Oct4 controls basement membrane development during human embryogenesis

Basement membranes (BMs) are sheet-like structures of extracellular matrix (ECM) that provide structural support for many tissues and play a central role in signaling. They are key regulators of cell behavior and tissue functions, and defects in their assembly or composition are involved in numerous human diseases. Due to the differences between human and animal embryogenesis, ethical concerns, legal constraints, the scarcity of human tissue material, and the inaccessibility of the in vivo condition, BM regulation during human embryo development has remained elusive. Using the post-implantation amniotic sac embryoid (PASE), we delineate BM assembly upon post-implantation development and BM disassembly during primitive streak (PS) cell dissemination. Further, we show that the transcription factor Oct4 regulates the expression of BM structural components and receptors and controls BM development by regulating Akt signaling and the small GTPase Rac1. These results represent a relevant step toward a more comprehensive understanding of early human development.

Nr5a2 ensures inner cell mass formation in mouse blastocyst

Recent studies have elucidated Nr5a2's role in activating zygotic genes during early mouse embryonic development. Subsequent research, however, reveals that Nr5a2 is not critical for zygotic genome activation but is vital for the gene program between the 4- and 8-cell stages. A significant gap exists in experimental evidence regarding its function during the first lineage differentiation's pivotal period. In this study, we observed that approximately 20% of embryos developed to the blastocyst stage following Nr5a2 ablation. However, these blastocysts lacked inner cell mass (ICM), highlighting Nr5a2's importance in first lineage differentiation. Mechanistically, using RNA sequencing and CUT&Tag, we found that Nr5a2 transcriptionally regulates ICM-specific genes, such as Oct4, to establish the pluripotent network. Interference with or overexpression of Nr5a2 in single blastomeres of 2-cell embryos can alter the fate of daughter cells. Our results indicate that Nr5a2 works as a doorkeeper to ensure ICM formation in mouse blastocyst.

Oct4 is a gatekeeper of epithelial identity by regulating cytoskeletal organization in skin keratinocytes

Oct4 is a pioneer transcription factor regulating pluripotency. However, it is not well known whether Oct4 has an impact on epidermal cells. We generated OCT4 knockout clonal cell lines using immortalized human skin keratinocytes to identify a functional role for the protein. Here, we report that Oct4-deficient cells transitioned into a mesenchymal-like phenotype with enlarged size and shape, exhibited accelerated migratory behavior, decreased adhesion, and appeared arrested at the G2/M cell cycle checkpoint. Oct4 absence had a profound impact on cortical actin organization, with loss of microfilaments from the cell membrane, increased puncta deposition in the cytoplasm, and stress fiber formation. E-cadherin, β-catenin, and ZO1 were almost absent from cell-cell contacts, while fibronectin deposition was markedly increased in the extracellular matrix (ECM). Mapping of the transcriptional and chromatin profiles of Oct4-deficient cells revealed that Oct4 controls the levels of cytoskeletal, ECM, and differentiation-related genes, whereas epithelial identity is preserved through transcriptional and non-transcriptional mechanisms.

Txnip regulates the Oct4-mediated pluripotency circuitry via metabolic changes upon differentiation

Thioredoxin interacting protein (Txnip) is a stress-responsive factor regulating Trx1 for redox balance and involved in diverse cellular processes including proliferation, differentiation, apoptosis, inflammation, and metabolism. However, the biological role of Txnip function in stem cell pluripotency has yet to be investigated. Here, we reveal the novel functions of mouse Txnip in cellular reprogramming and differentiation onset by involving in glucose-mediated histone acetylation and the regulation of Oct4, which is a fundamental component of the molecular circuitry underlying pluripotency. During reprogramming or PSC differentiation process, cellular metabolic and chromatin remodeling occur in order to change its cellular fate. Txnip knockout promotes induced pluripotency but hinders initial differentiation by activating pluripotency factors and promoting glycolysis. This alteration affects the intracellular levels of acetyl-coA, a final product of enhanced glycolysis, resulting in sustained histone acetylation on active PSC gene regions. Moreover, Txnip directly interacts with Oct4, thereby repressing its activity and consequently deregulating Oct4 target gene transcriptions. Our work suggests that control of Txnip expression is crucial for cell fate transitions by modulating the entry and exit of pluripotency.

Oct4 activates IL-17A to orchestrate M2 macrophage polarization and cervical cancer metastasis

BACKGROUND

Cervical cancer is a common malignant tumor in the female. Interleukin (IL)-17A is a proinflammatory factor and exerts a vital function in inflammatory diseases and cancers. M2 macrophage has been confirmed to promote tumor development. Nevertheless, it is not yet known whether IL-17A facilitates cervical cancer development by inducing M2 macrophage polarization. Therefore, this study was conducted to investigate the regulatory effect of IL-17A on M2 macrophage polarization and the underlying mechanism in cervical cancer development.

METHODS

RT-qPCR was utilized for testing IL-17A expression in cancer tissues and cells. Flow cytometry was applied to evaluate the M1 or M2 macrophage polarization. Cell proliferative, migratory, and invasive capabilities were measured through colony formation and transwell assays. ChIP and luciferase reporter assays were applied to determine the interaction between IL-17A and octamer-binding transcription factor 4 (OCT4).

