CCR4-NOT2 Promotes the Differentiation and Lipogenesis of 3T3-L1 Adipocytes via Upregulation of PPARγ, CEBPα and Inhibition of P-GSK3α/β and β-Catenin

Abstract

Background/Aims: Though CCR4-NOT2 (CNOT2), one of CCR4-NOT complex subunits, was known to be involved in metastasis and apoptosis through transcription and mRNA degradation, its other biological function is poorly understood so far. The aim of this study is to elucidate the molecular role of CNOT2 in the differentiation process of 3T3-L1 preadipocytes. Methods and Results: CNOT2 was overexpressed during the differentiation process of 3T3-L1 preadipocytes. Consistently, mRNA levels of CNOT2, adiponectin, adiponectin 2, PPARγ and CEBPα were enhanced in 3T3-L1 adipocytes. Conversely, CNOT2 depletion by siRNA transfection also reversed the activation of PPARγ and CEBPα and inhibition of GSK3α/β and β-catenin at the protein level in 3T3-L1 preadipocytes. Immunofluorescence assay revealed that CNOT2 was colocalized with PPARγ, but not with CEBPα in 3T3-L1 adipocyte. Consistently, IP western blots revealed that CNOT2 interacted with PPARγ in 3T3-L1 adipocyte. Conclusion: Our findings demonstrate that CNOT2 promotes the differentiation of 3T3-L1 preadipocytes via upregulation of PPARγ, and CEBPα and inhibition of GSK3α/β and β-catenin signaling as a potent molecular target for obesity.

Ceramide and sphingosine 1-phosphate in adipose dysfunction

“…The upregulation of the transcription factors such as peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding proteins (C/EBPs) and sterol regulatory elementbinding transcription factor 1 (SREBF1) and inhibition of Wnt/β-catenin signaling promotes differentiation of pre-adipocytes into lipid-storing adipocytes. This results in the expression of adipocyte-specific genes including the glucose transporter type 4 (GLUT-4) and fatty acidbinding protein 4 (FABP4) that maintain glucose and lipid homeostasis [28,40,41]. Considering the beneficial role of PPARγ and other transcription factors involved in TAG biosynthesis, de novo adipogenesis ensures normal glucose/NEFA metabolism in adipose tissue and maintains overall insulin sensitivity during subcutaneous expansion [40].…”

CNOT2 promotes degradation of p62/SQSTM1 as a negative regulator in ATG5 dependent autophagy

“…Among them, human CNOT2 is known to regulate the deadenylase activity and structural integrity of the CCR4–NOT complex and control embryonic development in C. elegans and D. melanogaster [ 20 , 21 , 24 ]. Furthermore, CNOT2 is critically involved in regulation of apoptotic cell death [ 18 ], metastasis [ 25 ] and adipogenic differentiation [ 26 ].…”

Colocalization of MID1IP1 and c-Myc is Critically Involved in Liver Cancer Growth via Regulation of Ribosomal Protein L5 and L11 and CNOT2

“…Emerging evidence reveals that CNOT2 acts as an oncogene [22,23], adipogenic molecule [21] and autophagy regulator [22,38]. Considering that nonalcoholic fatty liver disease (NAFLD) increases the risk of HCC progression [39], and obesity-like condition promotes the proliferation of breast cancer via Warburg effect inversion [40], hyperlipidemic or adipogenic molecules may be similarly involved in cancer progression.…”

“…Interestingly, midline1 interacting protein 1 (MID1IP1), one of the glucose-responsive genes regulated by carbohydrate-responsive element-binding protein (ChREBP) [19], is known to act as a negative regulator of AMP-activated protein kinase (AMPK) in lipid metabolism [20]. Similarly, CCR4-NOT2 (CNOT2) is reported to promote lipid metabolism [21], angiogenesis [22], proliferation [23] and autophagy [24] as a potent oncogenic molecule.…”