YAP/BRD4-controlled ROR1 promotes tumor-initiating cells and hyperproliferation in pancreatic cancer.

Tumor-initiating cells are major drivers of chemoresistance and attractive targets for cancer therapy, however, their identity in human pancreatic ductal adenocarcinoma (PDAC) and the key molecules underlying their traits remain poorly understood. Here, we show that a cellular subpopulation with partial epithelial-mesenchymal transition (EMT)-like signature marked by high expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) is the origin of heterogeneous tumor cells in PDAC. We demonstrate that ROR1 depletion suppresses tumor growth, recurrence after chemotherapy, and metastasis. Mechanistically, ROR1 induces the expression of Aurora kinase B (AURKB) by activating E2F through c-Myc to enhance PDAC proliferation. Furthermore, epigenomic analyses reveal that ROR1 is transcriptionally dependent on YAP/BRD4 binding at the enhancer region, and targeting this pathway reduces ROR1 expression and prevents PDAC growth. Collectively, our findings reveal a critical role for ROR1high cells as tumor-initiating cells and the functional importance of ROR1 in PDAC progression, thereby highlighting its therapeutic targetability.

Sexually dimorphic effects of pexidartinib on nerve injury-induced neuropathic pain in mice.

It is well-established that spinal microglia and peripheral macrophages play critical roles in the etiology of neuropathic pain; however, growing evidence suggests sex differences in pain hypersensitivity owing to microglia and macrophages. Therefore, it is crucial to understand sex- and androgen-dependent characteristics of pain-related myeloid cells in mice with nerve injury-induced neuropathic pain. To deplete microglia and macrophages, pexidartinib (PLX3397), an inhibitor of the colony-stimulating factor 1 receptor, was orally administered, and mice were subjected to partial sciatic nerve ligation (PSL). Following PSL induction, healthy male and female mice and male gonadectomized (GDX) mice exhibited similar levels of spinal microglial activation, peripheral macrophage accumulation, and mechanical allodynia. Treatment with PLX3397 significantly suppressed mechanical allodynia in normal males; this was not observed in female and GDX male mice. Sex- and androgen-dependent differences in the PLX3397-mediated preventive effects were observed on spinal microglia and dorsal root ganglia (DRG) macrophages, as well as in expression patterns of pain-related inflammatory mediators in these cells. Conversely, no sex- or androgen-dependent differences were detected in sciatic nerve macrophages, and inhibition of peripheral CC-chemokine receptor 5 prevented neuropathic pain in both sexes. Collectively, these findings demonstrate the presence of considerable sex- and androgen-dependent differences in the etiology of neuropathic pain in spinal microglia and DRG macrophages but not in sciatic nerve macrophages. Given that the mechanisms of neuropathic pain may differ among experimental models and clinical conditions, accumulating several lines of evidence is crucial to comprehensively clarifying the sex-dependent regulatory mechanisms of pain.

Mitochondrial stress induces AREG expression and epigenomic remodeling through c-JUN and YAP-mediated enhancer activation.

Nucleus-mitochondria crosstalk is essential for cellular and organismal homeostasis. Although anterograde (nucleus-to-mitochondria) pathways have been well characterized, retrograde (mitochondria-to-nucleus) pathways remain to be clarified. Here, we found that mitochondrial dysfunction triggered a retrograde signaling via unique transcriptional and chromatin factors in hepatic cells. Our transcriptomic analysis revealed that the loss of mitochondrial transcription factor A led to mitochondrial dysfunction and dramatically induced expression of amphiregulin (AREG) and other secretory protein genes. AREG expression was also induced by various mitochondria stressors and was upregulated in murine liver injury models, suggesting that AREG expression is a hallmark of mitochondrial damage. Using epigenomic and informatic approaches, we identified that mitochondrial dysfunction-responsive enhancers of AREG gene were activated by c-JUN/YAP1/TEAD axis and were repressed by chromatin remodeler BRG1. Furthermore, while mitochondrial dysfunction-activated enhancers were enriched with JUN and TEAD binding motifs, the repressed enhancers possessed the binding motifs for hepatocyte nuclear factor 4α, suggesting that both stress responsible and cell type-specific enhancers were reprogrammed. Our study revealed that c-JUN and YAP1-mediated enhancer activation shapes the mitochondrial stress-responsive phenotype, which may shift from metabolism to stress adaptation including protein secretion under such stressed conditions.

