Adipose tissue reduction in mice lacking the translational inhibitor 4E-BP1.
All nuclear-encoded mRNAs contain a 5' cap structure (m7GpppN, where N is any nucleotide), which is recognized by the eukaryotic translation initiation factor 4E (eIF4E) subunit of the eIF4F complex. The eIF4E-binding proteins constitute a family of three polypeptides that reversibly repress cap-dependent translation by binding to eIF4E, thus preventing the formation of the eIF4F complex. We investigated the biological function of 4E-BP1 by disrupting its gene (Eif4ebp1) in the mouse. Eif4ebp1-/- mice manifest markedly smaller white fat pads than wild-type animals, and knockout males display an increase in metabolic rate. The males' white adipose tissue contains cells that exhibit the distinctive multilocular appearance of brown adipocytes, and expresses the uncoupling protein 1 (UCP1), a specific marker of brown fat. Consistent with these observations, translation of the peroxisome proliferator-activated receptor-gamma co-activator 1 (PGC1), a transcriptional co-activator implicated in mitochondrial biogenesis and adaptive thermogenesis, is increased in white adipose tissue of Eif4ebp1-/- mice. These findings demonstrate that 4E-BP1 is a novel regulator of adipogenesis and metabolism in mammals.
Tsukiyama-Kohara
K
K
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec, Canada.
Poulin
F
F
Kohara
M
M
DeMaria
C T
CT
Cheng
A
A
Wu
Z
Z
Gingras
A C
AC
Katsume
A
A
Elchebly
M
M
Spiegelman
B M
BM
Harper
M E
ME
Tremblay
M L
ML
Sonenberg
N
N
D048868:Adaptor Proteins, Signal Transducing; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001481:Basal Metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D018797:Cell Cycle Proteins; D039561:Eukaryotic Initiation Factor-4E; D039642:Eukaryotic Initiation Factors; D005786:Gene Expression Regulation; D018390:Gene Targeting; D007003:Hypoglycemia / Q000378:metabolism; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D024101:Mitochondrial Proteins; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*; D000071256:Uncoupling Protein 1
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C499527:Eif4ebp1 protein, mouse; D039561:Eukaryotic Initiation Factor-4E; D039642:Eukaryotic Initiation Factors; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1