LSD1: Expanding Functions in Stem Cells and Differentiation

Cooperative role of LSD1 and CHD7 in regulating differentiation of mouse embryonic stem cells

Lysine-specific histone demethylase 1 (LSD1) is a histone demethylase that plays a critical role in epigenetic regulation by removing the methyl group from mono- and di-methylated lysine 4 on histone H3 (H3K4me1/2), acting as a repressor of gene expression. Recently, catalytically independent functions of LSD1, serving as a scaffold for assembling chromatin-regulator and transcription factor complexes, have been identified. Herein, we show for the first time that LSD1 interacts with chromodomain-helicase-DNA-binding protein 7 (CHD7) in mouse embryonic stem cells (ESCs). To further investigate the CHD7-LSD1 crosstalk, we engineered Chd7 and Chd7/Lsd1 knockout (KO) mouse ESCs. We show that CHD7 is dispensable for ESC self-renewal and survival, while Chd7 KO ESCs can differentiate towards embryoid bodies (EBs) with defective expression of ectodermal markers. Intriguingly, Chd7/Lsd1 double KO mouse ESCs exhibit proliferation defects similar to Lsd1 KO ESCs and have lost the capacity to differentiate properly. Furthermore, the increased co-occupancy of H3K4me1 and CHD7 on chromatin following Lsd1 deletion suggests that LSD1 is required for facilitating the proper binding of CHD7 to chromatin and regulating differentiation. Collectively, our results suggest that LSD1 and CHD7 work in concert to modulate gene expression and influence proper cell fate determination.

Chemical approaches targeting the hurdles of hepatocyte transplantation: mechanisms, applications, and advances

Hepatocyte transplantation (HTx) has been a novel cell-based therapy for severe liver diseases, as the donor livers for orthotopic liver transplantation are of great shortage. However, HTx has been confronted with two main hurdles: limited high-quality hepatocyte sources and low cell engraftment and repopulation rate. To cope with, researchers have investigated on various strategies, including small molecule drugs with unique advantages. Small molecules are promising chemical tools to modulate cell fate and function for generating high quality hepatocyte sources. In addition, endothelial barrier, immune responses, and low proliferative efficiency of donor hepatocytes mainly contributes to low cell engraftment and repopulation rate. Interfering these biological processes with small molecules is beneficial for improving cell engraftment and repopulation. In this review, we will discuss the applications and advances of small molecules in modulating cell differentiation and reprogramming for hepatocyte resources and in improving cell engraftment and repopulation as well as its underlying mechanisms.

The scaffolding function of LSD1 controls DNA methylation in mouse ESCs

Lysine-specific histone demethylase 1 (LSD1), which demethylates mono- or di- methylated histone H3 on lysine 4 (H3K4me1/2), is essential for early embryogenesis and development. Here we show that LSD1 is dispensable for mouse embryonic stem cell (ESC) self-renewal but is required for mouse ESC growth and differentiation. Reintroduction of a catalytically-impaired LSD1 (LSD1MUT) recovers the proliferation capability of mouse ESCs, yet the enzymatic activity of LSD1 is essential to ensure proper differentiation. Indeed, increased H3K4me1 in Lsd1 knockout (KO) mouse ESCs does not lead to major changes in global gene expression programs related to stemness. However, ablation of LSD1 but not LSD1MUT results in decreased DNMT1 and UHRF1 proteins coupled to global hypomethylation. We show that both LSD1 and LSD1MUT control protein stability of UHRF1 and DNMT1 through interaction with HDAC1 and the ubiquitin-specific peptidase 7 (USP7), consequently, facilitating the deacetylation and deubiquitination of DNMT1 and UHRF1. Our studies elucidate a mechanism by which LSD1 controls DNA methylation in mouse ESCs, independently of its lysine demethylase activity.