RESULTS

IL-17A expression and concentration were high in metastatic tissues and cells of cervical cancer. IL-17A was found to facilitate M2 macrophage polarization in cervical cancer. Furthermore, IL-17A facilitated the macrophage-mediated promotion of cervical cancer cell proliferative, migratory, and invasive capabilities. Mechanistic assays manifested that Oct4 binds to and transcriptionally activated IL-17A in cervical cancer cells. Furthermore, Oct4 promoted cervical cancer cell malignant phenotype and M2 macrophage polarization by activating the p38 pathway that, in turn, upregulated IL-17A. Additionally, in vivo experiments confirmed that Oct4 knockdown reduced tumor growth and metastasis.

CONCLUSION

Oct4 triggers IL-17A to facilitate the polarization of M2 macrophages, which promotes cervical cancer cell metastasis.

The expanding roles of Nr6a1 in development and evolution

The Nuclear Receptor (NR) family of transcriptional regulators possess the ability to sense signalling molecules and directly couple that to a transcriptional response. While this large class of proteins are united by sequence and structural homology, individual NR functional output varies greatly depending on their expression, ligand selectivity and DNA binding sequence specificity. Many NRs have remained somewhat enigmatic, with the absence of a defined ligand categorising them as orphan nuclear receptors. One example is Nuclear Receptor subfamily 6 group A member 1 (Nr6a1), an orphan nuclear receptor that has no close evolutionary homologs and thus is alone in subfamily 6. Nonetheless, Nr6a1 has emerged as an important player in the regulation of key pluripotency and developmental genes, as functionally critical for mid-gestational developmental progression and as a possible molecular target for driving evolutionary change in animal body plan. Here, we review the current knowledge on this enigmatic nuclear receptor and how it impacts development and evolution.

UTP11 promotes the growth of hepatocellular carcinoma by enhancing the mRNA stability of Oct4

BACKGROUND

Several publications suggest that UTP11 may be a promising gene engaged for involvement of hepatocellular carcinoma (HCC) pathology. However, there are extremely limited biological, mechanistic and clinical studies of UTP11 in HCC.

METHODS

To anayze the UTP11 mRNA expression in HCC and normal clinical samples and further investigate the correlation between UTP11 expression and pathology and clinical prognosis via the Cancer Tissue Gene Atlas (TCGA) database. The protein levels of UTP11 were checked using the Human Protein Atlas (HPA) database. GO-KEGG enrichment was performed from Cancer Cell Line Encyclopedia (CCLE) database and TCGA dataset. The levels of UTP11 were tested with qRT-PCR and western blotting assays. Cell viability, immunofluorescence and flow cytometry assays and animal models were used to explore the potential involvement of UTP11 in regulating HCC growth in vitro and in vivo. The correlation of UTP11 and tumor stemness scores and stemness-associated proteins from TCGA database. The mRNA stability was treated with Actinomycin D, followed by testing the mRNA expression using qRT-PCR assay.

RESULTS

UTP11 was highly expressed in HCC samples compared to normal tissues from TCGA database. Similarly, UTP11 protein expression levels were obviously elevated in HCC tissue samples from HPA database. Furthermore, UTP11 levels were correlated with poor prognosis in HCC patient samples in TCGA dataset. In addition, the UTP11 mRNA levels was notably enhanced in different HCC cell lines than in normal liver cells and knocking down UTP11 was obviously reduced the viability and cell death of HCC cells. UTP11 knockdown suppressed the tumor growth of HCC in vivo experiment and extended the mice survival time. GO-KEEG analysis from CCLE and TCGA database suggested that UTP11 might involve in RNA splicing and the stability of mRNA. Further, UTP11 was positively correlated with tumor stemness scores and stemness-associated proteins from TCGA database. Knockdown of UTP11 was reduced the expression of stem cell-related genes and regulated the mRNA stability of Oct4.

CONCLUSIONS

UTP11 is potentially a diagnostic molecule and a therapeutic candidate for treatment of HCC.

Highly cooperative chimeric super-SOX induces naive pluripotency across species

Our understanding of pluripotency remains limited: iPSC generation has only been established for a few model species, pluripotent stem cell lines exhibit inconsistent developmental potential, and germline transmission has only been demonstrated for mice and rats. By swapping structural elements between Sox2 and Sox17, we built a chimeric super-SOX factor, Sox2-17, that enhanced iPSC generation in five tested species: mouse, human, cynomolgus monkey, cow, and pig. A swap of alanine to valine at the interface between Sox2 and Oct4 delivered a gain of function by stabilizing Sox2/Oct4 dimerization on DNA, enabling generation of high-quality OSKM iPSCs capable of supporting the development of healthy all-iPSC mice. Sox2/Oct4 dimerization emerged as the core driver of naive pluripotency with its levels diminished upon priming. Transient overexpression of the SK cocktail (Sox+Klf4) restored the dimerization and boosted the developmental potential of pluripotent stem cells across species, providing a universal method for naive reset in mammals.

