Regulation of stem cell pluripotency and differentiation involves a mutual regulatory circuit of the NANOG, OCT4, and SOX2 pluripotency transcription factors with polycomb repressive complexes and stem cell microRNAs

Cell-cell communication in stem cells and cancer: Alone but in touch

BACKGROUND

Cellular communication and signaling pathways are fundamental regulators of stem cell and cancer cell behaviors. This review explores the intricate interplay of these pathways in governing cellular behaviors, focusing on their implications for diseases, particularly cancer.

OBJECTIVES

This comprehensive review aims to elucidate the significance of cellular signaling pathways in regulating the behavior of stem cells and cancer cells. It delves into the alterations in these pathways, their impact on cell fate, and their implications for developing diseases, notably cancer. The objective is to underscore the importance of understanding these signaling pathways for developing targeted therapeutic strategies.

METHODS

The review critically analyzes existing literature and research findings concerning the roles of signaling pathways in stem cell behavior regulation, emphasizing their parallels and disparities in cancer cells. It synthesizes information on both direct and indirect modes of cell communication to delineate the complexity of signaling networks.

RESULTS

Direct and indirect modes of cell communication intricately regulate the complex signaling pathways governing stem cell behaviors, influencing differentiation potential and tissue regeneration. Alterations in these pathways significantly impact stem cell fate, contributing to disease pathogenesis, including cancer. Understanding these signaling cascades offers insights into developing targeted therapies, particularly cancer treatment.

CONCLUSION

Understanding the regulation of signaling pathways in stem cells and the specialized subset of cancer stem cells holds promise for innovative therapeutic approaches. By targeting aberrant signaling pathways, tailored interventions may improve treatment outcomes. This review underscores the critical role of signaling pathways in cellular behaviors, offering a pathway toward developing novel, more effective therapies for diverse diseases and disorders.

ZFP982 confers mouse embryonic stem cell characteristics by regulating expression of Nanog, Zfp42, and Dppa3

BACKGROUND

Understanding the genetic underpinnings of protein networks conferring stemness is of broad interest for basic and translational research.

METHODS

We used multi-omics analyses to identify and characterize stemness genes, and focused on the zinc finger protein 982 (Zfp982) that regulates stemness through the expression of Nanog, Zfp42, and Dppa3 in mouse embryonic stem cells (mESC).

RESULTS

Zfp982 was expressed in stem cells, and bound to chromatin through a GCAGAGKC motif, for example near the stemness genes Nanog, Zfp42, and Dppa3. Nanog and Zfp42 were direct targets of ZFP982 that decreased in expression upon knockdown and increased upon overexpression of Zfp982. We show that ZFP982 expression strongly correlated with stem cell characteristics, both on the transcriptional and morphological levels. Zfp982 expression decreased with progressive differentiation into ecto-, endo- and mesodermal cell lineages, and knockdown of Zfp982 correlated with morphological and transcriptional features of differentiated cells. Zfp982 showed transcriptional overlap with members of the Hippo signaling pathway, one of which was Yap1, the major co-activator of Hippo signaling. Despite the observation that ZFP982 and YAP1 interacted and localized predominantly to the cytoplasm upon differentiation, the localization of YAP1 was not influenced by ZFP982 localization.

CONCLUSIONS

Together, our study identified ZFP982 as a transcriptional regulator of early stemness genes, and since ZFP982 is under the control of the Hippo pathway, underscored the importance of the context-dependent Hippo signals for stem cell characteristics.

Complex regulatory networks influence pluripotent cell state transitions in human iPSCs

Stem cells exist in vitro in a spectrum of interconvertible pluripotent states. Analyzing hundreds of hiPSCs derived from different individuals, we show the proportions of these pluripotent states vary considerably across lines. We discover 13 gene network modules (GNMs) and 13 regulatory network modules (RNMs), which are highly correlated with each other suggesting that the coordinated co-accessibility of regulatory elements in the RNMs likely underlie the coordinated expression of genes in the GNMs. Epigenetic analyses reveal that regulatory networks underlying self-renewal and pluripotency are more complex than previously realized. Genetic analyses identify thousands of regulatory variants that overlapped predicted transcription factor binding sites and are associated with chromatin accessibility in the hiPSCs. We show that the master regulator of pluripotency, the NANOG-OCT4 Complex, and its associated network are significantly enriched for regulatory variants with large effects, suggesting that they play a role in the varying cellular proportions of pluripotency states between hiPSCs. Our work bins tens of thousands of regulatory elements in hiPSCs into discrete regulatory networks, shows that pluripotency and self-renewal processes have a surprising level of regulatory complexity, and suggests that genetic factors may contribute to cell state transitions in human iPSC lines.

Novel Approaches to Studying SLC13A5 Disease

The role of the sodium citrate transporter (NaCT) SLC13A5 is multifaceted and context-dependent. While aberrant dysfunction leads to neonatal epilepsy, its therapeutic inhibition protects against metabolic disease. Notably, insights regarding the cellular and molecular mechanisms underlying these phenomena are limited due to the intricacy and complexity of the latent human physiology, which is poorly captured by existing animal models. This review explores innovative technologies aimed at bridging such a knowledge gap. First, I provide an overview of SLC13A5 variants in the context of human disease and the specific cell types where the expression of the transporter has been observed. Next, I discuss current technologies for generating patient-specific induced pluripotent stem cells (iPSCs) and their inherent advantages and limitations, followed by a summary of the methods for differentiating iPSCs into neurons, hepatocytes, and organoids. Finally, I explore the relevance of these cellular models as platforms for delving into the intricate molecular and cellular mechanisms underlying SLC13A5-related disorders.

Transcriptional Factors Mediated Reprogramming to Pluripotency

A unique kind of pluripotent cell, i.e., Induced pluripotent stem cells (iPSCs), now being targeted for iPSC synthesis, are produced by reprogramming animal and human differentiated cells (with no change in genetic makeup for the sake of high efficacy iPSCs formation). The conversion of specific cells to iPSCs has revolutionized stem cell research by making pluripotent cells more controllable for regenerative therapy. For the past 15 years, somatic cell reprogramming to pluripotency with force expression of specified factors has been a fascinating field of biomedical study. For that technological primary viewpoint reprogramming method, a cocktail of four transcription factors (TF) has required: Kruppel-like factor 4 (KLF4), four-octamer binding protein 34 (OCT3/4), MYC and SOX2 (together referred to as OSKM) and host cells. IPS cells have great potential for future tissue replacement treatments because of their ability to self-renew and specialize in all adult cell types, although factor-mediated reprogramming mechanisms are still poorly understood medically. This technique has dramatically improved performance and efficiency, making it more useful in drug discovery, disease remodeling, and regenerative medicine. Moreover, in these four TF cocktails, more than 30 reprogramming combinations were proposed, but for reprogramming effectiveness, only a few numbers have been demonstrated for the somatic cells of humans and mice. Stoichiometry, a combination of reprogramming agents and chromatin remodeling compounds, impacts kinetics, quality, and efficiency in stem cell research.

Derepressing of STAT3 and USP7 contributes to resistance of DLBCL to EZH2 inhibition

Diffuse large B-cell lymphoma is the most common subtype of lymphoma, representing ∼25 % of non-Hodgkin lymphoid malignancies. EZH2 is highly expressed in Diffuse large B-cell lymphoma and ∼22 % of patients contain EZH2 mutations. EZH2 have been studied as a potential therapeutic target for a decade, but efficient inhibition of EZH2 did not robustly kill lymphoma cells. Here, we found that EZH2 mediates repression of oncogenic genes STAT3 and USP7 in Diffuse large B-cell lymphoma cells. Inhibition of EZH2 leads to upregulation of STAT3 and USP7 at both RNA and protein levels. Along with USP7 upregulation, MDM2 is upregulated and its ubiquitylation substrate, Tumor suppressor P53, is downregulated. Upregulation of STAT3 and downregulation of p53 can strength cell proliferation and prevent cells from apoptosis, which suggests resistance mechanisms by which cells survive EZH2 inhibition-induced cell death. Short-course co-inhibition of USP7 and EZH2 showed increased apoptosis and cell proliferation prevention with the concentration as low as 0.08 μM. In STAT3 and USP7 depleted cells, EZH2 inhibition shows superior efficacy of apoptosis, and in EZH2 depleted cells, USP7 inhibition also shows superior efficacy of apoptosis. Thus, our findings suggest a new precision therapy by combinational inhibition of EZH2 with STAT3 or USP7 for Diffuse large B-cell lymphoma.

