Histone Demethylase KDM3A Functions As an Essential Factor for Epigenetic Control of Autophagy
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ABSTRACT: Autophagy phenomenon is an essential mechanism to regulate cell homeostasis and is activated by various stresses such as nutrient starvation. It is well known that when autophagy is activated and how important components in the cytoplasm cause a series of reactions, but the regulatory mechanism of transcription in the nucleus is poorly known. Here, we identify that histone demethylase KDM3A plays a crucial role in the transcription of autophagy and lysosomal genes. Notably, KDM3A is increased in transcriptional levels in both glucose and amino acid starvation. Especially, transcriptional increase of histone demethylase in response to glucose starvation is dependent on AMP-activated protein kinase (AMPK). Furthermore, genome-wide analysis reveals that KDM3A acts as a co-activator in the expression of autophagy and lysosomal genes. Our finding of histone demethylase signaling cascade in nucleus, modulating histone demethylation signature is one of the predominant epigenetic event in autophagy activation, thereby providing the functional and mechanistic link between epigenetic control and transcriptional regulation of autophagy upon nutrient starvation.
Project description:Autophagy is a highly conserved self-digestion process, essential to maintain homeostasis and viability in response to nutrient starvation. Although the components of autophagy in the cytoplasm have been well-studied, molecular basis for the epigenetic regulation of autophagy is poorly understood. Here, we identify histone arginine methyltransferase CARM1 as a critical component of autophagy. We found that nutrient starvation increased CARM1 protein level and subsequently histone H3R17 dimethylation. Genome-wide analyses reveal that CARM1 exerts transcriptional coactivator function on autophagy-related genes and lysosomal genes through TFEB. Our findings demonstrate a previously unrecognized role of CARM1-dependent histone arginine methylation as a critical nuclear event of autophagy.
Project description:Autophagy, a catabolic process to remove unnecessary or dysfunctional cells, is triggered by various signals including nutrient starvation. Depending on the type of the nutrient deficiency, diverse sensing mechanisms and pathways are used for autophagy, suggesting subsequent nutrient dependent transcriptional regulation. Still, however, our knowledge about nutrient specific transcriptional regulation during autophagy is limited. To understand nutrient type dependent transcriptional mechanisms during autophagy, we performed single cell RNA sequencing (scRNAseq) for the mouse embryonic fibroblasts (MEFs) before and after applying glucose- (GS) as well as amino acid starvation (AAS). Trajectory analysis using scRNAseq identified sequential induction of potential transcriptional regulators for each deficiency condition. Gene regulatory rules inferred using TENET newly identified CCAAT/enhancer binding protein γ (C/EBPγ) regulates autophagy processes specifically to AAS condition. Strikingly, knockdown of C/EBPγ attenuated the autophagic process only in the AAS condition. Cell biological and biochemical studies validated that C/EBPγ plays a switching role for ATF4 to activate autophagy genes under AAS, but not under GS. Together, our data identified C/EBPγ as a previously unidentified key regulator under amino acid starvation-induced autophagy.
Project description:Autophagy, a catabolic process to remove unnecessary or dysfunctional cells, is triggered by various signals including nutrient starvation. Depending on the type of the nutrient deficiency, diverse sensing mechanisms and pathways are used for autophagy, suggesting subsequent nutrient dependent transcriptional regulation. Still, however, our knowledge about nutrient specific transcriptional regulation during autophagy is limited. To understand nutrient type dependent transcriptional mechanisms during autophagy, we performed single cell RNA sequencing (scRNAseq) for the mouse embryonic fibroblasts (MEFs) before and after applying glucose- (GS) as well as amino acid starvation (AAS). Trajectory analysis using scRNAseq identified sequential induction of potential transcriptional regulators for each deficiency condition. Gene regulatory rules inferred using TENET newly identified CCAAT/enhancer binding protein γ (C/EBPγ) regulates autophagy processes specifically to AAS condition. Strikingly, knockdown of C/EBPγ attenuated the autophagic process only in the AAS condition. Cell biological and biochemical studies validated that C/EBPγ plays a switching role for ATF4 to activate autophagy genes under AAS, but not under GS. Together, our data identified C/EBPγ as a previously unidentified key regulator under amino acid starvation-induced autophagy.