Early gonadogenesis in Columba livia (birds: Columbiformes): Migration, colonization, and differentiation of germ cells

In birds, primordial germ cells (PGCs) use the bloodstream to travel to a specific region, where the cells undergo extravasation followed by intrastromal migration to the gonadal crest for further colonization. Currently, DDX4, SSEA1, and Oct4 are used to identify germ cells. Other germline cell-associated molecules are N-cadherin, GnRHR, and 3β hydroxysteroid dehydrogenase (3βHSD), which have been used in mice and birds during gonadal development; however, its role in early gonadogenesis in birds is poorly described. This study aimed to evaluate the differential immunodetection of N-cadherin binding molecule, Oct4 pluripotency protein, GnRHR receptor, and 3βHSD enzyme in Columba livia embryos during migration colonization of PGCs in the gonadal crest and early gonadogenesis. These markers were revealed by immunohistochemistry in histological preparations of C. livia corresponding to stages (S)15 to S40. Immunodetection of N-cadherin, Oct4, GnRHR, and 3βHSD in the germ line of C. livia allowed the identification of PGCs in the yolk sac membrane at the level of the splanchnic mesoderm during migration to the genital crest and its colonization. In the same way, it was possible to characterize and localize PGCs during early gonadogenesis. This study in C. livia demonstrates that Oct4, N-cadherin, GNRHR, and 3βHSD are immunodetected in PGCs and could be used as potential germline cell markers during cell migration out of blood vessels, colonization in the genital crest, and early gonadogenesis. Furthermore, this study could be used as a novel general model to understand the early gonadogenesis in altricial species.

Clinical Significance of Overexpression of Oct4 in Advanced Stage Gallbladder Carcinoma

BACKGROUND

Oct4 has critical role in maintaining pluripotency, proliferative potential, and self-renewal capacity in embryonic stem and germ cells. Although Oct4 has been shown to be upregulated in many cancers, its clinical significance in gallbladder carcinoma is poorly understood.

METHODS

We studied the expression profile of Oct4 in 61 GBC and 30 chronic cholecystitis (as control) using real time RT-PCR, western blotting, and immunohistochemistry. The expression data was correlated with clinico-pathological parameters. The diagnostic utility was assessed through ROC curve, and prognostic value was analyzed by Kaplan-Meier method.

RESULTS

Oct4 was significantly upregulated at mRNA as well as protein levels. The higher mRNA expression shows significant association with late stage, late T stage, and higher grade of tumor. A significant positive correlation was also observed with stage, T stage, and tumor grade. Sum score analysis of protein expression shows positive correlation with stage and the presence or absence of gallstone in tumor samples. The ROC curve analysis revealed the moderate diagnostic potential of Oct4. Kaplan-Meier analysis showed that patients having higher expression of Oct4 were having low mean survival compared with the patients with lower Oct4 expression.

CONCLUSION

In conclusion, our data suggests that higher expression of Oct4 may serve as potential biological indicator for tumor aggressiveness and poor prognosis of GBC.

A paradigm for post-embryonic Oct4 re-expression: E7-induced hydroxymethylation regulates Oct4 expression in cervical cancer

The Octamer-binding transcription factor-4 (Oct4) is upregulated in different malignancies, yet a paradigm for mechanisms of Oct4 post-embryonic re-expression is inadequately understood. In cervical cancer, Oct4 expression is higher in human papillomavirus (HPV)-related than HPV-unrelated cervical cancers and this upregulation correlates with the expression of the E7 oncogene. We have reported that E7 affects the Oct4-transcriptional output and Oct4-related phenotypes in cervical cancer, however, the underlying mechanism remains elusive. Here, we characterize the Oct4-protein interactions in cervical cancer cells via computational analyses and Mass Spectrometry and reveal that Methyl-binding proteins (MBD2 and MBD3), are determinants of Oct4-driven transcription. E7 triggers MBD2 downregulation and TET1 upregulation, thereby disrupting the methylation status of the Oct4 gene. This coincides with an increase in the total DNA hydroxymethylation leading to the re-expression of Oct4 in cervical cancer and likely affecting broader transcriptional patterns. Our findings reveal a previously unreported mechanism by which the E7 oncogene can regulate Oct4 re-expression and global transcriptional patterns by increasing DNA hydroxymethylation and lowering the barrier to cellular plasticity during carcinogenesis.

Effects of adriamycin on cell differentiation and proliferation in rat testis

Although adriamycin (ADR) is used to treat many cancers, it can be toxic to healthy organs including the testis. We investigated the effects of ADR on pluripotency in rat testis. Testicular damage was induced by either cumulative or single dose single dose administration of ADR in Wistar albino rats. Rats were divided randomly into three groups: untreated control, cumulative dose ADR group (2 mg/kg ADR every three days for 30 days) and single dose ADR group (15 mg/kg, single dose ADR). Testicular damage was evaluated and seminiferous tubule diameters were measured using light microscopy. Expression levels of Oct4, Sox2, Klf4, c-Myc, Utf1 and Dazl were assessed by immunohistochemistry and real time PCR. Serum testosterone levels were measured using ELISA assay. Histopathologic scores were lower and mean seminiferous tubule diameters were less compared to the ADR groups. Oct4, Sox2, Klf4 and Utf1 expressions were decreased significantly in spermatogenic cells of both cumulative and single dose ADR groups compared to the control group. We found that c-Myc expression in spermatogenic and Leydig cells were increased significantly in both ADR groups compared to the control group. Dazl expression was decreased in the cumulative adriamycin group compared to the control group, but increased in the single dose ADR group compared to both the control and cumulative ADR groups. Serum testosterone levels were decreased in both ADR groups compared to the control group. Our findings suggest that ADR is detrimental to regulation and maintenance of pluripotency in rat testis.

