PI3K/AKT Signaling Pathway Is Essential for Survival of Induced Pluripotent Stem Cells

Combination of Autophagy and Stem Cell Enhancing Properties of Natural Product Extracts in Human Dermal Papilla Stem Cells

BACKGROUND/AIM

Dermal papilla (DP) stem cells are known for their remarkable regenerative capacity, making them a valuable model for assessing the effects of natural products on cellular processes, including stemness, and autophagy.

MATERIALS AND METHODS

Autophagy and stemness characteristics were assessed using real-time RT-PCR to analyze mRNA levels, along with immunofluorescence and western blot techniques for protein level evaluation.

RESULTS

Butterfly Pea, Emblica Fruits, Kaffir Lime, and Thunbergia Laurifolia extracts induced autophagy in DP cells. Kaffir Lime-treated cells exhibited increase in the OCT4, NANOG, and SOX2 mRNA (6-, 5, and 5.5-fold, respectively), and protein levels (4-, 3-, and 1.5-fold, respectively). All extracts activated the survival protein kinase B (Akt) in DP cells.

CONCLUSION

Natural products are a promising source for promoting hair growth by rejuvenating hair stem cells.

Ischemic preconditioning modulates the DNA methylation process of the rat heart to provide tolerance to withstand ischemia reperfusion injury and its associated mitochondrial dysfunction

DNA methylation plays a crucial role in the pathogenesis of myocardial ischemia reperfusion injury(I/R) and the I/R injury can be combated effectively by ischemia preconditioning (IPC), but the role is DNA methylation in this process is unknown. In this study, we uncovered the role of ischemic preconditioning (IPC)- mediated cardioprotection of rat myocardium by using a Langendorff rat heart model with 30 min of ischemia followed by 60 min of reperfusion. Heart conditioned with short cycles of ischemia and reperfusion (IPC procedure) prior to I/R protocol significantly reduced the I/R-induced global DNA hypermethylation level by 32% and the DNMT activity by 33% while rendering cardioprotection. Blocking the PI3K pathway via wortmannin not only negates the cardio-protection by IPC, but also increases the methylation of DNA by 75%. Besides, the correlation analysis showed a negative relationship between PI3K gene expression and the global DNA methylation level (r = - 0.8690, p = 0.0419) in IPC-treated rat hearts. Moreover, the global level DNA hypomethylation induced by IPC exhibited a regulatory effect on the genes involved in I/R pathology mediators like apoptosis (Caspase3), mitochondrial function (PGC 1α, TFAM, ND1) and oxidative stress (CuZnSOD, SOD2), and their corresponding function. The present study results provide novel evidence for the involvement of DNA methylation in the IPC procedure, and suggest DNA methylation as one of the potential therapeutic targets regulated by ischemic preconditioning in rat hearts subjected to ischemia reperfusion.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03965-0.

Optical Genome Mapping Reveals Genomic Alterations upon Gene Editing in hiPSCs: Implications for Neural Tissue Differentiation and Brain Organoid Research

Genome editing, notably CRISPR (cluster regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9), has revolutionized genetic engineering allowing for precise targeted modifications. This technique's combination with human induced pluripotent stem cells (hiPSCs) is a particularly valuable tool in cerebral organoid (CO) research. In this study, CRISPR/Cas9-generated fluorescently labeled hiPSCs exhibited no significant morphological or growth rate differences compared with unedited controls. However, genomic aberrations during gene editing necessitate efficient genome integrity assessment methods. Optical genome mapping, a high-resolution genome-wide technique, revealed genomic alterations, including chromosomal copy number gain and losses affecting numerous genes. Despite these genomic alterations, hiPSCs retain their pluripotency and capacity to generate COs without major phenotypic changes but one edited cell line showed potential neuroectodermal differentiation impairment. Thus, this study highlights optical genome mapping in assessing genome integrity in CRISPR/Cas9-edited hiPSCs emphasizing the need for comprehensive integration of genomic and morphological analysis to ensure the robustness of hiPSC-based models in cerebral organoid research.

DPPA2/4 Promote the Pluripotency and Proliferation of Bovine Extended Pluripotent Stem Cells by Upregulating the PI3K/AKT/GSK3β/β-Catenin Signaling Pathway

Developmental pluripotency-associated 2 (DPPA2) and DPPA4 are crucial transcription factors involved in maintaining pluripotency in humans and mice. However, the role of DPPA2/4 in bovine extended pluripotent stem cells (bEPSCs) has not been investigated. In this study, a subset of bEPSC-related differentially expressed genes (DEGs), including DPPA2 and DPPA4, was identified based on multiomics data (ATAC-seq and RNA-seq). Subsequent investigations revealed that double overexpression of DPPA2/4 facilitates the reprogramming of bovine fetal fibroblasts (BFFs) into bEPSCs, whereas knockout of DPPA2/4 in BFFs leads to inefficient reprogramming. DPPA2/4 overexpression and knockdown experiments revealed that the pluripotency and proliferation capability of bEPSCs were maintained by promoting the transition from the G1 phase to the S phase of the cell cycle. By activating the PI3K/AKT/GSK3β/β-catenin pathway in bEPSCs, DPPA2/4 can increase the nuclear accumulation of β-catenin, which further upregulates lymphoid enhancer binding factor 1 (LEF1) transcription factor activity. Moreover, DPPA2/4 can also regulate the expression of LEF1 by directly binding to its promoter region. Overall, our results demonstrate that DPPA2/4 promote the reprogramming of BFFs into bEPSCs while also maintaining the pluripotency and proliferation capability of bEPSCs by regulating the PI3K/AKT/GSK3β/β-catenin pathway and subsequently activating LEF1. These findings expand our understanding of the gene regulatory network involved in bEPSC pluripotency.

Interconversion of Cancer Cells and Induced Pluripotent Stem Cells

Cancer cells, especially cancer stem cells (CSCs), share many molecular features with induced pluripotent stem cells (iPSCs) that enable the derivation of induced pluripotent cancer cells by reprogramming malignant cells. Conversely, normal iPSCs can be converted into cancer stem-like cells with the help of tumor microenvironment components and genetic manipulation. These CSC models can be utilized in oncogenic initiation and progression studies, understanding drug resistance, and developing novel therapeutic strategies. This review summarizes the role of pluripotency factors in the stemness, tumorigenicity, and therapeutic resistance of cancer cells. Different methods to obtain iPSC-derived CSC models are described with an emphasis on exposure-based approaches. Culture in cancer cell-conditioned media or cocultures with cancer cells can convert normal iPSCs into cancer stem-like cells, aiding the examination of processes of oncogenesis. We further explored the potential of reprogramming cancer cells into cancer-iPSCs for mechanistic studies and cancer dependencies. The contributions of genetic, epigenetic, and tumor microenvironment factors can be evaluated using these models. Overall, integrating iPSC technology into cancer stem cell research holds significant promise for advancing our knowledge of cancer biology and accelerating the development of innovative and tailored therapeutic interventions.

Advances in Genetic Reprogramming: Prospects from Developmental Biology to Regenerative Medicine

The foundations of cell reprogramming were laid by Yamanaka and co-workers, who showed that somatic cells can be reprogrammed into pluripotent cells (induced pluripotency). Since this discovery, the field of regenerative medicine has seen advancements. For example, because they can differentiate into multiple cell types, pluripotent stem cells are considered vital components in regenerative medicine aimed at the functional restoration of damaged tissue. Despite years of research, both replacement and restoration of failed organs/ tissues have remained elusive scientific feats. However, with the inception of cell engineering and nuclear reprogramming, useful solutions have been identified to counter the need for compatible and sustainable organs. By combining the science underlying genetic engineering and nuclear reprogramming with regenerative medicine, scientists have engineered cells to make gene and stem cell therapies applicable and effective. These approaches have enabled the targeting of various pathways to reprogramme cells, i.e., make them behave in beneficial ways in a patient-specific manner. Technological advancements have clearly supported the concept and realization of regenerative medicine. Genetic engineering is used for tissue engineering and nuclear reprogramming and has led to advances in regenerative medicine. Targeted therapies and replacement of traumatized , damaged, or aged organs can be realized through genetic engineering. Furthermore, the success of these therapies has been validated through thousands of clinical trials. Scientists are currently evaluating induced tissue-specific stem cells (iTSCs), which may lead to tumour-free applications of pluripotency induction. In this review, we present state-of-the-art genetic engineering that has been used in regenerative medicine. We also focus on ways that genetic engineering and nuclear reprogramming have transformed regenerative medicine and have become unique therapeutic niches.

