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.
Vankoningsloo
Sébastien
S
Laboratory of Biochemistry and Cellular Biology, University of Namur (F.U.N.D.P.), Rue de Bruxelles, 61, 5000 Namur, Belgium.
De Pauw
Aurélia
A
Houbion
Andrée
A
Tejerina
Silvia
S
Demazy
Catherine
C
de Longueville
Françoise
F
Bertholet
Vincent
V
Renard
Patricia
P
Remacle
José
J
Holvoet
Paul
P
Raes
Martine
M
Arnould
Thierry
T
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