Maternal exposure to hyperbaric oxygen at the preimplantation stages increases apoptosis and ectopic Cdx2 expression and decreases Oct4 expression in mouse blastocysts via Nrf2-Notch1 upregulation and Nf2 downregulation

BACKGROUND

The environmental oxygen tension has been reported to impact the blastocyst quality and cell numbers in the inner cell mass (ICM) during human and murine embryogenesis. While the molecular mechanisms leading to increased ICM cell numbers and pluripotency gene expression under hypoxia have been deciphered, it remains unknown which regulatory pathways caused the underweight fetal body and overweight placenta after maternal exposure to hyperbaric oxygen (HBO).

RESULTS

The blastocysts from the HBO-exposed pregnant mice revealed significantly increased signals of reactive oxygen species (ROS) and nuclear Nrf2 staining, decreased Nf2 and Oct4 expression, increased nuclear Tp53bp1 and active caspase-3 staining, and ectopic nuclear signals of Cdx2, Yap, and the Notch1 intracellular domain (N1ICD) in the ICM. In the ICM of the HBO-exposed blastocysts, both Nf2 cDNA microinjection and Nrf2 shRNA microinjection significantly decreased the ectopic nuclear expression of Cdx2, Tp53bp1, and Yap whereas increased Oct4 expression, while Nrf2 shRNA microinjection also significantly decreased Notch1 mRNA levels and nuclear expression of N1ICD and active caspase-3.

CONCLUSION

We show for the first time that maternal exposure to HBO at the preimplantation stage induces apoptosis and impairs ICM cell specification via upregulating Nrf2-Notch1-Cdx2 expression and downregulating Nf2-Oct4 expression.

Oct4 and Hypoxia Dual-Regulated Oncolytic Adenovirus Armed with shRNA-Targeting Dendritic Cell Immunoreceptor Exerts Potent Antitumor Activity against Bladder Cancer

Immunotherapy has emerged as a promising modality for cancer treatment. Dendritic cell immunoreceptor (DCIR), a C-type lectin receptor, is expressed mainly by dendritic cells (DCs) and mediates inhibitory intracellular signaling. Inhibition of DCIR activation may enhance antitumor activity. DCIR is encoded by CLEC4A in humans and by Clec4a2 in mice. Gene gun-mediated delivery of short hairpin RNA (shRNA) targeting Clec4a2 into mice bearing bladder tumors reduces DCIR expression in DCs, inhibiting tumor growth and inducing CD8+ T cell immune responses. Various oncolytic adenoviruses have been developed in clinical trials. Previously, we have developed Ad.LCY, an oncolytic adenovirus regulated by Oct4 and hypoxia, and demonstrated its antitumor efficacy. Here, we generated a Clec4a2 shRNA-expressing oncolytic adenovirus derived from Ad.LCY, designated Ad.shDCIR, aimed at inducing more robust antitumor immune responses. Our results show that treatment with Ad.shDCIR reduced Clec4a expression in DCs in cell culture. Furthermore, Ad.shDCIR exerted cytolytic effects solely on MBT-2 bladder cancer cells but not on normal NIH 3T3 mouse fibroblasts, confirming the tumor selectivity of Ad.shDCIR. Compared to Ad.LCY, Ad.shDCIR induced higher cytotoxic T lymphocyte (CTL) activity in MBT-2 tumor-bearing immunocompetent mice. In addition, Ad.shDCIR and Ad.LCY exhibited similar antitumor effects on inhibiting tumor growth. Notably, Ad.shDCIR was superior to Ad.LCY in prolonging the survival of tumor-bearing mice. In conclusion, Ad.shDCIR may be further explored as a combination therapy of virotherapy and immunotherapy for bladder cancer and likely other types of cancer.

Application of the Yamanaka Transcription Factors Oct4, Sox2, Klf4, and c-Myc from the Laboratory to the Clinic

The transcription factors Oct4, Sox2, Klf4, and c-Myc enable the reprogramming of somatic cells into induced pluripotent cells. Reprogramming generates newly differentiated cells for potential therapies in cancer, neurodegenerative diseases, and rejuvenation processes. In cancer therapies, these transcription factors lead to a reduction in the size and aggressiveness of certain tumors, such as sarcomas, and in neurodegenerative diseases, they enable the production of dopaminergic cells in Parkinson's disease, the replacement of affected neuronal cells in olivopontocerebellar atrophy, and the regeneration of the optic nerve. However, there are limitations, such as an increased risk of cancer development when using Klf4 and c-Myc and the occurrence of abnormal dyskinesias in the medium term, possibly generated by the uncontrolled growth of differentiated dopaminergic cells and the impairment of the survival of the new cells. Therefore, the Yamanaka transcription factors have shown therapeutic potential through cell reprogramming for some carcinomas, neurodegenerative diseases, and rejuvenation. However, the limitations found in the studies require further investigation before the use of these transcription factors in humans.