Improved Cryopreservation of Human Induced Pluripotent Stem Cell (iPSC) and iPSC-derived Neurons Using Ice-Recrystallization Inhibitors

Human induced pluripotent stem cells (iPSCs) and iPSC-derived neurons (iPSC-Ns) represent a differentiated modality toward developing novel cell-based therapies for regenerative medicine. However, the successful application of iPSC-Ns in cell-replacement therapies relies on effective cryopreservation. In this study, we investigated the role of ice recrystallization inhibitors (IRIs) as novel cryoprotectants for iPSCs and terminally differentiated iPSC-Ns. We found that one class of IRIs, N-aryl-D-aldonamides (specifically 2FA), increased iPSC post-thaw viability and recovery with no adverse effect on iPSC pluripotency. While 2FA supplementation did not significantly improve iPSC-N cell post-thaw viability, we observed that 2FA cryopreserved iPSC-Ns re-established robust neuronal network activity and synaptic function much earlier compared to CS10 cryopreserved controls. The 2FA cryopreserved iPSC-Ns retained expression of key neuronal specific and terminally differentiated markers and displayed functional electrophysiological and neuropharmacological responses following treatment with neuroactive agonists and antagonists. We demonstrate how optimizing cryopreservation media formulations with IRIs represents a promising strategy to improve functional cryopreservation of iPSCs and post-mitotic iPSC-Ns, the latter of which have been challenging to achieve. Developing IRI enabling technologies to support an effective cryopreservation and an efficiently managed cryo-chain is fundamental to support the delivery of successful iPSC-derived therapies to the clinic.

Dopaminergic neuroprotective effects of inosine in MPTP-induced parkinsonian mice via brain-derived neurotrophic factor upregulation

Parkinson's disease (PD) is the second most common neurodegenerative disease. However, no curative or modifying therapy is known. Inosine is a purine nucleoside that increases brain-derived neurotrophic factor (BDNF) expression in the brain through adenosine receptors. Herein, we investigated the neuroprotective effects of inosine and elucidated the mechanisms underlying its pharmacological action. Inosine rescued SH-SY5Y neuroblastoma cells from MPP⁺ injury in a dose-dependent manner. Inosine protection correlated with BDNF expression and the activation of its downstream signaling cascade, as the TrkB receptor inhibitor, K252a and siRNA against the BDNF gene remarkably reduced the protective effects of inosine. Blocking the A₁ or A_2A adenosine receptors diminished BDNF induction and the rescuing effect of inosine, indicating a critical role of adenosine A₁ and A_2A receptors in inosine-related BDNF elevation. We assessed whether the compound could protect dopaminergic neurons from MPTP-induced neuronal injury. Beam-walking and challenge beam tests revealed that inosine pretreatment for 3 weeks reduced the MPTP-induced motor function impairment. Inosine ameliorated dopaminergic neuronal loss and MPTP-mediated astrocytic and microglial activation in the substantia nigra and striatum. Inosine ameliorated the depletion of striatal dopamine and its metabolite following MPTP injection. BDNF upregulation and the activation of its downstream signaling pathway seemingly correlate with the neuroprotective effects of inosine. To our knowledge, this is the first study to demonstrate the neuroprotective effects of inosine against MPTP neurotoxicity via BDNF upregulation. These findings highlight the therapeutic potential of inosine in dopaminergic neurodegeneration in PD brains.

An Alzheimer's disease risk variant in TTC3 modifies the actin cytoskeleton organization and the PI3K-Akt signaling pathway in iPSC-derived forebrain neurons

A missense variant in the tetratricopeptide repeat domain 3 ( TTC3 ) gene (rs377155188, p.S1038C, NM_003316.4:c.3113C>G) was found to segregate with disease in a multigenerational family with late onset Alzheimer's disease. This variant was introduced into induced pluripotent stem cells (iPSCs) derived from a cognitively intact individual using CRISPR genome editing and the resulting isogenic pair of iPSC lines were differentiated into cortical neurons. Transcriptome analysis showed an enrichment for genes involved in axon guidance, regulation of actin cytoskeleton, and GABAergic synapse. Functional analysis showed that the TTC3 p.S1038C iPSC-derived neuronal progenitor cells had altered 3D morphology and increased migration, while the corresponding neurons had longer neurites, increased branch points, and altered expression levels of synaptic proteins. Pharmacological treatment with small molecules that target the actin cytoskeleton could revert many of these cellular phenotypes, suggesting a central role for actin in mediating the cellular phenotypes associated with the TTC3 p.S1038C variant.

Highlights

The AD risk variant TTC3 p.S1038C reduces the expression levels of TTC3 The variant modifies the expression of AD specific genes BACE1 , INPP5F , and UNC5C Neurons with the variant are enriched for genes in the PI3K-Akt pathwayiPSC-derived neurons with the alteration have increased neurite length and branchingThe variant interferes with actin cytoskeleton and is ameliorated by Cytochalasin D.

Stem cells in the treatment of Alzheimer's disease - Promises and pitfalls

Alzheimer's disease (AD) is the most widespread form of neurodegenerative disorder that causes memory loss and multiple cognitive issues. The underlying mechanisms of AD include the build-up of amyloid-β and phosphorylated tau, synaptic damage, elevated levels of microglia and astrocytes, abnormal microRNAs, mitochondrial dysfunction, hormonal imbalance, and age-related neuronal loss. However, the etiology of AD is complex and involves a multitude of environmental and genetic factors. Currently, available AD medications only alleviate symptoms and do not provide a permanent cure. Therefore, there is a need for therapies that can prevent or reverse cognitive decline, brain tissue loss, and neural instability. Stem cell therapy is a promising treatment for AD because stem cells possess the unique ability to differentiate into any type of cell and maintain their self-renewal. This article provides an overview of the pathophysiology of AD and existing pharmacological treatments. This review article focuses on the role of various types of stem cells in neuroregeneration, the potential challenges, and the future of stem cell-based therapies for AD, including nano delivery and gaps in stem cell technology.

Proteomic analysis of Fasciola gigantica excretory and secretory products (FgESPs) co-immunoprecipitated using a time course of infected buffalo sera

Introduction

Widespread Fasciola gigantica infection in buffaloes has caused great economic losses in buffalo farming. Studies on F. gigantica excretory and secretory products (FgESP) have highlighted their importance in F. gigantica parasitism and their potential in vaccine development. Identifying FgESP components involved in F. gigantica-buffalo interactions during different periods is important for developing effective strategies against fasciolosis.

Methods

Buffaloes were assigned to non-infection (n = 3, as control group) and infection (n = 3) groups. The infection group was orally administrated 250 metacercariae. Sera were collected at 3, 10, and 16 weeks post-infection (wpi) for the non-infection group and at 0 (pre-infection), 1, 3, 6, 8, 10, 13, and 16 wpi for the infection group. FgESP components interacting with sera from the non-infection and infection groups assay were pulled down by co-IP and identified using LC-MS/MS. Interacting FgESP components in infection group were subjected to Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway and gene ontology (GO) functional annotation to infer their potential functions.

Results and discussion

Proteins of FgESP components identified in the non-infection group at 3, 10, and 16 wpi accounted for 80.5%, 84.3%, and 82.1% of all proteins identified in these three time points, respectively, indicating surroundings did not affect buffalo immune response during maintenance. Four hundred and ninety proteins were identified in the infection group, of which 87 were consistently identified at 7 time points. Following GO analysis showed that most of these 87 proteins were in biological processes, while KEGG analysis showed they mainly functioned in metabolism and cellular processing, some of which were thought to functions throughout the infection process. The numbers of specific interactors identified for each week were 1 (n = 12), 3 (n = 5), 6 (n = 8), 8 (n = 15), 10 (n = 23), 13 (n = 22), and 16 (n = 14) wpi, some of which were thought to functions in specific infection process. This study screened the antigenic targets in FgESP during a dense time course over a long period. These findings may enhance the understanding of molecular F. gigantica-buffalo interactions and help identify new potential vaccine and drug target candidates.

Mechanisms Underlying Cognitive Impairment Induced by Prenatal Alcohol Exposure

Alcohol is one of the most commonly used illicit substances among pregnant women. Clinical and experimental studies have revealed that prenatal alcohol exposure affects fetal brain development and ultimately results in the persistent impairment of the offspring's cognitive functions. Despite this, the rate of alcohol use among pregnant women has been progressively increasing. Various aspects of human and animal behavior, including learning and memory, are dependent on complex interactions between multiple mechanisms, such as receptor function, mitochondrial function, and protein kinase activation, which are especially vulnerable to alterations during the developmental period. Thus, the exploration of the mechanisms that are altered in response to prenatal alcohol exposure is necessary to develop an understanding of how homeostatic imbalance and various long-term neurobehavioral impairments manifest following alcohol abuse during pregnancy. There is evidence that prenatal alcohol exposure results in vast alterations in mechanisms such as long-term potentiation, mitochondrial function, and protein kinase activation in the brain of offspring. However, to the best of our knowledge, there are very few recent reviews that focus on the cognitive effects of prenatal alcohol exposure and the associated mechanisms. Therefore, in this review, we aim to provide a comprehensive summary of the recently reported alterations to various mechanisms following alcohol exposure during pregnancy, and to draw potential associations with behavioral changes in affected offspring.

