title: Acetylation regulates the stability of glutamate carboxypeptidase II protein in human astrocytes.
abstract: Glutamate carboxypeptidase II (GCPII) is known to be implicated in brain diseases such as schizophrenia and bipolar disorder, and dramatically increases in prostate cancer. Here, we investigated the regulation of GCPII expression in astrocytes and examined whether GCPII is epigenetically regulated through histone modification. In this study, valproic acid (VPA), a drug used for bipolar disorder and epilepsy and a known histone deacetylase (HDAC) inhibitor was used. We found that acute exposure of VPA for 4-6h increased the GCPII protein level in human astrocyte U87MG cells but did not have a similar effect after 12-24h exposure. Real-time polymerase chain reaction analysis revealed that VPA did not affect the GCPII mRNA expression. In contrast, decrease in GCPII protein level by cycloheximide treatment was blocked by VPA, indicating that VPA increases GCPII protein stability. Treatment with MG132, a proteasome inhibitor, suggested that the VPA-induced increase of GCPII protein level is dependent on the ubiquitin/proteasome pathway. In addition, immunoprecipitation analysis revealed that VPA increased the acetylation of GCPII protein at the lysine residues and facilitated a decrease of the poly-ubiquitinated GCPII level. Similarly, M344, a specific HDAC 1/6 inhibitor, also increased the GCPII protein level. In contrast, treatment with C646, a histone acetyltransferase inhibitor of p300/CBP, significantly reduced the level of GCPII protein. Taken together, this study demonstrated that the increase in GCPII induced by VPA is not due to the classical epigenetic mechanism, but via enhanced acetylation of lysine residues in GCPII.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Dankook University, Cheonan-si, Chungnam, South Korea.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Choi
authors.affiliation: Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan-si, Chungnam, South Korea.
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Pharmacology, College of Pharmacy, Dankook University, Cheonan-si, Chungnam, South Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan-si, Chungnam, South Korea. Electronic address: smahn@dankook.ac.kr.
authors.forename: Sangmee Ahn
authors.initials: SA
authors.lastname: Jo
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000954:Antigens, Surface / Q000378:metabolism*; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology*; D002460:Cell Line; D004795:Enzyme Stability; D043425:Glutamate Carboxypeptidase II / Q000378:metabolism*; D006801:Humans; D014635:Valproic Acid / Q000494:pharmacology*
chemical_list: D000954:Antigens, Surface; D014635:Valproic Acid; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II
keywords: Acetylation; Glutamate carboxypeptidase II; Histone acetyltransferase; Histone deacetylase; Protein stability; Valproic acid