The mixed-lineage kinase DLK is a key regulator of 3T3-L1 adipocyte differentiation.
BACKGROUND
The mixed-lineage kinase (MLK) family member DLK has been proposed to serve as a regulator of differentiation in various cell types; however, its role in adipogenesis has not been investigated. In this study, we used the 3T3-L1 preadipocyte cell line as a model to examine the function of DLK in adipocyte differentiation.


RESULTS
Immunoblot analyses and kinase assays performed on 3T3-L1 cells showed that the expression and activity of DLK substantially increase as differentiation occurs. Interestingly, DLK appears crucial for differentiation since its depletion by RNA interference impairs lipid accumulation as well as expression of the master regulators of adipogenesis C/EBPalpha and PPARgamma2 at both the mRNA and protein levels. In contrast, neither the expression nor the DNA binding activity of C/EBPbeta, an activator for C/EBPalpha and PPARgamma, is affected by DLK loss.


CONCLUSIONS
Taken together, these results suggest that DLK is important for expression of mature adipocyte markers and that its action most likely takes place via regulation of C/EBPbeta transcriptional activity and/or initiation of C/EBPalpha and PPARgamma2 gene transcription.
Couture
Jean-Philippe
JP
Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Daviau
Alex
A
Fradette
Julie
J
Blouin
Richard
R
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000201:enzymology*; D050156:Adipogenesis; D052242:Adiponectin / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001391:Azo Compounds / Q000378:metabolism; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D064550:Death-Associated Protein Kinases; D015151:Immunoblotting; D016086:Lentivirus / Q000235:genetics; D008055:Lipids / Q000032:analysis; D051379:Mice; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism
D052242:Adiponectin; C499919:Adipoq protein, mouse; D051017:Apoptosis Regulatory Proteins; D001391:Azo Compounds; D022763:CCAAT-Enhancer-Binding Protein-alpha; D008055:Lipids; D047495:PPAR gamma; D012333:RNA, Messenger; D019014:fas Receptor; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C011049:oil red O