Laminin-511 activates the human induced pluripotent stem cell survival via α6β1 integrin-Fyn-RhoA-ROCK signaling

In human induced pluripotent stem cells (hiPSCs), laminin-511/α6β1 integrin interacts with E-cadherin, an intercellular adhesion molecule, to induce the activation of the PI3K-dependent signaling pathway. The interaction between laminin-511/α6β1 integrin and E-cadherin, an intercellular adhesion molecule, results in protection against apoptosis via the proto-oncogene tyrosine-protein kinase Fyn(Fyn)-RhoA-ROCK signaling pathway and the Ras homolog gene family member A (RhoA)/Rho kinase (ROCK) signaling pathway (the major pathway for cell death). In this paper, the impact of laminin-511 on hiPSC on α6β1 integrin-Fyn-RhoA-ROCK signaling is discussed and explored along with validation experiments. PIK3CA mRNA (mean [standard deviation {SD}]: iMatrix-511, 1.00 [0. 61]; collagen+MFGE8, 0.023 [0.02]; **P<0.01; n=6) and PIK3R1 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 79]; collagen+MFGE8, 0.040 [0.06]; *P<0.05; n=6) were upregulated by iMatrix-511 resulting from an increased expression of Integrin α6 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 42]; collagen+MFGE8, 0.23 [0.05]; **P<0.01; n=6). iMatrix-511 increased the expression of p120-Catenin mRNA (mean [SD]: iMatrix-511, 1.00 [0. 71]; collagen+MFGE8, 0.025 [0.03]; **P<0.01; n=6) and RAC1 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 28]; collagen+MFGE8, 0.39 [0.15]; **P<0.01; n=6) by increasing the expression of E-cadherin mRNA (mean [SD]: iMatrix-511, 1.00 [0. 38]; collagen+MFGE8, 0.16 [0.11]; **P<0.01; n=6). As a result, iMatrix-511 increased the expression of P190 RhoGAP (GTPase-activating proteins) mRNA, such as ARHGAP1 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 57]; collagen+MFGE8, 0.032 [0.03]; **P<0.01; n=6), ARHGAP4 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 56]; collagen+MFGE8, 0.039 [0.049]; **P<0.01; n=6), and ARHGAP5 mRNA (mean [SD]: iMatrix-511, 1.00 [0. 39]; collagen+MFGE8, 0.063 [0.043]; **P<0.01; n=6). Western blotting showed that phospho-Rac1 remained in the cytoplasm and phospho-Fyn showed nuclear transition in iPSCs cultured on iMatrix-511. Proteome analysis showed that PI3K signaling was enhanced and cytoskeletal actin was activated in iPSCs cultured on iMatrix-511. In conclusion, laminin-511 strongly activated the cell survival by promoting α6β1 integrin-Fyn-RhoA-ROCK signaling in hiPSCs.

The Role of Endoplasmic Reticulum and Mitochondria in Maintaining Redox Status and Glycolytic Metabolism in Pluripotent Stem Cells

Pluripotent stem cells (PSCs), including embryonic stem cells and induced pluripotent stem cells (iPSCs), can be applicable for regenerative medicine. They strangely rely on glycolysis metabolism akin to aerobic glycolysis in cancer cells. Upon differentiation, PSCs undergo a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS). The metabolic shift depends on organelles maturation, transcriptome modification, and metabolic switching. Besides, metabolism-driven chromatin regulation is necessary for cell survival, self-renewal, proliferation, senescence, and differentiation. In this respect, mitochondria may serve as key organelle to adapt environmental changes with metabolic intermediates which are necessary for maintaining PSCs identity. The endoplasmic reticulum (ER) is another organelle whose role in cellular identity remains under-explored. The purpose of our article is to highlight the recent progress on these two organelles' role in maintaining PSCs redox status focusing on metabolism. Topics include redox status, metabolism regulation, mitochondrial dynamics, and ER stress in PSCs. They relate to the maintenance of stem cell properties and subsequent differentiation of stem cells into specific cell types.

PI3K/Akt Signaling Pathway Ameliorates Oxidative Stress-Induced Apoptosis upon Manganese Exposure in PC12 Cells

Manganese (Mn)-induced neurotoxicity has aroused public concerns for many years, but its precise mechanism is still poorly understood. Herein, we report the impacts of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway in mediating neurological effects induced by manganese sulfate (MnSO₄) exposure in PC12 cells. In this study, cells were treated with MnSO₄ for 24 h in the absence or presence of LY294002 (a special inhibitor of PI3K). We investigated cell viability and apoptosis signals, as well as levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA). The mRNA levels of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and Caspase-3 were also quantified through real-time quantitative PCR (RT-qPCR); protein levels of serine/threonine protein kinase (Akt) and forkhead box O3A (Foxo3a) were determined by western blot. Increasing of MnSO₄ doses led to decreased SOD, GSH-Px, and CAT activities, while the level of MDA was upregulated. Moreover, cell apoptosis was significantly increased, as the mRNA of Bcl-2 and Caspase-3 was significantly decreased, while Bax mRNA was increased. Phosphorylated Akt (p-Akt) and Foxo3a (p-Foxo3a) were upregulated in a dose-dependent manner. In addition, LY294002 pretreatment reduced the activity of SOD, GSH-Px, and CAT but elevated MDA levels. Meanwhile, LY294002 pretreatment also increased cell apoptosis given the upregulated Bax and Caspase-3 mRNAs and decreased Bcl-2 mRNA. In summary, the PI3K/Akt signaling pathway can be activated by MnSO₄ exposure and mediate MnSO₄-induced neurotoxicity.

AKT signaling is associated with epigenetic reprogramming via the upregulation of TET and its cofactor, alpha-ketoglutarate during iPSC generation

Background

Phosphoinositide-3 kinase (PI3K)/AKT signaling participates in cellular proliferation, survival and tumorigenesis. The activation of AKT signaling promotes the cellular reprogramming including generation of induced pluripotent stem cells (iPSCs) and dedifferentiation of primordial germ cells (PGCs). Previous studies suggested that AKT promotes reprogramming by activating proliferation and glycolysis. Here we report a line of evidence that supports the notion that AKT signaling is involved in TET-mediated DNA demethylation during iPSC induction.

Methods

AKT signaling was activated in mouse embryonic fibroblasts (MEFs) that were transduced with OCT4, SOX2 and KLF4. Multiomics analyses were conducted in this system to examine the effects of AKT activation on cells undergoing reprogramming.

Results

We revealed that cells undergoing reprogramming with artificially activated AKT exhibit enhanced anabolic glucose metabolism and accordingly increased level of cytosolic α-ketoglutarate (αKG), which is an essential cofactor for the enzymatic activity of the 5-methylcytosine (5mC) dioxygenase TET. Additionally, the level of TET is upregulated. Consistent with the upregulation of αKG production and TET, we observed a genome-wide increase in 5-hydroxymethylcytosine (5hmC), which is an intermediate in DNA demethylation. Moreover, the DNA methylation level of ES-cell super-enhancers of pluripotency-related genes is significantly decreased, leading to the upregulation of associated genes. Finally, the transduction of TET and the administration of cell-permeable αKG to somatic cells synergistically enhance cell reprogramming by Yamanaka factors.

Conclusion

These results suggest the possibility that the activation of AKT during somatic cell reprogramming promotes epigenetic reprogramming through the hyperactivation of TET at the transcriptional and catalytic levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02578-1.

COVID19-associated cardiomyocyte dysfunction, arrhythmias and the effect of Canakinumab

Background

Cardiac injury associated with cytokine release frequently occurs in SARS-CoV-2 mediated coronavirus disease (COVID19) and mortality is particularly high in these patients. The mechanistic role of the COVID19 associated cytokine-storm for the concomitant cardiac dysfunction and associated arrhythmias is unclear. Moreover, the role of anti-inflammatory therapy to mitigate cardiac dysfunction remains elusive.

Aims and methods

We investigated the effects of COVID19-associated inflammatory response on cardiac cellular function as well as its cardiac arrhythmogenic potential in rat and induced pluripotent stem cell derived cardiomyocytes (iPS-CM). In addition, we evaluated the therapeutic potential of the IL-1β antagonist Canakinumab using state of the art in-vitro confocal and ratiometric high-throughput microscopy.

