Hyperacetylation of histone H4 correlates with the terminal, transcriptionally inactive stages of spermatogenesis in rainbow trout☆

[摘要] Developingtrouttestishasanunusuallyhighsteady-statelevelofhistoneH4hyperacetylationandthereforeprovidesanexcellentsysteminwhichtoinvestigatetherole(s)ofthismodification.WehavestudiedthepatternofH4hyperacetylationasafunctionoftrouttestiscelldifferentiationbyusing(a)wholetestesatprogressivestagesofdevelopment,and(b)individualtestiscellpopulationsseparatedinastage-dependentmanner.Thetranscriptionalactivityassociatedwiththedifferentiatingcelltypeshasalsobeeninvestigated.Theresultsprovidestrongevidencethattheproliferativeandtranscriptionallyactivespermatogoniaandspermatocytespossessnearlyundetectablesteady-statelevelsofH4hyperacetylation.ThecontentofhyperacetylatedH4risesdramatically(approaching50%ofthetotalH4)duringspermiogenesis—theprocesscomprisesthetransitionofspermatidstomaturespermandischaracterizedbydecliningtranscriptionalactivity.WeconcludethatthemajorityofthehyperacetylationofH4inthiscaseisnotassociatedwiththeproliferative,transcriptionallyactivestagesoftestisdevelopment,butratherisassociatedwithaneventoccurringlateindevelopment,duringspermiogenesis.Themostobviousprocessassociatedwiththisstageisthecompletereplacementofthehistoneswiththesperm-specificproteins,theprotamines.ItissuggestedthattheunusuallyhighlevelofhistoneH4hyperacetylationobservedintrouttestisisacting,insomemanner,toassistinthisreplacementprocess.

[学科分类] 生物科学（综合）