Project description:The effect of PGC-1α overexpression using adenovirus (PGC-1α-Ad) on hepatic gene expression was studied in mice primary hepatocytes.
Project description:Transcriptional coactivator PGC-1α and its splice variant NT-PGC-1α play crucial roles in regulating cold-induced thermogenesis in brown adipose tissue (BAT). PGC-1α and NT-PGC-1α are highly induced by cold in BAT and subsequently bind to and coactivate many different transcription factors to regulate expression of genes involved in mitochondrial biogenesis, fatty acid oxidation, respiration and thermogenesis. To identify the complete repertoire of PGC-1α and NT-PGC-1α target genes in BAT, we analyzed genome-wide DNA-binding and gene expression profiles. We find that PGC-1α-/NT-PGC-1α binding broadly associates with cold-mediated transcriptional activation. In addition to their known target genes in mitochondrial biogenesis, fatty acid oxidation, respiration and thermogenesis, PGC-1α and NT-PGC-1α target to a broad spectrum of genes involved in diverse biological pathways including ubiquitin-dependent protein catabolism, ribonucleoprotein complex biosynthesis, phospholipid biosynthesis, angiogenesis, glycogen metabolism, phosphorylation, and autophagy. Our findings expand the number of genes and biological pathways that may be regulated by PGC-1α and NT-PGC-1α and provide further insight into the transcriptional regulatory network in which PGC-1α and NT-PGC-1α coordinate a comprehensive transcriptional response in BAT in response to cold.
Project description:PGC-1α is a transcriptional coactivator that controls expression of metabolic/energetic genes programming cellular responses to nutrient and environmental adaptations such as fasting, cold or exercise. Unlike most other coactivators, PGC-1α contains protein domains involved in RNA binding and processing such as serine/arginine (SR) and RNA Recognition (RRM) motifs. However, little is known regarding the specific RNAs that bind PGC-1α to possibly control specific metabolic and energetic functions. To address this, we have performed single-end enhanced crosslinking and immunoprecipitation (seCLIP)-based transcriptome-wide analysis to identify specific RNA sequences that bind to PGC-1α. Primary hepatocytes were used to perform seCLIP experiments with glucagon-induced endogenous PGC-1α. RNA sequencing reveals that a large fraction of the RNAs bound to PGC-1α were intronic sequences related to genes involved in transcriptional, signaling or metabolic function linked to glucagon and fasting responses, but were not the canonical direct transcriptional targets of PGC-1α, such as OXPHOS or gluconeogenic genes. Validation of this analysis confirmed that among the top scoring RNA sequences bound to PGC-1α were Sik1, Camk1d, Ppard, Klf15, Gfra1 and Slc25a25. PGC-1α depletion decreased a fraction of mRNA transcript levels of these glucagon-induced genes. Importantly, knock-down of these genes affected glucagon-dependent glucose production, a PGC-1α-regulated metabolic pathway. These studies show that PGC-1α largely binds to intronic RNA sequences, some of them controlling transcript levels associated with glucagon action.
Project description:Transcriptional coactivator PGC-1α and its splice variant NT-PGC-1α play crucial roles in regulating cold-induced thermogenesis in brown adipose tissue (BAT). PGC-1α and NT-PGC-1α are highly induced by cold in BAT and subsequently bind to and coactivate many different transcription factors to regulate expression of genes involved in mitochondrial biogenesis, fatty acid oxidation, respiration and thermogenesis. To identify the complete repertoire of PGC-1α and NT-PGC-1α target genes in BAT, we analyzed genome-wide DNA-binding and gene expression profiles. We find that PGC-1α-/NT-PGC-1α binding broadly associates with cold-mediated transcriptional activation. In addition to their known target genes in mitochondrial biogenesis, fatty acid oxidation, respiration and thermogenesis, PGC-1α and NT-PGC-1α target to a broad spectrum of genes involved in diverse biological pathways including ubiquitin-dependent protein catabolism, ribonucleoprotein complex biosynthesis, phospholipid biosynthesis, angiogenesis, glycogen metabolism, phosphorylation, and autophagy. Our findings expand the number of genes and biological pathways that may be regulated by PGC-1α and NT-PGC-1α and provide further insight into the transcriptional regulatory network in which PGC-1α and NT-PGC-1α coordinate a comprehensive transcriptional response in BAT in response to cold.