SP2509 functions as a novel ferroptosis inhibitor by reducing intracellular iron level in vascular smooth muscle cells

Previous studies have shown that ferroptosis of vascular smooth muscle cells (VSMCs) is involved in the development of aortic dissection (AD) and that histone methylation regulates this process. SP2509 acts as a specific inhibitor of lysine-specific demethylase 1 (LSD1), which governs a variety of biological processes. However, the effect of SP2509 on VSMC ferroptosis and AD remains to be elucidated. This aim of this study was to investigate the role and underlying mechanism of SP2509-mediated histone methylation on VSMC ferroptosis. Here, a mouse model of AD was established, and significantly reduced levels of H3K4me1 and H3K4me2 (target of SP2509) were found in the aortas of AD mice. In VSMCs, SP2509 treatment led to a dose-dependent increase in H3K4me2 levels. Furthermore, we found that SP2509 provided equivalent protection to ferrostatin-1 against VSMC ferroptosis, as evidenced by increased cell viability, decreased cell death and lipid peroxidation. RNA-sequencing analysis and subsequent experiments revealed that SP2509 counteracted cystine deficiency-induced response to inflammation and oxidative stress. More importantly, we demonstrated that SP2509 inhibited the expression of TFR and ferritin to reduce intracellular iron levels, thereby effectively blocking the process of ferroptosis. Therefore, our findings indicate that SP2509 protects VSMCs from multiple stimulus-induced ferroptosis by reducing intracellular iron levels, thereby preventing lipid peroxidation and cell death. These findings suggest that SP2509 may be a promising drug to alleviate AD by reducing iron deposition and VSMC ferroptosis.

Mining the Dynamical Properties of Substrate and FAD Binding Pockets of LSD1: Hints for New Inhibitor Design Direction

Lysine-specific demethylase 1 (LSD1), a highly sophisticated epigenetic regulator, orchestrates a range of critical cellular processes, holding promising therapeutic potential for treating diverse diseases. However, the clinical research progress targeting LSD1 is very slow. After 20 years of research, only one small-molecule drug, BEA-17, targeting the degradation of LSD1 and CoREST has been approved by the U.S. Food and Drug Administration. The primary reason for this may be the lack of abundant structural data regarding its intricate functions. To gain a deeper understanding of its conformational dynamics and guide the drug design process, we conducted molecular dynamics simulations to explore the conformational states of LSD1 in the apo state and under the influence of cofactors of flavin adenine dinucleotide (FAD) and CoREST. Our results showed that, across all states, the substrate binding pocket exhibited high flexibility, whereas the FAD binding pocket remained more stable. These distinct dynamical properties are essential for LSD1's ability to bind various substrates while maintaining efficient demethylation activity. Both pockets can be enlarged by merging with adjacent pockets, although only the substrate binding pocket can shrink into smaller pockets. These new pocket shapes can inform inhibitor design, particularly for selectively FAD-competitive inhibitors of LSD1, given the presence of numerous FAD-dependent enzymes in the human body. More interestingly, in the absence of FAD binding, the united substrate and FAD binding pocket are partitioned by the conserved residue of Tyr761, offering valuable insights for the design of inhibitors that disrupt the crucial steric role of Tyr761 and the redox role of FAD. Additionally, we identified pockets that positively or negatively correlate with the substrate and FAD binding pockets, which can be exploited for the design of allosteric or concurrent inhibitors. Our results reveal the intricate dynamical properties of LSD1 as well as multiple novel conformational states, which deepen our understanding of its sophisticated functions and aid in the rational design of new inhibitors.

Role of epigenetic regulatory mechanisms in age-related bone homeostasis imbalance

Alterations to the human organism that are brought about by aging are comprehensive and detrimental. Of these, an imbalance in bone homeostasis is a major outward manifestation of aging. In older adults, the decreased osteogenic activity of bone marrow mesenchymal stem cells and the inhibition of bone marrow mesenchymal stem cell differentiation lead to decreased bone mass, increased risk of fracture, and impaired bone injury healing. In the past decades, numerous studies have reported the epigenetic alterations that occur during aging, such as decreased core histones, altered DNA methylation patterns, and abnormalities in noncoding RNAs, which ultimately lead to genomic abnormalities and affect the expression of downstream signaling osteoporosis treatment and promoter of fracture healing in older adults. The current review summarizes the impact of epigenetic regulation mechanisms on age-related bone homeostasis imbalance.

