Project description:Secreted proteins serve pivotal roles in the development of multicellular organisms, acting as structural matrix, extracellular enzymes and signal molecules. In this study we demonstrate, unexpectedly, that PGC-1α, a critical transcriptional co-activator of metabolic gene expression, functions to down-regulate expression of diverse genes encoding secreted molecules and extracellular matrix (ECM) components to modulate the secretome. We show that both endogenous and exogenous PGC-1α down-regulate expression of numerous genes encoding secreted molecules. Mechanistically, results obtained using mRNA stability measurements as well as intronic RNA expression analysis are consistent with a transcriptional effect of PGC-1α on expression of genes encoding secreted proteins. Interestingly, PGC-1α requires the central heat shock response regulator HSF1 to affect some of its targets, and both factors co-reside on several target genes encoding secreted molecules in cells. Finally, using a mass spectrometric analysis of secreted proteins, we demonstrate that PGC-1α modulates the secretome of mouse embryonic fibroblasts (MEFs).
Project description:Calorie restriction (CR) is a dietary intervention that extends lifespan and healthspan in a variety of organisms. CR improves mitochondrial energy production, fuel oxidation and reactive oxygen species scavenging in skeletal muscle and other tissues, and these processes are thought to be critical to the benefits of CR. PGC-1a is a transcriptional coactivator that regulates mitochondrial function and is induced by CR. Consequently, many of the mitochondrial and metabolic benefits of CR are attributed to increased PGC-1a activity. To test this model for the first time, we examined the metabolic and mitochondrial response to CR in mice lacking skeletal muscle PGC-1a (MKO). Surprisingly, MKO mice demonstrated a normal improvement in glucose homeostasis in response to CR, indicating that skeletal muscle PGC-1a is dispensable for the whole-body benefits of CR. In contrast, gene expression profiling and electron microscopy demonstrated that PGC-1a is required for the full CR-induced increases in mitochondrial gene expression and mitochondrial density in skeletal muscle. These results demonstrate that PGC-1a is a major regulator of the mitochondrial response to CR in skeletal muscle, but surprisingly show that neither PGC-1a nor mitochondrial biogenesis in skeletal muscle are required for the metabolic benefits of CR. Control (FLOX) and PGC-1a skeletal muscle specific knock out (MKO) mice were placed on a control diet [C] or a calorie restriction diet [CR] for 12 weeks. RNA was isolated from TA/EDL muscles for microarray analysis. The following numbers of mice were analyzed from each group: C FLOX: n = 6; C MKO: n = 7; CR FLOX: n = 6; CR MKO: n = 7. Mice were mixed C57/BL6 and 129 background.
Project description:Huntington’s Disease (HD) is an inherited neurodegenerative disease caused by a glutamine repeat expansion in huntingtin protein. Transcriptional deregulation and altered energy metabolism have been implicated in HD pathogenesis. We report here that mutant huntingtin causes disruption of mitochondrial function by inhibiting expression of PGC-1a, a transcriptional coactivator that regulates several metabolic processes including mitochondrial biogenesis and respiration. Mutant huntingtin represses PGC-1a gene transcription by associating with the promoter and interfering with the CREB/TAF4-dependent transcriptional pathway critical for the regulation of PGC-1a gene expression. Crossbreeding of PGC-1a knockout mice with HD knock-in mice leads to increased neurodegeneration of striatal neurons and motor abnormalities in the HD mice. Importantly, expression of PGC-1a partially reverses the toxic effects of mutant huntingtin in cultured striatal neurons. Moreover, lentiviral-mediated delivery of PGC-1a in the striatum provides neuroprotection in the transgenic HD mice. These studies suggest a key role for PGC-1a in the control of energy metabolism in the early stages of HD pathogenesis. Keywords: PGC-1a, striatum
Project description:Calorie restriction (CR) is a dietary intervention that extends lifespan and healthspan in a variety of organisms. CR improves mitochondrial energy production, fuel oxidation and reactive oxygen species scavenging in skeletal muscle and other tissues, and these processes are thought to be critical to the benefits of CR. PGC-1a is a transcriptional coactivator that regulates mitochondrial function and is induced by CR. Consequently, many of the mitochondrial and metabolic benefits of CR are attributed to increased PGC-1a activity. To test this model for the first time, we examined the metabolic and mitochondrial response to CR in mice lacking skeletal muscle PGC-1a (MKO). Surprisingly, MKO mice demonstrated a normal improvement in glucose homeostasis in response to CR, indicating that skeletal muscle PGC-1a is dispensable for the whole-body benefits of CR. In contrast, gene expression profiling and electron microscopy demonstrated that PGC-1a is required for the full CR-induced increases in mitochondrial gene expression and mitochondrial density in skeletal muscle. These results demonstrate that PGC-1a is a major regulator of the mitochondrial response to CR in skeletal muscle, but surprisingly show that neither PGC-1a nor mitochondrial biogenesis in skeletal muscle are required for the metabolic benefits of CR.
