CHIR-99021 regulates mitochondrial remodelling via β-catenin signalling and miRNA expression during endodermal differentiation

Dipeptidyl peptidase-4 marks distinct subtypes of human adipose stromal/stem cells with different hepatocyte differentiation and immunoregulatory properties

BACKGROUND

Human adipose-derived stromal/stem cells (hASCs) play important roles in regenerative medicine and numerous inflammatory diseases. However, their cellular heterogeneity limits the effectiveness of treatment. Understanding the distinct subtypes of hASCs and their phenotypic implications will enable the selection of appropriate subpopulations for targeted approaches in regenerative medicine or inflammatory diseases.

METHODS

hASC subtypes expressing dipeptidyl peptidase-4 (DPP4) were identified via fluorescence-activated cell sorting (FACS) analysis. DPP4 expression was knocked down in DPP4+ hASCs via DPP4 siRNA. The capacity for proliferation, hepatocyte differentiation, inflammatory factor secretion and T-cell functionality regulation of hASCs from DPP4-, DPP4+, and control siRNA-treated DPP4+ hASCs and DPP4 siRNA-treated DPP4+ hASCs were assessed.

RESULTS

DPP4+ hASCs and control siRNA-treated DPP4+ hASCs presented a lower proliferative capacity but greater hepatocyte differentiation capacity than DPP4- hASCs and DPP4 siRNA-treated DPP4+ hASCs. Both DPP4+ hASCs and DPP4- hASCs secreted high levels of vascular endothelial growth factor-A (VEGF-A), monocyte chemoattractant protein-1 (MCP-1), and interleukin 6 (IL-6), whereas the levels of other factors, including matrix metalloproteinase (MMP)-1, eotaxin-3, fractalkine (FKN, CX3CL1), growth-related oncogene-alpha (GRO-alpha, CXCL1), monokine induced by interferon-gamma (MIG), macrophage inflammatory protein (MIP)-1beta, and macrophage colony-stimulating factor (M-CSF), were significantly greater in the supernatants of DPP4+ hASCs than in those of DPP4- hASCs. Exposure to hASC subtypes and their conditioned media triggered changes in the secreted cytokine profiles of T cells from healthy donors. The percentage of functional T cells that secreted factors such as MIP-1beta and IL-8 increased when these cells were cocultured with DPP4+ hASCs. The percentage of polyfunctional CD8+ T cells that secreted multiple factors, such as IL-17A, tumour necrosis factor alpha (TNF-α) and TNF-β, decreased when these cells were cocultured with supernatants derived from DPP4+ hASCs.

CONCLUSIONS

DPP4 may regulate proliferation, hepatocyte differentiation, inflammatory cytokine secretion and T-cell functionality of hASCs. These data provide a key foundation for understanding the important role of hASC subpopulations in the regulation of T cells, which may be helpful for future immune activation studies and allow them to be customized for clinical application.

DeSUMOylation of RBMX regulates exosomal sorting of cargo to promote renal tubulointerstitial fibrosis in diabetic kidney disease

INTRODUCTION

Diabetic kidney disease (DKD) has become the primary cause of chronic renal failure in China, and renal tubulointerstitial fibrosis plays a central role in DKD progression. Urinary exosomes, which reflect kidney changes, are largely influenced by RNA-binding proteins (RBPs) in their miRNA content.

OBJECTIVES

Our research aimed to determine the effect of the RNA-binding protein RBMX on exosomal miRNA in DKD.

METHODS

We introduced a higher level of Rbmx into diabetic mice using an adenoassociated virus and isolated exosomes from their kidney tissue through advanced centrifugation techniques and specialized kits. We then conducted a series of tests, including qRT-PCR, Western blot, MitoSOX, ATP luminescence, coimmunoprecipitation, SUMOylation assays, RNA immunoprecipitation, and confocal microscopy.

