Inhibition of protein phosphatase 2A by okadaic acid induces translocation of nucleocytoplasmic O-GlcNAc transferase

• Published in: Biochemical and biophysical research communications 2023-02, Vol.646, p.50-55
• Main Authors: Sitosari, Heriati, Morimoto, Ikkei, Weng, Yao, Zheng, Yilin, Fukuhara, Yoko, Ikegame, Mika, Okamura, Hirohiko
• Format: Article
• Language: English
• Subjects: Acetylglucosamine - metabolism; N-Acetylglucosaminyltransferases - metabolism; O-GlcNAc transferase; O-GlcNAcylation; Okadaic acid; Okadaic Acid - pharmacology; Phosphorylation; Protein Isoforms - metabolism; Protein Phosphatase 2 - metabolism; Protein phosphatase 2A; Protein Processing, Post-Translational
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2023.01.033

Post-translational modification (PTM) is crucial for many biological events, such as the modulation of bone metabolism. Phosphorylation and O-GlcNAcylation are two examples of PTMs that can occur at the same site in the protein: serine and threonine residues. This phenomenon may cause crosstalk and possible interactions between the molecules involved. Protein phosphatase 2 A (PP2A) is widely expressed throughout the body and plays a major role in dephosphorylation. At the same location where PP2A acts, O-GlcNAc transferase (OGT) can introduce uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) molecules and mediates O-GlcNAc modifications. To examine the effects of PP2A inhibition on OGT localization and expression, osteoblastic MC3T3-E1 cells were treated with Okadaic Acid (OA), a potent PP2A inhibitor. In the control cells, OGT was strictly localized in the nucleus. However, OGT was observed diffusely in the cytoplasm of the OA-treated cells. This change in localization from the nucleus to the cytoplasm resulted from an increase in mitochondrial OGT expression and translocation of the nucleocytoplasmic isoform. Furthermore, knockdown of PP2A catalytic subunit α isoform (PP2A Cα) significantly affected OGT expression (p