INVESTIGADORES
SOMOZA Gustavo Manuel
congresos y reuniones científicas
Título:
Peptide identity crisis: is secretoneurin a new hormone?
Autor/es:
VANCE L. TRUDEAU; ZHAO, E.; AJOY BASAK; GABRIELA C. LÓPEZ; LUIS F. CANOSA; GUSTAVO M. SOMOZA; PAULA POUSO; ANA SILVA
Lugar:
Minneapolis
Reunión:
Congreso; The Inaugural Meeting of the North American Society for Comparative Endocrinology (NASCE 2011); 2011
Institución organizadora:
The North American Society for Comparative Endocrinology
Resumen:
Secretogranin II (SgII) is a 600 amino acid, tyrosine-sulfated protein localized to secretory granules of vertebrate neuroendocrine cells. Numerous small potentially bioactive peptides are derived from SgII precursor processing, but only the 33-34 amino acid segment termed secretoneurin (SN) is conserved from fish to mammals. SN has effects on angiogenesis, neuroinflammation and neurotransmitter release in rodents. The wide distribution of SN in neuroendocrine neurons and pituitary cells suggests important endocrine roles. We have shown that SN stimulates LH release in goldfish (GF) both in vivo and in vitro. The main SN-IR neurons in GF are the parvo- and magoncellular isotocin-positive preoptic cells. In GF, lactotrophs are SN-immunoreactive (SN-IR) and SN-IR neuronal fibres are located in the intermediate and distal pituitary lobes. Co-incubation of dispersed GF pituitary cells with anti-SN antiserum reduces the stimulatory effect of salmon GnRH on LH release, supporting a paracrine role for SN. SN-IR is found in mouse LβT2 cells, and SN stimulates LH release in vitro, suggesting an autocrine mechanism. Our data indicate that SN rapidly stimulates calcium entry into GF gonadotrophs, and SN activates cAMP production and ERK-dependent pathways in LbetaT2 cells. Neuromodulatory roles for SN have also been postulated. Similar to the GF, SN-IR neurons are found in the preotic area of the electric fish, Brachyhypopomus gauderio. SN-IR fibres also reach the hindbrain where the electromotor pacemaker nucleus (PN) lies, and SN modulates the firing rate of B. gauderio PN neurons in vitro. Critical evidence for the identity of the SN receptor in any species is still lacking; our data indicate that it is most likely a G-protein coupled protein. SN is multifunctional, has important neurohormonal activities in fish and mammalian cells, and exhibits all the characteristics of a new hormone.