Adrenomedullin: a novel hypotensive peptide isolated from human pheochromocytoma 1993

Natl Cardiovasc Ctr, Res Inst, Suita, Osaka 565, Japan and Miyazaki Med Coll, Biochem Rech Inst, Miyazaki 88916, Japan
Biochemical and Biophysical Research Communications (Impact Factor: 2.3). 08/2012; 425(3):548-55. DOI: 10.1016/j.bbrc.2012.08.022
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    • "AM binding to its plasma membrane receptor AM1 induces the activation of adenylate cyclase with consequent increase in intracellular cAMP [14]. To confirm the lack of RAMP2 in the plasma membrane of TECs and thymocytes, observed with confocal microscopy, we evaluated cAMP levels in these cells following exposure to AM. "
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    ABSTRACT: Adrenomedullin (AM) is a multifunctional peptide endowed with various biological actions mediated by the interaction with the calcitonin receptor-like receptor (CLR), which couples to the receptor activity-modifying proteins 2 or 3 (RAMP2 or RAMP3) to form the functional plasma membrane receptors AM1 and AM2, respectively. In this study, we investigated for the first time the expression and localization of AM, CLR, RAMP2 and RAMP3 in human thymic tissue from newborns and in primary cultures of thymic epithelial cells (TECs) and thymocytes. Immunohistochemical analysis of thymic tissue showed that both AM and RAMP2 are abundantly expressed in the epithelial cells of medulla and cortex, blood vessels and mastocytes. In contrast, RAMP3 could not be detected. In cultured TECs, double immunofluorescence coupled to confocal microscopy revealed that AM is present in the cytoplasmic compartment, whereas RAMP2 could be detected in the cytoplasm and nucleus, but not in the cell membrane. At variance with RAMP2, CLR was not only present in the nucleus and cytoplasm of TECs, but could also be detected in the cell membrane. The nuclear and cytoplasmic localizations of RAMP2 and CLR and the absence of RAMP2 in the cell membrane were confirmed by western-blot analysis performed on cell fractions. AM, RAMP2 and CLR could also be detected in thymocytes by means of double immunofluorescence coupled to confocal microscopy, although these proteins were not present in the whole thymocyte population. In these cells, AM and RAMP2 were detected in the cytoplasm, whereas CLR could be observed in the cytoplasm and the plasma membrane. In conclusion, our results show that the AM system is widely expressed in human thymus from newborns and suggest that both AM1 receptor components CLR and RAMP2 are not associated with the plasma membrane of TECs and thymocytes but are located intracellularly, notably in the nucleus.
    Full-text · Article · May 2014 · PLoS ONE
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    • "ADM, a 52-amino acid polypeptide, is well known as an expander of blood vessels and a diuretic active peptide [2]. Accumulating evidence suggests that ADM is a pro-angiogenesis factor that promotes the proliferation, migration, and tube formation of endothelial cells [15-17,19]. "
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    ABSTRACT: To investigate the roles of an adrenomedullin receptor antagonist (adrenomedullin22-52) on high-glucose-induced human retinal endothelial cell (HREC) in vitro cell biology. HRECs were cultured with different concentrations of glucose and adrenomedullin22-52. The proliferation of HRECs was evaluated by a cell counting kit-8 assay. Cell migration was assessed by scratch wound assay, and cell sprouting was detected by tube formation assay. The mRNA levels of adrenomedullin (ADM), vascular endothelial growth factor (VEGF), ADAMTS-1, and TSP-1 were measured by reverse-transcription polymerase chain reaction (RT-PCR). The VEGF and phosphatidylinositol 3' kinase (PI3K) pathway protein expression levels were assessed by western blot analysis. Compared with 5 mM normal glucose treatment, 30 mM glucose significantly promoted the migration of HRECs, which was attenuated by 1 μg/ml adrenomedullin22-52. The proliferation of HRECs was also suppressed by 1 μg/ml adrenomedullin22-52. Furthermore, compared with other groups, 5 μg/ml of adrenomedullin22-52 was shown to suppress high-glucose-induced tube formation of HRECs. With adrenomedullin22-52 treatment, the mRNA level of ADAMTS-1 was significantly increased. Moreover, western blot and RT-PCR analyses showed that HRECs treated with 30 mM glucose exhibited increased VEGF and PI3K pathway protein levels, while the expression levels were suppressed by 5 μg/ml of adrenomedullin22-52. Our study indicated that adrenomedullin22-52 mediated the migration, proliferation and tube formation after HRECs were exposed to high levels of glucose, which may be related to its ability to affect the expression of VEGF through the PI3K pathway.
    Full-text · Article · Mar 2014 · Molecular vision
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    • "Since the discovery of AM in human , a 52 - amino acid peptide ( Kitamura et al . , 1993a ) , sequences from other species have then been elucidated . For instance , the rat AM contains 50 amino acids with 2 residues deleted and 6 residues substituted when compared to the human peptide ( Sakata et al . , 1993 ) ; the porcine AM , is found to be nearly identical to the human peptide , except with one residue substitution at p"

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