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Identification of Creb3l4 as an essential negative regulator of adipogenesis.

Kim TH, Jo SH, Choi H, Park JM, Kim MY, Nojima H, Kim JW, Ahn YH - Cell Death Dis (2014)

Bottom Line: Constitutive overexpression of CREB3L4 resulted in the inhibition of adipocyte differentiation, whereas knockdown of Creb3l4 expression caused differentiation of preadipocytes into mature adipocytes, bypassing the mitotic clonal expansion step.In 3T3-L1 preadipocytes, Creb3l4 knockdown resulted in increased expression of peroxisome proliferator-activated receptor γ (PPARγ2) and CCAAT/enhancer binding protein (C/EBPα), either by increasing the protein stability of C/EBPβ or by decreasing the expression of GATA3, a negative regulator of PPARγ2 expression.Moreover, adipocytes of Creb3l4-knockout mice showed hyperplasia caused by increased adipogenesis, and exhibited improved glucose tolerance and insulin sensitivity, as compared with littermate wild-type mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea.

ABSTRACT
Understanding the molecular networks that regulate adipogenesis is crucial for combating obesity. However, the identity and molecular actions of negative regulators that regulate the early development of adipocytes remain poorly understood. In this study, we investigated the role of CREB3L4, a member of the CREB3-like family, in the regulation of adiposity. Constitutive overexpression of CREB3L4 resulted in the inhibition of adipocyte differentiation, whereas knockdown of Creb3l4 expression caused differentiation of preadipocytes into mature adipocytes, bypassing the mitotic clonal expansion step. In 3T3-L1 preadipocytes, Creb3l4 knockdown resulted in increased expression of peroxisome proliferator-activated receptor γ (PPARγ2) and CCAAT/enhancer binding protein (C/EBPα), either by increasing the protein stability of C/EBPβ or by decreasing the expression of GATA3, a negative regulator of PPARγ2 expression. Consequently, increased PPARγ2 and C/EBPα levels induced adipocyte differentiation, even in the presence of minimal hormonal inducer. Thus, it can be speculated that CREB3L4 has a role as gatekeeper, inhibiting adipogenesis in 3T3-L1 preadipocytes. Moreover, adipocytes of Creb3l4-knockout mice showed hyperplasia caused by increased adipogenesis, and exhibited improved glucose tolerance and insulin sensitivity, as compared with littermate wild-type mice. These results raise the possibility that Creb3l4 could be a useful therapeutic target in the fight against obesity and metabolic syndrome.

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GATA3 is another mediator of CREB3L4 downregulating the expression of PPARγ2. (a) Expression of PPARγ2 and C/EBPα in 3T3-L1 cells expressing siGata3, at D0. (b) The mRNA levels of Pparg2, Creb3l4, and Gata3 in 3T3-L1 cells transfected with siCreb3l4 and a CMV-mGata3-FL expression vector, at D0. Values are expressed as mean±S.E.M., n=3, *P<0.05. (c) In preadipocytes, CREB3L4 acts as a negative regulator of adipogenesis by both regulating the stability of C/EBPβ protein and increasing GATA3 expression. After induction of differentiation by DMI (DMI: 0.5 mM 3-isobutyl-1-methylzanthine [IBMX; M], 1 μM dexamethasone [D], and 1 μg/ml of insulin [I]), Creb3l4 and Gata3 expression is decreased, and increased C/EBPβ levels initiate adipogenesis by increasing the expression of PPARγ2 and C/EBPα. Suppression of Creb3l4 in preadipocytes induces adipogenesis by increasing PPARγ2 expression
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fig8: GATA3 is another mediator of CREB3L4 downregulating the expression of PPARγ2. (a) Expression of PPARγ2 and C/EBPα in 3T3-L1 cells expressing siGata3, at D0. (b) The mRNA levels of Pparg2, Creb3l4, and Gata3 in 3T3-L1 cells transfected with siCreb3l4 and a CMV-mGata3-FL expression vector, at D0. Values are expressed as mean±S.E.M., n=3, *P<0.05. (c) In preadipocytes, CREB3L4 acts as a negative regulator of adipogenesis by both regulating the stability of C/EBPβ protein and increasing GATA3 expression. After induction of differentiation by DMI (DMI: 0.5 mM 3-isobutyl-1-methylzanthine [IBMX; M], 1 μM dexamethasone [D], and 1 μg/ml of insulin [I]), Creb3l4 and Gata3 expression is decreased, and increased C/EBPβ levels initiate adipogenesis by increasing the expression of PPARγ2 and C/EBPα. Suppression of Creb3l4 in preadipocytes induces adipogenesis by increasing PPARγ2 expression

Mentions: Furthermore, because GATA3 is known to be a negative regulator of Pparg2 expression,16 it is possible that downregulation of GATA3 expression by siCreb3l4 (Figure 5d) could also contribute to the upregulation of PPARγ2 at D0. To test this hypothesis, we transfected 3T3-L1 cells with siGata3; we observed increased expression of PPARγ2, but not that of C/EBPα (Figure 8a). In addition, the siCreb3l4-mediated increase in Pparg2 expression was diminished by overexpression of Gata3 (Figure 8b). These data suggested that GATA3 is another mediator upregulating Pparg2 expression when Creb3l4 expression is knocked down. Taken together, these results indicated that CREB3L4 acts as a negative regulator that blocks adipogenesis at D0, by inducing both ubiquitination of C/EBPβ and expression of Gata3.