Project description:Autophagy is essential for cellular survival and energy homeostasis under nutrient deprivation. Despite the emerging importance of nuclear events in autophagy regulation, epigenetic control of autophagy gene transcription remains unclear. Here, we identify Jumonji-D3 (JMJD3/KDM6B) histone demethylase as a key epigenetic activator of hepatic autophagy. Upon fasting-induced fibroblast growth factor-21 (FGF21) signaling, JMJD3 epigenetically upregulated global autophagy-network genes, including Tfeb, Atg7, Atgl, and Fgf21, through demethylation of histone H3K27-me3, resulting in autophagy-mediated lipid degradation. Mechanistically, phosphorylation of JMJD3 at Thr-1044 by FGF21 signal-activated PKA increased its nuclear localization and interaction with the nuclear receptor PPARto transcriptionally activate autophagy. Chronic administration of FGF21 in obese mice improved defective autophagy and hepatosteatosis in a JMJD3-dependent manner. Remarkably, in non-alcoholic fatty liver disease patients, hepatic expression of JMJD3, ATG7, LC3, and KL were substantially decreased. These findings demonstrate that FGF21-JMJD3 signaling epigenetically links nutrient deprivation with hepatic autophagy and lipid degradation in mammals
Project description:Human lymphoblastoid cell lines (EBV-immortalised B cells, LcL) obtained from subjects of different age (young 28-40 years, centenarians >95 years) were analysed for gene expression at basal culture conditions and after 48 hours of serum starvation. Lymphoid B cells from centenarians were more resistant to apoptosis induction and displayed a more developed lysosomal compartment, the most critical component of phagic machinery. In addition, cells from centenarians were capable of engulfing and digesting other cells, i.e. their siblings (even entire cells). This behavior was improved by nutrient deprivation but, strikingly, it was unaffected by the autophagy modulating drugs rapamycin, an autophagy inducer, and 3-methyladenine, an autophagy inhibitor. 12 samples, divided into 4 groups: young basal, young starved, centenarians basal and centenarians starved.
Project description:Histone lysine (K) residues, which are modified by methyl- and acetyl-transferases, diversely regulate RNA synthesis. Unlike the ubiquitously activating effect of histone K acetylation, the effects of histone K methylation vary with the number of methyl groups added and with the position of these groups in the histone tails. Histone K demethylases (KDMs) counteract the activity of methyl-transferases and remove methyl group(s) from specific K residues in histones.KDM3A (also known as JHDM2A or JMJD1A) is an H3K9me2/1 demethylase. KDM3Aperforms diverse functions via the regulation of its associated genes, which are involved in spermatogenesis, metabolism, and cell differentiation. However, the mechanism by which the activity of KDM3A is regulated is largely unknown. First, we demonstrated that mitogen- and stress-activated protein kinase 1 (MSK1) specifically phosphorylates KDM3A at Ser264 (pKDM3A), which is enriched in the regulatory regions of gene loci in the human genome under heat shock conditions. p-KDM3A directly interacts with and is recruited by the transcription factor Stat1 to activate KDM3A target genes. The demethylation of H3K9me2 at the Stat1 binding site specifically depends on the co-expression of p-KDM3A under heat shock conditions. In contrast to heat shock treatment, IFN-M-NM-3 treatment does not phosphorylate KDM3A via MSK1, thereby abrogating its downstream effects. To our knowledge, this is the first evidence that a KDM can be modified via phosphorylation to determine its specific binding to target genes in response to cellular stress. 3 ChIP samples and two input as controls
Project description:Intricate regulation of lysosome and autophagy processes is essential for maintaining cellular homeostasis and basal metabolism. While the consequences of disrupting or attenuating lysosome and autophagy systems have been extensively studied, little is known about the impact of hyper-activation of lysosomal and autophagy genes on homeostasis. Our research uncovers previously unknown transcriptional repression mechanism by upstream stimulatory factor 2 (USF2), which inhibits lysosomal and autophagy genes in nutrient-rich conditions. USF2 binds to the CLEAR motif within lysosomal genes along with HDAC1, which diminishes H3K27 acetylation levels, restrains chromatin accessibility, and lowers lysosomal gene expression. Under starvation, USF2 competes with TFEB, a master transcriptional activator of lysosomal and autophagy genes, to bind target gene promoters in phosphorylation-dependent manner. Phosphorylation of the S155 site by GSK3b plays a pivotal role in controlling USF2's DNA binding activity for the repression of lysosomal genes while GSK3b-mediated phosphorylation of TFEB enhances its cytoplasmic retention. Applying these discoveries has potential for treating diseases associated with protein aggregation, including alpha-1 antitrypsin deficiency. These findings demonstrate that the USF2 repression mechanism could be a potent therapeutic strategy for various lysosome and autophagy-related diseases.
