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miR-155 regulates differentiation of brown and beige adipocytes via a bistable circuit.

Chen Y, Siegel F, Kipschull S, Haas B, Fröhlich H, Meister G, Pfeifer A - Nat Commun (2013)

Bottom Line: Brown adipocytes are a primary site of energy expenditure and reside not only in classical brown adipose tissue but can also be found in white adipose tissue.In contrast, transgenic overexpression of microRNA 155 in mice causes a reduction of brown adipose tissue mass and impairment of brown adipose tissue function.These data demonstrate that the bistable loop involving microRNA 155 and CCAAT/enhancer-binding protein β regulates brown lineage commitment, thereby, controlling the development of brown and beige fat cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmacology and Toxicology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.

ABSTRACT
Brown adipocytes are a primary site of energy expenditure and reside not only in classical brown adipose tissue but can also be found in white adipose tissue. Here we show that microRNA 155 is enriched in brown adipose tissue and is highly expressed in proliferating brown preadipocytes but declines after induction of differentiation. Interestingly, microRNA 155 and its target, the adipogenic transcription factor CCAAT/enhancer-binding protein β, form a bistable feedback loop integrating hormonal signals that regulate proliferation or differentiation. Inhibition of microRNA 155 enhances brown adipocyte differentiation and induces a brown adipocyte-like phenotype ('browning') in white adipocytes. Consequently, microRNA 155-deficient mice exhibit increased brown adipose tissue function and 'browning' of white fat tissue. In contrast, transgenic overexpression of microRNA 155 in mice causes a reduction of brown adipose tissue mass and impairment of brown adipose tissue function. These data demonstrate that the bistable loop involving microRNA 155 and CCAAT/enhancer-binding protein β regulates brown lineage commitment, thereby, controlling the development of brown and beige fat cells.

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miR-155 expression is induced by TGFβ signalling during brown cell differentiation.(a) qRT–PCR analysis of miR-155 expression levels in brown fat cells during in vitro differentiation (normalized to snoRNA202). Undifferentiated cells (day 2) were set as one. Data are represented as means±s.e.m. (*P<0.05; **P<0.005; one-way analysis of variance (ANOVA); n=5). (b) Effect of TGFβ1 (5 ng ml−1, 24 h) on miR-155 expression in brown fat cells as measured by qRT–PCR (normalized to snoRNA202 expression). Untreated cells were set as one. Data are represented as means±s.e.m. (***P<0.001; Student’s t-test; n=3). (c) TGFβ1 concentration in the cell culture supernatant during brown fat cell differentiation. Data are represented as means±s.e.m. (*P<0.05; ***P<0.001; one-way ANOVA; n=3). (d) Effect of SB-431542 (10 μM, 24 h) on miR-155 expression as measured by qRT–PCR (normalized to snoRNA202). Data are represented as means±s.e.m. (*P<0.05; Student’s t-test, as compared with untreated controls; n=3). (e) qRT–PCR analysis of miR-155 expression in in vitro differentiated brown fat cells treated with SB-431542 (10 μM, treatment day −2 to day 0) (normalized to snoRNA202). Undifferentiated cells (day −2) were set as one. Data are represented as means±s.e.m. (*P<0.05; one-way ANOVA; n=3) (f) Oil Red O staining of in vitro differentiated brown adipocytes treated with SB-431542 (10 μM, day −2 to day 0); mock, untreated cells. Scale bar, 3 mm.
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f2: miR-155 expression is induced by TGFβ signalling during brown cell differentiation.(a) qRT–PCR analysis of miR-155 expression levels in brown fat cells during in vitro differentiation (normalized to snoRNA202). Undifferentiated cells (day 2) were set as one. Data are represented as means±s.e.m. (*P<0.05; **P<0.005; one-way analysis of variance (ANOVA); n=5). (b) Effect of TGFβ1 (5 ng ml−1, 24 h) on miR-155 expression in brown fat cells as measured by qRT–PCR (normalized to snoRNA202 expression). Untreated cells were set as one. Data are represented as means±s.e.m. (***P<0.001; Student’s t-test; n=3). (c) TGFβ1 concentration in the cell culture supernatant during brown fat cell differentiation. Data are represented as means±s.e.m. (*P<0.05; ***P<0.001; one-way ANOVA; n=3). (d) Effect of SB-431542 (10 μM, 24 h) on miR-155 expression as measured by qRT–PCR (normalized to snoRNA202). Data are represented as means±s.e.m. (*P<0.05; Student’s t-test, as compared with untreated controls; n=3). (e) qRT–PCR analysis of miR-155 expression in in vitro differentiated brown fat cells treated with SB-431542 (10 μM, treatment day −2 to day 0) (normalized to snoRNA202). Undifferentiated cells (day −2) were set as one. Data are represented as means±s.e.m. (*P<0.05; one-way ANOVA; n=3) (f) Oil Red O staining of in vitro differentiated brown adipocytes treated with SB-431542 (10 μM, day −2 to day 0); mock, untreated cells. Scale bar, 3 mm.