Sexual fate of murine external genitalia development: Conserved transcriptional competency for male-biased genes in both sexes.

Testicular androgen is a master endocrine factor in the establishment of external genital sex differences. The degree of androgenic exposure during development is well known to determine the fate of external genitalia on a spectrum of female- to male-specific phenotypes. However, the mechanisms of androgenic regulation underlying sex differentiation are poorly defined. Here, we show that the genomic environment for the expression of male-biased genes is conserved to acquire androgen responsiveness in both sexes. Histone H3 at lysine 27 acetylation (H3K27ac) and H3K4 monomethylation (H3K4me1) are enriched at the enhancer of male-biased genes in an androgen-independent manner. Specificity protein 1 (Sp1), acting as a collaborative transcription factor of androgen receptor, regulates H3K27ac enrichment to establish conserved transcriptional competency for male-biased genes in both sexes. Genetic manipulation of MafB, a key regulator of male-specific differentiation, and Sp1 regulatory MafB enhancer elements disrupts male-type urethral differentiation. Altogether, these findings demonstrate conservation of androgen responsiveness in both sexes, providing insights into the regulatory mechanisms underlying sexual fate during external genitalia development.

Lactic acidosis induces metabolic and phenotypic reprogramming in cholangiocarcinoma cells via the upregulation of thrombospondin-1.

The high glycolytic activity of cancer cells leads to lactic acidosis (LA) in the tumor microenvironment. LA is not merely a consequence of metabolic activities but also has functional roles in metabolic reprogramming and cancer progression. Cholangiocarcinoma (CCA) cells exhibit a high dependency on glycolysis for survival and growth, but the specific effects of LA on cellular characteristics remain unknown. Here, we demonstrate that long-term LA (LLA) reprograms the metabolic phenotype of CCA cells from glycolytic to oxidative and enhances their migratory activity. In CCA cell culture, short-term LA (24 h) showed a growth inhibitory effect, while extended LA exposure for more than 2 weeks (LLA) led to enhanced cell motility. Coincidentally, LLA enhanced the respiratory capacity with an increase in mitochondrial mass. Inhibition of mitochondrial function abolished LLA-induced cell motility, suggesting that metabolic remodeling affects the phenotypic outcomes. RNA-sequencing analysis revealed that LLA upregulated genes associated with cell migration and epithelial-mesenchymal transition (EMT), including thrombospondin-1 (THBS1), which encodes a pro-EMT-secreted protein. Inhibition of THBS1 resulted in the suppression of both LLA-induced cell motility and respiratory capacity. Moreover, high THBS1 expression was associated with poor survival in patients with CCA. Collectively, our study suggests that the increased expression of THBS1 by LLA promotes phenotypic alterations, leading to CCA progression.

High glucose-ROS conditions enhance the progression in cholangiocarcinoma via upregulation of MAN2A2 and CHD8.

Diabetes is a major risk factor in the development and progression of several cancers including cholangiocarcinoma (CCA). However, the molecular mechanism by which hyperglycemia potentiates progression of CCA is not clearly understood. Here, we showed that a high glucose condition significantly increased reactive oxygen species (ROS) production and promoted aggressive phenotypes of CCA cells, including proliferation and migration activities. Mannosidase alpha class 2a member 2 (MAN2A2), was upregulated at both mRNA and protein levels in a high glucose- and ROS-dependent manner. In addition, cell proliferation and migration were significantly reduced by MAN2A2 knockdown. Based on our proteome and in silico analyses, we further found that chromodomain helicase DNA-binding protein 8 (CHD8) was induced by ROS signaling and regulated MAN2A2 expression. Overexpression of CHD8 increased MAN2A2 expression, while CHD8 knockdown dramatically reduced proliferation and migration as well as MAN2A2 expression in CCA cells. Moreover, both MAN2A2 and CHD8 were highly expressed with positive correlation in CCA tumor tissues. Collectively, these data suggested that high glucose conditions promote CCA progression through ROS-mediated upregulation of MAN2A2 and CHD8. Thus, glucose metabolism is a promising therapeutic target to control tumor progression in patients with CCA and diabetes.