Strategies that regulate LSD1 for novel therapeutics

Histone methylation plays crucial roles in regulating chromatin structure and gene transcription in epigenetic modifications. Lysine-specific demethylase 1 (LSD1), the first identified histone demethylase, is universally overexpressed in various diseases. LSD1 dysregulation is closely associated with cancer, viral infections, and neurodegenerative diseases, etc., making it a promising therapeutic target. Several LSD1 inhibitors and two small-molecule degraders (UM171 and BEA-17) have entered the clinical stage. LSD1 can remove methyl groups from histone 3 at lysine 4 or lysine 9 (H3K4 or H3K9), resulting in either transcription repression or activation. While the roles of LSD1 in transcriptional regulation are well-established, studies have revealed that LSD1 can also be dynamically regulated by other factors. For example, the expression or activity of LSD1 can be regulated by many proteins that form transcriptional corepressor complexes with LSD1. Moreover, some post-transcriptional modifications and cellular metabolites can also regulate LSD1 expression or its demethylase activity. Therefore, in this review, we will systematically summarize how proteins involved in the transcriptional corepressor complex, various post-translational modifications, and metabolites act as regulatory factors for LSD1 activity.

Exploring the interplay between methylation patterns and non-coding RNAs in non-small cell lung cancer: Implications for pathogenesis and therapeutic targets

Lung cancer is a global public health issue, with non-small cell lung cancer (NSCLC) accounting for 80-85 % of cases. With over two million new diagnoses annually, understanding the complex evolution of this disease is crucial. The development of lung cancer involves a complex interplay of genetic, epigenetic, and environmental factors, leading the key oncogenes and tumor suppressor genes to disorder, and activating the cancer related signaling pathway. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNA (circRNAs) are unique RNA transcripts with diverse biological functions. These ncRNAs are generated through genome transcription and play essential roles in cellular processes. Epigenetic modifications such as DNA methylation, N6-methyladenosine (m6A) modification, and histone methylation have gained significant attention in NSCLC research. The complexity of the interactions among these methylation modifications and ncRNAs contribute to the precise regulation of NSCLC development. This review comprehensively summarizes the associations between ncRNAs and different methylation modifications and discusses their effects on NSCLC. By elucidating these relationships, we aim to advance our understanding of NSCLC pathogenesis and identify potential therapeutic targets for this devastating disease.

Effect of the LSD1 inhibitor RN-1 on γ-globin and global gene expression during erythroid differentiation in baboons (Papio anubis)

Elevated levels of Fetal Hemoglobin interfere with polymerization of sickle hemoglobin thereby reducing anemia, lessening the severity of symptoms, and increasing life span of patients with sickle cell disease. An affordable, small molecule drug that stimulates HbF expression in vivo would be ideally suited to treat the large numbers of SCD patients that exist worldwide. Our previous work showed that administration of the LSD1 (KDM1A) inhibitor RN-1 to normal baboons increased Fetal Hemoglobin (HbF) and was tolerated over a prolonged treatment period. HbF elevations were associated with changes in epigenetic modifications that included increased levels of H3K4 di-and tri-methyl lysine at the γ-globin promoter. While dramatic effects of the loss of LSD1 on hematopoietic differentiation have been observed in murine LSD1 gene deletion and silencing models, the effect of pharmacological inhibition of LSD1 in vivo on hematopoietic differentiation is unknown. The goal of these experiments was to investigate the in vivo mechanism of action of the LSD1 inhibitor RN-1 by determining its effect on γ-globin expression in highly purified subpopulations of bone marrow erythroid cells enriched for varying stages of erythroid differentiation isolated directly from baboons treated with RN-1 and also by investigating the effect of RN1 on the global transcriptome in a highly purified population of proerythroblasts. Our results show that RN-1 administered to baboons targets an early event during erythroid differentiation responsible for γ-globin repression and increases the expression of a limited number of genes including genes involved in erythroid differentiation such as GATA2, GFi-1B, and LYN.