Results

Isolated rat ventricular cardiomyocytes were exposed to control or COVID19 serum from intensive care unit (ICU) patients with severe ARDS and impaired cardiac function (LVEF 41±5%; 1/3 of patients on veno-venous extracorporeal membrane oxygenation; CK 154±43 U/l). Rat cardiomyocytes showed an early increase of myofilament sensitivity, a decrease of Ca²⁺ transient amplitudes and altered baseline [Ca²⁺] upon exposure to patient serum. In addition, we used iPS-CM to explore the long-term effect of patient serum on cardiac electrical and mechanical function. In iPS-CM, spontaneous Ca²⁺ release events were more likely to occur upon incubation with COVID19 serum and nuclear as well as cytosolic Ca²⁺ release were altered. Co-incubation with Canakinumab had no effect on pro-arrhythmogenic Ca²⁺ release or Ca²⁺ signaling during excitation-contraction coupling, nor significantly influenced cellular automaticity.

Conclusion

Serum derived from COVID19 patients exerts acute cardio-depressant and chronic pro-arrhythmogenic effects in rat and iPS-derived cardiomyocytes. Canakinumab had no beneficial effect on cellular Ca²⁺ signaling during excitation-contraction coupling. The presented method utilizing iPS-CM and in-vitro Ca²⁺ imaging might serve as a novel tool for precision medicine. It allows to investigate cytokine related cardiac dysfunction and pharmacological approaches useful therein.

Enterococcus faecium L-15 Extract Enhances the Self-Renewal and Proliferation of Mouse Skin-Derived Precursor Cells

Lactic acid bacteria (LAB) in the gastrointestinal tract have beneficial health effects. LAB activate the proliferation of intestinal stem cells and speed the recovery of damaged intestinal cells, but little is known about effect of LAB on other adult stem cells. In this study, a cell-free extract of Enterococcus faecium L-15 (L15) was exposed to mouse skin-derived precursor cells (SKPs), and the changes in characteristics associated with proliferation and self-renewal capacity were investigated. L15 increased the size of the spheres and the proliferation rate of SKPs. Cell cycle analysis revealed that cells in the S-phase increased after treatment with L15. In the L15-treated group, the total number of spheres significantly increased. The expression level of pluripotency marker genes also increased, while the mesenchymal lineage-related differentiation marker genes significantly decreased in the L15-treated group. The PI3K/Akt signaling pathway was activated by L15 in SKPs. These results indicate that L15 enhances proliferation and self-renewal of SKPs and may be used as a supplement for stem cell maintenance or application of stem cell therapy. This is the first report to investigate the functional effects of E. faecium on the proliferation and self-renewal capacity of SKPs.

The Emerging Role of HDACs: Pathology and Therapeutic Targets in Diabetes Mellitus

Diabetes mellitus (DM) is one of the principal manifestations of metabolic syndrome and its prevalence with modern lifestyle is increasing incessantly. Chronic hyperglycemia can induce several vascular complications that were referred to be the major cause of morbidity and mortality in DM. Although several therapeutic targets have been identified and accessed clinically, the imminent risk of DM and its prevalence are still ascending. Substantial pieces of evidence revealed that histone deacetylase (HDAC) isoforms can regulate various molecular activities in DM via epigenetic and post-translational regulation of several transcription factors. To date, 18 HDAC isoforms have been identified in mammals that were categorized into four different classes. Classes I, II, and IV are regarded as classical HDACs, which operate through a Zn-based mechanism. In contrast, class III HDACs or Sirtuins depend on nicotinamide adenine dinucleotide (NAD+) for their molecular activity. Functionally, most of the HDAC isoforms can regulate β cell fate, insulin release, insulin expression and signaling, and glucose metabolism. Moreover, the roles of HDAC members have been implicated in the regulation of oxidative stress, inflammation, apoptosis, fibrosis, and other pathological events, which substantially contribute to diabetes-related vascular dysfunctions. Therefore, HDACs could serve as the potential therapeutic target in DM towards developing novel intervention strategies. This review sheds light on the emerging role of HDACs/isoforms in diabetic pathophysiology and emphasized the scope of their targeting in DM for constituting novel interventional strategies for metabolic disorders/complications.

Aromadendrin Protects Neuronal Cells from Methamphetamine-Induced Neurotoxicity by Regulating Endoplasmic Reticulum Stress and PI3K/Akt/mTOR Signaling Pathway

Methamphetamine (METH) is a highly addictive drug that induces irreversible damage to neuronal cells and pathological malfunction in the brain. Aromadendrin, isolated from the flowers of Chionanthus retusus, has been shown to have anti-inflammatory or anti-tumor activity. Nevertheless, it has been reported that METH exacerbates neurotoxicity by inducing endoplasmic reticulum (ER) stress via the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway in neuronal cells. There is little evidence that aromadendrin protects cells from neurotoxicity induced by METH. In this study, we found that aromadendrin partially suppressed the METH-induced cell death in SH-SY5y cells without causing cytotoxicity. Aromadendrin regulated METH-induced ER stress by preserving the phosphorylation of the PI3K/Akt/mTOR signaling pathway in METH-exposed SH-SY5y cells. In addition, aromadendrin mitigated METH-induced autophagic and the apoptotic pathways in METH-exposed SH-SY5y cells. Mechanistic studies revealed that pre-treatment with aromadendrin restored the expression of anti-apoptotic proteins in METH-exposed conditions. The inhibitor assay confirmed that aromadendrin-mediated restoration of mTOR phosphorylation protected cells from autophagy and apoptosis in METH-exposed cells. Therefore, these findings suggest that aromadendrin relatively has a protective effect on SH-SY5y cells against autophagy and apoptosis induced by METH via regulation of ER stress and the PI3K/Akt/mTOR signaling pathway.

Mitochondrial dysfunction in neurodegenerative diseases: A focus on iPSC-derived neuronal models

Progressive neuronal loss is a hallmark of many neurodegenerative diseases, including Alzheimer's and Parkinson's disease. These pathologies exhibit clear signs of inflammation, mitochondrial dysfunction, calcium deregulation, and accumulation of aggregated or misfolded proteins. Over the last decades, a tremendous research effort has contributed to define some of the pathological mechanisms underlying neurodegenerative processes in these complex brain neurodegenerative disorders. To better understand molecular mechanisms responsible for neurodegenerative processes and find potential interventions and pharmacological treatments, it is important to have robust in vitro and pre-clinical animal models that can recapitulate both the early biological events undermining the maintenance of the nervous system and early pathological events. In this regard, it would be informative to determine how different inherited pathogenic mutations can compromise mitochondrial function, calcium signaling, and neuronal survival. Since post-mortem analyses cannot provide relevant information about the disease progression, it is crucial to develop model systems that enable the investigation of early molecular changes, which may be relevant as targets for novel therapeutic options. Thus, the use of human induced pluripotent stem cells (iPSCs) represents an exceptional complementary tool for the investigation of degenerative processes. In this review, we will focus on two neurodegenerative diseases, Alzheimer's and Parkinson's disease. We will provide examples of iPSC-derived neuronal models and how they have been used to study calcium and mitochondrial alterations during neurodegeneration.

Both Hypoxia-Inducible Factor 1 and MAPK Signaling Pathway Attenuate PI3K/AKT via Suppression of Reactive Oxygen Species in Human Pluripotent Stem Cells

Mild hypoxia (5% O₂) as well as FGFR1-induced activation of phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B (PI3K/AKT) and MAPK signaling pathways markedly support pluripotency in human pluripotent stem cells (hPSCs). This study demonstrates that the pluripotency-promoting PI3K/AKT signaling pathway is surprisingly attenuated in mild hypoxia compared to the 21% O₂ environment. Hypoxia is known to be associated with lower levels of reactive oxygen species (ROS), which are recognized as intracellular second messengers capable of upregulating the PI3K/AKT signaling pathway. Our data denote that ROS downregulation results in pluripotency upregulation and PI3K/AKT attenuation in a hypoxia-inducible factor 1 (HIF-1)-dependent manner in hPSCs. Using specific MAPK inhibitors, we show that the MAPK pathway also downregulates ROS and therefore attenuates the PI3K/AKT signaling—this represents a novel interaction between these signaling pathways. This inhibition of ROS initiated by MEK1/2–ERK1/2 may serve as a negative feedback loop from the MAPK pathway toward FGFR1 and PI3K/AKT activation. We further describe the molecular mechanism resulting in PI3K/AKT upregulation in hPSCs—ROS inhibit the PI3K's primary antagonist PTEN and upregulate FGFR1 phosphorylation. These novel regulatory circuits utilizing ROS as second messengers may contribute to the development of enhanced cultivation and differentiation protocols for hPSCs. Since the PI3K/AKT pathway often undergoes an oncogenic transformation, our data could also provide new insights into the regulation of cancer stem cell signaling.

