Leder E H, Silverstein J T
National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, West Virginia 25430, USA.
J Endocrinol. 2006 Feb;188(2):355-63. doi: 10.1677/joe.1.06283.
Pro-opiomelanocortin (POMC) is a precursor for several important peptide hormones involved in a variety of functions ranging from stress response to energy homeostasis. In mammals and fish, the POMC-derived peptide alpha-melanocyte stimulating hormone (MSH) is known to be involved in appetite suppression through its interaction with melanocortin-4 receptors. The details of energy homeostasis in fishes are beginning to be elucidated and many of the genes involved in mammalian neuroendocrine signaling pathways are being discovered in fish. In salmonid fishes such as the rainbow trout, genome duplication adds another degree of complexity when trying to compare gene function and homology with other vertebrates. This is true of the POMC gene. Two copies of the POMC gene were previously identified, A and B, presumably resulting from the salmonid duplication. However, while investigating POMC involvement in the feeding response of rainbow trout, a second copy of POMC-A was discovered which is more likely the result of the salmonid duplication and suggests that POMC-B is a duplicate resulting from the earlier teleost duplication prior to tetrapod divergence. The duplicated POMC-A had five deleted amino acids, five inserted amino acids, and 39 amino acid differences from the published POMC-A. In addition to the duplicate POMC-A, a splice variant of the published POMC-A sequence was also identified. Quantitative real-time PCR assays were developed for the different POMC transcripts, and expression was examined in a variety of tissues. Expression of POMC transcripts was highest in the pituitary for all POMC genes, but varied among other tissues for POMC-A1, POMC-A2, POMC-A2s, and POMC-B. POMC-A1 was the only transcript to respond significantly to food deprivation.
阿片-促黑素细胞皮质素原（POMC）是几种重要肽类激素的前体，这些激素参与从应激反应到能量平衡等多种功能。在哺乳动物和鱼类中，已知源自POMC的肽α-黑素细胞刺激素（MSH）通过与黑素皮质素-4受体相互作用参与食欲抑制。鱼类能量平衡的细节开始得到阐明，并且在鱼类中发现了许多参与哺乳动物神经内分泌信号通路的基因。在虹鳟等鲑科鱼类中，基因组复制在试图将基因功能与其他脊椎动物进行比较时增加了另一个复杂程度。POMC基因就是如此。先前已鉴定出POMC基因的两个拷贝，A和B，推测是鲑科鱼类基因组复制的结果。然而，在研究POMC参与虹鳟摄食反应时，发现了POMC-A的第二个拷贝，它更可能是鲑科鱼类基因组复制的结果，这表明POMC-B是硬骨鱼在四足动物分化之前早期复制产生的重复基因。复制的POMC-A有五个缺失的氨基酸、五个插入的氨基酸，并且与已发表的POMC-A有39个氨基酸差异。除了复制的POMC-A外，还鉴定出了已发表的POMC-A序列的一个剪接变体。针对不同的POMC转录本开发了定量实时PCR检测方法，并在多种组织中检测了表达情况。所有POMC基因的POMC转录本在垂体中的表达最高，但POMC-A1、POMC-A2、POMC-A2s和POMC-B在其他组织中的表达有所不同。POMC-A1是唯一对食物剥夺有显著反应的转录本。
