Project description:Mitochondria play an essential role in the ability of brown fat to generate heat, and the PGC-1 coactivators control several aspects of mitochondrial biogenesis. To investigate their specific roles in brown fat cells, we generated immortal preadipocyte lines from the brown adipose tissue of mice lacking PGC-1±. We could then efficiently knockdown PGC-1β expression by shRNA expression. Loss of PGC-1± did not alter brown fat differentiation but severely reduced the induction of thermogenic genes. Cells deficient in either PGC-1α or PGC-1β coactivators showed a small decrease in the differentiation-dependant program of mitochondrial biogenesis and respiration; however, this increase in mitochondrial number and function was totally abolished during brown fat differentiation when both PGC-1± and PGC-1 were deficient. These data show that PGC-1± is essential for brown fat thermogenesis but not brown fat differentiation, and the PGC-1 coactivators play an absolutely essential but complementary function in differentiation-induced mitochondrial biogenesis. Affymetrix microarray analysis of total RNA from wt, PGC-1± KO and PGC-1± KO; cells expressing an RNAi specific for PGC-1 knockdown was performed. Of the 461; mitochondrial genes analyzed, 181 were found to be at least 20% different between wt; and defective PGC-1± and β adipocytes (p < 0.05). More than 85% of these genes were downregulated in cells deficient for PGC-1alpha and PGC-1beta. Experiment Overall Design: Brown preadipocytes that were either WT, KO for PGC-1alpha, or KO for PGC-1alpha and deficient for PGC-1beta (knockdown through siRNA expression) were differentiated for seven days. RNA was made from biological replicates of the three different types of brown adipocytes (WT, KO expressing a control siRNA, KO expressing a siRNA specific for PGC-1beta knockdown).
Project description:Mitochondria play an essential role in the ability of brown fat to generate heat, and the PGC-1 coactivators control several aspects of mitochondrial biogenesis. To investigate their specific roles in brown fat cells, we generated immortal preadipocyte lines from the brown adipose tissue of mice lacking PGC-1α. We could then efficiently knockdown PGC-1β expression by shRNA expression. Loss of PGC-1α did not alter brown fat differentiation but severely reduced the induction of thermogenic genes. Cells deficient in either PGC-1α or PGC-1β coactivators showed a small decrease in the differentiation-dependant program of mitochondrial biogenesis and respiration; however, this increase in mitochondrial number and function was totally abolished during brown fat differentiation when both PGC-1α and PGC-1β were deficient. These data show that PGC-1α is essential for brown fat thermogenesis but not brown fat differentiation, and the PGC-1 coactivators play an absolutely essential but complementary function in differentiation-induced mitochondrial biogenesis. Affymetrix microarray analysis of total RNA from wt, PGC-1α KO and PGC-1α KO cells expressing an RNAi specific for PGC-1β knockdown was performed. Of the 461 mitochondrial genes analyzed, 181 were found to be at least 20% different between wt and defective PGC-1α and β adipocytes (p < 0.05). More than 85% of these genes were downregulated in cells deficient for PGC-1alpha and PGC-1beta. Keywords: Analysis of mitochondrial gene expression
Project description:Mesenchymal stem cells (MSCs) are a multipotent cell type that can differentiate into non-hematopoietic cells, such as adipocytes. Adipocyte tissue is central to regulate energy balance. PGC-1 alpha controls several aspects of mitochondrial biogenesis. However, roles of PGC-1 alpha in brown fat differentiation of MSCs remain uncertain. To investigate roles of PGC-1 alpha in brown fat differentiation immortalized human MSCs were used for all experiments. The changes in genetic profiling between MSCs and PGC-1 alpha-expressing MSCs were analyzed by microarray analysis. The genetic profiling of PGC-1 alpha-expressing MSCs shows the significant increase of genes related to mitochondrial functions and lipid metabolism compared to that of MSCs. When expressed in MSCs, PGC-1 alpha activates a robust mitochondrial biogenesis and respiration. The expression of thermogenic markers, such as cytochrome C and complex II, was significantly increased in MSCs with treatment of adenovirus expressing PGC-1 alpha. Our microarray results also indicate that genetic pattern of PGC-1 alpha-expressing MSCs is very closed to that of adipose tissues. Bone marrow-derived MSCs were infected with Ad-GFP, or Ad-PGC-1? at a multiplicity of infection (m.o.i.) of 500 overnight.