Hsa-miR-27b-5p suppresses the osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth via targeting BMPR1A: An ex vivo study

AIM

Recently, miR-27b-5p was shown to be abundantly expressed in extracellular vehicles (EVs) from the inflammatory microenvironment. This study determined the role of miR-27b-5p in regulating osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth (SHEDs) and further examined the regulatory mechanism of bone morphogenetic protein receptor type-1A (BMPR1A).

METHODOLOGY

Characteristics of SHEDs and SHEDs-EVs derived from SHEDs were evaluated respectively. The expression of miR-27b-5p in SHEDs and EVs was detected during osteo-induction. Mechanically, SHEDs were treated with miR-27b-5p mimics or an inhibitor, and the osteogenic/odontogenic differentiation and proliferation were assessed. Bioinformatic analysis and luciferase reporter were utilized for target gene prediction and verification. Finally, BMPR1A-overexpressed plasmids were transfected into SHEDs to investigate the participation of the BMPR1A/SMAD4 pathway. Data were analysed using Student's t-test, one-way analysis of variance and Chi-square test.

RESULTS

MiR-27b-5p was expressed in both SHEDs and EVs and was significantly increased at the initial stage of differentiation and then decreased in a time-dependent manner (p < .01). Upregulation of miR-27b-5p significantly suppressed osteogenic/odontogenic differentiation of SHEDs and inhibited proliferation (p < .05), whereas inhibition of miR-27b-5p enhanced the differentiation (p < .05). Dual-luciferase reporter assay and pull-down assay confirmed the binding site between miR-27b-5p and BMPR1A (p < .05). The overexpression of BMPR1A rescued the effect of miR-27b-5p, while contributed to the decrease of pluripotency (p < .05). Additionally, miR-27b-5p maintained pluripotency in BMPR1A-overexpressed SHEDs (p < .05).

CONCLUSIONS

MiR-27b-5p in SHEDs/EVs was inversely associated with differentiation and suppressed the osteogenic and odontogenic differentiation of SHEDs and maintained the pluripotency of SHEDs partly by shuttering BMPR1A-targeting BMP signalling. Theoretically, inhibition of miR-27b-5p represents a potential strategy to promote osteanagenesis and dentinogenesis. However, miR-27b-5p capsuled EVs might maintain cell pluripotency and self-renewal for non-cell-targeted therapy.

High-Dimensional Mass Cytometry Analysis of Embryonic Antigens and Their Signaling Pathways in Myeloid Cells from Bone Marrow Aspirates in AML Patients at Diagnosis

BACKGROUND

Embryonic antigens (EA) regulate pluripotency, self-renewal, and differentiation in embryonic stem (ES) cells during their development. In adult somatic cells, EA expression is normally inhibited; however, EAs can be re-expressed by cancer cells and are involved in the deregulation of different signaling pathways (SPs). In the context of AML, data concerning the expression of EAs are scarce and contradictory.

METHODS

We used mass cytometry to explore the expression of EAs and three SPs in myeloid cells from AML patients and normal bone marrow (NBM). Imaging flow cytometry was used for morphological assessment of cells in association with their OCT3/4 expression status (positive vs. negative).

RESULTS

An overall reduction in or absence of EA expression was observed in immature myeloid cells from AML patients compared to their normal counterparts. Stage-specific embryonic antigen-3 (SSEA-3) was consistently expressed at low levels in immature myeloid cells, whereas SSEA-1 was overexpressed in hematopoietic stem cells (HSCs) and myeloblasts from AML with monocytic differentiation (AML M4/M5). Therefore, these markers are valuable for distinguishing between normal and abnormal myeloid cells. These preliminary results show that the exploration of myeloid cell intracellular SPs in the setting of AML is very informative. Deregulation of three important leukemogenic SPs was also observed in myeloid cells from AML.

CONCLUSIONS

Exploring EAs and SPs in myeloid cells from AML patients by mass cytometry may help identify characteristic phenotypes and facilitate AML follow-up.

Potential Natural Products Regulation of Molecular Signaling Pathway in Dermal Papilla Stem Cells

Stem cells have demonstrated significant potential for tissue engineering and repair, anti-aging, and rejuvenation. Hair follicle stem cells can be found in the dermal papilla at the base of the follicle and the bulge region, and they have garnered increased attention because of their potential to regenerate hair as well as their application for tissue repair. In recent years, these cells have been shown to affect hair restoration and prevent hair loss. These stem cells are endowed with mesenchymal characteristics and exhibit self-renewal and can differentiate into diverse cell types. As research in this field continues, it is probable that insights regarding stem cell maintenance, as well as their self-renewal and differentiation abilities, will benefit the application of these cells. In addition, an in-depth discussion is required regarding the molecular basis of cellular signaling and the influence of nature-derived compounds in stimulating the stemness properties of dermal papilla stem cells. This review summarizes (i) the potential of the mesenchymal cells component of the hair follicle as a target for drug action; (ii) the molecular mechanism of dermal papilla stem cells for maintenance of their stem cell function; and (iii) the positive effects of the natural product compounds in stimulating stemness in dermal papilla stem cells. Together, these insights may help facilitate the development of novel effective hair loss prevention and treatment.

The applications of 3D printing in wound healing: the external delivery of stem cells and antibiosis

As the global number of chronic wound patients rises, the financial burden and social pressure on patients increase daily. Stem cells have emerged as promising tissue engineering seed cells due to their enriched sources, multidirectional differentiation ability, and high proliferation rate. However, delivering them in vitro for the treatment of skin injury is still challenging. In addition, bacteria from the wound site and the environment can significantly impact wound healing. In the last decade, 3D bioprinting has dramatically enriched cell delivery systems. The produced scaffolds by this technique can be precisely localized within cells and perform antibacterial actions. In this review, we summarized the 3D bioprinting-based external delivery of stem cells and their antibiosis to improve wound healing.

Cell differentiation modifies the p53 transcriptional program through a combination of gene silencing and constitutive transactivation

The p53 transcription factor is a master regulator of cellular responses to stress that is commonly inactivated in diverse cancer types. Despite decades of research, the mechanisms by which p53 impedes tumorigenesis across vastly different cellular contexts requires further investigation. The bulk of research has been completed using in vitro studies of cancer cell lines or in vivo studies in mouse models, but much less is known about p53 action in diverse non-transformed human tissues. Here, we investigated how different cellular states modify the p53 transcriptional program in human cells through a combination of computational analyses of publicly available large-scale datasets and in vitro studies using an isogenic system consisting of induced pluripotent stem cells (iPSCs) and two derived lineages. Analysis of publicly available mRNA expression and genetic dependency data demonstrated wide variation in terms of expression and function of a core p53 transcriptional program across various tissues and lineages. To monitor the impact of cell differentiation on the p53 transcriptome within an isogenic cell culture system, we activated p53 by pharmacological inhibition of its negative regulator MDM2. Using cell phenotyping assays and genome wide transcriptome analyses, we demonstrated that cell differentiation confines and modifies the p53 transcriptional network in a lineage-specific fashion. Although hundreds of p53 target genes are transactivated in iPSCs, only a small fraction is transactivated in each of the differentiated lineages. Mechanistic studies using small molecule inhibitors and genetic knockdowns revealed the presence of two major regulatory mechanisms contributing to this massive heterogeneity across cellular states: gene silencing by epigenetic regulatory complexes and constitutive transactivation by lineage-specific transcription factors. Altogether, these results illuminate the impact of cell differentiation on the p53 program, thus advancing our understanding of how this tumor suppressor functions in different contexts.

Identification and characterization of a flexile G-quadruplex in the distal promoter region of stemness gene REX1

We have identified a parallel G-quadruplex (R1WT) in the distal promoter region (-821 base-pairs upstream of the TSS) of the pluripotent gene REX1. Through biophysical and biochemical approach, we have characterized the G-quadruplex (GQ) as a potential molecular switch that may control REX1 promoter activity to determine the transcriptional fate. Small- molecule interactive study of the monomeric form of R1WT (characterized as R1mut2) with TMPyP4 and BRACO-19 revealed GQ destabilization upon interaction with TMPyP4 and stabilization upon interaction with BRACO-19. This distinctive drug interactivity suggests the in cellulo R1WT to be a promising drug target. The endogenous existence of R1WT was confirmed by BG4 antibody derived chromatin immunoprecipitation experiment. Here in, we also report the endogenous interaction of GQ specific transcription factors (TFs) with R1WT region in the human chromatin of cancer cell. The wild-type G-quadruplex was found to interact with four important transcription factors, (i) specificity protein (Sp1) (ii) non-metastatic cell 2 (NM23-H2): a diphosphatase (iii) cellular nucleic acid binding protein (CNBP) and (iv) heterogenous nuclear ribonucleoprotein K (hnRNPK) in the REX1 promoter. In contrast, nucleolin protein (NCL) binding was found to be low to the said G-quadruplex. The flexibility of R1WT between folded and unfolded states, obtained from experimental and computational analysis strongly suggests R1WT to be an important gene regulatory element in the genome. It controls promoter DNA relaxation with the coordinated interaction of transcription factors, the deregulation of which seeds stemness characteristic in cancer cells for further metastatic progression.

