Regulation of epigenetic state by non-histone chromatin proteins and transcription factors: Implications in disease

Besides the fundamental components of the chromatin, DNA and octameric histone, the non-histone chromatinproteins and non-coding RNA play a critical role in the organization of functional chromatin domains. Thenon-histone chromatin proteins therefore regulate the transcriptional outcome in both physiological andpathophysiological state as well. They also help to maintain the epigenetic state of the genome indirectly.Several transcription factors and histone interacting factors also contribute in the maintenance of the epigeneticstates, especially acetylation by the induction of autoacetylation ability of p300/CBP. Alterations of KATactivity have been found to be causally related to disease manifestation, and thus could be potential therapeutictarget.

Homocysteine induces glyceraldehyde-3-phosphate dehydrogenase acetylation and apoptosis in the neuroblastoma cell line Neuro2a

High plasma levels of homocysteine (Hcy) promote the progression of neurodegenerative diseases. However, the mechanism by which Hcy mediates neurotoxicity has not been elucidated. We observed that upon incubation with Hcy, the viability of a neuroblastoma cell line Neuro2a declined in a dose-dependent manner, and apoptosis was induced within 48 h. The median effective concentration (EC50) of Hcy was approximately 5 mM. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) nuclear translocation and acylation has been implicated in the regulation of apoptosis. We found that nuclear translocation and acetylation of GAPDH increased in the presence of 5 mM Hcy and that higher levels of acetyltransferase p300/CBP were detected in Neuro2a cells. These findings implicate the involvement of GAPDH in the mechanism whereby Hcy induces apoptosis in neurons. This study highlights a potentially important pathway in neurodegenerative disorders, and a novel target pathway for neuroprotective therapy.

Research progress on P300/CBP in malignant tumors / 实用肿瘤学杂志

P300/CBP is one of the most important high molecular weight protein histone acetyltransferase ( HAT) Although it is encoded by multiple different genes , P300/CBP is highly homologous , Because they have the similar amino acid sequence and functions ,and belong to the same class of proteins ,normolly they are all called P300/CBP.P300/CBP is involved in the activation of many kinds of transcription factors ,the protein itself alsohas acetyltransferase activity ,and is capable of acetylation of 4 core histones and transcription factor .More and more studies have confirmed the relationship of P 300/CBP variation withmultiple human diseases , including in-flammation,diabetes,heart disease and especially cancer .In tumor P300/CBP is associated with some pathways , and these pathways play a different roles in the tumor .Although P300/CBP is usually regarded as a tumor sup-pressor factor ,is plays different roles in different tumors ,This review mainly introduces the relationship of P 300/CBP with some solid tumor disease genes ,related transcription factors and their signaling pathways .

Convergence role of transcriptional coactivator p300 and apparent modification on hmcs metabolic memory induced by high glucose / 解放军医学杂志