Postweaning Iron Deficiency in Male Rats Leads to Long-Term Hyperactivity and Decreased Reelin Gene Expression in the Nucleus Accumbens.

BACKGROUND: Epidemiological research indicates that iron deficiency (ID) in infancy correlates with long-term cognitive impairment and behavioral disturbances, despite therapy. However, the mechanisms underlying these effects are unknown. OBJECTIVE: We investigated how ID affected postweaning behavior and monoamine concentration in rat brains to determine whether ID during the juvenile period affected gene expression and synapse formation in the prefrontal cortex (PFC) and nucleus accumbens (NAcc). METHODS: Fischer 344/Jcl postweaning male rats aged 21-39 d were fed low-iron diets (0.35 mg/kg iron; ID group) or standard AIN-93 G diets [3.5 mg/kg iron; control (CN) group]. After day 39, all rats were fed the iron-adequate diet. The locomotor activity was evaluated by the open field and elevated plus maze tests at 8 and 12 wk of age. Monoamine concentrations in the brain were analyzed using HPLC at 9 and 13 wk of age. Comprehensive gene expression analysis was performed in the PFC and NAcc at 13 wk of age. Finally, we investigated synaptic density in the PFC and NAcc by synaptophysin immunostaining. RESULTS: Behavioral tests revealed a significant reduction of the age-related decline in the total distance traveled in ID rats compared with CN rats (P < 0.05), indicating that ID affected hyperactivity, which persisted into adulthood (13 wk of age). At this age, reelin (Reln) mRNA expression (adjusted P < 0.01) decreased and synaptic density (P < 0.01) increased in the NAcc in the ID group. Regarding the mesolimbic pathway, homovanillic acid concentration increased in the NAcc, whereas the dopamine concentration decreased in the ventral midbrain. CONCLUSIONS: Our results suggest that ID during the postweaning period in male rats, despite complete iron repletion following ID, led to long-term hyperactivity via monoamine disturbance in the brain and an alteration in the synaptic plasticity accompanied by downregulation of Reln expression in the NAcc.

Lysine-specific demethylase-2 is distinctively involved in brown and beige adipogenic differentiation.

Transcriptional and epigenetic regulation is fundamentally involved in initiating and maintaining progression of cellular differentiation. The 2 types of thermogenic adipocytes, brown and beige, are thought to be of different origins but share functionally similar phenotypes. Here, we report that lysine-specific demethylase 2 (LSD2) regulates the expression of genes associated with lineage identity during the differentiation of brown and beige adipogenic progenitors in mice. In HB2 mouse brown preadipocytes, short hairpin RNA-mediated knockdown (KD) of LSD2 impaired formation of lipid droplet-containing adipocytes and down-regulated brown adipogenesis-associated genes. Transcriptomic analysis revealed that myogenesis-associated genes were up-regulated in LSD2-KD cells under adipogenic induction. In addition, loss of LSD2 during later phases of differentiation had no obvious influence on adipogenic traits, suggesting that LSD2 functions during earlier phases of brown adipocyte differentiation. Using adipogenic cells from the brown adipose tissues of LSD2-knockout (KO) mice, we found reduced expression of brown adipogenesis genes, whereas myogenesis genes were not affected. In contrast, when LSD2-KO cells from inguinal white adipose tissues were subjected to beige induction, these cells showed a dramatic rise in myogenic gene expression. Collectively, these results suggest that LSD2 regulates distinct sets of genes during brown and beige adipocyte formation.-Takase, R., Hino, S., Nagaoka, K., Anan, K., Kohrogi, K., Araki, H., Hino, Y., Sakamoto, A., Nicholson, T. B., Chen, T., Nakao, M. Lysine-specific demethylase-2 is distinctively involved in brown and beige adipogenic differentiation.