Complementary transcriptomic and proteomic analyses reveal the cellular and molecular processes that drive growth and development of Fasciola hepatica in the host liver

Background

The major pathogenesis associated with Fasciola hepatica infection results from the extensive tissue damage caused by the tunnelling and feeding activity of immature flukes during their migration, growth and development in the liver. This is compounded by the pathology caused by host innate and adaptive immune responses that struggle to simultaneously counter infection and repair tissue damage.

Results

Complementary transcriptomic and proteomic approaches defined the F. hepatica factors associated with their migration in the liver, and the resulting immune-pathogenesis. Immature liver-stage flukes express ~ 8000 transcripts that are enriched for transcription and translation processes reflective of intensive protein production and signal transduction pathways. Key pathways that regulate neoblast/pluripotent cells, including the PI3K-Akt signalling pathway, are particularly dominant and emphasise the importance of neoblast-like cells for the parasite’s rapid development. The liver-stage parasites display different secretome profiles, reflecting their distinct niche within the host, and supports the view that cathepsin peptidases, cathepsin peptidase inhibitors, saposins and leucine aminopeptidases play a central role in the parasite’s destructive migration, and digestion of host tissue and blood. Immature flukes are also primed for countering immune attack by secreting immunomodulating fatty acid binding proteins (FABP) and helminth defence molecules (FhHDM). Combined with published host microarray data, our results suggest that considerable immune cell infiltration and subsequent fibrosis of the liver tissue exacerbates oxidative stress within parenchyma that compels the expression of a range of antioxidant molecules within both host and parasite.

Conclusions

The migration of immature F. hepatica parasites within the liver is associated with an increase in protein production, expression of signalling pathways and neoblast proliferation that drive their rapid growth and development. The secretion of a defined set of molecules, particularly cathepsin L peptidases, peptidase-inhibitors, saponins, immune-regulators and antioxidants allow the parasite to negotiate the liver micro-environment, immune attack and increasing levels of oxidative stress. This data contributes to the growing F. hepatica -omics information that can be exploited to understand parasite development more fully and for the design of novel control strategies to prevent host liver tissue destruction and pathology.

Insulin Promotes Mitochondrial Respiration and Survival through PI3K/AKT/GSK3 Pathway in Human Embryonic Stem Cells

Insulin is an essential growth factor for the survival and self-renewal of human embryonic stem cells (hESCs). Although it is best known as the principal hormone promoting glycolysis in somatic cells, insulin's roles in hESC energy metabolism remain unclear. In this report, we demonstrate that insulin is essential to sustain hESC mitochondrial respiration that is rapidly decreased upon insulin removal. Insulin-dependent mitochondrial respiration is stem cell specific, and mainly relies on pyruvate and glutamine, while glucose suppresses excessive oxidative phosphorylation. Pharmacologic and genetic manipulations reveal that continuous insulin signal sustains mitochondrial respiration through PI3K/AKT activation and downstream GSK3 inhibition. We further show that insulin acts through GSK3 inhibition to suppress caspase activation and rescue cell survival. This study uncovers a critical role of the AKT/GSK3 pathway in the regulation of mitochondrial respiration and cell survival, highlighting insulin as an essential factor for accurate assessment of mitochondrial respiration in hESCs.

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Insulin is continuously required to sustain mitochondrial respiration in hESCs

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Insulin-dependent mitochondrial respiration is substrate specific

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GSK3 is a major regulator of insulin-dependent respiration and cell survival

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Insulin is essential for accurate assessment of mitochondrial respiration in hESCs

Functional in vivo and in vitro effects of 20q11.21 genetic aberrations on hPSC differentiation

Human pluripotent stem cells (hPSCs) have promising therapeutic applications due to their infinite capacity for self-renewal and pluripotency. Genomic stability is imperative for the clinical use of hPSCs; however, copy number variation (CNV), especially recurrent CNV at 20q11.21, may contribute genomic instability of hPSCs. Furthermore, the effects of CNVs in hPSCs at the whole-transcriptome scale are poorly understood. This study aimed to examine the functional in vivo and in vitro effects of frequently detected CNVs at 20q11.21 during early-stage differentiation of hPSCs. Comprehensive transcriptome profiling of abnormal hPSCs revealed that the differential gene expression patterns had a negative effect on differentiation potential. Transcriptional heterogeneity identified by single-cell RNA sequencing (scRNA-seq) of embryoid bodies from two different isogenic lines of hPSCs revealed alterations in differentiated cell distributions compared with that of normal cells. RNA-seq analysis of 22 teratomas identified several differentially expressed lineage-specific markers in hPSCs with CNVs, consistent with the histological results of the altered ecto/meso/endodermal ratio due to CNVs. Our results suggest that CNV amplification contributes to cell proliferation, apoptosis, and cell fate specification. This work shows the functional consequences of recurrent genetic abnormalities and thereby provides evidence to support the development of cell-based applications.

DEPDC5 haploinsufficiency drives increased mTORC1 signaling and abnormal morphology in human iPSC-derived cortical neurons

Mutations in the DEPDC5 gene can cause epilepsy, including forms with and without brain malformations. The goal of this study was to investigate the contribution of DEPDC5 gene dosage to the underlying neuropathology of DEPDC5-related epilepsies. We generated induced pluripotent stem cells (iPSCs) from epilepsy patients harboring heterozygous loss of function mutations in DEPDC5. Patient iPSCs displayed increases in both phosphorylation of ribosomal protein S6 and proliferation rate, consistent with elevated mTORC1 activation. In line with these findings, we observed increased soma size in patient iPSC-derived cortical neurons that was rescued with rapamycin treatment. These data indicate that human cells heterozygous for DEPDC5 loss-of-function mutations are haploinsufficient for control of mTORC1 signaling. Our findings suggest that human pathology differs from mouse models of DEPDC5-related epilepsies, which do not show consistent phenotypic differences in heterozygous neurons, and support the need for human-based models to affirm and augment the findings from animal models of DEPDC5-related epilepsy.

PI3Kinase-p110δ Overexpression Impairs Dendritic Morphogenesis and Increases Dendritic Spine Density

Activity and expression of the phosphoinositide 3-kinase (PI3K) catalytic isoform, PIK3CD/p110δ, is increased in schizophrenia, autism, and intellectual delay and pro-cognitive preclinical efficacy of p110δ-inhibition has been demonstrated in pharmacological, genetic, and developmental rodent models of psychiatric disorders. Although PI3K signaling has been implicated in the development and function of neurons and glia; isoform-specific roles of the individual PI3Ks are less clear and the biological effects of increased p110δ on neuronal development are unknown. Since the pathobiological direction of p110δ changes in neurodevelopmental disorders are increased expression and activity, we hypothesized that overexpression of p110δ would impact measures of neuronal development and maturation relevant to connectivity and synaptic transmission. p110δ overexpression in primary rat hippocampal cultures significantly reduced dendritic morphogenesis and arborization and increased immature and mature dendritic spine densities, without impacting cell viability, soma size, or axon length. Together, our novel findings demonstrate the importance of homeostatic regulation of the p110δ isoform for normative neuronal development and highlight a potential pathophysiological mechanism of association to disorders of neurodevelopment.

SOX2 protein biochemistry in stemness, reprogramming, and cancer: the PI3K/AKT/SOX2 axis and beyond

Research of the past view years expanded our understanding of the various physiological functions the cell-fate determining transcription factor SOX2 exerts in ontogenesis, reprogramming, and cancer. However, while scientific reports featuring novel and exciting aspects of SOX2-driven biology are published in near weekly routine, investigations in the underlying protein-biochemical processes that transiently tailor SOX2 activity to situational demand are underrepresented and have not yet been comprehensively summarized. Largely unrecognizable to modern array or sequencing-based technology, various protein secondary modifications and concomitant function modulations have been reported for SOX2. The chemical modifications imposed onto SOX2 are inherently heterogeneous, comprising singular or clustered events of phosphorylation, methylation, acetylation, ubiquitination, SUMOylation, PARPylation, and O-glycosylation that reciprocally affect each other and critically impact SOX2 functionality, often in a tissue and species-specific manner. One recurring regulatory principle though is the canonical PI3K/AKT signaling axis to which SOX2 relates in various entangled, albeit not exclusive ways. Here we provide a comprehensive review of the current knowledge on SOX2 protein modifications, their proposed relationship to the PI3K/AKT pathway, and regulatory influence on SOX2 with regards to stemness, reprogramming, and cancer.