The addition of arginine deiminase potentiates Mithramycin A-induced cell death in patient-derived glioblastoma cells via ATF4 and cytochrome C

BACKGROUND

Arginine auxotrophy constitutes a shortcoming for ~ 30% of glioblastoma multiforme (GBM). Indeed, arginine-depleting therapy using arginine deiminase from Streptococcus pyogenes (SpyADI) has proven activity against GBM in preclinical studies. The good safety profile of SpyADI renders this agent an ideal combination partner for cytostatic therapy.

METHODS

In this study, we combined the antineoplastic antibiotic Mithramycin A (MitA) with SpyADI to boost single-agent activity and analyzed underlying response mechanisms in-depth.

RESULTS

MitA monotherapy induced a time- and dose-dependent cytotoxicity in eight patient-derived GBM cell lines and had a radiosensitizing effect in all but one cell line. Combination treatment boosted the effects of the monotherapy in 2D- and 3D models. The simultaneous approach was superior to the sequential application and significantly impaired colony formation after repetitive treatment. MitA monotherapy significantly inhibited GBM invasiveness. However, this effect was not enhanced in the combination. Functional analysis identified SpyADI-triggered senescence induction accompanied by increased mitochondrial membrane polarization upon mono- and combination therapy. In HROG63, induction of lysosomes was seen after both monotherapies, indicative of autophagy. These cells seemed swollen and had a more pronounced cortically formed cytoskeleton. Also, cytochrome C and endoplasmatic reticulum-stress-associated proteins ATF4 and Calnexin were enhanced in the combination, contributing to apoptosis. Notably, no significant increases in glioma-stemness marker were seen.

CONCLUSIONS

Therapeutic utilization of a metabolic defect in GBM along with cytostatic therapy provides a novel combination approach. Whether this SpyADI/MitA regimen will provide a safe alternative to combat GBM, will have to be addressed in subsequent (pre-)clinical trials.

Structural Plasticity of Pioneer Factor Sox2 and DNA Bendability Modulate Nucleosome Engagement and Sox2-Oct4 Synergism

Pioneer transcription factors (pTFs) can bind directly to silent chromatin and promote vital transcriptional programs. Here, by integrating high-resolution nuclear magnetic resonance (NMR) spectroscopy with biochemistry, we reveal new structural and mechanistic insights into the interaction of pluripotency pTFs and functional partners Sox2 and Oct4 with nucleosomes. We find that the affinity and conformation of Sox2 for solvent-exposed nucleosome sites depend strongly on their position and DNA sequence. Sox2, which is partially disordered but becomes structured upon DNA binding and bending, forms a super-stable nucleosome complex at superhelical location +5 (SHL+5) with similar affinity and conformation to that with naked DNA. However, at suboptimal internal and end-positioned sites where DNA may be harder to deform, Sox2 favors partially unfolded and more dynamic states that are encoded in its intrinsic flexibility. Importantly, Sox2 structure and DNA bending can be stabilized by synergistic Oct4 binding, but only on adjacent motifs near the nucleosome edge and with the full Oct4 DNA-binding domain. Further mutational studies reveal that strategically impaired Sox2 folding is coupled to reduced DNA bending and inhibits nucleosome binding and Sox2-Oct4 cooperation, while increased nucleosomal DNA flexibility enhances Sox2 association. Together, our findings fit a model where the site-specific DNA bending propensity and structural plasticity of Sox2 govern distinct modes of nucleosome engagement and modulate Sox2-Oct4 synergism. The principles outlined here can potentially guide pTF site selection in the genome and facilitate interaction with other chromatin factors or chromatin opening in vivo.

Management of Obesity and Obesity-Related Disorders: From Stem Cells and Epigenetics to Its Treatment

Obesity is a complex worldwide disease, characterized by an abnormal or excessive fat accumulation. The onset of this pathology is generally linked to a complex network of interactions among genetic and environmental factors, aging, lifestyle, and diets. During adipogenesis, several regulatory mechanisms and transcription factors are involved. As fat cells grow, adipose tissue becomes increasingly large and dysfunctional, losing its endocrine function, secreting pro-inflammatory cytokines, and recruiting infiltrating macrophages. This long-term low-grade systemic inflammation results in insulin resistance in peripheral tissues. In this review we describe the main mechanisms involved in adipogenesis, from a physiological condition to obesity. Current therapeutic strategies for the management of obesity and the related metabolic syndrome are also reported.

SOX2 suppresses osteoblast differentiation of MC3T3-E1 cells through activating the transcription of LGR4

Osteogenic differentiation is a crucial process of new bone formation. This study aimed to explore the roles and mechanism of SRY-Box Transcription Factor 2 (SOX2) on proliferation and osteogenic differentiation of MC3T3-E1 cells. Bone morphogenetic protein 2 (BMP2) was used to induce the osteogenic differentiation of MC3T3-E1 cells. The expression of SOX2 was determined by quantitative real-time PCR (RT-PCR) at different time points after induction. The SOX2 overexpression plasmids were constructed and transfected into MC3T3-E1 cells. Osteogenic differentiation was evaluated by Alizarin Red S staining and alkaline phosphatase (ALP) assay. The expressions of osteogenic differentiation markers including runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN) were detected by western blot assay. Luciferase reporter and CHIP assays were used to confirm that SOX2 regulated the transcriptional activation of leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4). We found that SOX2 was down-regulated upon BMP2-induced osteogenic differentiation in MC3T3-E1 cells. Overexpression of SOX2 effectively inhibited osteogenic differentiation with decreased ALP activity, calcification, and osteogenic differentiation markers' expression including Runx2, OPN, and OCN. LGR4 was identified as a target of SOX2, and the inhibitory effect of SOX2 on osteogenic differentiation was reversed by knockdown of LGR4. The present study confirmed that SOX2 suppressed osteogenic differentiation of MC3T3-E1 cells through targeting LGR4, which possesses a therapeutic strategy for bone formation and generation.

Increased glucose influx and glycogenesis in lung cancer cells surviving after irradiation

PURPOSE

Lung cancer is considered as one of the most frequent malignancies worldwide. Radiotherapy is the main treatment modality applied for locally advanced disease, but remnant surviving cancer tissue results in disease progression in the majority of irradiated lung carcinomas. Metabolic reprogramming is regarded as a cancer hallmark and is associated with resistance to radiation therapy. Here, we explored metabolic alterations possibly related to cancer cell radioresistance.

MATERIALS AND METHODS

We compared the expression of metabolism-related enzymes in the parental A549 lung cancer cell line along with two new cell lines derived from A549 cells after recovery from three (A549-IR3) and six (A549-IR6) irradiation doses with 4 Gy. Differential GLUT1 and GYS1 expression on proliferation and radioresistance were also comparatively investigated.

RESULTS

A549-IR cells displayed increased extracellular glucose absorption, and enhanced mRNA and protein levels of the GLUT1 glucose transporter. GLUT1 inhibition with BAY-876, suppressed cell proliferation and the effect was significantly more profound on A549-IR3 cells. Protein levels of molecules associated with aerobic or anaerobic glycolysis, or the phosphate pentose pathway were similar in all three cell lines. However, glycogen synthase 1 (GYS1) was upregulated, especially in the A549-IR3 cell line, suggestive of glycogen accumulation in cells surviving post irradiation. GYS1-gene silencing repressed the proliferation capacity of A549, but this increased their radioresistance. The radio-protective effect of the suppression of proliferative activity induced by GYS1 silencing did not protect A549-IR3 cells against further irradiation.