Project description:Mesenchymal stem cells (MSCs) are a multipotent cell type that can differentiate into non-hematopoietic cells, such as adipocytes. Adipocyte tissue is central to regulate energy balance. PGC-1 alpha controls several aspects of mitochondrial biogenesis. However, roles of PGC-1 alpha in brown fat differentiation of MSCs remain uncertain. To investigate roles of PGC-1 alpha in brown fat differentiation immortalized human MSCs were used for all experiments. The changes in genetic profiling between MSCs and PGC-1 alpha-expressing MSCs were analyzed by microarray analysis. The genetic profiling of PGC-1 alpha-expressing MSCs shows the significant increase of genes related to mitochondrial functions and lipid metabolism compared to that of MSCs. When expressed in MSCs, PGC-1 alpha activates a robust mitochondrial biogenesis and respiration. The expression of thermogenic markers, such as cytochrome C and complex II, was significantly increased in MSCs with treatment of adenovirus expressing PGC-1 alpha. Our microarray results also indicate that genetic pattern of PGC-1 alpha-expressing MSCs is very closed to that of adipose tissues.
Project description:To investigate the specific role of PGC-1 coactivators in brown fat cells, we generated immortal preadipocyte lines from the brown adipose tissue of mice lacking PGC-1alpha. We could then efficiently knockdown PGC-1beta expression by shRNA expression. Loss of PGC-1alpha did not alter brown fat differentiation but severly reduced the induction of thermogenic genes. In order to assess the specific requirement for PGC-1± in the global transcriptional response to cAMP, we used Affymetrix arrays to compare the sets of genes induced in response to a 4 hr dbcAMP treatment in differentiated wt and KO cells. This analysis revealed that 88 genes were induced more than 3-fold in the wt cells; of these, 54 (61% of total) were similarly increased in both wt and KO. However, 28 genes (32% of total) were decreased by at least 50% in the KO cells compared to wt cells. These data were confirmed by quantitative PCR for a subset of genes. These data indicate that PGC-1± is required for proper expression of approximately one third of the genes induced in response to cAMP in brown fat cells, but this set of sensitive genes is enriched in those involved in adaptative thermogenesis. Experiment Overall Design: WT and PGC-1alpha KO brown preadipocytes were differentiated into mature brown adipocytes for seven days. Cells were then treated with dibutyryl cAMP for four hours. Two replicates were made for each condition: WT non treated, WT treated with cAMP, KO non treated, KO treated with cAMP. Transcription profiling of wild type and PGC-1 alpha knockout mouse mature brown adipocytes treated with dibutyryl cAMP to investigate the specific role of PGC-1 coactivators in brown fat cells
Project description:Mammalian PGC-1alpha, PGC-1beta and PRC are structurally related transcriptional coactivators, and are involved in multiple metabolic functions, including the regulation of mitochondrial biogenesis. However, due to redundancy, their in vivo roles are still poorly understood. By a genome-wide microarray study, we show that in the Drosophila larval fat body, Spargel (CG9809), the only fly PGC-1 family homologue, is required for proper expression of multiple genes encoding mitochondrial proteins. Experiment Overall Design: Six samples were analyzed in total: three biological replicates of the control (wt) and three biological replicates of the mutant (KG).
Project description:Mammalian PGC-1alpha, PGC-1beta and PRC are structurally related transcriptional coactivators, and are involved in multiple metabolic functions, including the regulation of mitochondrial biogenesis. However, due to redundancy, their in vivo roles are still poorly understood. By a genome-wide microarray study, we show that in the Drosophila larval fat body, Spargel (CG9809), the only fly PGC-1 family homologue, is required for proper expression of multiple genes encoding mitochondrial proteins.