A GLIS3-CD133-WNT-signaling axis regulates the self-renewal of adult murine pancreatic progenitor-like cells in colonies and organoids

The existence and regenerative potential of resident stem and progenitor cells in the adult pancreas are controversial topics. A question that has been only minimally addressed is the capacity of a progenitor cell to self-renew, a key attribute that defines stem cells. Previously, our laboratory has identified putative stem and progenitor cells from the adult murine pancreas. Using an ex vivo colony/organoid culture system, we demonstrated that these stem/progenitor-like cells have self-renewal and multilineage differentiation potential. We have named these cells pancreatic colony-forming units (PCFUs) because they can give rise to three-dimensional colonies. However, the molecular mechanisms by which PCFUs self-renew have remained largely unknown. Here, we tested the hypothesis that PCFU self-renewal requires GLIS family zinc finger 3 (GLIS3), a zinc-finger transcription factor important in pancreas development. Pancreata from 2- to 4-month-old mice were dissociated, sorted for CD133^highCD71^low ductal cells, known to be enriched for PCFUs, and virally transduced with shRNAs to knock down GLIS3 and other proteins. We then plated these cells into our colony assays and analyzed the resulting colonies for protein and gene expression. Our results revealed a previously unknown GLIS3-to-CD133-to-WNT signaling axis in which GLIS3 and CD133 act as factors necessary for maintaining WNT receptors and signaling molecules in colonies, allowing responses to WNT ligands. Additionally, we found that CD133, but not GLIS3 or WNT, is required for phosphoinositide 3-kinase (PI3K)/AKT Ser/Thr kinase (AKT)-mediated PCFU survival. Collectively, our results uncover a molecular pathway that maintains self-renewal of adult murine PCFUs.

The role of insulin as a key regulator of seeding, proliferation, and mRNA transcription of human pluripotent stem cells

Background

Human-induced pluripotent stem cells (hiPSCs) show a great promise as a renewable source of cells with broad biomedical applications. Since insulin has been used in the maintenance of hiPSCs, in this study we explored the role of insulin in culture of these cells.

Methods

We report conditions for insulin starvation and stimulation of hiPSCs. Crystal violet staining was used to study the adhesion and proliferation of hiPSCs. Apoptosis and cell cycle assays were performed through flow cytometry. Protein arrays were used to confirm phosphorylation targets, and mRNA sequencing was used to evaluate the effect of transcriptome.

Results

Insulin improved the seeding and proliferation of hiPSCs. We also observed an altered cell cycle profile and increase in apoptosis in hiPSCs in the absence of insulin. Furthermore, we confirmed phosphorylation of key components of insulin signaling pathway in the presence of insulin and demonstrated the significant effect of insulin on regulation of the mRNA transcriptome of hiPSCs.

Conclusion

Insulin is a major regulator of seeding, proliferation, phosphorylation and mRNA transcriptome in hiPSCs. Collectively, our work furthers our understanding of human pluripotency and paves the way for future studies that use hiPSCs for modeling genetic ailments affecting insulin signaling pathways.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1319-5) contains supplementary material, which is available to authorized users.

Preconditioned adipose-derived stem cells ameliorate cardiac fibrosis by regulating macrophage polarization in infarcted rat hearts through the PI3K/STAT3 pathway

Stem cells can modify macrophage phenotypes; however, the mechanisms remain unclear. We investigated whether n-butylidenephthalide (BP) primed adipose-derived stem cells (ADSCs) attenuated cardiac fibrosis via regulating macrophage phenotype by a PI3K/STAT3-dependent pathway in postinfarcted rats. Male Wistar rats after coronary ligation were allocated to receive either intramyocardial injection of vehicle, ADSCs (1 × 10⁶ cells), BP-preconditioned ADSCs, (BP + lithium)-preconditioned ADSCs, (BP + LY294002)-preconditioned ADSCs, and (BP + S3I-201)-preconditioned ADSCs. ADSCs were primed for 16 h before implantation. BP-pretreated ADSCs increased the cell viability compared with naive ADSCs in the in vitro experiments. Infarct sizes were similar among the infarcted groups at the acute and chronic stages of infarction. At day 3 after infarction, post-infarction was associated with increased M1 macrophage infiltration, which was inhibited by administering naive ADSCs. Compared with naive ADSCs, BP-preconditioned ADSCs provided a significant increase of Akt and STAT3 phosphorylation, STAT3 activity, STAT3 nuclear translocation, myocardial IL-10 levels, and the percentage of M2 macrophage infiltration. The effects of BP on M2 polarization were reversed by LY294002 or S3I-201. Furthermore, the phosphorylation of both Akt and STAT3 was abolished by LY294002, whereas Akt phosphorylation was not affected following the inhibition of STAT3. The addition of lithium did not have additional effects compared with BP alone. After 4 weeks of implantation, ADSCs remained in the myocardium, and reduced fibrosis and improved cardiac function. BP-preconditioned ADSCs provided superior cardioprotection, greater ADSC engraftment, and antifibrotic effects compared with naive ADSCs. These results suggest that BP-pretreated ADSCs polarize macrophages into M2 cells more efficiently than naive ADSCs via the PI3K/STAT3 pathway.

When the skin is in the center of interest: An aging issue

The skin represents the first bearer of marks of time as well as an easily accessible model for the assessment and determination of the involved molecular mechanisms. The deterioration of important skin functions due to intrinsic and extrinsic aging leads to clinical manifestations, which mirror several internal age-associated diseases, such as neurodegenerative, cardiovascular, skeletal, and endocrine/metabolic skin diseases. Current molecular data indicate that skin aging, especially intrinsic aging, mirrors age-related deficiencies in the entire human body. These data and the development of new biologic technologies highlight the importance of the skin in aging research and should enable future interdisciplinary projects on internal diseases, which could barely have been performed until recently due mainly to the lack of respective tissue.

Influenza a virus-triggered autophagy decreases the pluripotency of human-induced pluripotent stem cells

Maternal influenza infection during pregnancy was reported multiple times as the possible cause of many defects and congenital anomalies. Apart from several cases of influenza-related miscarriage during various trimesters of pregnancy, some epidemiological data suggest a link between maternal influenza infection and genetic abnormalities in offspring. However, there are no reports yet describing how maternal influenza alters cellular pathways at early stages of development to result in congenital defects in the fetus. In the present study, using proteomic approaches, we utilized human-induced pluripotent stem cells (hiPSCs) for modeling intrablastocyst infection with influenza virus to not only investigate the vulnerability and responses of pluripotent stem cells to this virus but also to determine the possible impacts of influenza on pluripotency and signaling pathways controlling differentiation and embryogenesis. Our data indicated viral protein production in influenza A virus (IAV)-infected hiPSCs. However, viral replication was restricted in these cells, but cell viability and pluripotency were negatively affected. These events occurred simultaneously with an excessive level of IAV-induced autophagy as well as cytopathic effects. Quantitative SOMAscan screening also indicated that changes in the proteome of hiPSCs corresponded to abnormal differentiation in these cells. Taken together, our results showed that IAV-modulated reduction in hiPSC pluripotency is associated with significant activation of autophagy. Further investigations are required to explore the role of IAV-induced autophagy in leading pluripotent stem cells toward abnormal differentiation and impaired development in early stages of embryogenesis.

Iws1 and Spt6 Regulate Trimethylation of Histone H3 on Lysine 36 through Akt Signaling and are Essential for Mouse Embryonic Genome Activation

The mRNA processing and export factor, Iws1, interacts with the histone H3/H4 chaperone, Spt6 (Supt6 in mouse gene ontology) and recruits the lysine methyltransferase, Setd2, to chromatin to regulate H3K36me3. This recruitment is known to be crucial for pre-mRNA splicing and Iws1 has been shown to interact with REF1/Aly to mediate mRNA export. However, the role of this complex has not yet been examined in embryonic development. Here, we show that knockdown of either Iws1 or Supt6 blocked embryo development, primarily at the 8/16-cell stage, indicating that Iws1 and Supt6 are crucial for mouse preimplantation development. In the knockdown embryos, we observed decreases in pre-mRNA splicing, mRNA export and the expression of the lineage-specific transcription factor, Nanog. We found that either Iws1 or Supt6 are required for H3K36 trimethylation and that concurrent knockdown of both Iws1 and Supt6 blocks embryonic development at the 2-cell stage. We show that H3K36me3 is modulated by the Pi3k/Akt pathway, as inhibition of this pathway reduced the global level of H3K36me3 while activation of the pathway increased the level of this modification in 2-cell embryos. We observed that Iws1 interacts with nuclear Akt in early embryos, and herein propose that Akt modulates H3K36me3 through interaction with Iws1. Together, our results indicate that the Iws1 and Supt6 play crucial roles in embryonic genome activation, lineage specification, and histone modification during mouse early development.