Project description:PGC-1a is a transcriptional coactivator known to regulate a broad gene program of nutrient and mitochondrial metabolism. Many splice variants of this protein have been identified, but their functions were unknown. This experiment was designed to delineate the downstream targets of two different PGC-1alpha isoforms (PGC-1a1 and PGC-1a4) in hepatocytes, and to determine whether inflammatory signaling (via TNFR activation) modulated these targets Liver is exposed to constantly changing metabolic and inflammatory environments. It must quickly sense and adapt to metabolic need while balancing resources required to protect itself from harmful inflammatory molecules. PGC-1α is a transcriptional coactivator that mediates cellular adaptation to diverse stimuli including inflammation. PGC-1α has a protective role against inflammation in several organs, including brain, heart, kidney, muscle, and liver. However, it is not known how hepatic PGC-1α integrates extracellular signals to mitigate inflammatory outcomes. PGC-1α exists as multiple, alternatively spliced variants whose expression is differentially regulated by different gene promoters. In human liver, we found that inflammatory conditions preferentially activated the alternative versus proximal PPARGC1A promoter. Gene expression analysis performed in primary mouse hepatocytes identified many shared and isoform-specific roles for PGC-1α variants during acute inflammation. PGC-1α1 primarily impacted gene programs of nutrient and mitochondrial metabolism, while TNFα treatment revealed that PGC-1α4 uniquely influenced several pathways related to innate immunity and cell death. Gain- and loss-of-function models showed that PGC-1α4 specifically attenuated apoptosis in response to TNFα or LPS, in contrast to PGC-1α1, which reduced expression of a wide inflammatory gene network. We conclude that PGC-1α variants have distinct, yet complimentary roles in hepatic responses to inflammation, with PGC-1α4 being an important mitigator of apoptosis.
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:The peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) integrates environmental cues by controlling complex transcriptional networks in various metabolically active tissues. However, it is unclear how a transcriptional coregulator coordinates dynamic biological programs in response to multifaceted stimuli such as endurance training or fasting. Here, we discovered a central function of the poorly understood C-terminal domain (CTD) of PGC-1α to bind RNAs and assemble multi-protein complexes. Surprisingly, in addition to controlling the coupling of transcription and processing of target genes, RNA binding is indispensable for the recruitment of PGC-1α to chromatin into liquid-like nuclear condensates, which compartmentalize and regulate active transcription. These results demonstrate a hitherto unsuspected molecular mechanism by which complexity in the regulation of large transcriptional networks by PGC-1α is achieved. These findings are not only essential for the basic understanding of transcriptional coregulator-driven control of biological programs, but will also help to devise new strategies to modulate these processes in pathological contexts in which PGC-1α function is dysregulated, such as type 2 diabetes, cardiovascular diseases or skeletal muscle wasting.
Project description:PGC-1α in microglia protects against ischemia-induced brain damage in mice. The data suggest that microglia-specific PGC-1α play a key role in limiting ischemia-induced brain damage and potently participates in regulating microglial function. To further clarify the mechanism of PGC-1α, we conducted chromatin immunoprecipitation-sequencing (ChIP-Seq) analysis to identify the targets of PGC-1α in microglia from mPGC-1α mice at 24 h after ischemic stroke. KEGG pathway analysis of these genes identified the mitophagy signaling pathway as one of the most highly enriched pathways. Finally, we demonstrated that PGC-1α induces mitophagy by regulating ULK1 expression in an ERRα-dependent manner, thereby reducing neuroinflammatory reactions.
Project description:PGC-1α plays a central role in maintaining the mitochondrial and energy metabolism homeostasis, linking external stimuli to the transcriptional co-activation of genes involved in adaptive and age-related pathways. The carboxyl-terminus encodes a serine/arginine-rich (RS) region and a putative RNA recognition motif, however potential RNA-processing role(s) have remained elusive for the past 20 years. Here, we show that the RS domain of human PGC-1α directly interacts with RNA and the nuclear RNA export factor NXF1. Inducible depletion of endogenous PGC-1α and expression of RNAi-resistant RS-deleted PGC-1α further demonstrate that the RNA-binding activity is required for nuclear export of co-activated transcripts and mitochondrial homeostasis. Moreover, a quantitative proteomics approach confirmed PGC-1α-dependent RNA transport and mitochondrial-related functions, identifying also novel mRNA nuclear export targets in age-related telomere maintenance. Discovering a novel function for a major cellular homeostasis regulator provides new directions to further elucidate the roles of PGC-1α in gene expression, metabolic disorders, ageing and neurodegenerative diseases.
Project description:We found that TLS can work as a PGC-1alpha cofactor and this assay was carried out to test the functional dependency of TLS on PGC-1alpha on a whole genome scale Three independently-isolated cultures of primary hepatocytes from PGC-1α+/+ and PGC-1α-/- mice were infected with shTLS or control adenovirus. RNA was extracted by Trizol extraction, re-purified with RNAeasy (Invitrogen), and checked for integrity and quantity with the Agilent Bio-Analyzer QC. RNA was amplified and labeled with the One-Color Microarray-Based Gene Expression Analysis Protocol (Agilent Technologies, Palo Alto, CA, USA). Samples were hybridized to a G4122F 4x44K whole mouse genome microarray (Agilent Technologies). Arrays were scanned at 5 mm resolution with a G2565BA DNA microarray scanner (Agilent Technologies) at the default settings for 4x44k format one-color arrays. Images were analyzed using Feature Extraction software v10.1.1.1 (Agilent Technologies). Raw signals were thresholded to 1 and normalized by quantile (Bolstad et al., 2003) was performed using GeneSpring software. Data were analyzed on the log2 scale. Default flags were considered as absent, except for saturated spots that were flagged as marginal.