Sequential deregulation of histone marks, chromatin accessibility and gene expression in response to PROTAC-induced degradation of ASH2L

The trithorax protein ASH2L is essential for organismal and tissue development. As a subunit of COMPASS/KMT2 complexes, ASH2L is necessary for methylation of histone H3 lysine 4 (H3K4). Mono- and tri-methylation at this site mark active enhancers and promoters, respectively, although the functional relevance of H3K4 methylation is only partially understood. ASH2L has a long half-life, which results in a slow decrease upon knockout. This has made it difficult to define direct consequences. To overcome this limitation, we employed a PROTAC system to rapidly degrade ASH2L and address direct effects. ASH2L loss resulted in inhibition of proliferation of mouse embryo fibroblasts. Shortly after ASH2L degradation H3K4me3 decreased with its half-life varying between promoters. Subsequently, H3K4me1 increased at promoters and decreased at some enhancers. H3K27ac and H3K27me3, histone marks closely linked to H3K4 methylation, were affected with considerable delay. In parallel, chromatin compaction increased at promoters. Of note, nascent gene transcription was not affected early but overall RNA expression was deregulated late after ASH2L loss. Together, these findings suggest that downstream effects are ordered but relatively slow, despite the rapid loss of ASH2L and inactivation of KMT2 complexes. It appears that the systems that control gene transcription are well buffered and strong effects are only beginning to unfold after considerable delay.

LSD1 promotes prostate cancer reprogramming by repressing TP53 signaling independently of its demethylase function

Lysine-specific demethylase 1 (LSD1) is a histone demethylase that promotes stemness and cell survival in cancers such as prostate cancer. Most prostate malignancies are adenocarcinomas with luminal differentiation. However, some tumors undergo cellular reprogramming to a more lethal subset termed neuroendocrine prostate cancer (NEPC) with neuronal differentiation. The frequency of NEPC is increasing since the widespread use of potent androgen receptor signaling inhibitors. Currently, there are no effective treatments for NEPC. We previously determined that LSD1 promotes survival of prostate adenocarcinoma tumors. However, the role of LSD1 in NEPC is unknown. Here, we determined that LSD1 is highly upregulated in NEPC versus adenocarcinoma patient tumors. LSD1 suppression with RNAi or allosteric LSD1 inhibitors - but not catalytic inhibitors - reduced NEPC cell survival. RNA-Seq analysis revealed that LSD1 represses pathways linked to luminal differentiation, and TP53 was the top reactivated pathway. We confirmed that LSD1 suppressed the TP53 pathway by reducing TP53 occupancy at target genes while LSD1's catalytic function was dispensable for this effect. Mechanistically, LSD1 inhibition disrupted LSD1-HDAC interactions, increasing histone acetylation at TP53 targets. Finally, LSD1 inhibition suppressed NEPC tumor growth in vivo. These findings suggest that blocking LSD1's noncatalytic function may be a promising treatment strategy for NEPC.

LSD1: an emerging face in altering the tumor microenvironment and enhancing immune checkpoint therapy

Dysregulation of various cells in the tumor microenvironment (TME) causes immunosuppressive functions and aggressive tumor growth. In combination with immune checkpoint blockade (ICB), epigenetic modification-targeted drugs are emerging as attractive cancer treatments. Lysine-specific demethylase 1 (LSD1) is a protein that modifies histone and non-histone proteins and is known to influence a wide variety of physiological processes. The dysfunction of LSD1 contributes to poor prognosis, poor patient survival, drug resistance, immunosuppression, etc., making it a potential epigenetic target for cancer therapy. This review examines how LSD1 modulates different cell behavior in TME and emphasizes the potential use of LSD1 inhibitors in combination with ICB therapy for future cancer research studies.

Histone modifications in drug-resistant cancers: From a cancer stem cell and immune evasion perspective

The development and immune evasion of cancer stem cells (CSCs) limit the efficacy of currently available anticancer therapies. Recent studies have shown that epigenetic reprogramming regulates the expression of characteristic marker proteins and tumor plasticity associated with cancer cell survival and metastasis in CSCs. CSCs also possess unique mechanisms to evade external attacks by immune cells. Hence, the development of new strategies to restore dysregulated histone modifications to overcome cancer resistance to chemotherapy and immunotherapy has recently attracted attention. Restoring abnormal histone modifications can be an effective anticancer strategy to increase the therapeutic effect of conventional chemotherapeutic and immunotherapeutic drugs by weakening CSCs or by rendering them in a naïve state with increased sensitivity to immune responses. In this review, we summarize recent findings regarding the role of histone modifiers in the development of drug-resistant cancer cells from the perspectives of CSCs and immune evasion. In addition, we discuss attempts to combine currently available histone modification inhibitors with conventional chemotherapy or immunotherapy.