Important advances in Alzheimer's disease from the use of induced pluripotent stem cells

Among the various types of dementia, Alzheimer’s disease (AD) is the most prevalent and is clinically defined as the appearance of progressive deficits in cognition and memory. Considering that AD is a central nervous system disease, getting tissue from the patient to study the disease before death is challenging. The discovery of the technique called induced pluripotent stem cells (iPSCs) allows to reprogram the patient’s somatic cells to a pluripotent state by the forced expression of a defined set of transcription factors. Many studies have shown promising results and made important conclusions beyond AD using iPSCs approach. Due to the accumulating knowledge related to this topic and the important advances obtained until now, we review, using PubMed, and present an update of all publications related to AD from the use of iPSCs. The first iPSCs generated for AD were carried out in 2011 by Yahata et al. (PLoS One 6:e25788, 2011) and Yaqi et al. (Hum Mol Genet 20:4530–9, 2011). Like other authors, both authors used iPSCs as a pre-clinical tool for screening therapeutic compounds. This approach is also essential to model AD, testing early toxicity and efficacy, and developing a platform for drug development. Considering that the iPSCs technique is relatively recent, we can consider that the AD field received valuable contributions from iPSCs models, contributing to our understanding and the treatment of this devastating disorder.

Microphysiological systems meet hiPSC technology - New tools for disease modeling of liver infections in basic research and drug development

Complex cell culture models such as microphysiological models (MPS) mimicking human liver functionality in vitro are in the spotlight as alternative to conventional cell culture and animal models. Promising techniques like microfluidic cell culture or micropatterning by 3D bioprinting are gaining increasing importance for the development of MPS to address the needs for more predictivity and cost efficiency. In this context, human induced pluripotent stem cells (hiPSCs) offer new perspectives for the development of advanced liver-on-chip systems by recreating an in vivo like microenvironment that supports the reliable differentiation of hiPSCs to hepatocyte-like cells (HLC). In this review we will summarize current protocols of HLC generation and highlight recently established MPS suitable to resemble physiological hepatocyte function in vitro. In addition, we are discussing potential applications of liver MPS for disease modeling related to systemic or direct liver infections and the use of MPS in testing of new drug candidates.

Oxidative stress modulates the expression of apoptosis-associated microRNAs in bovine granulosa cells in vitro

Despite its essential role in ovulation, oxidative stress (OS) has been found to be cytotoxic to cells, while microRNAs (miRNAs) are known as a major regulator of genes involved in cellular defense against cytotoxicity. However, a functional link between OS and miRNA expression changes in granulosa cells (GCs) remains to be investigated. Here, we investigate the OS modulation of apoptosis-associated miRNAs and their biological relevance in bovine GCs. Following the evaluation of cell viability, accumulation of reactive oxygen species (ROS), cytotoxicity and mitochondrial activity, we used a ready-to-use miRNA PCR array to identify differentially regulated miRNAs. The results showed that exposure to 150 μM H₂O₂ for 4 h creates remarkable signs of OS in GCs characterized by more than 50% loss of cell viability, higher nuclear factor erythroid 2-related factor 2 (NRF2) nuclear translocation, significantly (p < 0.05) higher abundance of antioxidant genes, significantly (p < 0.001) higher accumulation of ROS, lower mitochondrial activity and a higher (p < 0.001) number of apoptotic nuclei compared to that of the control group. miRNA expression analysis revealed that a total of 69 miRNAs were differentially regulated in which 47 and 22 miRNAs were up- and downregulated, respectively, in stressed GCs. By applying the 2-fold and p < 0.05 criteria, we found 16 miRNAs were upregulated and 10 miRNAs were downregulated. Target prediction revealed that up- and downregulated miRNAs potentially targeted a total of 6210 and 3575 genes, respectively. Pathway analysis showed that upregulated miRNAs are targeting the genes involved mostly in cell survival, intracellular communication and homeostasis, cellular migration and growth control and disease pathways. Our results showed that OS modulates the expression of apoptosis-associated miRNAs that might have effects on cellular or molecular damages.

bFGF-mediated pluripotency maintenance in human induced pluripotent stem cells is associated with NRAS-MAPK signaling

BACKGROUND

Human pluripotent stem cells (PSCs) open new windows for basic research and regenerative medicine due to their remarkable properties, i.e. their ability to self-renew indefinitely and being pluripotent. There are different, conflicting data related to the role of basic fibroblast growth factor (bFGF) in intracellular signal transduction and the regulation of pluripotency of PSCs. Here, we investigated the effect of bFGF and its downstream pathways in pluripotent vs. differentiated human induced (hi) PSCs.

METHODS

bFGF downstream signaling pathways were investigated in long-term culture of hiPSCs from pluripotent to differentiated state (withdrawing bFGF) using immunoblotting, immunocytochemistry and qPCR. Subcellular distribution of signaling components were investigated by simple fractionation and immunoblotting upon bFGF stimulation. Finally, RAS activity and RAS isoforms were studied using RAS assays both after short- and long-term culture in response to bFGF stimulation.

RESULTS

Our results revealed that hiPSCs were differentiated into the ectoderm lineage upon withdrawing bFGF as an essential pluripotency mediator. Pluripotency markers OCT4, SOX2 and NANOG were downregulated, following a drastic decrease in MAPK pathway activity levels. Notably, a remarkable increase in phosphorylation levels of p38 and JAK/STAT3 was observed in differentiated hiPSCs, while the PI3K/AKT and JNK pathways remained active during differentiation. Our data further indicate that among the RAS paralogs, NRAS predominantly activates the MAPK pathway in hiPSCs.

CONCLUSION

Collectively, the MAPK pathway appears to be the prime signaling pathway downstream of bFGF for maintaining pluripotency in hiPSCs and among the MAPK pathways, the activity of NRAS-RAF-MEK-ERK is decreased during differentiation, whereas p38 is activated and JNK remains constant.

Gambogic acid prevents angiotensin II‑induced abdominal aortic aneurysm through inflammatory and oxidative stress dependent targeting the PI3K/Akt/mTOR and NF‑κB signaling pathways

Gamboge is the dry resin secreted by Garcinia hanbaryi Hook.f, with the function of promoting blood circulation and anti‑cancer effects, detoxification, hemostasis and killing insects. It is also used for the treatment of cancer, brain edema and other diseases. Gambogic acid is the main effective constituent of Gamboge. The present study tested the hypothesis that the effect of Gambogic acid prevents angiotensin II‑induced abdominal aortic aneurysm (AAA), and explored its underlying mechanism. It was demonstrated that gambogic acid significantly inhibited AAA incidence rate, and reduced edge leading aortic diameter and aortic wall thickness in AAA mice. Gambogic acid treatment markedly decreased the levels of proinflammatory cytokines and oxidative stress factors, and transforming growth factor‑β (TGF‑β) and matrix metalloproteinase (MMP)‑2 and MMP‑9 protein expression in AAA mice. Furthermore, Gambogic acid decreased expression of phosphatidylinositol 3‑kinase (PI3K), and phosphorylation of protein kinase B (Akt), mechanistic target of rapamycin (mTOR) and p70‑S6 kinase 1. It also suppressed nuclear factor (NF)‑κB protein expression in AAA mice. The findings of the present study indicated that Gambogic acid prevents angiotensin II‑induced AAA through inflammatory and oxidative stress‑dependent targeting of the PI3K/Akt/mTOR and NF‑κB signaling pathways.

Anti-microRNA-132 causes sevoflurane‑induced neuronal apoptosis via the PI3K/AKT/FOXO3a pathway

In the present study, the mechanisms underlying the protective effects of microRNA‑132 (miRNA‑132) on sevoflurane‑induced neuronal apoptosis were investigated. Reverse transcription‑quantitative polymerase chain reaction and gene microarray hybridization were used to analyze alterations in microRNA levels. Cell viability, apoptosis and caspase‑3/9 activity were measured using MTT, flow cytometry and caspase‑3/9 activity kits. Immunofluorescence staining and western blot analysis were used to measure protein expression of phosphoinositide 3‑kinase (PI3K) and phosphorylated (p‑)AKT, forkhead box O3a (FOXO3a). In sevoflurane‑induced rats, the expression of miRNA‑132 was downregulated, compared with that in negative control rats. The downregulation of miRNA‑132 increased neuronal apoptosis and the upregulation of miRNA‑132 inhibited neuronal apoptosis in the sevoflurane‑induced in vitro model. The downregulation of miRNA‑132 suppressed the protein expression of PI3K and p‑AKT, and suppressed the protein expression of FOXO3a in the sevoflurane‑induced in vitro model. The PI3K inhibitor increased the effects of anti‑miRNA‑132 on neuronal apoptosis through the AKT/FOXO3a pathway in the sevoflurane‑induced in vitro model. The promotion of FOXO3a inhibited the effects of anti‑miRNA‑132 on neuronal apoptosis through the AKT/FOXO3a pathway in the sevoflurane‑induced in vitro model. These data suggested that miRNA‑132 caused sevoflurane‑induced neuronal apoptosis via suppression of the PI3K/AKT/FOXO3a pathway.