LSD1 mediates metabolic reprogramming by glucocorticoids during myogenic differentiation.

The metabolic properties of cells are formed under the influence of environmental factors such as nutrients and hormones. Although such a metabolic program is likely initiated through epigenetic mechanisms, the direct links between metabolic cues and activities of chromatin modifiers remain largely unknown. In this study, we show that lysine-specific demethylase-1 (LSD1) controls the metabolic program in myogenic differentiation, under the action of catabolic hormone, glucocorticoids. By using transcriptomic and epigenomic approaches, we revealed that LSD1 bound to oxidative metabolism and slow-twitch myosin genes, and repressed their expression. Consistent with this, loss of LSD1 activity during differentiation enhanced the oxidative capacity of myotubes. By testing the effects of various hormones, we found that LSD1 levels were decreased by treatment with the glucocorticoid dexamethasone (Dex) in cultured myoblasts and in skeletal muscle from mice. Mechanistically, glucocorticoid signaling induced expression of a ubiquitin E3 ligase, JADE-2, which was responsible for proteasomal degradation of LSD1. Consequently, in differentiating myoblasts, chemical inhibition of LSD1, in combination with Dex treatment, synergistically de-repressed oxidative metabolism genes, concomitant with increased histone H3 lysine 4 methylation at these loci. These findings demonstrated that LSD1 serves as an epigenetic regulator linking glucocorticoid action to metabolic programming during myogenic differentiation.

Maternal undernutrition during early pregnancy inhibits postnatal growth of the tibia in the female offspring of rats by alteration of chondrogenesis.

Epidemiological research has suggested that birth weights are correlated with adult leg lengths. However, the relationship between prenatal undernutrition (UN) and postnatal leg growth remains controversial. We investigated the effects of UN during early pregnancy on postnatal hindlimb growth and determined whether early embryonic malnutrition affects the functions of postnatal chondrocytes in rats. Undernourished Wistar dams were fed 40% of the daily intake of rats in the control groups from gestational days 5.5-11.5, and femurs, tibias, and trunks or spinal columns were morphologically measured at birth and at 16 weeks of age in control and undernourished offspring of both sexes. We evaluated cell proliferation and differentiation of cultured chondrocytes derived from neonatal tibias of female offspring and determined chondrocyte-related gene expression levels in neonatal epiphysis and embryonic limb buds. Tibial lengths of undernourished female, but not male, offspring were longer at birth and shorter at 16 weeks of age (p < .05) compared with those of control rats. In chondrocyte culture studies, stimulating effects of IGF-1 on cell proliferation (p < .01) were significantly decreased and levels of type II collagen were lower in female undernourished offspring (p < .05). These phenomena were accompanied by decreased expression levels of Col2a1 and Igf1r and increased expression levels of Fgfr3 (p < .05), which might be attributable to the decreased expression of specificity protein 1 (p < .05), a key transactivator of Col2a1 and Igf1r. In conclusion, UN stress during early pregnancy reduces postnatal tibial growth in female offspring by altering the function of chondrocytes, likely reflecting altered expression of gene transactivators.

Endoplasmic Reticulum (ER) Stress Induces Sirtuin 1 (SIRT1) Expression via the PI3K-Akt-GSK3ß Signaling Pathway and Promotes Hepatocellular Injury.

Sirtuin 1 (SIRT1), an NAD(+)-dependent histone deacetylase, plays crucial roles in various biological processes including longevity, stress response, and cell survival. Endoplasmic reticulum (ER) stress is caused by dysfunction of ER homeostasis and exacerbates various diseases including diabetes, fatty liver, and chronic obstructive pulmonary disease. Although several reports have shown that SIRT1 negatively regulates ER stress and ER stress-induced responses in vitro and in vivo, the effect of ER stress on SIRT1 is less explored. In this study, we showed that ER stress induced SIRT1 expression in vitro and in vivo. We further determined the molecular mechanisms of how ER stress induces SIRT1 expression. Surprisingly, the conventional ER stress-activated transcription factors XBP1, ATF4, and ATF6 seem to be dispensable for SIRT1 induction. Based on inhibitor screening experiments with SIRT1 promoter, we found that the PI3K-Akt-GSK3ß signaling pathway is required for SIRT1 induction by ER stress. Moreover, we showed that pharmacological inhibition of SIRT1 by EX527 inhibited the ER stress-induced cellular death in vitro and severe hepatocellular injury in vivo, indicating a detrimental role of SIRT1 in ER stress-induced damage responses. Collectively, these data suggest that SIRT1 expression is up-regulated by ER stress and contributes to ER stress-induced cellular damage.