Post-translational modifications of histones: Mechanisms, biological functions, and therapeutic targets

Histones are DNA-binding basic proteins found in chromosomes. After the histone translation, its amino tail undergoes various modifications, such as methylation, acetylation, phosphorylation, ubiquitination, malonylation, propionylation, butyrylation, crotonylation, and lactylation, which together constitute the "histone code." The relationship between their combination and biological function can be used as an important epigenetic marker. Methylation and demethylation of the same histone residue, acetylation and deacetylation, phosphorylation and dephosphorylation, and even methylation and acetylation between different histone residues cooperate or antagonize with each other, forming a complex network. Histone-modifying enzymes, which cause numerous histone codes, have become a hot topic in the research on cancer therapeutic targets. Therefore, a thorough understanding of the role of histone post-translational modifications (PTMs) in cell life activities is very important for preventing and treating human diseases. In this review, several most thoroughly studied and newly discovered histone PTMs are introduced. Furthermore, we focus on the histone-modifying enzymes with carcinogenic potential, their abnormal modification sites in various tumors, and multiple essential molecular regulation mechanism. Finally, we summarize the missing areas of the current research and point out the direction of future research. We hope to provide a comprehensive understanding and promote further research in this field.

LSD1 inhibition modulates transcription factor networks in myeloid malignancies

Acute Myeloid Leukemia (AML) is a type of cancer of the blood system that is characterized by an accumulation of immature hematopoietic cells in the bone marrow and blood. Its pathogenesis is characterized by an increase in self-renewal and block in differentiation in hematopoietic stem and progenitor cells. Underlying its pathogenesis is the acquisition of mutations in these cells. As there are many different mutations found in AML that can occur in different combinations the disease is very heterogeneous. There has been some progress in the treatment of AML through the introduction of targeted therapies and a broader application of the stem cell transplantation in its treatment. However, many mutations found in AML are still lacking defined interventions. These are in particular mutations and dysregulation in important myeloid transcription factors and epigenetic regulators that also play a crucial role in normal hematopoietic differentiation. While a direct targeting of the partial loss-of-function or change in function observed in these factors is very difficult to imagine, recent data suggests that the inhibition of LSD1, an important epigenetic regulator, can modulate interactions in the network of myeloid transcription factors and restore differentiation in AML. Interestingly, the impact of LSD1 inhibition in this regard is quite different between normal and malignant hematopoiesis. The effect of LSD1 inhibition involves transcription factors that directly interact with LSD1 such as GFI1 and GFI1B, but also transcription factors that bind to enhancers that are modulated by LSD1 such as PU.1 and C/EBPα as well as transcription factors that are regulated downstream of LSD1 such as IRF8. In this review, we are summarizing the current literature on the impact of LSD1 modulation in normal and malignant hematopoietic cells and the current knowledge how the involved transcription factor networks are altered. We are also exploring how these modulation of transcription factors play into the rational selection of combination partners with LSD1 inhibitors, which is an intense area of clinical investigation.

Transcriptome profiling of histone writers/erasers enzymes across spermatogenesis, mature sperm and pre-cleavage embryo: Implications in paternal epigenome transitions and inheritance mechanisms

Accumulating evidence points out that sperm carry epigenetic instructions to embryo in the form of retained histones marks and RNA cargo that can transmit metabolic and behavioral traits to offspring. However, the mechanisms behind epigenetic inheritance of paternal environment are still poorly understood. Here, we curated male germ cells RNA-seq data and analyzed the expression profile of all known histone lysine writers and erasers enzymes across spermatogenesis, unraveling the developmental windows at which they are upregulated, and the specific activity related to canonical and non-canonical histone marks deposition and removal. We also characterized the epigenetic enzymes signature in the mature sperm RNA cargo, showing most of them positive translation at pre-cleavage zygote, suggesting that paternally-derived enzymes mRNA cooperate with maternal factors to embryo chromatin assembly. Our study shows several histone modifying enzymes not described yet in spermatogenesis and even more, important mechanistic aspects behind transgenerational epigenetics. Epigenetic enzymes not only can respond to environmental stressors, but could function as vectors of epigenetic information and participate in chromatin organization during maternal-to-zygote transition.