CONCLUSIONS

These findings indicate that GYS1 activity is a critical component of the metabolism of lung cancer cells surviving after fractionated radiotherapy. Targeting the glycogen metabolic reprogramming after irradiation may be a valuable approach to pursue eradication of the post-radiotherapy remnant of disease.

Species origin of exogenous transcription factors affects the activation of endogenous pluripotency markers and signaling pathways of porcine induced pluripotent stem cells

The incomplete silencing of exogenous transcription factors (TFs) and the lack of endogenous counterpart activation hampers the application of porcine induced pluripotent stem cells (piPSCs). We used porcine, bovine and murine TFs to reprogram porcine fetal fibroblasts. Porcine TFs-derived piPSCs (ppiPSCs) showed the highest levels of endogenous pluripotency markers activation, were able to differentiate into three germ layers and primordial germ cell-like cells (PGCLCs) and integrated into neural ectoderm of E7.5 mouse embryos in vitro. The bovine TFs derived piPSCs (bpiPSCs) expressed endogenous pluripotency markers higher than murine TFs derived piPSCs (mpiPSCs), but both had limited differentiation ability in vitro and depended on continuous expression of exogenous TFs for the maintenance. RNA sequencing confirmed ppiPSCs had distinct global transcriptional profiling, upregulated Hippo, PI3K-Akt, MAPK and relevant pluripotency signaling pathways as porcine blastocyst inner cell mass and expressed PGC early related genes. In addition, a positive and a negative correlation between exogenous and endogenous TFs' expression level were observed in ppiPSCs and bpiPSCs lines, respectively. The TFs' protein structures in pig were more similar to cattle than to mouse. In conclusion, the species affinity of the exogenous TFs is a key element, and the own species origin of TFs is optimal for iPSCs generation and application.

The role of Wnt signaling in the development of the epiblast and axial progenitors

Understanding how the body plan is established during embryogenesis remains a fundamental biological question. The Wnt/β-catenin signaling pathway plays a crucial and highly conserved role in body plan formation, functioning to polarize the primary anterior-posterior (AP) or head-to-tail body axis in most metazoans. In this chapter, we focus on the roles that the mammalian Wnt/β-catenin pathway plays to prepare the pluripotent epiblast for gastrulation, and to elicit the emergence of multipotent axial progenitors from the caudal epiblast. Interactions between Wnt and retinoic acid (RA), another powerful family of developmental signaling molecules, in axial progenitors will also be discussed. Gastrulation movements and somitogenesis result in the anterior displacement of the RA source (the rostral somites and lateral plate mesoderm (LPM)), from the posterior Wnt source (the primitive streak (PS)), leading to the establishment of antiparallel gradients of RA and Wnt that control the self-renewal and successive differentiation of neck, trunk and tail progenitors.

METTL3 modulates chromatin and transcription dynamics during cell fate transition

Transcriptional programming plays a key role in determining the cell state. Timely reconfiguration of chromatin structure and attenuation of pluripotent genes are required for efficient embryonic stem cell (ESC) differentiation. Here, we identify METTL3, a core N⁶-methyladenosine (m⁶A) catalyzing enzyme, as a crucial modulator of dynamic transcription and chromatin accessibility upon ESC-derived cardiac differentiation. Genome-wide analysis of chromatin-associated RNAs revealed that depletion of METTL3 failed to dramatically attenuate the transcription of pluripotent genes, as well as activate nascent cardiomyocyte-specific transcripts upon differentiation. Consistently, ATAC-seq analysis showed that loss of METTL3 markedly attenuated the dynamic alteration of chromatin accessibility at both promoters and gene bodies, resulting in reduced sensitivity of ESC chromatin structure to cardiac differentiation signal. Furthermore, we found that METTL3 negatively regulated the histone modifications H3K4me3 and H3K36me3, which are involved in METTL3-modulated dynamic chromatin architecture during cell state transition. Unexpectedly, using chromatin-associated m⁶A sequencing, we found that nuclear m⁶A underwent a dramatic increase upon differentiation, which correlates with the decrease of chromatin accessibility. Collectively, our findings reveal that METTL3 and nuclear m⁶A epitranscriptome couple with chromatin state to ensure transcriptional regulation of cell fate transition.

Lin28 Regulates Cancer Cell Stemness for Tumour Progression

Tumours develop therapy resistance through complex mechanisms, one of which is that cancer stem cell (CSC) populations within the tumours present self-renewable capability and phenotypical plasticity to endure therapy-induced stress conditions and allow tumour progression to the therapy-resistant state. Developing therapeutic strategies to cope with CSCs requires a thorough understanding of the critical drivers and molecular mechanisms underlying the aforementioned processes. One such hub regulator of stemness is Lin28, an RNA-binding protein. Lin28 blocks the synthesis of let-7, a tumour-suppressor microRNA, and acts as a global regulator of cell differentiation and proliferation. Lin28also targets messenger RNAs and regulates protein translation. In this review, we explain the role of the Lin28/let-7 axis in establishing stemness, epithelial-to-mesenchymal transition, and glucose metabolism reprogramming. We also highlight the role of Lin28 in therapy-resistant prostate cancer progression and discuss the emergence of Lin28-targeted therapeutics and screening methods.

Cryobanking European Mink (Mustela lutreola) Mesenchymal Stem Cells and Oocytes

The European mink (Mustela lutreola) is one of Europe’s most endangered species, and it is on the brink of extinction in the Iberian Peninsula. The species’ precarious situation requires the application of new ex situ conservation methodologies that complement the existing ex situ and in situ conservation measures. Here, we report for the first time the establishment of a biobank for European mink mesenchymal stem cells (emMSC) and oocytes from specimens found dead in the Iberian Peninsula, either free or in captivity. New emMSC lines were isolated from different tissues: bone marrow (emBM-MSC), oral mucosa (emOM-MSc), dermal skin (emDS-MSC), oviduct (emO-MSc), endometrium (emE-MSC), testicular (emT-MSC), and adipose tissue from two different adipose depots: subcutaneous (emSCA-MSC) and ovarian (emOA-MSC). All eight emMSC lines showed plastic adhesion, a detectable expression of characteristic markers of MSCs, and, when cultured under osteogenic and adipogenic conditions, differentiation capacity to these lineages. Additionally, we were able to keep 227 Cumulus-oocyte complexes (COCs) in the biobank, 97 of which are grade I or II. The European mink MSC and oocyte biobank will allow for the conservation of the species’ genetic variability, the application of assisted reproduction techniques, and the development of in vitro models for studying the molecular mechanisms of infectious diseases that threaten the species’ precarious situation.

Dehydroepiandrosterone (DHEA) Sensitizes Irinotecan to Suppress Head and Neck Cancer Stem-Like Cells by Downregulation of WNT Signaling

Purpose

Current treatment options for head and neck squamous cell carcinoma (HNSCC) are limited, especially for cases with cancer stem cell-induced chemoresistance and recurrence. The WNT signaling pathway contributes to maintenance of stemness via translocation of β-catenin into the nucleus, and represents a promising druggable target in HNSCC. Dehydroepiandrosterone (DHEA), a steroid hormone, has potential as an anticancer drug. However, the potential anticancer mechanisms of DHEA including inhibition of stemness, and its therapeutic applications in HNSCC remain unclear.

Methods

Firstly, SRB assay and sphere formation assay were used to examine cellular viability and cancer stem cell-like phenotype, respectively. The expressions of stemness related factors were measured by RT-qPCR and western blotting. The luciferase reporter assay was applied to evaluate transcriptional potential of stemness related pathways. The alternations of WNT signaling pathway were measured by nuclear translocation of β-catenin, RT-qPCR and western blotting. Furthermore, to investigate the effect of drugs in vivo, both HNSCC orthotopic and subcutaneous xenograft mouse models were applied.

Results

We found that DHEA reduced HNSCC cell viability, suppressed sphere formation, and inhibited the expression of cancer-stemness markers, such as BMI-1 and Nestin. Moreover, DHEA repressed the transcriptional activity of stemness-related pathways. In the WNT pathway, DHEA reduced the nuclear translocation of the active form of β-catenin and reduced the protein expression of the downstream targets, CCND1 and CD44. Furthermore, when combined with the chemotherapeutic drug, irinotecan (IRN), DHEA enhanced the sensitivity of HNSCC cells to IRN as revealed by reduced cell viability, sphere formation, expression of stemness markers, and activation of the WNT pathway. Additionally, this combination reduced in vivo tumor growth in both orthotopic and subcutaneous xenograft mouse models.

