Berberine increases expression of GATA-2 and GATA-3 during inhibition of adipocyte differentiation

It is known that a number of transcription factors are key regulators in the complex process of adipocyte differentiation including peroxisome proliferator activated receptor gamma (PPAR gamma) and the CCAAT enhancer binding protein alpha (C/EBP alpha). Studies have demonstrated that in pre-adipocyte 3T3-L1 cells constitutive expression of the DNA binding proteins GATA-2 and GATA-3 results in protein/protein interactions with C/EBP alpha resulting in down regulation of PPAR gamma and Subsequent suppressed adipocyte differentiation with cells trapped at the pre-adipocyte stage. Thus it appears that GATA-2 and GATA-3 are of critical importance in regulating adipocyte differentiation through molecular interactions with PPAR gamma and C/EBP alpha. Recent reports suggest that berberine, an isoquinoline derivative alkaloid isolated from many medicinal herbs prevents differentiation of 3T3-L1 cells via a down regulation of PPAR gamma and C/EBP alpha expression. The aim of this study was to determine the effect of berberine on GATA-2 and 3 gene and protein expression levels during differentiation of 3T3-L1 cells. MTT (Methylthiazolyldiphenyl-tetrazolium bromide) was used to detect the cytotoxic effects of berberine on the viability of 3T3-L1 cells during proliferation and differentiation. Differentiation of 3T3-L1 cells was monitored by Oil Red O staining and RT-PCR of PPAR gamma and C/EBP alpha and the expression of GATA-2 and 3 was determined by RT-PCR and Western Blot. Results show that following treatment with 8 mu M berberine the mRNA and protein expression levels of GATA-2 and 3 were elevated and accompanied by inhibited adipocyte differentiation. These results may lead to the use of berberine to target the induction of specific genes such as GATA-2 and GATA-3 which affect adipocyte differentiation. (c) 2009 Elsevier GmbH. All rights reserved.