LSD1 for the Targeted Regulation of Adipose Tissue

White and thermal (brown and beige) adipose tissue energy storage and oxidative regulation pathways play a central role in maintaining the energy balance throughout the body, and the dysregulation of these pathways is closely related to glucose and lipid metabolism disorders and adipose tissue dysfunction, including obesity, chronic inflammation, insulin resistance, mitochondrial dysfunction, and fibrosis. Recent epigenetic studies have identified the novel regulatory element LSD1, which controls the above parameters, and have provided new mechanistic possibilities for re-encoding the fate and function of adipocytes. In this review, we outline the current advances in adipocyte metabolism in physiology and disease and discuss possible strategies for LSD1 to alter the phenotype of adipose tissue and thus influence energy utilization to improve metabolic health.

Histone lysine-specific demethylase 1 regulates the proliferation of hemocytes in the oyster Crassostrea gigas

Background

Lysine-specific demethylase 1 (LSD1) is an essential epigenetic regulator of hematopoietic differentiation, which can specifically mono-methylate H3K4 (H3K4me1) and di-methylate H3K4 (H3K4me2) as a transcriptional corepressor. Previous reports have been suggested that it participated in hematopoiesis and embryonic development process. Here, a conserved LSD1 (CgLSD1) with a SWIRM domain and an amino oxidase (AO) domain was identified from the Pacific oyster Crassostrea gigas.

Methods

We conducted a comprehensive analysis by various means to verify the function of CgLSD1 in hematopoietic process, including quantitative real-time PCR (qRT-PCR) analysis, western blot analysis, immunofluorescence assay, RNA interference (RNAi) and flow cytometry.

Results

The qRT-PCR analysis revealed that the transcripts of CgLSD1 were widely expressed in oyster tissues with the highest level in the mantle. And the transcripts of CgLSD1 were ubiquitously expressed during larval development with the highest expression level at the early D-veliger larvae stage. In hemocytes after Vibrio splendidus stimulation, the transcripts of CgLSD1 were significantly downregulated at 3, 6, 24, and 48 h with the lowest level at 3 h compared to that in the Seawater group (SW group). Immunocytochemical analysis showed that CgLSD1 was mainly distributed in the nucleus of hemocytes. After the CgLSD1 was knocked down by RNAi, the H3K4me1 and H3K4me2 methylation level significantly increased in hemocyte protein. Besides, the percentage of hemocytes with EdU-positive signals in the total circulating hemocytes significantly increased after V. splendidus stimulation. After RNAi of CgLSD1, the expression of potential granulocyte markers CgSOX11 and CgAATase as well as oyster cytokine-like factor CgAstakine were increased significantly in mRNA level, while the transcripts of potential agranulocyte marker CgCD9 was decreased significantly after V. splendidus stimulation.

Conclusion

The above results demonstrated that CgLSD1 was a conserved member of lysine demethylate enzymes that regulate hemocyte proliferation during the hematopoietic process.

Mechanism of LSD1 in oxygen-glucose deprivation/reoxygenation-induced pyroptosis of retinal ganglion cells via the miR-21-5p/NLRP12 axis

Background

Retinal ganglion cells (RGCs) are important retinal neurons that connect visual receptors to the brain, and lysine-specific demethylase 1 (LSD1) is implicated in the development of RGCs. This study expounded the mechanism of LSD1 in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced pyroptosis of RGCs.

Methods

Mouse RGCs underwent OGD/R exposure, and then RGC viability was examined using the cell counting kit-8 method. The mRNA levels of Caspase 1, the protein levels of NOD-like receptor family pyrin domain-containing 3 (NLRP3), N-terminal fragment of gasdermin D (GSDMD-N), and cleaved-Caspase1, and the concentrations of interleukin (IL)-1β and IL-18 were respectively examined. Subsequently, LSD1 expression was intervened to explore the underlying effect of LSD1 on OGD/R-induced pyroptosis of RGCs. Afterwards, the enrichments of LSD1 and histone H3 lysine 4 methylation (H3K4me) 1/2 on the microRNA (miR)-21-5p promoter were determined using chromatin-immunoprecipitation assay. And the binding interaction between miR-21-5p and NLRP12 was detected using dual-luciferase and RNA pull-down assays. Finally, the effects of miR-21-5p/NLRP12 on LSD1-mediated pyroptosis of RGCs were verified through functional rescue experiments.