Conclusion

These findings indicate that DHEA has anti-stemness potential in HNSCC and serves as a promising anticancer agent. The combination of DHEA and IRN may provide a potential therapeutic strategy for patients with advanced HNSCC.

Revisiting Epithelial Carcinogenesis

The origin of cancer remains one of the most important enigmas in modern biology. This paper presents a hypothesis for the origin of carcinomas in which cellular aging and inflammation enable the recovery of cellular plasticity, which may ultimately result in cancer. The hypothesis describes carcinogenesis as the result of the dedifferentiation undergone by epithelial cells in hyperplasia due to replicative senescence towards a mesenchymal cell state with potentially cancerous behavior. In support of this hypothesis, the molecular, cellular, and histopathological evidence was critically reviewed and reinterpreted when necessary to postulate a plausible generic series of mechanisms for the origin and progression of carcinomas. In addition, the implications of this theoretical framework for the current strategies of cancer treatment are discussed considering recent evidence of the molecular events underlying the epigenetic switches involved in the resistance of breast carcinomas. The hypothesis also proposes an epigenetic landscape for their progression and a potential mechanism for restraining the degree of dedifferentiation and malignant behavior. In addition, the manuscript revisits the gradual degeneration of the nonalcoholic fatty liver disease to propose an integrative generalized mechanistic explanation for the involution and carcinogenesis of tissues associated with aging. The presented hypothesis might serve to understand and structure new findings into a more encompassing view of the genesis of degenerative diseases and may inspire novel approaches for their study and therapy.

Modeling of mitochondrial bioenergetics and autophagy impairment in MELAS-mutant iPSC-derived retinal pigment epithelial cells

Background

Mitochondrial dysfunction and mitochondrial DNA (mtDNA) damage in the retinal pigment epithelium (RPE) have been implicated in the pathogenesis of age-related macular degeneration (AMD). However, a deeper understanding is required to determine the contribution of mitochondrial dysfunction and impaired mitochondrial autophagy (mitophagy) to RPE damage and AMD pathobiology. In this study, we model the impact of a prototypical systemic mitochondrial defect, mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), in RPE health and homeostasis as an in vitro model for impaired mitochondrial bioenergetics.

Methods

We used induced pluripotent stem cells (iPSCs) derived from skin biopsies of MELAS patients (m.3243A > G tRNA leu mutation) with different levels of mtDNA heteroplasmy and differentiated them into RPE cells. Mitochondrial depletion of ARPE-19 cells (p⁰ cells) was also performed using 50 ng/mL ethidium bromide (EtBr) and 50 mg/ml uridine. Cell fusion of the human platelets with the p⁰ cells performed using polyethylene glycol (PEG)/suspension essential medium (SMEM) mixture to generate platelet/RPE “cybrids.” Confocal microscopy, FLowSight Imaging cytometry, and Seahorse XF Mito Stress test were used to analyze mitochondrial function. Western Blotting was used to analyze expression of autophagy and mitophagy proteins.

Results

We found that MELAS iPSC-derived RPE cells exhibited key characteristics of native RPE. We observed heteroplasmy-dependent impairment of mitochondrial bioenergetics and reliance on glycolysis for generating energy in the MELAS iPSC-derived RPE. The degree of heteroplasmy was directly associated with increased activation of signal transducer and activator of transcription 3 (STAT3), reduced adenosine monophosphate-activated protein kinase α (AMPKα) activation, and decreased autophagic activity. In addition, impaired autophagy was associated with aberrant lysosomal function, and failure of mitochondrial recycling. The mitochondria-depleted p⁰ cells replicated the effects on autophagy impairment and aberrant STAT3/AMPKα signaling and showed reduced mitochondrial respiration, demonstrating phenotypic similarities between p⁰ and MELAS iPSC-derived RPE cells.

Conclusions

Our studies demonstrate that the MELAS iPSC-derived disease models are powerful tools for dissecting the molecular mechanisms by which mitochondrial DNA alterations influence RPE function in aging and macular degeneration, and for testing novel therapeutics in patients harboring the MELAS genotype.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02937-6.

Fractionated irradiation of MCF7 breast cancer cells rewires a gene regulatory circuit towards a treatment-resistant stemness phenotype

Radiotherapy is the standard of care for breast cancer. However, surviving radioresistant cells can repopulate following treatment and provoke relapse. Better understanding of the molecular mechanisms of radiation resistance may help improve treatment of radioresistant tumors. To emulate radiation therapy at the cellular level, we exposed MCF7 breast cancer cells to daily radiation doses of 2 Gy up to an accumulated dose of 20 Gy. Fractionally irradiated cells (FIR20) displayed increased clonogenic survival and population doubling time as compared to age-matched sham-irradiated cells and untreated parental MCF7 cells. RNA-sequencing revealed a core signature of 229 mRNAs and 7 circular RNAs of which the expression was significantly altered in FIR20 cells. Dysregulation of several top genes was mirrored at the protein level. The FIR20 cell transcriptome overlapped significantly with canonical radiation response signatures and demonstrated a remarkable commonality with radiation and endocrine therapy resistance expression profiles, suggesting crosstalk between both acquired resistance pathways, as indicated by reduced sensitivity to tamoxifen cytotoxicity of FIR20 cells. Using predictive analyses and functional enrichment, we identified a gene-regulatory network that promotes stemness and inflammatory signaling in FIR20 cells. We propose that these phenotypic traits render breast cancer cells more radioresistant but may at the same time serve as potential targets for combination therapies.

Molecular complexity and gene expression controlling cell turnover during a digestive cycle of carnivorous sponge Lycopodina hypogea

Lycopodina hypogea is a carnivorous sponge that tolerates laboratory husbandry very well. During a digestion cycle, performed without any digestive cavity, this species undergoes spectacular morphological changes leading to a total regression of long filaments that ensure the capture of prey and their reformation at the end of the cycle. This phenomenon is a unique opportunity to analyze the molecular and cellular determinants that ensure digestion in the sister group of all other metazoans. Using differential transcriptomic analysis coupled with cell biology studies of proliferation, differentiation, and programmed cell deaths (i.e., autophagy and the destructive/constructive function of apoptosis), we demonstrate that the molecular and cellular actors that ensure digestive homeostasis in a sister group of all remaining animals are similar in variety and complexity to those controlling tissue homeostasis in higher vertebrates. During a digestion cycle, most of these actors are finely tuned in a coordinated manner. Our data benefits from complementary approaches coupling in silico and cell biology studies and demonstrate that the nutritive function is provided by the coordination of molecular network that impacts the cells turnover in the entire organism.

Inhibiting ALK2/ALK3 Signaling to Differentiate and Chemo-Sensitize Medulloblastoma

Simple Summary

Many cancers re-emerge after treatment, despite the sensitivity of the bulk of tumor cells to treatments. This observation has led to the ‘cancer stem cell’ (CSCs) hypothesis, stating that a subpopulation of cancer cells survive therapy and lead to tumor relapse. However, the lack of universal markers to target CSCs is the main constraint to fully eradicate the CSC pool. Differentiation therapy (DT) might in principle suppress tumorigenesis through conversion of undifferentiated cancer cells of high malignancy into differentiated cells of low tumorigenic potential. Here, we provide evidence that CSCs of medulloblastoma can be forced to resume their differentiation potential by inhibiting the BMP4–ALK2/3 axis, providing a new entry point for medulloblastoma treatment.

Abstract

Background: Medulloblastoma (MB) is a malignant pediatric brain tumor, and it represents the leading cause of death related to cancer in childhood. New perspectives for therapeutic development have emerged with the identification of cancer stem cells (CSCs) displaying tumor initiating capability and chemoresistance. However, the mechanisms responsible for CSCs maintenance are poorly understood. The lack of a universal marker signature represents the main constraints to identify and isolate CSCs within the tumor. Methods: To identify signaling pathways promoting CSC maintenance in MB, we combined tumorsphere assays with targeted neurogenesis PCR pathway arrays. Results: We showed a consistent induction of signaling pathways regulating pluripotency of CSCs in all the screened MB cells. BMP4 signaling was consistently enriched in all tumorsphere(s) independently of their specific stem-cell marker profile. The octamer-binding transcription factor 4 (OCT4), an important regulator of embryonic pluripotency, enhanced CSC maintenance in MBs by inducing the BMP4 signaling pathway. Consistently, inhibition of BMP4 signaling with LDN-193189 reduced stem-cell traits and promoted cell differentiation. Conclusions: Our work suggests that interfering with the BMP4 signaling pathway impaired the maintenance of the CSC pool by promoting cell differentiation. Hence, differentiation therapy might represent an innovative therapeutic to improve the current standard of care in MB patients.

