Project description:The present study examines the impact of altering energy provision on mitochondrial biogenesis in muscle cells. C2C12 myoblasts were chronically treated with supraphysiological levels of sodium pyruvate for 72 hr. Treated cells exhibited increased mitochondrial protein expression, basal respiratory rate and maximal oxidative capacity. The increase in mitochondrial biogenesis was independent of increases in PGC-1alpha and PGC-1alpha mRNA expression. To further assess whether PGC-1alpha expression was necessary for pyruvate action, cells were infected with adenovirus containing shRNA for PGC-1alpha prior to treatment with pyruvate. Despite a 70% reduction in PGC-1alpha mRNA the effect of pyruvate was preserved. Furthermore, pyruvate induced mitochondrial biogenesis in primary myoblasts from PGC-1alpha null mice. These data suggest that regulation of mitochondrial biogenesis by pyruvate in myoblasts is independent of PGC-1alpha, suggesting the existence of a novel energy-sensing pathway regulating oxidative capacity. Keywords: basal state versus treatment at one time point
Project description:PGC-1alpha; is a coactivator of nuclear receptors and other transcription factors that regulates several metabolic processes, including mitochondrial biogenesis and respiration, hepatic gluconeogenesis, and muscle fiber-type switching. We show here that, while hepatocytes lacking PGC-1alpha; are defective in the program of hormone-stimulated gluconeogenesis, the mice have constitutively activated gluconeogenic gene expression that is completely insensitive to normal feeding controls. C/EBPbeta; is elevated in the livers of these mice and activates the gluconeogenic genes in a PGC-1α-independent manner. Despite having reduced mitochondrial function, PGC-1alpha; null mice are paradoxically lean and resistant to diet-induced obesity. This is largely due to a profound hyperactivity displayed by the null animals and is associated with lesions in the striatal region of the brain that controls movement. These data illustrate a central role for PGC-1alpha; in the control of energy metabolism but also reveal novel systemic compensatory mechanisms and pathogenic effects of impaired energy homeostasis.
Project description:Amyotrophic later sclerosis is a motor neuron disease accompanied by metabolic changes. PGC (PPAR gamma coactivator)-1alpha is a master regulator of mitochondrial biogenesis and function and of critical importance for all metabolically active tissues. PGC-1alpha is a genetic modifier of ALS. We used microarray analysis to identify PGC-1alpha target genes in the brain.
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:Microarray time-course of mouse myotubes transduced with the transcriptional co-activator PGC-1alpha, which is known to induce mitochondrial biogenesis in muscle cells. Experiment Overall Design: Cultured mouse myoblasts (C2C12 cells) were differentiated into myotubes and on day 3 were infected with an adenovirus expressing either green fluorescent protein (GFP) or PGC-1alpha. Gene expression was measured at three time points (days 0, 1, 2, 3) in biological triplicate.
Project description:Microarray time-course of mouse myotubes transduced with the transcriptional co-activator PGC-1alpha, which is known to induce mitochondrial biogenesis in muscle cells. Keywords: time course
Project description:Decreased mitochondrial mass and function in muscle of diabetic patients is associated with low PGC-1alpha, a transcriptional coactivator of the mitochondrial gene program. To investigate whether reduced PGC-1alpha and oxidative capacity in muscle directly contributes to age-related glucose intolerance, we compared the genetic signatures and metabolic profiles of aging mice lacking muscle PGC-1alpha. Microarray analysis revealed that a significant proportion of PGC-1alpha-dependent changes in gene expression overlapped with age-associated effects, and aging muscle and muscle lacking PGC-1alpha shared gene signatures of impaired electron transport chain activity and TGFbeta signalling. Gastrocnemius muscle mRNA from young (10 week old) and old (24 month old) wild-type and knock-out (muscle-specific PGC-1alpha, myogenin-cre) C57Bl/6N/6J/129 mice
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.