Project description:To investigate the specific role of PGC-1 coactivators in brown fat cells, we generated immortal preadipocyte lines from the brown adipose tissue of mice lacking PGC-1alpha. We could then efficiently knockdown PGC-1beta expression by shRNA expression. Loss of PGC-1alpha did not alter brown fat differentiation but severly reduced the induction of thermogenic genes. In order to assess the specific requirement for PGC-1α in the global transcriptional response to cAMP, we used Affymetrix arrays to compare the sets of genes induced in response to a 4 hr dbcAMP treatment in differentiated wt and KO cells. This analysis revealed that 88 genes were induced more than 3-fold in the wt cells; of these, 54 (61% of total) were similarly increased in both wt and KO. However, 28 genes (32% of total) were decreased by at least 50% in the KO cells compared to wt cells. These data were confirmed by quantitative PCR for a subset of genes. These data indicate that PGC-1α is required for proper expression of approximately one third of the genes induced in response to cAMP in brown fat cells, but this set of sensitive genes is enriched in those involved in adaptative thermogenesis. Keywords: thermogenic gene program
Project description:The β-adrenergic receptor signaling pathway is a major component of adaptive thermogenesis in brown and white adipose tissue during cold acclimation. The β-AR activation highly induces transcriptional coactivator PGC-1α and its splice variant N-terminal (NT)-PGC-1α, promoting the transcription program of mitochondrial biogenesis and thermogenesis. In the present study, we evaluated the role of NT-PGC-1α in brown adipocyte energy metabolism by genome-wide profiling of NT-PGC-1α-responsive genes. Canonical pathway analysis revealed that a number of genes upregulated by NT-PGC-1α are highly enriched in mitochondrial pathways including fatty acid transport and β-oxidation, TCA cycle and electron transport system, thus reinforcing the crucial role of NT-PGC-1α in the enhancement of mitochondrial function. Moreover, gene expression profiling of NT-PGC-1α revealed activation of distinct metabolic pathways such as glucose, lipid and nucleotide metabolism and of signaling pathways such as RAR and PPAR-γ/RXRα activation in brown adipocytes. Together, our data strengthen our previous findings that NT-PGC-1α is a key regulator of mitochondrial oxidative metabolism and thermogenesis in brown adipocytes and further suggest that NT-PGC-1α influences a broader spectrum of thermogenic processes to meet cellular needs for adaptive thermogenesis. Two samples from two groups: NT-PGC-1α overexpression and empty vector. There are technical replicates (A and B) for each group. Two RNA samples were pooled for each group.
Project description:Great progress has been made in identifying positive regulators that activate adipocyte thermogenesis, but negative regulatory signaling of thermogenesis remains poorly understood. Here, we found that cardiotrophin-like cytokine factor 1 (CLCF1) signaling led to loss of brown fat identity, which impaired thermogenic capacity. CLCF1 levels decreased during thermogenic stimulation but were considerably increased in obesity. Adipocyte-specific CLCF1 transgenic (CLCF1-ATG) mice showed impaired energy expenditure and severe cold intolerance. Elevated CLCF1 triggered whitening of brown adipose tissue by suppressing mitochondrial biogenesis. Mechanistically, CLCF1 bound and activated ciliary neurotrophic factor receptor (CNTFR) and augmented signal transducer and activator of transcription 3 (STAT3) signaling. STAT3 transcriptionally inhibited both peroxisome proliferator-activated receptor-γ coactivator (PGC) 1α and 1β, which thereafter restrained mitochondrial biogenesis in adipocytes. Inhibition of CNTFR or STAT3 could diminish the inhibitory effects of CLCF1 on mitochondrial biogenesis and thermogenesis. As a result, CLCF1-TG mice were predisposed to develop metabolic dysfunction even without external metabolic stress. Our findings revealed a previously unknown brake signal on nonshivering thermogenesis and suggested that targeting this pathway could be used to restore brown fat activity and systemic metabolic homeostasis in obesity.