Pluripotent Core in Bovine Embryos: A Review

Early development in mammals is characterized by the ability of each cell to produce a complete organism plus the extraembryonic, or placental, cells, defined as pluripotency. During subsequent development, pluripotency is lost, and cells begin to differentiate to a particular cell fate. This review summarizes the current knowledge of pluripotency features of bovine embryos cultured in vitro, focusing on the core of pluripotency genes (OCT4, NANOG, SOX2, and CDX2), and main chemical strategies for controlling pluripotent networks during early development. Finally, we discuss the applicability of manipulating pluripotency during the morula to blastocyst transition in cattle species.

Expression of pluripotency-related genes in human glioblastoma

Background

Cancer is a group of heterogeneous diseases characterized by several disruptions of the genetic and epigenetic components of cell biology. Some types of cancer have been shown to be constituted by a mosaic of cells with variable differentiation states, with more aggressive tumors being more undifferentiated. In most cases, undifferentiated tumor cells express associated embryonic markers such as the OCT4, NANOG, SOX2, and CARM1 genes. The ectopic or reminiscent expression of some master regulator genes of pluripotency has been indicated as the cause of the poorly differentiated state of tumors, and based on the evidence of some reports, can be used as a possible therapeutic target. Considering this information, a more detailed investigation of the expression of pluripotency-associated genes is necessary to evaluate the roles of these genes in the etiology of some tumors and their use targets of therapy.

Methods

The expression of four pluripotency-related genes was investigated (OCT4, NANOG, SOX2, and CARM1) in the most malignant primary human brain tumor, glioblastoma (GBM).

Results and Conclusion

The results demonstrated a signature of OCT4/SOX2/CARM1 genes and a significant increase of CARM1 expression in GBM cases.

MicroRNA 630 Represses NANOG Expression through Transcriptional and Post-Transcriptional Regulation in Human Embryonal Carcinoma Cells

The pluripotent transcription factor NANOG is essential for maintaining embryonic stem cells and driving tumorigenesis. We previously showed that PKC activity is involved in the regulation of NANOG expression. To explore the possible involvement of microRNAs in regulating the expression of key pluripotency factors, we performed a genome-wide analysis of microRNA expression in the embryonal carcinoma cell line NT2/D1 in the presence of the PKC activator, PMA. We found that MIR630 was significantly upregulated in PMA-treated cells. Experimentally, we showed that transfection of MIR630 mimic into embryonal carcinoma cell lines directly targeted the 3′UTR of OCT4, SOX2, and NANOG and markedly suppressed their expression. RNAhybrid and RNA22 algorithms were used to predict miRNA target sites in the NANOG 3′UTR, four possible target sites of MIR630 were identified. To examine the functional interaction between MIR630 and NANOG mRNA, the predicted MIR630 target sites in the NANOG 3′UTR were deleted and the activity of the reporters were compared. After targeted mutation of the predicted MIR630 target sites, the MIR630 mimic inhibited NANOG significantly less than the wild-type reporters. It is worth noting that mutation of a single putative binding site in the 3′UTR of NANOG did not completely abolish MIR630-mediated suppression, suggesting that MIR630 in the NANOG 3′UTR may have multiple binding sites and act together to maximally repress NANOG expression. Interestingly, MIR630 mimics significantly downregulated NANOG gene transcription. Exogenous expression of OCT4, SOX2, and NANOG lacking the 3′UTR almost completely rescued the reduced transcriptional activity of MIR630. MIR630 mediated the expression of differentiation markers in NT2/D1 cells, suggesting that MIR630 leads to the differentiation of NT2/D1 cell. Our findings show that MIR630 represses NANOG through transcriptional and post-transcriptional regulation, suggesting a direct link between core pluripotency factors and MIR630.

Recognition of the Possible miRNA-mRNA Controlling Network in Stroke by Bioinformatics Examination

BACKGROUND

Based on the latest research of WHO, it has been revealed that more than 15 million people suffer from stroke every year worldwide. Of these 15 million people, 6 million succumb to death, and 5 million get permanently disabled. This is the prime reason for the substantial economic burden on all parts of the world.

METHODS

These data have been obtained from the GEO database, and the GEO2R tool was used to find out the differentially expressed miRNAs (DEMs) between the stroke and normal patients' blood. FunRich and miRNet were considered to find potential upstream transcription factors and downstream target genes of candidate EMRs. Next, we use GO annotation and KEGG pathway enrichment. Target genes were analyzed with the help of the R software. Then, the STRING database and Cytoscape software were used to conduct PPI and DEM-hub gene networks. Finally, GSE58294 was used to estimate the hub gene expressions.

RESULTS

Six DEMs in total were selected out from GSE95204 and GSE117064 datasets. 663 DEMs' target genes were predicted, and NRF1, EGR1, MYC, YY1, E2F1, SP4, and SP1 were predicted as an upstream transcription factor for DEMs' target genes. Target genes of DEMs were primarily augmented in the PI3K-Akt signaling pathway and p53 signaling pathway. The network construction of DEM hygiene is potentially modulated by hsa-miR-3591-5p, hsa-miR-548as-3p, hsa-miR-206, and hsa-miR-4503 hub genes which were found among the top 10 of the hub genes. Among the top 10 hub genes, justification of CTNNB1, PTEN, ESR1, CCND1, KRAS, AKT1, CCND2, CDKN1B, and MYCN was constant with that in the GSE58294 dataset.

CONCLUSION

In summary, our research first constructs the miRNA-mRNA network in stroke, which probably renders an awakening purview into the pathogenesis and cure of stroke.

Luteolin attenuates cancer cell stemness in PTX-resistant oesophageal cancer cells through mediating SOX2 protein stability

Cancer drug resistance is a formidable obstacle that enhances cancer stem-like cell properties, tumour metastasis and relapse. Luteolin (Lut) is a natural flavonoid with strong antitumor effects. However, the underlying mechanism(s) by which Lut protects against paclitaxel-resistant (PTX-resistant) cancer cell remains unknown. Herein, we found that Lut significantly attenuated the stem-like properties of PTX-resistant cancer cells by downregulating the expression of SOX2 protein. Additionally, further study showed that Lut could inhibit the PI3K/AKT pathway to decrease the phosphorylation level of AKT(S473) and UBR5 expression, which is an ubiquitin E3 ligase that promotes SOX2 degradation. In addition, Lut also inhibited PTX-resistant cancer cell migration and invasion by blocking epithelial-mesenchymal transition (EMT). Importantly, Lut inhibited the tumorigenic ability of oesophageal PTX-resistant cancer cells and showed no obvious toxicity in vivo. Thus, Lut has potential as a promising agent for drug-resistant oesophageal cancer therapy.

Detection of Novel Potential Regulators of Stem Cell Differentiation and Cardiogenesis through Combined Genome-Wide Profiling of Protein-Coding Transcripts and microRNAs

In vitro differentiation of embryonic stem cells (ESCs) provides a convenient basis for the study of microRNA-based gene regulation that is relevant for early cardiogenic processes. However, to which degree insights gained from in vitro differentiation models can be readily transferred to the in vivo system remains unclear. In this study, we profiled simultaneous genome-wide measurements of mRNAs and microRNAs (miRNAs) of differentiating murine ESCs (mESCs) and integrated putative miRNA-gene interactions to assess miRNA-driven gene regulation. To identify interactions conserved between in vivo and in vitro, we combined our analysis with a recent transcriptomic study of early murine heart development in vivo. We detected over 200 putative miRNA-mRNA interactions with conserved expression patterns that were indicative of gene regulation across the in vitro and in vivo studies. A substantial proportion of candidate interactions have been already linked to cardiogenesis, supporting the validity of our approach. Notably, we also detected miRNAs with expression patterns that closely resembled those of key developmental transcription factors. The approach taken in this study enabled the identification of miRNA interactions in in vitro models with potential relevance for early cardiogenic development. Such comparative approaches will be important for the faithful application of stem cells in cardiovascular research.

