Thyrotropin-Releasing Activity of Histone H2A, H2B and Peptide MB35

Brown, O. A., Y. E. Sosa and R. G. Goya. Thyrotropin-releasing activity of histones H2A, H2B and peptide MB35. Peptides 18(9) 1315–1319, 1997.—Histones possess multiple hormone-like activities. We studied the specificity and signal transduction pathways involved in the thyrotrophin (TSH)-releasing activity of histones H2A, H2B and peptide MB35, a H2A fragment, using perifused and incubated dispersed rat pituitary cells and measuring TSH release by a specific R1A. Histones released TSH in a dose- and time-dependent fashion while peptide MB35 behaved as a weaker secretagogue. Trifluoperazine and EGTA blocked histone-stimulated TSH release while forskolin and other cAMP enhancers did not. We conclude that the TSH-releasing activity of histones H2A and H2B is mediated by calcium- and diacylglycerol-associated pathways.