A. Takahashi's research while affiliated with Kitasato University and other places

Publications (35)

Article
Prolactin (PRL)-releasing peptides (PrRP) have been identified in mammals, amphibians and fishes, and these animals have several PrRPs that consist of different numbers of amino acids such as 20, 31 and 37. In the present study, we identified the cDNA encoding chicken prepro-PrRP, which can generate putative PrRPs, and cloned and sequenced it. Sequ...
Article
Full-text available
Prolactin (PRL)-releasing peptide (PrRP) is a strong candidate stimulator of pituitary PRL transcription and secretion in teleosts. However, the role in control of extrapituitary PRL expression is unclear even in mammals. To study the possible presence of PrRP-PRL axes not only in the brain-pituitary but also in peripheral organs, the expression pa...
Article
Full-text available
Prolactin-releasing peptide (PrRP), recently isolated from the brain of mammals and teleosts, is a strong candidate for being a stimulatory hormone of pituitary prolactin secretion. The present study examined whether or not PrRP is capable of inducing prolactin gene expression and elevating plasma prolactin levels in vivo in cannulated rainbow trou...
Article
In the tilapia (Oreochromis mossambicus), as in many teleosts, prolactin (PRL) plays a major role in osmoregulation in freshwater. Recently, PRL-releasing peptides (PrRPs) have been characterized in mammals. Independently, a novel C-terminal RF (arginine-phenylalanine) amide peptide (Carrasius RF amide; C-RFa), which is structurally related to mamm...
Article
For the investigation of the evolution of the proopiomelanocortin (POMC) gene in early ray-finned fishes, nucleotide sequence of POMC cDNA from a chondrostean fish, the sturgeon has been determined. POMC cDNA was amplified by PCR from double-strand cDNA prepared from sturgeon pituitary and ligated with lambdaZAP II. The POMC cDNA consists of 1079 b...
Article
In the lamprey, which is a member of the oldest extant class of vertebrates, the agnathans, melanotropins (MSH) and corticotropin (ACTH) were found to be encoded on two distinct genes. In all other vertebrates, a single precursor gene, proopiomelanocortin (POMC), encodes MSH and ACTH, as well as beta-endorphin (END). Two different cDNAs were cloned...
Article
Full-text available
A novel homodimeric glycoprotein was isolated and characterized from the pituitaries of adult sea lampreys, Petromyzon marinus, modern representatives of the earliest vertebrates. The monomer consists of 121 amino-acid residues in a sequence that has no resemblance to any known pituitary hormone. Whereas this protein is localized in most cells of t...

