Premium
HISTONES AS EXTRACELLULAR MESSENGERS: EFFECTS ON GROWTH HORMONE SECRETION
Author(s) -
BROWN O. A.,
SOSA Y. E.,
GOYA R. G.
Publication year - 1997
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1006/cbir.1998.0203
Subject(s) - histone , medicine , extracellular , endocrinology , biology , somatotropic cell , protein kinase c , egta , second messenger system , calcium , signal transduction , chemistry , microbiology and biotechnology , biochemistry , pituitary gland , hormone , gene
Histones display hormone‐like properties when present in extracellular fluids. The authors report that histones H2A and H2B possess growth hormone (GH)‐releasing activity in vitro and describe the specificity and signal transduction pathways involved in these effects. Perfused and incubated rat pituitary cells were used in different sets of experiments and GH release was measured by radio‐immunoassay (RIA). Perfusion of cells with 30μ m histone H2A or H2B, generated significant GH secretory responses. Cells incubated with histone H2A showed a dose‐ and time‐dependent stimulatory effect on GH release which was blocked by peptide MB35, a synthetic fragment of histone H2A. Incubation of pituitary cells with the GH secretagogue GHRP‐6, and histones revealed an additive release of GH, whereas GHRH and histones revealed a synergistic effect. The basic peptide poly‐Lys did not mimetize the action of histones. Both EGTA and the protein kinase C inhibitor trifluoperazine, but not the calcium ionophre A23187, were able to reduce significantly the GH response of somatotrophs to histones. Pituitary cell incubation with 30μ m forskolin alone or in the presence of H2A or H2B, stimulated GH release in the same magnitude. The results confirm previous evidence that histones may act as hypophysotropic signals and suggest, although do not prove, that this activity is receptor dependent. Calcium‐ and diacylglycerol‐associated pathways participate in these effects.