RESULTS

RBMX is found in higher levels in DKD and contributes to worsening kidney fibrosis, mitochondrial damage, and miRNA mismanagement in exosomes. It specifically binds with miR-26a, miR-23c, and miR-874 within the exosomes. This dysfunction may be linked to changes in RBMX SUMOylation. These miRNAs seem to protect against mitochondrial damage in kidney cells by targeting CERS6.

CONCLUSION

DeSUMOylation of RBMX plays a crucial role in determining the makeup of miRNAs in kidney cell exosomes, impacting the protective miRNAs which regulate mitochondrial damage through their interaction with CERS6 mRNA, ultimately affecting mitochondrial health in DKD.

Small Molecule-Mediated Stage-Specific Reprogramming of MSCs to Hepatocyte-Like Cells and Hepatic Tissue for Liver Injury Treatment

BACKGROUND

Derivation of hepatocytes from stem cells has been established through various protocols involving growth factor (GF) and small molecule (SM) agents, among others. However, mesenchymal stem cell-based derivation of hepatocytes still remains expensive due to the use of a cocktail of growth factors, and a long duration of differentiation is needed, thus limiting its potential clinical application.

METHODS

In this study, we developed a chemically defined differentiation strategy that is exclusively based on SM and takes 14 days, while the GF-based protocol requires 23-28 days.

RESULTS

We optimized a stage-specific differentiation protocol for the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into functional hepatocyte-like cells (dHeps) that involved four stages, i.e., definitive endoderm (DE), hepatic competence (HC), hepatic specification (HS) and hepatic differentiation and growth. We further generated hepatic tissue using human decellularized liver extracellular matrix and compared it with hepatic tissue derived from the growth factor-based protocol at the transcriptional level. dHep, upon transplantation in a rat model of acute liver injury (ALI), was capable of ameliorating liver injury in rats and improving liver function and tissue damage compared to those in the ALI model.

CONCLUSIONS

In summary, this is the first study in which hepatocytes and hepatic tissue were derived from MSCs utilizing a stage-specific strategy by exclusively using SM as a differentiation factor.

MicroRNA Expression in Patients with Coronary Artery Disease and Hypertension-A Systematic Review

Coronary artery disease (CAD) and hypertension significantly contribute to cardiovascular morbidity and mortality. MicroRNAs (miRNAs) have recently emerged as promising biomarkers and therapeutic targets for these conditions. This systematic review conducts a thorough analysis of the literature, with a specific focus on investigating miRNA expression patterns in patients with CAD and hypertension. This review encompasses an unspecified number of eligible studies that employed a variety of patient demographics and research methodologies, resulting in diverse miRNA expression profiles. This review highlights the complex involvement of miRNAs in CAD and hypertension and the potential for advances in diagnostic and therapeutic strategies. Future research endeavors are imperative to validate these findings and elucidate the precise roles of miRNAs in disease progression, offering promising avenues for innovative diagnostic tools and targeted interventions.

Silencing of keratin 15 impairs viability and mobility while facilitating the doxorubicin chemosensitivity by inactivating the β‑catenin pathway in liver cancer

Keratin 15 (KRT15) regulates the invasion as well as the stemness and is associated with tumor size and metastasis of several gastrointestinal cancers apart from liver cancer. The present study aimed to explore the effect of KRT15 knockdown on liver cancer malignant behaviors and its interaction with the β-catenin pathway. Small interfering (si)-KRT15 and si-negative control (NC) were transfected into liver cancer cell lines, followed by the addition or not of CHIR-99021 (a β-catenin agonist). Cell viability, invasion, apoptosis, and the half maximal inhibitory concentration (IC50) value of doxorubicin (Dox) were then assessed. The present study illustrated that KRT15 gene and protein expression levels were upregulated in most liver cancer cell lines (Huh7, PLC, Hep3B and HepG2) compared to the normal liver cell line THLE-2. si-KRT15 reduced cell viability and invasive cell count while promoting the apoptosis rate in Huh7 and HepG2 cells. In addition, si-KRT15 also reduced the IC50 value of Dox. Furthermore, si-KRT15 inactivated the β-catenin pathway as reflected by β-catenin, cyclin D1 and c-Myc expression levels in Huh7 and HepG2 cells. Subsequently, CHIR-99021 treatment increased the cell viability and invasive cell count while reducing the apoptosis rate in Huh7 and HepG2 cells. Concurrently, the IC50 value of Dox was also increased. Notably, CHIR-99021 treatment attenuated the effect of si-KRT15 on mediating the aforementioned Huh7 and HepG2 cell malignant behaviors and Dox chemosensitivity. In conclusion, KRT15 knockdown suppressed viability and mobility but facilitated Dox chemosensitivity via inactivating the β-catenin pathway in liver cancer, suggesting its potential as a target for liver cancer treatment.