Citations

... Determination of MCR sequences, together with previous determination of POMC sequence containing several melanocortin peptide sequences (Amemiya et al., 2000 ), have enabled homologous assay for ligand binding to clarify properties of MCRs. The presence of pituitary-interrenal (PI) axis in cartilaginous fish has been shown for a long time only by the presence of POMC containing ACTH in the pituitary (Lowry et al., 1974; Nozaki et al., 1999; Takahashi et al., 1999 Takahashi et al., , 2008), and by activity of ACTH to stimulate the corticosteroid (1a-hydroxycorticosteron) secretion from the interrenal tissue, a homologous tissue to mammalian adrenal cortex (Anderson, 2012; Hazon and Henderson, 1985; Nunez and Trant, 1999 ). The present study has finally established the (functional ) PI axis at the level of MCRs by demonstrating the expression of the responsible genes in stingray interrenal tissues. ...
... In Cypriniformes, early immunoreativity (ir) studies in goldfish showed the presence of MCH in neuron populations related to the regulation of feeding and of sleep and arousal (Huesa et al., 2005). In goldfish, central injections of MCH decrease feeding but have no effect on locomotor activity (Shimakura et al., 2006), anti-MCH serum treatments increase feeding (Matsuda et al., 2007a), and the number of certain hypothalamic neuronal cell bodies containing MCH-ir decreases in fasted fish (Matsuda et al., 2007a), altogether suggesting an anorexigenic role for MCH in this species. However, in Ya fish, MCH hypothalamic mRNA expression is higher in fasted compared to fed fish, suggesting an orexigenic role . ...
... DeLuca et al. performed a structural study based on NMR and CD spectroscopy, where they determined the α-helical conformation in trifluoroethanol of the C-terminal sequence of PrRP20 [57]. Shorter PrRP20 analogs, PrRP(4-20), PrRP13 (PrRP (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)), and heptapeptide PrRP (14)(15)(16)(17)(18)(19)(20), decreased the stability of the helical segment and their biological activity was reduced. Therefore, this stable Cterminal α-helical structure facilitates ligand recognition by the receptor and enables its activation [57]. ...
... In addition, MCRs bind the agouti signaling peptide (ASIP) and agoutirelated protein (AGPR), which are endogenous antagonists that regulate pigmentation and food intake through the MCR1 and MCR4 receptors, respectively. In lampreys, unlike other vertebrates, melanotropins (MSHs) and corticotropin (ACTH) are encoded by two different genes: proopiocortin (POC encoding ACTH and a form of β-EP) and proopiomelanotropin (POM encoding two MSHs, MSH-A and MSH-B, and a different β-EP) (Heinig et al., 1995;Takahashi et al., 2006;Takahashi, Amemiya, Sarashi, et al., 1995). The two melanotropins identified in the sea lamprey, MSH-A and MSH-B, differ significantly from the MSHs of gnathostome and, therefore, cannot be assigned as α-MSH, β-MSH, γ-MSH, or δ-MSH based on sequence similarity . ...
... The most prominent glycoprotein that we first identified was nasohypophseal factor ( ), which corresponded Sower et al., 1995 to the N-terminal peptide of pro-opiocortin (POC), consisting of 121 amino acids with one glycosylation site. From our continued collaborations, we identified the adrenocorticotropin (ACTH), melanotropins A and B (MSH A and B), and -endorphins ( -EP). ...
... In sarcopterygian fish (lobe-finned fish), the POMC precursor exhibits the same three MSH domains (Amemiya et al., 1999a;Dores et al., 1999). The c-MSH domain occurs only as a remnant in non-teleost actinopterygians, including sturgeons (Amemiya et al., 1997;Alrubaian et al., 1999), and is absent in the most derived group, the teleosts (Salbert et al., 1992;Arends et al., 1998;Cerdá-Reverter et al., 2003). In contrast, elasmobranch fish have an additional fourth MSH domain, termed d-MSH, which probably arose as a duplication from the b-MSH-b-endorphin segment. ...
... However, in nonmammalian vertebrate species, another novel bioactive peptide has been isolated from crucian carp, namely Carassius RFamide (C-RFa) (41). This 20-amino acid peptide, as a homologue of PrRP20, was subsequently found in chicken (42), frog, zebrafish (43), tilapia (44), and chum salmon (45). This form of PrRP is highly conserved and shows almost 100% similarity in identified species. ...
... This phenomenon is regulated by feedback based on circulating PRL levels, like many hormones. (Sakamoto et al., 2003;Sakamoto et al., 2005;Fujimoto et al., 2006;Kwong and Woo, 2008). 2) In various mammalian models, the generation of anti-PRL autoantibodies triggers increased synthesis of PRL at the transcript and protein level, but to date, this has not been demonstrated in fish. ...
... All of these responses appear to be regulated/stimulated by the release of various hormones, such as prolactin and the neurohypophysial hormones vasotocin and isotocin. During terrestrial exposure, prolactin mRNA levels in the pituitary, and prolactin levels in the blood, increase in the mudskippers Periophthalmus modestus (Sakamoto et al. 2005) and P. chrysospilos (Lee & Ip 1987), respectively. Further, when the high intertidal Periophthalmus modestus is kept out of water, the expression of vaso-and isotocin precursors in the brain is upregulated, and after an intracerebroventricular injection of vaso-and isotocin, there is an increased tendency to remain in the water (Sakamoto et al. 2015). ...