SeATAC: a tool for exploring the chromatin landscape and the role of pioneer factors

Assay for Transposase-Accessible Chromatin with sequencing (ATAC-seq) reveals chromatin accessibility across the genome. Currently, no method specifically detects differential chromatin accessibility. Here, SeATAC uses a conditional variational autoencoder model to learn the latent representation of ATAC-seq V-plots and outperforms MACS2 and NucleoATAC on six separate tasks. Applying SeATAC to several pioneer factor-induced differentiation or reprogramming ATAC-seq datasets suggests that induction of these factors not only relaxes the closed chromatin but also decreases chromatin accessibility of 20% to 30% of their target sites. SeATAC is a novel tool to accurately reveal genomic regions with differential chromatin accessibility from ATAC-seq data.

Molecular Mechanisms Underlying Pluripotency and Self-Renewal of Embryonic Stem Cells

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. ESCs have two distinctive properties: ability to proliferate indefinitely, a feature referred as "self-renewal", and to differentiate into different cell types, a peculiar characteristic known as "pluripotency". Self-renewal and pluripotency of ESCs are finely orchestrated by precise external and internal networks including epigenetic modifications, transcription factors, signaling pathways, and histone modifications. In this systematic review, we examine the main molecular mechanisms that sustain self-renewal and pluripotency in both murine and human ESCs. Moreover, we discuss the latest literature on human naïve pluripotency.

Oct4 reduction contributes to testicular injury of unilateral testicular torsion in mice model and apoptotic death of Sertoli cells through mediating CIP2A expression

This study explored the mechanism of ipsilateral testis injury after ipsilateral testicular torsion detorsion (T/D) and the potential testis-protective part of the octamer-binding transcription factor 4 (Oct4)-cancerous inhibitors of protein phosphatase 2A (CIP2A) axis in a T/D animal model and in ischemia-reperfusion (IR)-treated testicular Sertoli TM4 cells. Quantitative Polymerase chain reaction (PCR) and western blot (WB) confirmed the downregulation of both CIP2A and Oct4 expression in the testicular tissue from T/D mice compared with sham-operated mice. T/D model was then established in mice with upregulated Oct4 expression in the testis. Oct4 elevation restored CIP2A expression in testes after T/D treatment. Furthermore, we observed that an increase in Oct4 ameliorated the testicular damage caused by torsion in the testis. Biochemical analysis indicated that T/D treatment increased serum anti-sperm antibody levels, but reduced testosterone levels. Meanwhile, in testicular tissue, reactive oxygen species (ROS), malondialdehyde (MDA), and activity of testicular myeloperoxidase (MPO) enzymes were promoted, while glutathione peroxidase activity (GPx) was decreased by T/D injury. Notably, testicular Oct4 restoration partially counteracted the effect of T/D treatment on these biochemical indices. Hypoxia/reoxygenation (HR) treatment was applied to TM4 cells to mimic TT injury in vitro. A gain-of-function study showed that Oct4 overexpression partly counteracted the promoting role of HR in cell damage, apoptosis, and oxidative stress in TM4 cells. These observations provide novel insights into the possible biochemical mechanism underlying the mediation of the Oct4-CIP2A axis in T/D injury.

Transcriptional activation of endogenous Oct4 via the CRISPR/dCas9 activator ameliorates Hutchinson-Gilford progeria syndrome in mice

Partial cellular reprogramming via transient expression of Oct4, Sox2, Klf4, and c-Myc induces rejuvenation and reduces aged-cell phenotypes. In this study, we found that transcriptional activation of the endogenous Oct4 gene by using the CRISPR/dCas9 activator system can efficiently ameliorate hallmarks of aging in a mouse model of Hutchinson-Gilford progeria syndrome (HGPS). We observed that the dCas9-Oct4 activator induced epigenetic remodeling, as evidenced by increased H3K9me3 and decreased H4K20me3 levels, without tumorization. Moreover, the progerin accumulation in HGPS aorta was significantly suppressed by the dCas9 activator-mediated Oct4 induction. Importantly, CRISPR/dCas9-activated Oct4 expression rescued the HGPS-associated vascular pathological features and lifespan shortening in the mouse model. These results suggest that partial rejuvenation via CRISPR/dCas9-mediated Oct4 activation can be used as a novel strategy in treating geriatric diseases.

Specific Activation of Yamanaka Factors via HSF1 Signaling in the Early Stage of Zebrafish Optic Nerve Regeneration

In contrast to the case in mammals, the fish optic nerve can spontaneously regenerate and visual function can be fully restored 3-4 months after optic nerve injury (ONI). However, the regenerative mechanism behind this has remained unknown. This long process is reminiscent of the normal development of the visual system from immature neural cells to mature neurons. Here, we focused on the expression of three Yamanaka factors (Oct4, Sox2, and Klf4: OSK), which are well-known inducers of induced pluripotent stem (iPS) cells in the zebrafish retina after ONI. mRNA expression of OSK was rapidly induced in the retinal ganglion cells (RGCs) 1-3 h after ONI. Heat shock factor 1 (HSF1) mRNA was most rapidly induced in the RGCs at 0.5 h. The activation of OSK mRNA was completely suppressed by the intraocular injection of HSF1 morpholino prior to ONI. Furthermore, the chromatin immunoprecipitation assay showed the enrichment of OSK genomic DNA bound to HSF1. The present study clearly showed that the rapid activation of Yamanaka factors in the zebrafish retina was regulated by HSF1, and this sequential activation of HSF1 and OSK might provide a key to unlocking the regenerative mechanism of injured RGCs in fish.

