Islet-1Assist Histone Acetylation To Regulate Cardiac Development-related Transcription Factors

ObjectiveHistone acetylation is a important epigenetic method. Our previousstudies showed that cardiac development-related transcription factors wereregulated by histone acetylation. Histone acetylation level depends onhistone acetyltransferases (HATs) and histone deacetylase (HDACs).However, Histone acetylation has no specificity. There may be anassiantant factor to recognize cardiac development-related transcriptionfactors and regulate histone acetylation on their promoters. TheLIM-Homeodomain transcription factors Islet-1is a important transcriptionfactors during cardiac development. It may be the assistant factors. Thisstudy investigated whether Islet-1assisted histone acetylation as an assistantfactor to regulate the expression of cardiac development-relatedtranscription factors via a cardiac progenitor cell model which wastransfected lentivirus with a Islet-1RNAi vector.Material and MethodCardiac progenitor cells that were transfected with lentivirus vectors to inhibit Islet-1expression served as RNAi group. The cardiac progenitor cellsthat were transfected with empty vectors served as negative control.Transfection efficiency was measured by flow cytometry. The expression ofcardiac development-related transcription factors were measured usingQ-PCR. Histone acetylation level was detected by western blotting.Cardiac development-related transcription factors that physically interactedwith acetylated histone H3in cardiac progenitor cells were analyzed usingChIP assays. Cardiac development-related transcription factors thatphysically interacted with p300in cardiac progenitor cells were analyzedusing ChIP assays.Results1. Flow cytometry showed that transfection efficiency of negativecontrol and RNAi group were both more than30%. Q-PCR result showedthat the expression of Islet-1, Mef2c and Tbx5at RNAi group were less thanblank control and negative control (p<0.05). However, there are nosignificant difference of the expression of Gata4at RNAi group compared tocontrol groups (p>0.05).2. Western blotting showed that there were no significant difference ofhistone H3acetylation level at RNAi group compared to control groups(p>0.05). ChIP-PCR assays revealed that histone H3acetylation level ofMef2c promter at RNAi group was less than control groups (p<0.05), andthere were no significant difference of histone H3acetylation level of Gata4 promter and Tbx5promter. Meanwhile, binding level of p300to Mef2cpromter at RNAi group was less than control groups (p<0.05). There were nosignificant difference of binding level of p300to Gata4promter and Tbx5promter.ConclusionThese data indicated that inhibiting Islet-1can decrease p300tocombine with Mef2c promter, and down-regulate histone H3acetylationlevel of Mef2c promter to reduce expression of Mef2c. However, histoneacetylation may regulate expression of Gata4and Tbx5through othermethod.