Results

OGD/R treatment increased pyroptosis of RGCs and LSD1 expression. Silencing LSD1 declined levels of Caspase 1 mRNA, NLRP3, GSDMD-N, cleaved-Caspase1, IL-1β, and IL-18 and limited pyroptosis of OGD/R-treated RGCs. Mechanically, LSD1 suppressed miR-21-5p expression via demethylation of H3K4me2 on the miR-21-5p promoter to hamper the binding of miR-21-5p to NLRP12, and thereby increased NLRP12 expression. Silencing miR-21-5p or overexpressing NLRP12 facilitated OGD/R-induced pyroptosis of RGCs.

Conclusion

LSD1-mediated demethylation of H3K4me2 decreased miR-21-5p expression to increase NLRP12 expression, promoting pyroptosis of OGD/R-treated RGCs.

Antitumor Effect of Demethylzeylasteral (T-96) on Triple-Negative Breast Cancer via LSD1-Mediate Epigenetic Mechanisms

Background and Purpose. Breast cancer ranks first in the incidence of female tumors. Triple-negative breast cancer (TNBC), one type of breast cancer, is more aggressive and has a worse prognosis. Demethylzeylasteral (T-96) is isolated from Tripterygium wilfordii Hook F. Our previous study found that T96 could inhibit TNBC invasion via suppressing the canonical and noncanonical TGF-β signaling pathways. However, the antitumor effects and mechanisms of T-96 on TNBC have not been studied. This study is aimed at investigating the antitumor effect and mechanism of T-96 on breast cancer. Experimental approach. MTT assay, Live and Dead cell assay, and TUNEL were used to observe the antitumor effect of breast cancer cells treated with T-96. siRNA of LSD1, Co-IP, and molecular docking were used to explore the direct target and mechanism of T-96. Subcutaneous murine xenograft models were used to detect the efficacy of T-96 antitumor activity in vivo. Key Results. T-96 was more susceptible to inducing the apoptosis of highly metastatic TNBC cell lines (SUM-1315). An abnormal level of histone methylation is a crucial characteristic of metastatic cancer cells. LSD1 is a histone demethylase. We found that T-96 could significantly decrease the protein expression of LSD1, increase its target protein PTEN expression and enhance histone methylation. T-96 could also down-regulate the PI3K/AKT signaling pathway, which could be blocked by PTEN. Knockdown of LSD1 by siRNA blocked the pharmacological activity of T-96. And the molecular docking predicted T-96 processed affinity toward LSD1 through hydrogen bonding. Finally, T-96 was evaluated in a murine xenograft model of SUM-1315 cells. And T-96 could significantly inhibit tumor growth without showing marked toxicity. Conclusions & Implications. The results illustrated that T-96 exerted antitumor activity in highly metastatic TNBC by inactivating the LSD1 function.

An interferon-γ/FLT3 axis positively regulates hemopoietic progenitor cell expansion from human pluripotent stem cells

Since it became possible to differentiate human pluripotent stem cells (hPSCs) into hematopoietic cells in vitro, great efforts have been made to obtain highly potent hematopoietic stem/progenitor cells (HSPCs) from hPSCs. Immunophenotypical HSPCs can be obtained from hPSCs, but their repopulating potential in vivo is low. Here, we developed a novel hematopoietic differentiation method for human induced pluripotent stem cells (hiPSCs) to determine why the existing hPSC differentiation systems are inadequate. hiPSC-derived CD45 +CD34 + cells in our system were mostly CD38 - immunophenotypical HSPCs. The vast majority of human CD45 +CD34 + cells in umbilical cord blood, fetal liver, and bone marrow are CD38 + hematopoietic progenitor cells (HPCs); therefore, the poor production of CD38 + HPCs was indicative of a systematic problem. hiPSC-derived CD45 +CD34 + cells did not express FLT3, a receptor tyrosine kinase. Exogenous FLT3 activity significantly enhanced production of CD38 + HPCs from hiPSCs. Thus, poor production of CD38 + HPCs was due to a lack of FLT3 expression. Interferon-γ upregulated expression of FLT3 and increased the number of CD38 + HPCs among hiPSC-derived CD45 +CD34 + cells. These results suggest that poor production of CD38 + HPCs with hPSC differentiation systems is due to a lack of FLT3 expression, and that addition of interferon-γ can solve this problem.