Isolation of a Population of Cells Co-Expressing Markers of Embryonic Stem Cells and Mesenchymal Stem Cells from the Rudimentary Uterine Horn of a Patient with Uterine Aplasia

More than 50% cells isolated from the endometrial cavity scraping and the myometrium of the rudimentary horn of an underdeveloped uterus removed from a patient with uterine aplasia and maintained under culturing conditions normal for mesenchymal stem cells (MSC) expressed embryonic transcription factors Oct4 and Nanog, embryonic cell membrane sialyl glycolipid SSEA4, and MSC markers. After 2-3 passages, the cells lost the expression of the early embryogenesis markers, but retained MSC markers. The presence of dormant stem cells in the underdeveloped endometrium and in the uterus indicates that this tissue has a regenerative potential that can be activated and used for completion of organ morphogenesis. This task requires the development of methods of early diagnosis of morphogenesis impairment and tools for safe reactivation of the ontogenesis.

Developmental Exposure to DDT Disrupts Transcriptional Regulation of Postnatal Growth and Cell Renewal of Adrenal Medulla

Dichlorodiphenyltrichloroethane (DDT) is the most widespread persistent pollutant with endocrine-disrupting properties. DDT has been shown to disrupt secretory and morphogenetic processes in the adrenal cortex. The present investigation aimed to evaluate transcriptional regulation of postnatal growth of the adrenal medulla and formation of the pools necessary for self-renewal of medullary cells in rats that developed under low-dose exposure to DDT. The study was performed using male Wistar rats exposed to low doses of o,p'-DDT during prenatal and postnatal development. Light microscopy and histomorphometry revealed diminished medulla growth in the DDT-exposed rats. Evaluation of Ki-67 expression in chromaffin cells found later activation of proliferation indicative of retarded growth of the adrenal medulla. All DDT-exposed rats exhibited a gradual decrease in tyrosine hydroxylase production by adrenal chromaffin cells. Immunohistochemical evaluation of nuclear β-catenin, transcription factor Oct4, and ligand of sonic hedgehog revealed increased expression of all factors after termination of growth in the control rats. The DDT-exposed rats demonstrated diminished increases in Oct4 and sonic hedgehog expression and lower levels of canonical Wnt signaling activation. Thus, developmental exposure to the endocrine disruptor o,p'-DDT alters the transcriptional regulation of morphogenetic processes in the adrenal medulla and evokes a slowdown in its growth and in the formation of a reserve pool of cells capable of dedifferentiation and proliferation that maintain cellular homeostasis in adult adrenals.

Oct4 promoted proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in colon cancer cells by activating the SCF/c-Kit signaling pathway

Octamer-binding transcription factor 4 (Oct4) is closely related to the occurrence and development of cancer. In the present study, we paid a special interest in exploring the effect of Oct4 on colon cancer (CC) proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) and its molecular mechanism. Immunohistochemistry (IHC) was used to detect the expression level of Oct4 in colon tissue of patients with colon cancer. Oct4 overexpression vector pcDNA-Oct4 was used to stably express Oct4 in human colon cancer cells HT29 and SW480. Cell counting kit-8 (CCK-8) assay was used to detect the cell proliferation. The invasion and migration abilities were observed by transwell and wound healing assays. The expression of EMT relate genes were observed by Western blot. We found that Oct4 was up-regulated in human colon cancer tissues than that in paracancerous tissues. The proliferation, migration, and invasion of HT29 and SW480 cells was significantly induced by transfection of pcDNA-Oct4. Furthermore, Oct4 overexpression enhanced EMT of CC cells, characterized by the increased expression of vimentin, Twist, and Snail, as well as decreased expression of E-cadherin. Mechanistically, Oct4 overexpression activated stem cell factor (SCF)/c-Kit signaling pathway in CC cells, and the SCF/c-Kit signaling inhibitor imatinib reversed pro-oncogenic effects of Oct4. These finding provide an insight into the potential of Oct4 for CC diagnosis and therapy.

Evaluation of the Effectiveness of Various Autophagy Inhibitors in A549 Cancer Stem Cells

