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PMID:21047783

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Citation

Park, UH, Yoon, SK, Park, T, Kim, EJ and Um, SJ (2011) Additional sex comb-like (ASXL) proteins 1 and 2 play opposite roles in adipogenesis via reciprocal regulation of peroxisome proliferator-activated receptor {gamma}. J. Biol. Chem. 286:1354-63

Abstract

Our previous studies have suggested that the mammalian additional sex comb-like 1 protein functions as a coactivator or repressor of retinoic acid receptors in a cell-specific manner. Here, we investigated the roles of additional sex comb-like 1 proteins in regulating peroxisome proliferator-activated receptors (PPARs). In pulldown assays in vitro and in immunoprecipitation assays in vivo, ASXL1 and its paralog, ASXL2, interacted with PPARα and PPARγ. In 3T3-L1 preadipocyte cells, overexpression of ASXL1 inhibited the induction of PPARγ activity by rosiglitazone, as shown by transcription assays, and completely suppressed adipogenesis, as shown by Oil Red O staining. In contrast, overexpression of ASXL2 greatly enhanced rosiglitazone-induced PPARγ activity and enhanced adipogenesis. Deletion of the heterochromatin protein 1 (HP1)-binding domain from ASXL1 caused the mutant protein to enhance adipogenesis similarly to ASXL2, indicating that HP1 binding is required for the adipogenesis-suppressing activity of ASXL1. Adipocyte differentiation was associated with a gradual decrease in ASXL1 expression but did not affect ASXL2 expression. Knockdown of ASXL1 and ASXL2 had reciprocal effects on adipogenesis. In chromatin immunoprecipitation assays in 3T3-L1 cells, ASXL1 occupied the promoter of the PPARγ target gene aP2 together with HP1α and Lys-9-methylated histone H3, whereas ASXL2 occupied the aP2 promoter together with histone-lysine N-methyltransferase MLL1 and Lys-9-acetylated and Lys-4-methylated H3 histones. Finally, microarray analysis demonstrated that ASXL1 represses, whereas ASXL2 increases, the expression of adipogenic genes, most of which are PPARγ targets. These results suggest that members of the additional sex comb-like family provide complex regulation of adipogenesis via differential modulation of PPARγ activity.

Links

PubMed PMC3020743 Online version:10.1074/jbc.M110.177816

Keywords

3T3-L1 Cells; Adipogenesis/physiology; Animals; Chromatin/physiology; Gene Knockdown Techniques; HEK293 Cells; Humans; Mice; Oligonucleotide Array Sequence Analysis; PPAR gamma/genetics; PPAR gamma/metabolism; Peptides; Promoter Regions, Genetic/physiology; Repressor Proteins/genetics; Repressor Proteins/metabolism; Reverse Transcriptase Polymerase Chain Reaction; Transcriptional Activation/physiology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

MOUSE:ASXL1

involved_in

GO:0035359: negative regulation of peroxisome proliferator activated receptor signaling pathway

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

MOUSE:ASXL1

enables

GO:0042975: peroxisome proliferator activated receptor binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

MOUSE:ASXL1

involved_in

GO:0045599: negative regulation of fat cell differentiation

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ASXL2

involved_in

GO:0045600: positive regulation of fat cell differentiation

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ASXL2

involved_in

GO:0035360: positive regulation of peroxisome proliferator activated receptor signaling pathway

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ASXL2

involved_in

GO:0045944: positive regulation of transcription by RNA polymerase II

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ASXL2

enables

GO:0042975: peroxisome proliferator activated receptor binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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