Tubular β-catenin alleviates mitochondrial dysfunction and cell death in acute kidney injury

Mitochondria take part in a network of intracellular processes that regulate homeostasis. Defects in mitochondrial function are key pathophysiological changes during AKI. Although Wnt/β-catenin signaling mediates mitochondrial dysfunction in chronic kidney fibrosis, little is known of the influence of β-catenin on mitochondrial function in AKI. To decipher this interaction, we generated an inducible mouse model of tubule-specific β-catenin overexpression (TubCat), and a model of tubule-specific β-catenin depletion (TubcatKO), and induced septic AKI in these mice with lipopolysaccharide (LPS) and aseptic AKI with bilateral ischemia-reperfusion. In both AKI models, tubular β-catenin stabilization in TubCat animals significantly reduced BUN/serum creatinine, tubular damage (NGAL-positive tubules), apoptosis (TUNEL-positive cells) and necroptosis (phosphorylation of MLKL and RIP3) through activating AKT phosphorylation and p53 suppression; enhanced mitochondrial biogenesis (increased PGC-1α and NRF1) and restored mitochondrial mass (increased TIM23) to re-establish mitochondrial homeostasis (increased fusion markers OPA1, MFN2, and decreased fission protein DRP1) through the FOXO3/PGC-1α signaling cascade. Conversely, kidney function loss and histological damage, tubular cell death, and mitochondrial dysfunction were all aggravated in TubCatKO mice. Mechanistically, β-catenin transfection maintained mitochondrial mass and activated PGC-1α via FOXO3 in LPS-exposed HK-2 cells. Collectively, these findings provide evidence that tubular β-catenin mitigates cell death and restores mitochondrial homeostasis in AKI through the common mechanisms associated with activation of AKT/p53 and FOXO3/PGC-1α signaling pathways.

Mitochondrial homeostasis regulates definitive endoderm differentiation of human pluripotent stem cells

Cellular organelles play fundamental roles in almost all cell behaviors. Mitochondria have been reported to be functionally linked to various biological processes, including reprogramming and pluripotency maintenance. However, very little about the role of mitochondria has been revealed in human early development and lineage specification. Here, we reported the characteristics and function of mitochondria during human definitive endoderm differentiation. Using a well-established differentiation system, we first investigated the change of mitochondrial morphology by comparing undifferentiated pluripotent stem cells, the intermediate mesendoderm cells, and differentiated endoderm cells, and found that mitochondria were gradually elongated and matured along differentiation. We further analyzed the expression pattern of mitochondria-related genes by RNA-seq, indicating that mitochondria became active during differentiation. Supporting this notion, the production of adenosine triphosphate (ATP) and reactive oxygen species (ROS) was increased as well. Functionally, we utilized chemicals and genome editing techniques, which could interfere with mitochondrial homeostasis, to determine the role of mitochondria in human endoderm differentiation. Treatment with mitochondrial inhibitors, or genetic depletion of mitochondrial transcription factor A (TFAM), significantly reduced the differentiation efficiency of definitive endoderm. In addition, the defect in endoderm differentiation due to dysfunctional mitochondria could be restored to some extent by the addition of ATP. Moreover, the clearance of excessive ROS due to dysfunctional mitochondria by N-acetylcysteine (NAC) improved the differentiation as well. We further found that ATP and NAC could partially replace the growth factor activin A for definitive endoderm differentiation. Our study illustrates the essential role of mitochondria during human endoderm differentiation through providing ATP and regulating ROS levels, which may provide new insight for metabolic regulation of cell fate determination.