Numerous studies have already established that autophagy plays a central role in the survival of all cells, including malignant ones. Autophagy is a central cog in the general mechanism that provides the intracellular proteostasis determining cellular physiological and phenotypic characteristics. The accumulated data show that autophagy largely contributes to cancer cell stemness. Thus, autophagy modulation is considered one of the promising pharmacological targets in therapy aimed at cancer stem cell elimination. However, autophagy is a multi-stage intracellular process that involves numerous protein participants. In addition, the process can be activated simultaneously by various signaling modules. Therefore, it is no small feat to select an effective pharmacological drug against autophagy. What's more, the search for potential chemotherapeutic agents that could eliminate cancer stem cells through pharmacological inhibition of autophagy is still under way. In the present work, we selected a panel of autophagy inhibitors (Autophinib, SBI-0206965, Siramesine, MRT68921, and IITZ-01), some of whom have been recently identified as effective autophagy inhibitors in cancer cells. Using A549 cancer cells, which express the core stem factors Oct4 and Sox2, we evaluated the effect of these drugs on the survival and preservation of the original properties of cancer stem cells. Among the agents selected, only Autophinib demonstrated a significant toxic effect on cancer stem cells. The obtained results demonstrate that autophagy inhibition by Autophinib downregulates the expression of the Sox2 protein in A549 cells, and that this downregulation correlates with a pronounced induction of apoptosis. Moreover, Autophinib-treated A549 cells are unable to form spheroids, which indicates a reduction in stemness. Thus, among the drugs studied, only Autophinib can be considered a potential agent against cancer stem cells.

LncRNA Osilr9 coordinates promoter DNA demethylation and the intrachromosomal loop structure required for maintaining stem cell pluripotency

Nuclear reprogramming of somatic cells into a pluripotent status has the potential to create patient-specific induced pluripotent stem cells for regenerative medicine. Currently, however, the epigenetic mechanisms underlying this pluripotent reprogramming are poorly understood. To delineate this epigenetic regulatory network, we utilized a chromatin RNA in situ reverse transcription sequencing (CRIST-seq) approach to identify long noncoding RNAs (lncRNAs) embedded in the 3-dimensional intrachromosomal architecture of stem cell core factor genes. By combining CRIST-seq and RNA sequencing, we identified Oct4-Sox2 interacting lncRNA 9 (Osilr9) as a pluripotency-associated lncRNA. Osilr9 expression was associated with the status of stem cell pluripotency in reprogramming. Using short hairpin RNA (shRNA) knockdown, we showed that this lncRNA was required for the optimal maintenance of stem cell pluripotency. Overexpression of Osilr9 induced robust activation of endogenous stem cell core factor genes in fibroblasts. Osilr9 participated in the formation of the intrachromosomal looping required for the maintenance of pluripotency. After binding to the Oct4 promoter, Osilr9 recruited the DNA demethylase ten-eleven translocation 1, leading to promoter demethylation. These data demonstrate that Osilr9 is a critical chromatin epigenetic modulator that coordinates the promoter activity of core stem cell factor genes, highlighting the critical role of pluripotency-associated lncRNAs in stem cell pluripotency and reprogramming.

Regulation of Oct4 in stem cells and neural crest cells

During embryonic development, cells gradually restrict their developmental potential as they exit pluripotency and differentiate into various cell types. The POU transcription factor Oct4 (encoded by Pou5f1) lies at the center of the pluripotency machinery that regulates stemness and differentiation in stem cells, and is required for reprogramming of somatic cells into induced pluripotent stem cells (iPSCs). Several studies have revealed that Oct4 and other stemness genes are also expressed in multipotent cell populations such as neural crest cells (NCCs), and are required to expand the NCC developmental potential. Transcriptional regulation of Oct4 has been studied extensively in stem cells during early embryonic development and reprogramming, but not in NCCs. Here, we review how Oct4 is regulated in pluripotent stem cells, and address some of the gaps in knowledge about regulation of the pluripotency network in NCCs.

Oct4:Sox2 binding is essential for establishing but not maintaining active and silent states of dynamically regulated genes in pluripotent cells

Much has been learned about the mechanisms of action of pluripotency factors Oct4 and Sox2. However, as with other regulators of cell identity, little is known about the impact of disrupting their binding motifs in a native environment or the characteristics of genes they regulate. By quantitatively examining dynamic ranges of gene expression instead of focusing on conventional measures of differential expression, we found that Oct4 and Sox2 enhancer binding is strongly enriched near genes subject to large dynamic ranges of expression among cell types, with binding sites near these genes usually within superenhancers. Mutagenesis of representative Oct4:Sox2 motifs near such active, dynamically regulated genes revealed critical roles in transcriptional activation during reprogramming, with more limited roles in transcriptional maintenance in the pluripotent state. Furthermore, representative motifs near silent genes were critical for establishing but not maintaining the fully silent state, while genes whose transcript levels varied by smaller magnitudes among cell types were unaffected by nearby Oct4:Sox2 motifs. These results suggest that Oct4 and Sox2 directly establish both active and silent transcriptional states in pluripotent cells at a large number of genes subject to dynamic regulation during mammalian development, but are less important than expected for maintaining transcriptional states.

Oct4 cooperates with c-Myc to improve mesenchymal-to-endothelial transition and myocardial repair of cardiac-resident mesenchymal stem cells

BACKGROUND

Cardiac-resident mesenchymal stem cells (cMSCs) can exhibit fibrotic, proinflammatory, and proangiogenic phenotype in response to myocardial ischemia (Isch). How their phenotypic fate decisions are determined remains poorly understood. Here, we demonstrate that the cooperation of Oct4 and c-Myc in cMSCs creates a preferable mesenchymal-to-endothelial transition (MEndoT) to promote angiogenesis and consequent myocardial repair.