Lysine-specific demethylase-1 contributes to malignant behavior by regulation of invasive activity and metabolic shift in esophageal cancer.

Lysine-specific demethylase-1 (LSD1) removes the methyl groups from mono- and di-methylated lysine 4 of histone H3. Previous studies have linked LSD1 to malignancy in several human tumors, and LSD1 is considered to epigenetically regulate the energy metabolism genes in adipocytes and hepatocellular carcinoma. This study investigates the function of LSD1 in the invasive activity and the metabolism of esophageal cancer cells. We investigated whether LSD1 immunohistochemical expression levels are related to clinical and pathological features, including the maximum standard uptake value in fluorodeoxyglucose positron emission tomography assay. The influence of LSD1 on cell proliferation, invasion and glucose uptake was evaluated in vitro by using specific small interfering RNA for LSD1, and an LSD1 inhibitor. We also evaluated two major energy pathways (glycolytic pathway and mitochondrial respiration) by measuring the extracellular acidification rate (ECAR) and the oxygen consumption rate (OCR) with an extracellular flux analyzer. High LSD1 immunohistochemical expression was significantly associated with high tumor stage, lymphovascular invasion, poor prognosis, and high maximum standard uptake value in esophageal cancer patients. In the in vitro analysis, LSD1 knockdown significantly suppressed the invasive activity and glucose uptake of cancerous cells, reduced their ECAR and increased their OCR and OCR/ECAR. LSD1 may contribute to malignant behavior by regulating the invasive activity and metabolism, activating the glycolytic pathway and inhibiting the mitochondrial respiration of esophageal cancer cells. The results support LSD1 as a potential therapeutic target.

Histone demethylase LSD1 controls the phenotypic plasticity of cancer cells.

Epigenetic mechanisms underlie the phenotypic plasticity of cells, while aberrant epigenetic regulation through genetic mutations and/or misregulated expression of epigenetic factors leads to aberrant cell fate determination, which provides a foundation for oncogenic transformation. Lysine-specific demethylase-1 (LSD1, KDM1A) removes methyl groups from methylated proteins, including histone H3, and is frequently overexpressed in various types of solid tumors and hematopoietic neoplasms. While LSD1 is involved in a wide variety of normal physiological processes, including stem cell maintenance and differentiation, it is also a key player in oncogenic processes, including compromised differentiation, enhanced cell motility and metabolic reprogramming. Here, we present an overview of how LSD1 epigenetically regulates cellular plasticity through distinct molecular mechanisms in different biological contexts. Targeted inhibition of the context-dependent activities of LSD1 may provide a highly selective means to eliminate cancer cells.

HMGA2 promotes adipogenesis by activating C/EBPß-mediated expression of PPARγ.

Adipogenesis is orchestrated by a highly ordered network of transcription factors including peroxisome-proliferator activated receptor-gamma (PPARγ) and CCAAT-enhancer binding protein (C/EBP) family proteins. High mobility group protein AT-hook 2 (HMGA2), an architectural transcription factor, has been reported to play an essential role in preadipocyte proliferation, and its overexpression has been implicated in obesity in mice and humans. However, the direct role of HMGA2 in regulating the gene expression program during adipogenesis is not known. Here, we demonstrate that HMGA2 is required for C/EBPß-mediated expression of PPARγ, and thus promotes adipogenic differentiation. We observed a transient but marked increase of Hmga2 transcript at an early phase of differentiation of mouse 3T3-L1 preadipocytes. Importantly, Hmga2 knockdown greatly impaired adipocyte formation, while its overexpression promoted the formation of mature adipocytes. We found that HMGA2 colocalized with C/EBPß in the nucleus and was required for the recruitment of C/EBPß to its binding element at the Pparγ2 promoter. Accordingly, HMGA2 and C/EBPß cooperatively enhanced the Pparγ2 promoter activity. Our results indicate that HMGA2 is an essential constituent of the adipogenic transcription factor network, and thus its function may be affected during the course of obesity.