GSK3β Interacts With CRMP2 and Notch1 and Controls T-Cell Motility

The trafficking of T-cells through peripheral tissues and into afferent lymphatic vessels is essential for immune surveillance and an adaptive immune response. Glycogen synthase kinase 3β (GSK3β) is a serine/threonine kinase and regulates numerous cell/tissue-specific functions, including cell survival, metabolism, and differentiation. Here, we report a crucial involvement of GSK3β in T-cell motility. Inhibition of GSK3β by CHIR-99021 or siRNA-mediated knockdown augmented the migratory behavior of human T-lymphocytes stimulated via an engagement of the T-cell integrin LFA-1 with its ligand ICAM-1. Proteomics and protein network analysis revealed ongoing interactions among GSK3β, the surface receptor Notch1 and the cytoskeletal regulator CRMP2. LFA-1 stimulation in T-cells reduced Notch1-dependent GSK3β activity by inducing phosphorylation at Ser9 and its nuclear translocation accompanied by the cleaved Notch1 intracellular domain and decreased GSK3β-CRMP2 association. LFA-1-induced or pharmacologic inhibition of GSK3β in T-cells diminished CRMP2 phosphorylation at Thr514. Although substantial amounts of CRMP2 were localized to the microtubule-organizing center in resting T-cells, this colocalization of CRMP2 was lost following LFA-1 stimulation. Moreover, the migratory advantage conferred by GSK3β inhibition in T-cells by CHIR-99021 was lost when CRMP2 expression was knocked-down by siRNA-induced gene silencing. We therefore conclude that GSK3β controls T-cell motility through interactions with CRMP2 and Notch1, which has important implications in adaptive immunity, T-cell mediated diseases and LFA-1-targeted therapies.

Small-molecule suppression of calpastatin degradation reduces neuropathology in models of Huntington's disease

Mitochondrial dysfunction is a common hallmark of neurological disorders, and reducing mitochondrial damage is considered a promising neuroprotective therapeutic strategy. Here, we used high-throughput small molecule screening to identify CHIR99021 as a potent enhancer of mitochondrial function. CHIR99021 improved mitochondrial phenotypes and enhanced cell viability in several models of Huntington’s disease (HD), a fatal inherited neurodegenerative disorder. Notably, CHIR99201 treatment reduced HD-associated neuropathology and behavioral defects in HD mice and improved mitochondrial function and cell survival in HD patient-derived neurons. Independent of its known inhibitory activity against glycogen synthase kinase 3 (GSK3), CHIR99021 treatment in HD models suppressed the proteasomal degradation of calpastatin (CAST), and subsequently inhibited calpain activation, a well-established effector of neural death, and Drp1, a driver of mitochondrial fragmentation. Our results established CAST-Drp1 as a druggable signaling axis in HD pathogenesis and highlighted CHIR99021 as a mitochondrial function enhancer and a potential lead for developing HD therapies.

Mitochondrial dysfunction is a common hallmark of neurological disorders. Here, the authors identify CHIR99021 as a potent enhancer of mitochondrial function, which improved mitochondrial phenotypes in Huntington’s disease models. CHIR99021 was shown to stabilize calpastatin, which suppressed calpain activation and Drp1-induced mitochondrial fragmentation.

microRNA-130a-5p suppresses myocardial ischemia reperfusion injury by downregulating the HMGB2/NF-κB axis

BACKGROUND

Myocardial ischemia reperfusion injury (MIRI) is defined as tissue injury in the pathological process of progressive aggravation in ischemic myocardium after the occurrence of acute coronary artery occlusion. Research has documented the involvement of microRNAs (miRs) in MIRI. However, there is obscure information about the role of miR-130a-5p in MIRI. Herein, this study aims to investigate the effect of miR-130a-5p on MIRI.

