一氧化氮信号通路的刺激作用。

Neuropeptide stimulation of the nitric oxide signaling pathway in Drosophila melanogaster Malpighian tubules.

作者信息

Davies S A, Stewart E J, Huesmann G R, Skaer N J, Maddrell S H, Tublitz N J, Dow J A

机构信息

Division of Molecular Genetics, University of Glasgow, United Kingdom.

出版信息

Am J Physiol. 1997 Aug;273(2 Pt 2):R823-7. doi: 10.1152/ajpregu.1997.273.2.R823.

Abstract

Activation of the nitric oxide (NO) and guanosine 3', 5'-cyclic monophosphate (cGMP) signaling pathway stimulates fluid secretion by the Drosophila melanogaster Malpighian tubule. The neuropeptide cardioacceleratory peptide 2b (CAP2b) has been previously shown to stimulate fluid secretion in this epithelium by elevating intracellular cGMP levels. Therefore, it was of interest to investigate if CAP2b acts through NO in isolated tubules and thus presumably through stimulation of a tubule NO synthase (NOS). We show here by reverse-transcription polymerase chain reaction that Drosophila NOS (dNOS) is expressed in Malpighian tubules. Biochemical assays of NOS activity in whole tubules show that CAP2b significantly stimulates NOS activity. Additionally, fluid secretion and cyclic nucleotide assays show that CAP2b-induced elevation of intracellular cGMP levels and fluid secretion rates are dependent on the activation of a soluble guanylate cyclase. Treatment of tubules with a specific NOS inhibitor abolishes the CAP2b-induced rise in intracellular cGMP levels. These data indicate that CAP2b stimulates NOS and therefore, endogenous NO production, which, in turn, stimulates a soluble guanylate cyclase. This is the first demonstration of stimulation of an endogenous NOS by a defined peptide in Drosophila.

摘要

一氧化氮(NO)和鸟苷3',5'-环磷酸(cGMP)信号通路的激活可刺激果蝇马氏管的液体分泌。神经肽心脏加速肽2b(CAP2b)先前已被证明可通过提高细胞内cGMP水平来刺激该上皮细胞的液体分泌。因此,研究CAP2b是否通过NO在分离的小管中起作用,从而可能通过刺激小管一氧化氮合酶(NOS)来起作用,是很有意义的。我们在这里通过逆转录聚合酶链反应表明,果蝇NOS(dNOS)在马氏管中表达。对整个小管中NOS活性的生化分析表明,CAP2b可显著刺激NOS活性。此外,液体分泌和环核苷酸分析表明,CAP2b诱导的细胞内cGMP水平升高和液体分泌速率取决于可溶性鸟苷酸环化酶的激活。用特异性NOS抑制剂处理小管可消除CAP2b诱导的细胞内cGMP水平升高。这些数据表明,CAP2b刺激NOS,因此刺激内源性NO生成,进而刺激可溶性鸟苷酸环化酶。这是首次证明在果蝇中一种特定肽刺激内源性NOS。

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