Objective To investigate the protein expression of transcriptional coactivator p300, acetylated histone H3 (Ac-H3) and Ac-H4 in human renal mesangial cell (HMCs) as imitative "metabolic memory" in vitro, and explore the potential role of convergence point of p300. Methods The HMCs were divided into the following groups: {circled digit 1} High glucose metabolic memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d), high glucose group (HG, 2Smmol/L D-glucose × 2d), memory groups (Ml, M2, M3, 2Smmol/L D-glucose × 2days + S.Smmol/L D-glucose × 3d, 6d or 9d), persisting normal glucose group (NG, S.Smmol/L D-glucose × 9d). {circled digit 2} Advanced glycation end products memory model: normal glucose group (NG, S.Smmol/ L D-glucose × 2d), NG+AGEs group (AGEs, S.Smmol/L D-glucose+2S0μg/ml AGEs × 2d); AGEs memory group (AGEs-M, S.Smmol/L D-glucose + 2S0μg/ml AGEs × 2d + S.Smmol/L D-glucose × 3d); BSA control group (NG+BSA, S.Smmol/L D-glucose + 2S0μg/ml BSA × 2d). {circled digit 3} H202 was used to simulate oxidative stress memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d), NG+H202 group (H202, S.Smmol/L D-glucose +100μmol/L H202 × 30min); H202 memory group [(S.Smmol/ L D-glucose + 100μmol/L H202 × 30min) + S.Smmol/L D-glucose × 3d]; normal glucose control group (NG3, S.Smmol/L D-glucose X 3d). {circled digit 4} Transfection with PKCβ2 memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d); high glucose group (HG, 2Smmol/L D-glucose × 2d); memory group (M, 2Smmol/L D-glucose × 2d + S.Smmol/L D-glucose × 3d); AdS-null memory group (HN, 2Smmol/L D-glucose + AdS-null × 2d + S.Smmol/L D-glucose × 3d); PKCβ2 memory group (PO, 2Smmol/L D-glucose + AdS-PKCβ2 × 2d + S.Smmol/L D-glucose × 3d); inhibitor of PKCβ2 memory group (PI, 2Smmol/L D-glucose × 2d + 10μmol/L CGPS33S3 + S.Smmol/L D-glucose × 3d). The expression of intracellular reactive oxygen species (ROS) was detected by fluorescence microscope and fluorescence microplate reader. The expression levels of p300, Ac-H3, Ac-H4 and PKCβ2 proteins were determined by Western blotting. Results The expression levels of p300, Ac-H3 and Ac-H4 protein in HG group increased, being 2.15, 1.93 and 1.87 fold of those in group NG (P<0.05), accompanying with the up-regulation of PKCβ2 protein and ROS levels in HG group. The p300, Ac-H3, Ac-H4, PKCβ2 protein expression and ROS levels in Ml, M2, M3 group were higher than those in NG group, and was 1.75, 1.49, 1.47, 1.98 and 1.48 fold higher in M3 group than in NG group. The protein expressions of p300, Ac-H3 and Ac-H4 in AGEs group were increased by 1.73, 1.08 and 1.05 folds, and in AGE-M group increased by 1.47, 0.95 and 1.03 folds of that in control group (P<0.05). The protein expression levels of p300, Ac-H3 and Ac-H4 in H202 group increased by 1.03, 0.85 and 0.79 folds of those in control group (P<0.05). However, no significantly difference in these indices was found between H202-M and control groups. The protein expression levels of p300, Ac-H3 and Ac-H4 in PO group increased more obviously by 1.25, 1.06 and 1.10 folds of those in M group (P<0.05). However, the elective PKCβ2 inhibitor CGP533S3 could lower those indices significantly. Conclusion Persistent activation of transcriptional coactivator p300 and apparent modification may be normalized in HMCs. p300 may be the convergent point of glucose-induced metabolic "memory" stimulations.

The biological characteristics of p300/CBP-associated factor and relationship with disease / 国际儿科学杂志

p300/CBP-associated factor (PCAF)is an important histone acetyltransferase in eukaryotic cells. PCAF can acetylizes histone and non-histone. PCAF participates in various biological processes of cells and in the interaction between virus and cells. The imbalance of PCAF would lead to abnormal development of various organs, and related to the development of some tumors.

Transcriptional induction of DLC-1 gene through Sp1 sites by histone deacetylase inhibitors in gastric cancer cells

We previously reported that trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, induced DLC-1 mRNA expression and accumulated acetylated histones H3 and H4 associated with the DLC-1 promoter in DLC-1 non-expressing gastric cancer cells. In this study, we demonstrated the molecular mechanisms by which TSA induced the DLC-1 gene expression. Treatment of the gastric cancer cells with TSA activates the DLC-1 promoter activity through Sp1 sites located at -219 and -174 relative to the transcription start site. Electrophoretic mobility-shift assay (EMSA) revealed that Sp1 and Sp3 specifically interact with these Sp1 sites and showed that TSA did not change their binding activities. The ectopic expression of Sp1, but not Sp3, enhances the DLC-1 promoter responsiveness by TSA. Furthermore, the TSA-induced DLC-1 promoter activity was increased by p300 expression and reduced by knockdown of p300. These results demonstrated the requirement of specific Sp1 sites and dependence of Sp1 and p300 for TSA-mediated activation of DLC-1 promoter.

Prokaryotic Expression and Acetylation Assays of Histone Acetyltransferase PCAF / 中国生物工程杂志

P300/CBP-associated factor(PCAF),an important member of histone acetyltransferase family(HATs) within eukaryotic cells,is capable of inducing the acetylation of histone,promoting the transcription of specific genes and involving in many biological effects.In the present study,full-length cDNA of PCAF was inserted into plasmid pGEX-5x-1,then the soluble protein GST-PCAF was expressed in E.coli BL21(DE3) after the optimization of inducing conditions.The recombinant protein was further purified with affinity chromatography and tested the activity by in vitro acetylation assays.High efficient PCAF protein produced by this method could serve for the study on the role of PCAF in gene regulation and the interaction between PCAF and other proteins.