Sall1 maintains nephron progenitors and nascent nephrons by acting as both an activator and a repressor.

The balanced self-renewal and differentiation of nephron progenitors are critical for kidney development and controlled, in part, by the transcription factor Six2, which antagonizes canonical Wnt signaling-mediated differentiation. A nuclear factor, Sall1, is expressed in Six2-positive progenitors as well as differentiating nascent nephrons, and it is essential for kidney formation. However, the molecular functions and targets of Sall1, especially the functions and targets in the nephron progenitors, remain unknown. Here, we report that Sall1 deletion in Six2-positive nephron progenitors results in severe progenitor depletion and apoptosis of the differentiating nephrons in mice. Analysis of mice with an inducible Sall1 deletion revealed that Sall1 activates genes expressed in progenitors while repressing genes expressed in differentiating nephrons. Sall1 and Six2 co-occupied many progenitor-related gene loci, and Sall1 bound to Six2 biochemically. In contrast, Sall1 did not bind to the Wnt4 locus suppressed by Six2. Sall1-mediated repression was also independent of its binding to DNA. Thus, Sall1 maintains nephron progenitors and their derivatives by a unique mechanism, which partly overlaps but is distinct from that of Six2: Sall1 activates progenitor-related genes in Six2-positive nephron progenitors and represses gene expression in Six2-negative differentiating nascent nephrons.

Architectural roles of multiple chromatin insulators at the human apolipoprotein gene cluster.

Long-range regulatory elements and higher-order chromatin structure coordinate the expression of multiple genes in cluster, and CTCF/cohesin-mediated chromatin insulator may be a key in this regulation. The human apolipoprotein (APO) A1/C3/A4/A5 gene region, whose alterations increase the risk of dyslipidemia and atherosclerosis, is partitioned at least by three CTCF-enriched sites and three cohesin protein RAD21-enriched sites (two overlap with the CTCF sites), resulting in the formation of two transcribed chromatin loops by interactions between insulators. The C3 enhancer and APOC3/A4/A5 promoters reside in the same loop, where the APOC3/A4 promoters are pointed towards the C3 enhancer, whereas the APOA1 promoter is present in the different loop. The depletion of either CTCF or RAD21 disrupts the chromatin loop structure, together with significant changes in the APO expression and the localization of transcription factor hepatocyte nuclear factor (HNF)-4alpha and transcriptionally active form of RNA polymerase II at the APO promoters. Thus, CTCF/cohesin-mediated insulators maintain the chromatin loop formation and the localization of transcriptional apparatus at the promoters, suggesting an essential role of chromatin insulation in controlling the expression of clustered genes.

Metabolism-epigenome crosstalk in physiology and diseases.

The way in which energy is used in cells is determined under the influence of environmental factors such as nutritional availability. Metabolic adaptation is mainly achieved through the modulation of metabolic gene expression, and may also involve epigenetic mechanisms that enable long-term regulation. Recent studies have identified that nutrients and their metabolites exert an important influence on the epigenome, as they serve as substrates and/or coenzymes for epigenetic-modifying enzymes. Some epigenetic factors have been shown to regulate metabolic genes leading to a shift in energy flow. These findings suggest the concept of metabolism-epigenome crosstalk that may contribute to the formation of a long-term metabolic phenotype. This is particularly relevant to the pathogenesis of obesity and associated metabolic disorders, in which pre- and post-natal nutritional conditions affect disease risks in adulthood. Moreover, most cancer cells exploit metabolic pathways for their hyperproliferative activity, while metabolic misregulation leads to aberrant epigenetic regulation in some cancers. This review explores the possible mechanisms of metabolism-epigenome crosstalk that may facilitate our understanding of physiology and diseases.