Connexins in the development and physiology of stem cells

Connexins (Cxs) form gap junction (GJ) channels linking vertebrate cells. During embryogenesis, Cxs are expressed as early as the 4-8 cell stage. As cells differentiate into pluripotent stem cells (PSCs) and during gastrulation, the Cx expression pattern is adapted. Knockdown of Cx43 and Cx45 does not interfere with embryogenic development until the blastula stage, questioning the role of Cxs in PSC physiology and development. Studies in cultivated and induced PSCs (iPSCs) showed that Cx43 is essential for the maintenance of self-renewal and the expression of pluripotency markers. It was found that the role of Cxs in PSCs is more related to regulation of transcription or cell-cell adherence than to formation of GJ channels. Furthermore, a crucial role of Cxs for the self-renewal and differentiation was shown in cultivated adult mesenchymal stem cells. This review aims to highlight aspects that link Cxs to the function and physiology of stem cell development.

The pluripotency transcription factor OCT4 represses heme oxygenase-1 gene expression

In embryonic stem (ES) cells, oxidative stress control is crucial for genomic stability, self-renewal, and cell differentiation. Heme oxygenase-1 (HO-1) is a key player of the antioxidant system and is also involved in stem cell differentiation and pluripotency acquisition. We found that the HO-1 gene is expressed in ES cells and induced after promoting differentiation. Moreover, downregulation of the pluripotency transcription factor (TF) OCT4 increased HO-1 mRNA levels in ES cells, and analysis of ChIP-seq public data revealed that this TF binds to the HO-1 gene locus in pluripotent cells. Finally, ectopic expression of OCT4 in heterologous systems repressed a reporter carrying the HO-1 gene promoter and the endogenous gene. Hence, this work highlights the connection between pluripotency and redox homeostasis.

The Core Stem Genes SOX2, POU5F1/OCT4, and NANOG Are Expressed in Human Parathyroid Tumors and Modulated by MEN1, YAP1, and β-catenin Pathways Activation

Tumors of the parathyroid glands are the second most common endocrine neoplasia. Epigenetic studies revealed an embryonic signature involved in parathyroid tumorigenesis. Here, we investigated the expression of the stem core genes SOX2, POU5F1/OCT4, and NANOG. Rare cells within normal parathyroid glands expressed POU5F1/OCT4 and NANOG, while SOX2 was undetectable. Nuclear SOX2 expression was detectable in 18% of parathyroid adenomas (PAds, n = 34) involving 5–30% of cells, while OCT4 and NANOG were expressed at the nuclear level in a more consistent subset of PAds involving 15–40% of cells. Most parathyroid carcinomas expressed the core stem genes. SOX2-expressing cells co-expressed parathormone (PTH). In PAds-derived primary cultures, silencing of the tumor suppressor gene MEN1 induced the expression of SOX2, likely through a MEN1/HAR1B/SOX2 axis, while calcium-sensing receptor activation increased SOX2 mRNA levels through YAP1 activation. In addition, inducing nuclear β-catenin accumulation in PAds-derived primary cultures by short-term incubation with lithium chloride (LiCl), SOX2 and POU5F1/OCT4 expression levels increased, while NANOG transcripts were reduced, and LiCl long-term incubation induced an opposite pattern of gene expression. In conclusion, detection of the core stem genes in parathyroid tumors supports their embryogenic signature, which is modulated by crucial genes involved in parathyroid tumorigenesis.

Deep learning-based predictive identification of neural stem cell differentiation

The differentiation of neural stem cells (NSCs) into neurons is proposed to be critical in devising potential cell-based therapeutic strategies for central nervous system (CNS) diseases, however, the determination and prediction of differentiation is complex and not yet clearly established, especially at the early stage. We hypothesize that deep learning could extract minutiae from large-scale datasets, and present a deep neural network model for predictable reliable identification of NSCs fate. Remarkably, using only bright field images without artificial labelling, our model is surprisingly effective at identifying the differentiated cell types, even as early as 1 day of culture. Moreover, our approach showcases superior precision and robustness in designed independent test scenarios involving various inducers, including neurotrophins, hormones, small molecule compounds and even nanoparticles, suggesting excellent generalizability and applicability. We anticipate that our accurate and robust deep learning-based platform for NSCs differentiation identification will accelerate the progress of NSCs applications.

The differentiation of neural stem cells (NSCs) into neurons is a critical part in devising potential cell-based therapeutic strategies for central nervous system diseases but NSCs fate determination and prediction is problematic. Here, the authors present a deep neural network model for predictable reliable identification of NSCs fate.

Comparative Study of Biological Characteristics, and Osteoblast Differentiation of Mesenchymal Stem Cell Established from Camelus dromedarius Skeletal Muscle, Dermal Skin, and Adipose Tissues

Mesenchymal stem cells (MSCs) showed in vitro mesoderm-lineage differentiation and self-renewal capacity. However, no comparative study was reported on the biological characteristics of stem cells derived from skeletal muscle (SM-MSCs), dermal skin (DS-MSCs), and adipose tissues (A-MSCs) from a single donor in camels. The present study aimed to evaluate the influence of MSCs source on stem cell characteristics. We evaluated proliferation capacity and mesoderm-lineage differentiation potential from SM-MSCs, DS-MSCs, and A-MSCs. They showed spindle-like morphology after homogenization. The proliferation ability was not significantly difference in any of the groups. Furthermore, the portion of the cell cycle and expression of pluripotent markers (Oct4, Sox2, and Nanog) were similar in all cell lines at passage 3. The differentiation capacity of A-MSCs into adipocytes was significantly higher than that of SM-MSCs and DS-MSCs. However, the osteoblast differentiation capacity of A-MSCs was significantly lower than that of SM-MSCs and DS-MSCs. Additionally, after osteoblast differentiation, the alkaline phosphatase (ALP) activity and calcium content significantly decreased in A-MSCs compared to SM-MSCs and DS-MSCs. To the best of our knowledge, we primarily established MSCs from the single camel and demonstrated their comparative characteristics, including expression of pluripotent factors and proliferation, and in vitro differentiation capacity into adipocytes and osteoblasts.

The effects of 3D culture on the expansion and maintenance of nucleus pulposus progenitor cell multipotency

INTRODUCTION

Low back pain (LBP) is a global health concern. Increasing evidence implicates intervertebral disk (IVD) degeneration as a major contributor. In this respect, tissue-specific progenitors may play a crucial role in tissue regeneration, as these cells are perfectly adapted to their niche. Recently, a novel progenitor cell population was described in the nucleus pulposus (NP) that is positive for Tie2 marker. These cells have self-renewal capacity and in vitro multipotency potential. However, extremely low numbers of the NP progenitors limit the feasibility of cell therapy strategies.

OBJECTIVE

Here, we studied the influence of the culture method and of the microenvironment on the proliferation rate and the differentiation potential of human NP progenitors in vitro.

METHOD

Cells were obtained from human NP tissue from trauma patients. Briefly, the NP tissue cells were cultured in two-dimensional (2D) (monolayer) or three-dimensional (3D) (alginate beads) conditions. After 1 week, cells from 2D or 3D culture were expanded on fibronectin-coated flasks. Subsequently, expanded NP cells were then characterized by cytometry and tri-lineage differentiation, which was analyzed by qPCR and histology. Moreover, experiments using Tie2+ and Tie2- NP cells were also performed.

RESULTS

The present study aims to demonstrate that 3D expansion of NP cells better preserves the Tie2+ cell populations and increases the chondrogenic and osteogenic differentiation potential compared to 2D expansion. Moreover, the cell sorting experiments reveal that only Tie2+ cells were able to maintain the pluripotent gene expression if cultured in 3D within alginate beads. Therefore, our results highly suggest that the maintenance of the cell's multipotency is mainly, but not exclusively, due to the higher presence of Tie2+ cells due to 3D culture.

CONCLUSION

This project not only might have a scientific impact by evaluating the influence of a two-step expansion protocol on the functionality of NP progenitors, but it could also lead to an innovative clinical approach.

Perspectives of pluripotent stem cells in livestock

The recent progress in derivation of pluripotent stem cells (PSCs) from farm animals opens new approaches not only for reproduction, genetic engineering, treatment and conservation of these species, but also for screening novel drugs for their efficacy and toxicity, and modelling of human diseases. Initial attempts to derive PSCs from the inner cell mass of blastocyst stages in farm animals were largely unsuccessful as either the cells survived for only a few passages, or lost their cellular potency; indicating that the protocols which allowed the derivation of murine or human embryonic stem (ES) cells were not sufficient to support the maintenance of ES cells from farm animals. This scenario changed by the innovation of induced pluripotency and by the development of the 3 inhibitor culture conditions to support naïve pluripotency in ES cells from livestock species. However, the long-term culture of livestock PSCs while maintaining the full pluripotency is still challenging, and requires further refinements. Here, we review the current achievements in the derivation of PSCs from farm animals, and discuss the potential application areas.

