CREB activation induced by mitochondrial dysfunction triggers triglyceride accumulation in 3T3-L1 preadipocytes.
Several mitochondrial pathologies are characterized by lipid redistribution and microvesicular cell phenotypes resulting from triglyceride accumulation in lipid-metabolizing tissues. However, the molecular mechanisms underlying abnormal fat distribution induced by mitochondrial dysfunction remain poorly understood. In this study, we show that inhibition of respiratory complex III by antimycin A as well as inhibition of mitochondrial protein synthesis trigger the accumulation of triglyceride vesicles in 3T3-L1 fibroblasts. We also show that treatment with antimycin A triggers CREB activation in these cells. To better delineate how mitochondrial dysfunction induces triglyceride accumulation in preadipocytes, we developed a low-density DNA microarray containing 89 probes, which allows gene expression analysis for major effectors and/or markers of adipogenesis. We thus determined gene expression profiles in 3T3-L1 cells incubated with antimycin A and compared the patterns obtained with differentially expressed genes during the course of in vitro adipogenesis induced by a standard pro-adipogenic cocktail. After an 8-day treatment, a set of 39 genes was found to be differentially expressed in cells treated with antimycin A, among them CCAAT/enhancer-binding protein alpha (C/EBPalpha), C/EBP homologous protein-10 (CHOP-10), mitochondrial glycerol-3-phosphate dehydrogenase (GPDmit), and stearoyl-CoA desaturase 1 (SCD1). We also demonstrate that overexpression of two dominant negative mutants of the cAMP-response element-binding protein CREB (K-CREB and M1-CREB) and siRNA transfection, which disrupt the factor activity and expression, respectively, inhibit antimycin-A-induced triglyceride accumulation. Furthermore, CREB knockdown with siRNA also downregulates the expression of several genes that contain cAMP-response element (CRE) sites in their promoter, among them one that is potentially involved in synthesis of triglycerides such as SCD1. These results highlight a new role for CREB in the control of triglyceride metabolism during the adaptative response of preadipocytes to mitochondrial dysfunction.
Laboratory of Biochemistry and Cellular Biology, University of Namur (F.U.N.D.P.), Rue de Bruxelles, 61, 5000 Namur, Belgium.
Sébastien
S
Vankoningsloo
Aurélia
A
De Pauw
Andrée
A
Houbion
Silvia
S
Tejerina
Catherine
C
Demazy
Françoise
F
de Longueville
Vincent
V
Bertholet
Patricia
P
Renard
José
J
Remacle
Paul
P
Holvoet
Martine
M
Raes
Thierry
T
Arnould
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D015153:Blotting, Western; D002454:Cell Differentiation; D002701:Chloramphenicol / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004247:DNA / Q000032:analysis / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005452:Fluoresceins; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D020869:Gene Expression Profiling; D020868:Gene Silencing; D017930:Genes, Reporter; D017403:In Situ Hybridization; D050356:Lipid Metabolism; D008156:Luciferases / Q000032:analysis / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000096:biosynthesis*
D017362:Cyclic AMP Response Element-Binding Protein; D018076:DNA, Complementary; D005452:Fluoresceins; D005456:Fluorescent Dyes; D034741:RNA, Small Interfering; D014280:Triglycerides; D000968:Antimycin A; D002701:Chloramphenicol; D004247:DNA; D008156:Luciferases