Project description:To understand global expression changes in a knockdown of PGC1alpha (siPGC1alpha) vs control (siControl) in a lung metastatic cell line (4175) Metabolic adaptations play a key role in fuelling tumour growth. However, less is known regarding the metabolic changes that promote cancer progression to metastatic disease. Herein, we reveal that PGC-1a expression and activity are differentially regulated depending on breast cancer metastatic sites. Breast cancer cells that preferentially metastasize to lung display striking upregulation of PGC-1a expression. PGC-1a promotes breast cancer cell migration and invasion in vitro and augments lung metastasis in vivo. MDA-MB-231 lung variant (4175) cells were treated with a short interfering RNA (siRNA) for human PGC-1a (PPARG1A) or control siRNA for 48hrs 24 hours post-plating cells.
Project description:Huntington's Disease (HD) is an inherited neurodegenerative disease caused by a glutamine repeat expansion in huntingtin protein. Transcriptional deregulation and altered energy metabolism have been implicated in HD pathogenesis. We report here that mutant huntingtin causes disruption of mitochondrial function by inhibiting expression of PGC-1a, a transcriptional coactivator that regulates several metabolic processes including mitochondrial biogenesis and respiration. Mutant huntingtin represses PGC-1a gene transcription by associating with the promoter and interfering with the CREB/TAF4-dependent transcriptional pathway critical for the regulation of PGC-1a gene expression. Crossbreeding of PGC-1a knockout mice with HD knock-in mice leads to increased neurodegeneration of striatal neurons and motor abnormalities in the HD mice. Importantly, expression of PGC-1a partially reverses the toxic effects of mutant huntingtin in cultured striatal neurons. Moreover, lentiviral-mediated delivery of PGC-1a in the striatum provides neuroprotection in the transgenic HD mice. These studies suggest a key role for PGC-1a in the control of energy metabolism in the early stages of HD pathogenesis. Experiment Overall Design: Total RNA was extracted from striata of 3 pgc1 KO mice and 3 littermate controls using the RNeasy Mini Kit (Qiagen) according to manufacturer's protocol. Samples were analyzed using RNA 6000 Nano LabChip kit on a 2100 Bioanalyzer (Agilent Technologies) to ensure integrity of RNA.
Project description:PGC-1a is a master regulator for cell mitochondrial and metabolism function. In this experiment neurons were infected with a PGC-1a/GFP adenovirus to examine what genes were upregulated by over expression. Known targets related to mitochondrial health were confirmed while new neuron specific targets were discovered.
Project description:SH-SY5Y cells were transfected with either GFP control or PGC-1a overexpression adenovirus and RNA was isolated after 48 hours and sequenced in order to understand what genes are differentially expressed with the presence of PGC-1a in neuron like cells. This experiment shows that genes related to neuron health and mitochondiral function are controlled by PGC-1a. We also analyze the promoter of upregualted genes found here to figure out potential partners that co-regulate with PGC-1a.
Project description:The peroxisome proliferator-activated receptor c coactivator 1 (PGC-1) proteins are key regulators of cellular bioenergetics and are accordingly expressed in tissues with a high energetic demand. For example, PGC-1a and PGC-1b control organ function of brown adipose tissue, heart, brain, liver and skeletal muscle. Surprisingly, despite their prominent role in the control of mitochondrial biogenesis and oxidative metabolism, expression and function of the PGC-1 coactivators in the retina, an organ with one of the highest energy demands per tissue weight, are completely unknown. Moreover, the molecular mechanisms that coordinate energy production with repair processes in the damaged retina remain enigmatic. In the present study, we thus investigated the expression and function of the PGC-1 coactivators in the healthy and the damaged retina. We show that PGC-1a and PGC-1b are found at high levels in different structures of the mouse retina, most prominently in the photoreceptors. Furthermore, PGC-1a knockout mice suffer from a striking deterioration in retinal morphology and function upon detrimental light exposure. Gene expression studies revealed dysregulation of all major pathways involved in retinal damage and apoptosis, repair and renewal in the PGC-1a knockouts. The light-induced increase in apoptosis in vivo in the absence of PGC-1a was substantiated in vitro, where overexpression of PGC-1a evoked strong anti-apoptotic effects. Finally, we found that retinal levels of PGC-1 expression are reduced in different mouse models for retinitis pigmentosa. We demonstrate that PGC-1a is a central coordinator of energy production and, importantly, all of the major processes involved in retinal damage and subsequent repair. Together with the observed dysregulation of PGC-1a and PGC-1b in retinitis pigmentosa mouse models, these findings thus imply that PGC-1a might be an attractive target for therapeutic approaches aimed at retinal degeneration diseases.