Epigenetic Control of Muscle Stem Cells: Focus on Histone Lysine Demethylases

Adult skeletal muscle is mainly composed of post-mitotic, multinucleated muscle fibers. Upon injury, it has the unique ability to regenerate thanks to the activation of a subset of quiescent muscle stem cells (MuSCs). Activated MuSCs either differentiate to repair muscle, or self-renew to maintain the pool of MuSC. MuSC fate determination is regulated by an intricate network of intrinsic and extrinsic factors that control the expression of specific subsets of genes. Among these, the myogenic regulatory factors (MRFs) are key for muscle development, cell identity and regeneration. More globally, cell fate determination involves important changes in the epigenetic landscape of the genome. Such epigenetic changes, which include DNA methylation and post-translational modifications of histone proteins, are able to alter chromatin organization by controlling the accessibility of specific gene loci for the transcriptional machinery. Among the numerous epigenetic modifications of chromatin, extensive studies have pointed out the key role of histone methylation in cell fate control. Particularly, since the discovery of the first histone demethylase in 2004, the role of histone demethylation in the regulation of skeletal muscle differentiation and muscle stem cell fate has emerged to be essential. In this review, we highlight the current knowledge regarding the role of histone demethylases in the regulation of muscle stem cell fate choice.

Diagnostic and Therapeutic Perspectives Associated to Cobalamin-Dependent Metabolism and Transcobalamins' Synthesis in Solid Cancers

Cobalamin or vitamin B12 (B12) is a cofactor for methionine synthase and methylmalonyl-CoA mutase, two enzymes implicated in key pathways for cell proliferation: methylation, purine synthesis, succinylation and ATP production. Ensuring these functions in cancer cells therefore requires important cobalamin needs and its uptake through the transcobalamin II receptor (TCII-R). Thus, both the TCII-R and the cobalamin-dependent metabolic pathways constitute promising therapeutic targets to inhibit cancer development. However, the link between cobalamin and solid cancers is not limited to cellular metabolism, as it also involves the circulating transcobalamins I and II (TCI or haptocorrin and TCII) carrier proteins, encoded by TCN1 and TCN2, respectively. In this respect, elevations of B12, TCI and TCII concentrations in plasma are associated with cancer onset and relapse, and with the presence of metastases and worse prognosis. In addition, TCN1 and TCN2 overexpressions are associated with chemoresistance and a proliferative phenotype, respectively. Here we review the involvement of cobalamin and transcobalamins in cancer diagnosis and prognosis, and as potential therapeutic targets. We further detail the relationship between cobalamin-dependent metabolic pathways in cancer cells and the transcobalamins' abundancies in plasma and tumors, to ultimately hypothesize screening and therapeutic strategies linking these aspects.

Targeting Cancer Stem Cells through Epigenetic Modulation of Interferon Response

Cancer stem cells (CSCs) are a small subset of cancer cells and are thought to play a critical role in the initiation and maintenance of tumor mass. CSCs exhibit similar hallmarks to normal stem cells, such as self-renewal, differentiation, and homeostasis. In addition, CSCs are equipped with several features so as to evade anticancer mechanisms. Therefore, it is hard to eliminate CSCs by conventional anticancer therapeutics that are effective at clearing bulk cancer cells. Interferons are innate cytokines and are the key players in immune surveillance to respond to invaded pathogens. Interferons are also crucial for adaptive immunity for the killing of specific aliens including cancer cells. However, CSCs usually evolve to escape from interferon-mediated immune surveillance and to shape the niche as a “cold” tumor microenvironment (TME). These CSC characteristics are related to their unique epigenetic regulations that are different from those of normal and bulk cancer cells. In this review, we introduce the roles of epigenetic modifiers, focusing on LSD1, BMI1, G9a, and SETDB1, in contributing to CSC characteristics and discussing the interplay between CSCs and interferon response. We also discuss the emerging strategy for eradicating CSCs by targeting these epigenetic modifiers, which can elevate cytosolic nuclei acids, trigger interferon response, and reshape a “hot” TME for improving cancer immunotherapy. The key epigenetic and immune genes involved in this crosstalk can be used as biomarkers for precision oncology.