Mentions: Analysis of miR-155 expression during BAT differentiation revealed that miR-155 expression peaks when cells reach confluency around day −1 of the differentiation protocol (Supplementary Fig. S1a) and decreases continuously after induction of adipogenesis (Fig. 2a). Transforming growth factor-β1 (TGFβ1) increases miR-155 in epithelial cells31. Furthermore, TGFβ1 has been shown to potently inhibit adipogenesis in 3T3-L1 cells32. Therefore, we addressed the question if TGFβ1/Smad signalling is regulating miR-155 expression in brown fat cells. Treatment of preadipocytes with TGFβ1 significantly increased miR-155 levels within 24 h (Fig. 2b), whereas inhibition of Smad4 blocked TGFβ1-mediated miR-155 induction (Supplementary Fig. S3a,b). Interestingly, we found that TGFβ1 is expressed by brown preadipocytes and is regulated in a differentiation-dependent manner similar to miR-155 (Fig. 2a).


miR-155 regulates differentiation of brown and beige adipocytes via a bistable circuit.

Chen Y, Siegel F, Kipschull S, Haas B, Fröhlich H, Meister G, Pfeifer A - Nat Commun (2013)

miR-155 expression is induced by TGFβ signalling during brown cell differentiation.(a) qRT–PCR analysis of miR-155 expression levels in brown fat cells during in vitro differentiation (normalized to snoRNA202). Undifferentiated cells (day 2) were set as one. Data are represented as means±s.e.m. (*P<0.05; **P<0.005; one-way analysis of variance (ANOVA); n=5). (b) Effect of TGFβ1 (5 ng ml−1, 24 h) on miR-155 expression in brown fat cells as measured by qRT–PCR (normalized to snoRNA202 expression). Untreated cells were set as one. Data are represented as means±s.e.m. (***P<0.001; Student’s t-test; n=3). (c) TGFβ1 concentration in the cell culture supernatant during brown fat cell differentiation. Data are represented as means±s.e.m. (*P<0.05; ***P<0.001; one-way ANOVA; n=3). (d) Effect of SB-431542 (10 μM, 24 h) on miR-155 expression as measured by qRT–PCR (normalized to snoRNA202). Data are represented as means±s.e.m. (*P<0.05; Student’s t-test, as compared with untreated controls; n=3). (e) qRT–PCR analysis of miR-155 expression in in vitro differentiated brown fat cells treated with SB-431542 (10 μM, treatment day −2 to day 0) (normalized to snoRNA202). Undifferentiated cells (day −2) were set as one. Data are represented as means±s.e.m. (*P<0.05; one-way ANOVA; n=3) (f) Oil Red O staining of in vitro differentiated brown adipocytes treated with SB-431542 (10 μM, day −2 to day 0); mock, untreated cells. Scale bar, 3 mm.
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f2: miR-155 expression is induced by TGFβ signalling during brown cell differentiation.(a) qRT–PCR analysis of miR-155 expression levels in brown fat cells during in vitro differentiation (normalized to snoRNA202). Undifferentiated cells (day 2) were set as one. Data are represented as means±s.e.m. (*P<0.05; **P<0.005; one-way analysis of variance (ANOVA); n=5). (b) Effect of TGFβ1 (5 ng ml−1, 24 h) on miR-155 expression in brown fat cells as measured by qRT–PCR (normalized to snoRNA202 expression). Untreated cells were set as one. Data are represented as means±s.e.m. (***P<0.001; Student’s t-test; n=3). (c) TGFβ1 concentration in the cell culture supernatant during brown fat cell differentiation. Data are represented as means±s.e.m. (*P<0.05; ***P<0.001; one-way ANOVA; n=3). (d) Effect of SB-431542 (10 μM, 24 h) on miR-155 