METHODS

MIRI mouse models were established. Then, the cardiac function and hemodynamics were detected using ultrasonography and multiconductive physiological recorder. Functional assays in miR-130a-5p were adopted to test the degrees of oxidative stress, mitochondrial functions, inflammation and apoptosis. Hematoxylin and eosin (HE) staining was performed to validate the myocardial injury in mice. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was employed to assess the expression patterns of miR-130a-5p, high mobility group box (HMGB)2 and NF-κB. Then, dual-luciferase reporter gene assay was performed to elucidate the targeting relation between miR-130a-5p and HMGB2.

RESULTS

Disrupted structural arrangement in MIRI mouse models was evident from HE staining. RT-qPCR revealed that overexpressed miR-130a-5p alleviated MIRI, MIRI-induced oxidative stress and mitochondrial disorder in the mice. Next, the targeting relation between miR-130a-5p and HMGB2 was ascertained. Overexpressed HMGB2 annulled the protective effects of miR-130a-5p in MIRI mice. Additionally, miR-130a-5p targets HMGB2 to downregulate the nuclear factor kappa-B (NF-κB) axis, mitigating the inflammatory injury induced by MIRI.

CONCLUSION

Our study demonstrated that miR-130a-5p suppresses MIRI by down-regulating the HMGB2/NF-κB axis. This investigation may provide novel insights for development of MIRI treatments.

GSK3 inhibitor ameliorates steatosis through the modulation of mitochondrial dysfunction in hepatocytes of obese patients

Obesity is an important risk factor and a potential treatment target for hepatic steatosis. The maladaptation of hepatic mitochondrial flexibility plays a key role in the hepatic steatosis. Herein, we found that hepatocyte-like cells derived from human adipose stem cell of obese patients exhibited the characteristics of hepatic steatosis and accompanied with lower expression of the subunits of mitochondrial complex I and lower oxidative phosphorylation levels. The GSK3 inhibitor CHIR-99021 promoted the expression of NDUFB8, NDUFB9, the subunits of mitochondrial complex I, the basal oxygen consumption rate, and the fatty acid oxidation of the hepatocytes of obese patients by upregulating the expression of the transcription factor PGC-1α, TFAM, and NRF1 involved in mitochondrial biogenesis. Moreover, CHIR-99021 decreased the lipid droplets size and the triglyceride levels in hepatocytes of obese patients. The results demonstrate that GSK3 inhibition ameliorates hepatic steatosis by elevating the mitochondrial function in hepatocytes of obese patients.

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Obese patients’ adipose-stem-cell-derived hepatocytes reveal hepatic steatosis

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Hepatic steatosis is accompanied the mitochondrial dysfunction

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The mitochondrial dysfunction is governed by the low expression PGC-1α, TFAM, and NRF1

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GSK3 inhibitor ameliorates hepatic steatosis via mitochondrial dysfunction modulation

SLCO4A1-AS1 promotes cell growth and induces resistance in lung adenocarcinoma by modulating miR-4701-5p/NFE2L1 axis to activate WNT pathway

