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

Mervi T Hyvönen, Taina Koponen, Janne Weisell, Marko Pietilä, Alex R Khomutov, Jouko Vepsäläinen, Leena Alhonen, Tuomo A Keinänen

A.I. Virtanen Institute, University of Eastern Finland, Yliopistonranta 1E, 70210 Kuopio, Finland. mervi.hyvonen@uef.fi

The Biochemical journal 2013 Aug 1

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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.

Citation

Mervi T Hyvönen, Taina Koponen, Janne Weisell, Marko Pietilä, Alex R Khomutov, Jouko Vepsäläinen, Leena Alhonen, Tuomo A Keinänen. Spermidine promotes adipogenesis of 3T3-L1 cells by preventing interaction of ANP32 with HuR and PP2A. The Biochemical journal. 2013 Aug 1;453(3):467-74