Downregulation of E-cadherin in pluripotent stem cells triggers partial EMT

Epithelial to mesenchymal transition (EMT) is a critical cellular process that has been well characterized during embryonic development and cancer metastasis and it also is implicated in several physiological and pathological events including embryonic stem cell differentiation. During early stages of differentiation, human embryonic stem cells pass through EMT where deeper morphological, molecular and biochemical changes occur. Though initially considered as a decision between two states, EMT process is now regarded as a fluid transition where cells exist on a spectrum of intermediate states. In this work, using a CRISPR interference system in human embryonic stem cells, we describe a molecular characterization of the effects of downregulation of E-cadherin, one of the main initiation events of EMT, as a unique start signal. Our results suggest that the decrease and delocalization of E-cadherin causes an incomplete EMT where cells retain their undifferentiated state while expressing several characteristics of a mesenchymal-like phenotype. Namely, we found that E-cadherin downregulation induces SNAI1 and SNAI2 upregulation, promotes MALAT1 and LINC-ROR downregulation, modulates the expression of tight junction occludin 1 and gap junction connexin 43, increases human embryonic stem cells migratory capacity and delocalize β-catenin. Altogether, we believe our results provide a useful tool to model the molecular events of an unstable intermediate state and further identify multiple layers of molecular changes that occur during partial EMT.

Embryonic Stem Cell-Derived Extracellular Vesicles Maintain ESC Stemness by Activating FAK

It is critical that epiblast cells within blastocyst-stage embryos receive the necessary regulatory cues to remain pluripotent until the appropriate time when they are stimulated to undergo differentiation, ultimately to give rise to an entire organism. Here, we show that exposure of embryonic stem cells (ESCs), which are the in vitro equivalents of epiblasts, to ESC-derived extracellular vesicles (EVs) helps to maintain their stem cell properties even under culture conditions that would otherwise induce differentiation. EV-treated ESCs continued to express stemness genes, preserving their pluripotency and ability to generate chimeric mice. These effects were triggered by fibronectin bound to the surfaces of EVs, enabling them to interact with ESC-associated integrins and activate FAK more effectively than fibronectin alone. Overall, these findings highlight a potential regulatory mechanism whereby epiblast cells, via their shed EVs, create an environment within the blastocyst that prevents their premature differentiation and maintains their pluripotent state.

A novel lncRNA PTTG3P/miR-132/212-3p/FoxM1 feedback loop facilitates tumorigenesis and metastasis of pancreatic cancer

Pseudogene pituitary tumor-transforming 3 (PTTG3P) is emerging as a key player in the development and progression of cancer. However, the biological role and clinical significance of PTTG3P in pancreatic ductal adenocarcinoma (PDAC) remain unclear. Here, we found that PTTG3P was significantly upregulated in PDAC tissues. Elevated PTTG3P expression correlated with larger tumor size and worse differentiation, and reduced overall survival. Bioinformatics and experimental evidence revealed that PTTG3P promoted malignant phenotypes and FoxM1 signaling pathway in PDAC cells. Mechanistically, PTTG3P functions as a microRNA sponge to positively regulate the expression of FoxM1 through sponging miR-132/212-3p. Moreover, it showed that FoxM1 transcriptionally activated PTTG3P expression, thus forming a feedback loop to promote the aggressiveness of PDAC cells. Taken together, our findings suggest that PTTG3P promotes PDAC progression through PTTG3P/miR-132/212-3p/FoxM1 feedforward circuitry and it may serve as a promising diagnostic marker or target for treatment in PDAC patients.

How the Pathological Microenvironment Affects the Behavior of Mesenchymal Stem Cells in the Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by fibroblasts activation, ECM accumulation, and diffused alveolar inflammation. The role of inflammation in IPF is still controversial and its involvement may follow nontraditional mechanisms. It is seen that a pathological microenvironment may affect cells, in particular mesenchymal stem cells (MSCs) that may be able to sustain the inflamed microenvironment and influence the surrounding cells. Here MSCs have been isolated from fibrotic (IPF-MSCs) and control (C-MSCs) lung tissue; first cells were characterized and compared by the expression of molecules related to ECM, inflammation, and other interdependent pathways such as hypoxia and oxidative stress. Subsequently, MSCs were co-cultured between them and with NHLF to test the effects of the cellular crosstalk. Results showed that pathological microenvironment modified the features of MSCs: IPF-MSCs, compared to C-MSCs, express higher level of molecules related to ECM, inflammation, oxidative stress, and hypoxia; notably, when co-cultured with C-MSCs and NHLF, IPF-MSCs are able to induce a pathological phenotype on the surrounding cell types. In conclusion, in IPF the pathological microenvironment affects MSCs that in turn can modulate the behavior of other cell types favoring the progression of IPF.

Identification of the Lineage Markers and Inhibition of DAB2 in In Vitro Fertilized Porcine Embryos

Specification of embryonic lineages is an important question in the field of early development. Numerous studies analyzed the expression patterns of the candidate transcripts and proteins in humans and mice and clearly determined the markers of each lineage. To overcome the limitations of human and mouse embryos, the expression of the marker transcripts in each cell has been investigated using in vivo embryos in pigs. In vitro produced embryos are more accessible, can be rapidly processed with low cost. Therefore, we analyzed the characteristics of lineage markers and the effects of the DAB2 gene (trophectoderm marker) in in vitro fertilized porcine embryos. We investigated the expression levels of the marker genes during embryonic stages and distribution of the marker proteins was assayed in day 7 blastocysts. Then, the shRNA vectors were injected into the fertilized embryos and the differences in the marker transcripts were analyzed. Marker transcripts showed diverse patterns of expression, and each embryonic lineage could be identified with localization of marker proteins. In DAB2-shRNA vectors injected embryos, HNF4A and PDGFRA were upregulated. DAB2 protein level was lower in shRNA-injected embryos without significant differences. Our results will contribute to understanding of the mechanisms of embryonic lineage specification in pigs.

Sodium lactate promotes stemness of human mesenchymal stem cells through KDM6B mediated glycolytic metabolism

Mesenchymal stem cells (MSCs) are an important cell source for tissue homeostasis and repair due to their stemness characteristic. Lots of intrinsic signaling pathways have been reported to regulate MSC stemness, but the extrinsic signals such as sodium lactate, particularly in physiological conditions, are poorly understood. Herein, we evaluated the effect of sodium lactate on human MSC stemness regulation by examining colony-forming ability, energy metabolism, multi-lineage differentiation ability, and pluripotent gene and protein expression. The underlying mechanism was further investigated with gene knockdown as well as small molecule interference and rescue experiments. We found that: (1) low concentration (1 mM) of sodium lactate promoted the stemness of human MSCs; (2) the upregulation of glycolysis was responsible for the MSC stemness promotion; (3) lysine demethylase 6B (KDM6B) was the key regulator which mediated sodium lactate-induced glycolysis and human MSC stemness enhancement. This study indicated that sodium lactate played an important role in human MSC stemness maintenance in physiological conditions, which could be related to KDM6B mediated metabolic regulation. It would provide new insight into stem cell biology, and contribute to cell transplantation and tissue regeneration strategies.

Selective Translation of Cell Fate Regulators Mediates Tolerance to Broad Oncogenic Stress

Human skin tolerates a surprisingly high burden of oncogenic lesions. Although adult epidermis can suppress the expansion of individual mutant clones, the mechanisms behind tolerance to oncogene activation across broader regions of tissue are unclear. Here, we uncover a dynamic translational mechanism that coordinates oncogenic HRAS-induced hyperproliferation with loss of progenitor self-renewal to restrain aberrant growth and tumorigenesis. We identify translation initiator eIF2B5 as a central co-regulator of HRAS proliferation and cell fate choice. By coupling in vivo ribosome profiling with genetic screening, we provide direct evidence that oncogene-induced loss of progenitor self-renewal is driven by eIF2B5-mediated translation of ubiquitination genes. Ubiquitin ligase FBXO32 specifically inhibits epidermal renewal without affecting overall proliferation, thus restraining HRAS-driven tumorigenesis while maintaining normal tissue growth. Thus, oncogene-driven translation is not necessarily inherently tumor promoting but instead can manage widespread oncogenic stress by steering progenitor fate to prolong normal tissue growth.