Identification of Creb3l4 as an essential negative regulator of adipogenesis.

Kim TH, Jo SH, Choi H, Park JM, Kim MY, Nojima H, Kim JW, Ahn YH - Cell Death Dis (2014)

GATA3 is another mediator of CREB3L4 downregulating the expression of PPARγ2. (a) Expression of PPARγ2 and C/EBPα in 3T3-L1 cells expressing siGata3, at D0. (b) The mRNA levels of Pparg2, Creb3l4, and Gata3 in 3T3-L1 cells transfected with siCreb3l4 and a CMV-mGata3-FL expression vector, at D0. Values are expressed as mean±S.E.M., n=3, *P<0.05. (c) In preadipocytes, CREB3L4 acts as a negative regulator of adipogenesis by both regulating the stability of C/EBPβ protein and increasing GATA3 expression. After induction of differentiation by DMI (DMI: 0.5 mM 3-isobutyl-1-methylzanthine [IBMX; M], 1 μM dexamethasone [D], and 1 μg/ml of insulin [I]), Creb3l4 and Gata3 expression is decreased, and increased C/EBPβ levels initiate adipogenesis by increasing the expression of PPARγ2 and C/EBPα. Suppression of Creb3l4 in preadipocytes induces adipogenesis by increasing PPARγ2 expression
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260748&req=5

fig8: GATA3 is another mediator of CREB3L4 downregulating the expression of PPARγ2. (a) Expression of PPARγ2 and C/EBPα in 3T3-L1 cells expressing siGata3, at D0. (b) The mRNA levels of Pparg2, Creb3l4, and Gata3 in 3T3-L1 cells transfected with siCreb3l4 and a CMV-mGata3-FL expression vector, at D0. Values are expressed as mean±S.E.M., n=3, *P<0.05. (c) In preadipocytes, CREB3L4 acts as a negative regulator of adipogenesis by both regulating the stability of C/EBPβ protein and increasing GATA3 expression. After induction of differentiation by DMI (DMI: 0.5 mM 3-isobutyl-1-methylzanthine [IBMX; M], 1 μM dexamethasone [D], and 1 μg/ml of insulin [I]), Creb3l4 and Gata3 expression is decreased, and increased C/EBPβ levels initiate adipogenesis by increasing the expression of PPARγ2 and C/EBPα. Suppression of Creb3l4 in preadipocytes induces adipogenesis by increasing PPARγ2 expression
Mentions: Furthermore, because GATA3 is known to be a negative regulator of Pparg2 expression,16 it is possible that downregulation of GATA3 expression by siCreb3l4 (Figure 5d) could also contribute to the upregulation of PPARγ2 at D0. To test this hypothesis, we transfected 3T3-L1 cells with siGata3; we observed increased expression of PPARγ2, but not that of C/EBPα (Figure 8a). In addition, the siCreb3l4-mediated increase in Pparg2 expression was diminished by overexpression of Gata3 (Figure 8b). These data suggested that GATA3 is another mediator upregulating Pparg2 expression when Creb3l4 expression is knocked down. Taken together, these results indicated that CREB3L4 acts as a negative regulator that blocks adipogenesis at D0, by inducing both ubiquitination of C/EBPβ and expression of Gata3.

Bottom Line: Constitutive overexpression of CREB3L4 resulted in the inhibition of adipocyte differentiation, whereas knockdown of Creb3l4 expression caused differentiation of preadipocytes into mature adipocytes, bypassing the mitotic clonal expansion step.In 3T3-L1 preadipocytes, Creb3l4 knockdown resulted in increased expression of peroxisome proliferator-activated receptor γ (PPARγ2) and CCAAT/enhancer binding protein (C/EBPα), either by increasing the protein stability of C/EBPβ or by decreasing the expression of GATA3, a negative regulator of PPARγ2 expression.Moreover, adipocytes of Creb3l4-knockout mice showed hyperplasia caused by increased adipogenesis, and exhibited improved glucose tolerance and insulin sensitivity, as compared with littermate wild-type mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea.

ABSTRACT
Understanding the molecular networks that regulate adipogenesis is crucial for combating obesity. However, the identity and molecular actions of negative regulators that regulate the early development of adipocytes remain poorly understood. In this study, we investigated the role of CREB3L4, a member of the CREB3-like family, in the regulation of adiposity. Constitutive overexpression of CREB3L4 resulted in the inhibition of adipocyte differentiation, whereas knockdown of Creb3l4 expression caused differentiation of preadipocytes into mature adipocytes, bypassing the mitotic clonal expansion step. In 3T3-L1 preadipocytes, Creb3l4 knockdown resulted in increased expression of peroxisome proliferator-activated receptor γ (PPARγ2) and CCAAT/enhancer binding protein (C/EBPα), either by increasing the protein stability of C/EBPβ or by decreasing the expression of GATA3, a negative regulator of PPARγ2 expression. Consequently, increased PPARγ2 and C/EBPα levels induced adipocyte differentiation, even in the presence of minimal hormonal inducer. Thus, it can be speculated that CREB3L4 has a role as gatekeeper, inhibiting adipogenesis in 3T3-L1 preadipocytes. Moreover, adipocytes of Creb3l4-knockout mice showed hyperplasia caused by increased adipogenesis, and exhibited improved glucose tolerance and insulin sensitivity, as compared with littermate wild-type mice. These results raise the possibility that Creb3l4 could be a useful therapeutic target in the fight against obesity and metabolic syndrome.

Show MeSH
Related in: MedlinePlus