expression as measured by qRT–PCR (normalized to snoRNA202). Data are represented as means±s.e.m. (*P<0.05; Student’s t-test, as compared with untreated controls; n=3). (e) qRT–PCR analysis of miR-155 expression in in vitro differentiated brown fat cells treated with SB-431542 (10 μM, treatment day −2 to day 0) (normalized to snoRNA202). Undifferentiated cells (day −2) were set as one. Data are represented as means±s.e.m. (*P<0.05; one-way ANOVA; n=3) (f) Oil Red O staining of in vitro differentiated brown adipocytes treated with SB-431542 (10 μM, day −2 to day 0); mock, untreated cells. Scale bar, 3 mm.
Mentions: Analysis of miR-155 expression during BAT differentiation revealed that miR-155 expression peaks when cells reach confluency around day −1 of the differentiation protocol (Supplementary Fig. S1a) and decreases continuously after induction of adipogenesis (Fig. 2a). Transforming growth factor-β1 (TGFβ1) increases miR-155 in epithelial cells31. Furthermore, TGFβ1 has been shown to potently inhibit adipogenesis in 3T3-L1 cells32. Therefore, we addressed the question if TGFβ1/Smad signalling is regulating miR-155 expression in brown fat cells. Treatment of preadipocytes with TGFβ1 significantly increased miR-155 levels within 24 h (Fig. 2b), whereas inhibition of Smad4 blocked TGFβ1-mediated miR-155 induction (Supplementary Fig. S3a,b). Interestingly, we found that TGFβ1 is expressed by brown preadipocytes and is regulated in a differentiation-dependent manner similar to miR-155 (Fig. 2a).

Bottom Line: Brown adipocytes are a primary site of energy expenditure and reside not only in classical brown adipose tissue but can also be found in white adipose tissue.In contrast, transgenic overexpression of microRNA 155 in mice causes a reduction of brown adipose tissue mass and impairment of brown adipose tissue function.These data demonstrate that the bistable loop involving microRNA 155 and CCAAT/enhancer-binding protein β regulates brown lineage commitment, thereby, controlling the development of brown and beige fat cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmacology and Toxicology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.

ABSTRACT
Brown adipocytes are a primary site of energy expenditure and reside not only in classical brown adipose tissue but can also be found in white adipose tissue. Here we show that microRNA 155 is enriched in brown adipose tissue and is highly expressed in proliferating brown preadipocytes but declines after induction of differentiation. Interestingly, microRNA 155 and its target, the adipogenic transcription factor CCAAT/enhancer-binding protein β, form a bistable feedback loop integrating hormonal signals that regulate proliferation or differentiation. Inhibition of microRNA 155 enhances brown adipocyte differentiation and induces a brown adipocyte-like phenotype ('browning') in white adipocytes. Consequently, microRNA 155-deficient mice exhibit increased brown adipose tissue function and 'browning' of white fat tissue. In contrast, transgenic overexpression of microRNA 155 in mice causes a reduction of brown adipose tissue mass and impairment of brown adipose tissue function. These data demonstrate that the bistable loop involving microRNA 155 and CCAAT/enhancer-binding protein β regulates brown lineage commitment, thereby, controlling the development of brown and beige fat cells.

Show MeSH
Related in: MedlinePlus