Project description:Intricate regulation of lysosome and autophagy processes is essential for maintaining cellular homeostasis and basal metabolism. While the consequences of disrupting or attenuating lysosome and autophagy systems have been extensively studied, little is known about the impact of hyper-activation of lysosomal and autophagy genes on homeostasis. Our research uncovers previously unknown transcriptional repression mechanism by upstream stimulatory factor 2 (USF2), which inhibits lysosomal and autophagy genes in nutrient-rich conditions. USF2 binds to the CLEAR motif within lysosomal genes along with HDAC1, which diminishes H3K27 acetylation levels, restrains chromatin accessibility, and lowers lysosomal gene expression. Under starvation, USF2 competes with TFEB, a master transcriptional activator of lysosomal and autophagy genes, to bind target gene promoters in phosphorylation-dependent manner. Phosphorylation of the S155 site by GSK3b plays a pivotal role in controlling USF2's DNA binding activity for the repression of lysosomal genes while GSK3b-mediated phosphorylation of TFEB enhances its cytoplasmic retention. Applying these discoveries has potential for treating diseases associated with protein aggregation, including alpha-1 antitrypsin deficiency. These findings demonstrate that the USF2 repression mechanism could be a potent therapeutic strategy for various lysosome and autophagy-related diseases.
Project description:Intricate regulation of lysosome and autophagy processes is essential for maintaining cellular homeostasis and basal metabolism. While the consequences of disrupting or attenuating lysosome and autophagy systems have been extensively studied, little is known about the impact of hyper-activation of lysosomal and autophagy genes on homeostasis. Our research uncovers previously unknown transcriptional repression mechanism by upstream stimulatory factor 2 (USF2), which inhibits lysosomal and autophagy genes in nutrient-rich conditions. USF2 binds to the CLEAR motif within lysosomal genes along with HDAC1, which diminishes H3K27 acetylation levels, restrains chromatin accessibility, and lowers lysosomal gene expression. Under starvation, USF2 competes with TFEB, a master transcriptional activator of lysosomal and autophagy genes, to bind target gene promoters in phosphorylation-dependent manner. Phosphorylation of the S155 site by GSK3b plays a pivotal role in controlling USF2's DNA binding activity for the repression of lysosomal genes while GSK3b-mediated phosphorylation of TFEB enhances its cytoplasmic retention. Applying these discoveries has potential for treating diseases associated with protein aggregation, including alpha-1 antitrypsin deficiency. These findings demonstrate that the USF2 repression mechanism could be a potent therapeutic strategy for various lysosome and autophagy-related diseases.
Project description:Autophagy is essential for cellular survival and energy homeostasis under nutrient deprivation. Despite the emerging importance of nuclear events in autophagy regulation, epigenetic control of autophagy gene transcription remains unclear. Here, we identify Jumonji-D3 (JMJD3/KDM6B) histone demethylase as a key epigenetic activator of hepatic autophagy. Upon fasting-induced fibroblast growth factor-21 (FGF21) signaling, JMJD3 epigenetically upregulated global autophagy-network genes, including Tfeb, Atg7, Atgl, and Fgf21, through demethylation of histone H3K27-me3, resulting in autophagy-mediated lipid degradation. Mechanistically, phosphorylation of JMJD3 at Thr-1044 by FGF21 signal-activated PKA increased its nuclear localization and interaction with the nuclear receptor PPARa to transcriptionally activate autophagy. Chronic administration of FGF21 in obese mice improved defective autophagy and hepatosteatosis in a JMJD3-dependent manner. Remarkably, in non-alcoholic fatty liver disease patients, hepatic expression of JMJD3, ATG7, LC3, and bKL were substantially decreased. These findings demonstrate that FGF21-JMJD3 signaling epigenetically links nutrient deprivation with hepatic autophagy and lipid degradation in mammals.