Long noncoding RNAs (lncRNAs) possessed essential functions in the biological behaviors of various human cancers. SLCO4A1 antisense RNA 1 (SLCO4A1-AS1) is a lncRNA that has been reported as a oncogenic regulator in colorectal cancer and bladder cancer. However, whether it exerted functions in the gene expression and cellular processes in lung adenocarcinoma (LUAD) remains still obscure. In the present research, we unveiled the high level of SLCO4A1-AS1 in LUAD tissues and cells. Moreover, functional assays indicated that SLCO4A-AS1 facilitated LUAD cell proliferation, motility, and cisplatin-resistance. Besides, mechanism investigation revealed that miR-4701-5p could interact with SLCO4A1-AS1 and directly target to NFE2L1. The expression correlation between miR-4701-5p and SLCO4A1-AS1 or NFE2L1 was found to be negative. Moreover, NFE2L1 was expressed at a same tendency with SLCO4A1-AS1 in LUAD tissues and cells. In addition, it was confirmed that NFE2L1 was involved in SLCO4A1-AS1-mediated activation of WNT pathway. According to rescue assays, NFE2L1 could involve in SLCO4A1-AS1-mediated LUAD cell growth. Conclusively, our study demonstrated that SLCO4A1-AS1 facilitated cell growth and enhanced the resistance of LUAD cells to chemotherapy via activating WNT pathway through miR-4701-5p/NFE2L1 axis.

Altered mechanisms of genital development identified through integration of DNA methylation and genomic measures in hypospadias

Hypospadias is a common birth defect where the urethral opening forms on the ventral side of the penis. We performed integrative methylomic, genomic, and transcriptomic analyses to characterize sites of DNA methylation that influence genital development. In case–control and case-only epigenome-wide association studies (EWAS) of preputial tissue we identified 25 CpGs associated with hypospadias characteristics and used one-sample two stage least squares Mendelian randomization (2SLS MR) to show a causal relationship for 21 of the CpGs. The largest difference was 15.7% lower beta-value at cg14436889 among hypospadias cases than controls (EWAS P = 5.4e−7) and is likely causal (2SLS MR P = 9.8e−15). Integrative annotation using two-sample Mendelian randomization of these methylation regions highlight potentially causal roles of genes involved in germ layer differentiation (WDHD1, DNM1L, TULP3), beta-catenin signaling (PKP2, UBE2R2, TNKS), androgens (CYP4A11, CYP4A22, CYP4B1, CYP4X1, CYP4Z2P, EPHX1, CD33/SIGLEC3, SIGLEC5, SIGLEC7, KLK5, KLK7, KLK10, KLK13, KLK14), and reproductive traits (ACAA1, PLCD1, EFCAB4B, GMCL1, MKRN2, DNM1L, TEAD4, TSPAN9, KLK family). This study identified CpGs that remained differentially methylated after urogenital development and used the most relevant tissue sample available to study hypospadias. We identified multiple methylation sites and candidate genes that can be further evaluated for their roles in regulating urogenital development.

Histone Acetyltransferase MOF Blocks Acquisition of Quiescence in Ground-State ESCs through Activating Fatty Acid Oxidation

Self-renewing embryonic stem cells (ESCs) respond to environmental cues by exiting pluripotency or entering a quiescent state. The molecular basis underlying this fate choice remains unclear. Here, we show that histone acetyltransferase MOF plays a critical role in this process through directly activating fatty acid oxidation (FAO) in the ground-state ESCs. We further show that the ground-state ESCs particularly rely on elevated FAO for oxidative phosphorylation (OXPHOS) and energy production. Mof deletion or FAO inhibition induces bona fide quiescent ground-state ESCs with an intact core pluripotency network and transcriptome signatures akin to the diapaused epiblasts in vivo. Mechanistically, MOF/FAO inhibition acts through reducing mitochondrial respiration (i.e., OXPHOS), which in turn triggers reversible pluripotent quiescence specifically in the ground-state ESCs. The inhibition of FAO/OXPHOS also induces quiescence in naive human ESCs. Our study suggests a general function of the MOF/FAO/OXPHOS axis in regulating cell fate determination in stem cells.

First person – Yuejiao Ma

First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Yuejiao Ma is first author on ‘CHIR-99021 regulates mitochondrial remodelling via β-catenin signalling and miRNA expression during endodermal differentiation’, published in JCS. Yuejiao is a PhD student in the lab of Haiyan Zhang at the School of Basic Medical Science, Capital Medical University, Beijing, China, investigating the differentiation of human adipose stem cells, as well as hepatocytes and mitochondria.