Spermidine promotes adipogenesis of 3T3-L1 cells by preventing interaction of ANP32 with HuR and PP2A

• Published in: Biochemical journal Vol. 453; no. 3; p. 467
• Main Authors: Hyvönen, Mervi T, Koponen, Taina, Weisell, Janne, Pietilä, Marko, Khomutov, Alex R, Vepsäläinen, Jouko, Alhonen, Leena, Keinänen, Tuomo A
• Format: Journal Article
• Language: English
• Published: England 01-08-2013
• Subjects: 3T3-L1 Cells; Adipogenesis - drug effects; Adipogenesis - genetics; Animals; Eflornithine - pharmacology; ELAV Proteins - genetics; ELAV Proteins - metabolism; Female; Male; Mice; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Polyamines - chemistry; Polyamines - pharmacology; Protein Phosphatase 2 - genetics; Protein Phosphatase 2 - metabolism; Rats; Rats, Wistar; Spermidine - pharmacology
• ISSN: 1470-8728
• DOI: 10.1042/BJ20130263

We have shown previously that the polyamine spermidine is indispensable for differentiation of 3T3-L1 preadipocytes. In the present study, we examined the mechanism of spermidine function by using the polyamine biosynthesis inhibitor α-difluoromethylornithine in combination with the metabolically stable polyamine analogues γ-methylspermidine or (R,R)-α,ω-bismethylspermine. At the early phase of differentiation, spermidine-depleted 3T3-L1 cells showed decreased translation of the transcription factor C/EBPβ (CCAAT/enhancer-binding protein β), decreased PP2A (protein phosphatase 2A) activity and increased cytoplasmic localization of the RNA-binding protein HuR (human antigen R). The amount of HuR bound to C/EBPβ mRNA was reduced, whereas the amount of bound CUGBP2, an inhibitor of C/EBPβ translation, was increased. ANP32 (acidic nuclear phosphoprotein 32) proteins, which are known PP2A inhibitors and HuR ligands, bound more PP2A and HuR in spermidine-depleted than in control cells, whereas immunodepletion of ANP32 proteins from the lysate of spermidine-depleted cells restored PP2A activity. Taken together, our data shows that spermidine promotes C/EBPβ translation in differentiating 3T3-L1 cells, and that this process is controlled by the interaction of ANP32 with HuR and PP2A.