Role of cell-secreted extracellular matrix formation in aggregate formation and stability of human induced pluripotent stem cells in suspension culture

Clinical and industrial applications require large quantities of human induced pluripotent stem cells (hiPSCs); however, little is known regarding the mechanisms governing aggregate formation and stability in suspension culture. To address this, we determined differences in growth processes among hiPSC lines in suspension culture. Using an hiPSC aggregate suspension culture system, hiPSCs from different lines formed multicellular aggregates classified as large compact or small loose based on their size and morphology. Time-lapse observation of the growth processes of two different hiPSC lines revealed that the balance between cell division and the extent of subsequent cell death determined the final size and morphology of aggregates. Comparison of the cell survival and death of two hiPSC lines showed that the formation of small, loose aggregates was due to continued cell death during the exponential phase of growth, with apoptotic cells extruded from growing hiPSC aggregates by the concerted contraction of their neighbors. Western blot and immunofluorescent staining revealed that aggregate morphology and proliferative ability relied to a considerable extent upon secretion of the extracellular matrix (ECM). hiPSCs forming large compact and stable aggregates showed enhanced production of collagen type I in suspension culture at 120 h. Furthermore, these aggregates exhibited higher expression of E-cadherin and proliferation marker Ki-67 as compared with levels observed in small and loose aggregates at 120 h. These findings indicated that differences in both aggregate formation and stability in suspension culture among hiPSC lines were caused by differences in ECM secretion capacity.

SIRT2 is required for efficient reprogramming of mouse embryonic fibroblasts toward pluripotency

The role of sirtuins (SIRTs) in cancer biology has been the focus of recent research. The similarities between underlying pathways involved in the induction of pluripotent stem cells and transformation of cancer cells revealed the role of SIRTs in cellular reprogramming. Seven SIRTs have been identified in mammals and downregulation of SIRT2 was found to facilitate the generation of primed pluripotent stem cells, such as human induced pluripotent stem cells. Herein, we evaluated the role of SIRT2 in naive pluripotent stem cell generation using murine cells. We found that absolute depletion of SIRT2 in mouse embryonic fibroblasts resulted in a notable reduction in reprogramming efficiency. SIRT2 depletion not only upregulated elements of the INK4/ARF locus, which in turn had an antiproliferative effect, but also significantly altered the expression of proteins related to the PI3K/Akt and Hippo pathways, which are important signaling pathways for stemness. Thus, this study demonstrated that SIRT2 is required for cellular reprogramming to naive states of pluripotency in contrast to primed pluripotency states.

Double-edged sword of gonadotropin-releasing hormone (GnRH): A novel role of GnRH in the multiple beneficial functions of endometrial stem cells

Gonadotropin-releasing hormone (GnRH) stimulates the synthesis and release of gonadotropins, which induce estrogen production and subsequent ovulation. Therefore, long-term GnRH exposure to regulate ovarian hyperstimulation is recognized as the gold standard for most in vitro fertilization (IVF) strategies. However, one of the most disappointing aspects of current IVF technology is relatively low rate (between 35 and 50%) of positive pregnancy outcomes, and the major reason for this high cancellation rate has not yet been revealed. Previous studies have demonstrated that resident stem cell deficiency limits the cyclic regenerative capacity of the endometrium and subsequently increases pregnancy failure rates. Therefore, we hypothesized that long-term GnRH exposure directly damages endometrial stem cells and consequently negatively affects pregnancy outcomes in GnRH-based IVF. In addition to their well-known roles in regulating the hypothalamus-pituitary-gonadal axis, GnRH and its receptors also localize in the extra-hypothalamic endometrium, suggesting a possible non-canonical role in endometrial stem cells. Consistent with our hypothesis, we show for the first time that GnRH suppresses the multiple beneficial functions of endometrial stem cells via the PI3K/Akt signaling pathway in vitro and in vivo. To the best of our knowledge, this is the first study to focus on the direct effects of GnRH on the regenerative potential of stem cells, and the findings will facilitate the development of more promising IVF strategies.

Stem Cells as Potential Targets of Polyphenols in Multiple Sclerosis and Alzheimer's Disease

Alzheimer's disease (AD) and multiple sclerosis are major neurodegenerative diseases, which are characterized by the accumulation of abnormal pathogenic proteins due to oxidative stress, mitochondrial dysfunction, impaired autophagy, and pathogens, leading to neurodegeneration and behavioral deficits. Herein, we reviewed the utility of plant polyphenols in regulating proliferation and differentiation of stem cells for inducing brain self-repair in AD and multiple sclerosis. Firstly, we discussed the genetic, physiological, and environmental factors involved in the pathophysiology of both the disorders. Next, we reviewed various stem cell therapies available and how they have proved useful in animal models of AD and multiple sclerosis. Lastly, we discussed how polyphenols utilize the potential of stem cells, either complementing their therapeutic effects or stimulating endogenous and exogenous neurogenesis, against these diseases. We suggest that polyphenols could be a potential candidate for stem cell therapy against neurodegenerative disorders.

Reprogramming of mouse fibroblasts into neural lineage cells using biomaterials

Introduction: Induced neural stem cells (iNSCs) have the ability of differentiation into neurons, astrocytes and oligodendrocytes. iNSCs are very useful in terms of research and treatment. The present study offers an idea that biomaterials could be one of the tools that could modulate reprogramming process in the fibroblasts.

Methods: Gelatin biomaterials were fabricated into 3 types, including (i) gelatin, (ii) gelatin with 1 mg/mL hydroxyapatite, and (iii) gelatin with hydroxyapatite and pig brain. NIH/3T3 fibroblasts were cultured on each type of biomaterial for 7, 9 and 14 days. RT-PCR was performed to investigate the gene expression of the fibroblasts on biomaterials compared to the fibroblasts on tissue culture plates. PI3K/Akt signaling was performed by flow cytometry after 24 hours seeding on the biomaterials. The biomaterials were also tested with the human APCs and PDL cells.

Results: The fibroblasts exhibited changes in the expression of the reprogramming factor; Klf‫4 and the neural transcription factors; NFIa, NFIb and Ptbp1 after 9 days culture. The cultivation of fibroblasts on the biomaterials for 7 days showed a higher expression of the transcription factor SOX9. The expression of epigenetic genes; Kat2a and HDAC3 were changed upon the cultivation on the biomaterials for 9 days. The fibroblasts cultured on the biomaterials showed an activation of PI3K/Akt signaling. The human APCs and human PDL cells developed mineralization process on biomaterials

Conclusion: Changes in the expression of Klf4, NFIa, NFIb, Ptbp1 and SOX9 indicated that fibroblasts were differentiated into an astrocytic lineage. It is possible that the well-designed biomaterials could work as powerful tools in the reprogramming process of fibroblasts into iNSCs.

Infection of iPSC Lines with Miscarriage-Associated Coxsackievirus and Measles Virus and Teratogenic Rubella Virus as a Model for Viral Impairment of Early Human Embryogenesis

Human induced pluripotent stem cell (iPSC) lines are a promising model for the early phase of human embryonic development. Here, their contribution to the still incompletely understood pathogenesis of congenital virus infections was evaluated. The infection of iPSC lines with miscarriage-associated coxsackievirus B3 (CVB3) and measles virus (MV) was compared to the efficient teratogen rubella virus (RV). While CVB3 and MV were found to be cytopathogenic on iPSC lines, RV replicated without impairment of iPSC colony morphology and integrity. This so far outstanding course of infection enabled maintenance of RV-infected iPSC cultures over several passages and their subsequent differentiation to ectoderm, endoderm, and mesoderm. A modification of the metabolic profile of infected iPSC lines was the only common aspect for all three viruses. This study points toward two important aspects. First, iPSC lines represent a suitable cell culture model for early embryonic virus infection. Second, metabolic activity represents an important means for evaluation of pathogen-associated alterations in iPSC lines.