Chromatin Immunoprecipitation Sequencing (ChIP-seq) for Detecting Histone Modifications and Modifiers.

Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) is the most widely used method for analyzing genome-wide DNA-protein interactions. Because there is considerable variation in the modes and strengths of DNA-protein interactions, chromatin immunoprecipitation (ChIP) protocols have been diversified and optimized for different needs. Here, we describe protocols for detecting histone modifications and modifiers using various crosslinking and immunoprecipitation conditions. We provide a complete ChIP-seq workflow covering sample preparation, immunoprecipitation, next-generation sequencing (NGS) library preparation, and data analyses.

LSD1 defines the fiber type-selective responsiveness to environmental stress in skeletal muscle.

Skeletal muscle exhibits remarkable plasticity in response to environmental cues, with stress-dependent effects on the fast-twitch and slow-twitch fibers. Although stress-induced gene expression underlies environmental adaptation, it is unclear how transcriptional and epigenetic factors regulate fiber type-specific responses in the muscle. Here, we show that flavin-dependent lysine-specific demethylase-1 (LSD1) differentially controls responses to glucocorticoid and exercise in postnatal skeletal muscle. Using skeletal muscle-specific LSD1-knockout mice and in vitro approaches, we found that LSD1 loss exacerbated glucocorticoid-induced atrophy in the fast fiber-dominant muscles, with reduced nuclear retention of Foxk1, an anti-autophagic transcription factor. Furthermore, LSD1 depletion enhanced endurance exercise-induced hypertrophy in the slow fiber-dominant muscles, by induced expression of ERRγ, a transcription factor that promotes oxidative metabolism genes. Thus, LSD1 serves as an 'epigenetic barrier' that optimizes fiber type-specific responses and muscle mass under the stress conditions. Our results uncover that LSD1 modulators provide emerging therapeutic and preventive strategies against stress-induced myopathies such as sarcopenia, cachexia, and disuse atrophy.

Lactic acidosis promotes aggressive features of cholangiocarcinoma cells via upregulating ALDH1A3 expression through EGFR axis.

AIMS: Lactic acidosis (LA) generated in tumor microenvironment promotes tumor metastasis and drug resistance. This study aimed to demonstrate the impacts and the mechanisms of LA on aldehyde dehydrogenase1A3 (ALDH1A3) in promoting aggressiveness and gemcitabine resistance in cholangiocarcinoma (CCA) cell lines. The clinical relevance and the molecular pathway related to the upregulation of ALDH1A3 in LA cells will be revealed. MAIN METHODS: ALDH1A3 expression and its clinical significances in CCA tissues were analyzed using the GEO databases. Human CCA cell lines, KKU-213A-LA and KKU-213B-LA maintained in the LA medium were studied and compared with its parental cells cultured in normal medium. Aggressive features-proliferation, colony formation, migration, invasion, and gemcitabine response were determined. Expression of ALDH1A3, EGFR and the downstream effectors were analyzed using real-time PCR and Western blotting. KEY FINDINGS: ALDH1A3 was upregulated in patient CCA tissues and correlated with LDHA and shorter survival of CCA patients. mRNA and protein of ALDH1A3 were increased in LA cells. Attenuation of ALDH1A3 expression by siRNA significantly reduced cell proliferation, colony formation, migration, invasion, and gemcitabine resistance of LA cells, and gemcitabine resistant cells. The EGF/EGFR signaling via Erk and STAT3 was pinned to be involved in the induction of ALDH1A3 expression in LA cells. The transcriptomic analysis from TCGA dataset supported the links between LDHA, EGFR and ALDH1A3 in several tumor tissues. SIGNIFICANCE: Lactic acidosis upregulated EGFR and ALDH1A3 expression, leading to the aggressiveness of CCA cells. The EGFR/ALDH1A3 axis could be a novel therapeutic target to eradicate metastatic CCA.