METHODS

We collected MSCs from cardiac and peripheral blood of rat with left ventricular Isch (LV Isch) 30 days after myocardial infarction (MI) or sham operation. After a comparison of characterization between cMSCs and peripheral blood MSCs (pbMSCs), we conducted transcriptome analysis and RNA sequencing of cMSCs. Using loss/gain-of-function approaches to understand the cooperation of c-Myc and Oct4 on MEndoT of cMSCs under hypoxic condition, we explored the mechanisms through transcriptome and functional experiment, and chromatin immunoprecipitation. Next, we transplanted male cMSCs with overexpression or inhibition of c-Myc/Oct4 into the infarcted myocardium of female rats and evaluated infarct size, cell retention, inflammation, remodeling, and function after 30 days.

RESULTS

LV Isch switched cMSCs toward both inflammatory and proangiogenic phenotypes, with increased secretion of inflammatory cytokines as well as decreased expression of proangiogenic factors. The effect of LV Isch on pbMSCs was less remarkable. Gene expression heatmap showed imbalance in expression of Oct4 and c-Myc regulating genes associated with remodeling of cMSCs. We provided evidence that cMSCs-specific c-Myc- versus Oct4-overexpression showed divergent genomic signatures, and their corresponding target genes play an important role in regulating cMSCs phenotypic changes. In particular, Oct4 accelerated angiogenesis induced by c-Myc overexpression in cMSCs and inhibited their phenotypic transition into inflammatory cells and fibroblast. Mechanistically, exogenous Oct4 caused c-Myc to translocate from the nucleus to the cytoplasm and activated some of its target signalings including VEGF signaling. Although transplantation of cMSCs alone did not improve LV remodeling and function, cMSCs co-transfected with c-Myc and Oct4 promoted a more positive effect in their survival and reparative properties, increased animal survival, reduced infarct size, decreased scar thickness, inhibited LV remodeling, and improved heart function 30 days after MI. Significantly, Oct4 promoted MEndoT ("Rescue me" signal) of cMSCs after both c-Myc stimulation in vitro and transplantation into the infarcted heart.

CONCLUSIONS

Myocardial Isch drives resident cMSCs toward multiple phenotypes. Oct4 interacts with c-Myc to promote MEndoT capacity of cMSCs and improve their survival and reparative effects through upregulation of angiogenesis-related signaling pathways. These findings may identify novel targets for stem cell therapy.

ISG15 enhances glioma cell stemness by promoting Oct4 protein stability

The effects of ISG15 or ISGylation on tumor progression have been widely revealed; however, its roles in glioma progression are largely unknown. This study aims to explore the roles and underlying mechanisms of ISG15 in glioma progression. Here, ISG15 level was found to be upregulated in glioma tissues compared to the paired/unpaired normal tissues, and positively correlated with the level of stemness markers in glioma tissues. Loss of functional experiments indicated that ISG15 positively regulated glioma cell stemness, as evident by the increase of sphere formation ability, ALDH activity, stemness marker expression, and tumor-initiating ability. Further mechanistic studies revealed that ISG15 directly interacted with Oct4 protein, a critical stemness promoter, induced the ISGylation of Oct4 protein, and thus enhanced Oct4 protein stability. Additionally, it was found that Oct4 was ISGylated at lysine 284 (K284), which has been confirmed to be the ubiquitination site of Oct4 protein, and ISG15 knockdown did not degrade K284R mutant Oct4. Furthermore, ISG15 knockdown-induced downregulation of glioma cell stemness was rescued by Oct4 overexpression, but not by K284R mutant Oct4. Altogether, we suggest that ISG15-induced ISGylation of Oct4 protein is essential for glioma cell stemness.

Stub1 maintains proteostasis of master transcription factors in embryonic stem cells

The pluripotency and differentiation states of embryonic stem cells (ESCs) are regulated by a set of core transcription factors, primarily Sox2, Oct4, and Nanog. Although their transcriptional regulation has been studied extensively, the contribution of posttranslational modifications in Sox2, Oct4, and Nanog are poorly understood. Here, using a CRISPR-Cas9 knockout library screen in murine ESCs, we identify the E3 ubiquitin ligase Stub1 as a negative regulator of pluripotency. Manipulation of Stub1 expression in murine ESCs shows that ectopic Stub1 expression significantly reduces the protein half-life of Sox2, Oct4, and Nanog. Mechanistic investigations reveal Stub1 catalyzes the polyubiquitination and 26S proteasomal degradation of Sox2 and Nanog through K48-linked ubiquitin chains and Oct4 via K63 linkage. Stub1 deficiency positively enhances somatic cell reprogramming and delays differentiation, whereas its enforced expression triggers ESC differentiation. The discovery of Stub1 as an integral pluripotency regulator strengthens our understanding of ESC regulation beyond conventional transcriptional control mechanisms.

The functional diversity of the POUV-class proteins across vertebrates

POUV is a relatively newly emerged class of POU transcription factors present in jawed vertebrates (Gnathostomata). The function of POUV-class proteins is inextricably linked to zygotic genome activation (ZGA). A large body of evidence now extends the role of these proteins to subsequent developmental stages. While some functions resemble those of other POU-class proteins and are related to neuroectoderm development, others have emerged de novo. The most notable of the latter functions is pluripotency control by Oct4 in mammals. In this review, we focus on these de novo functions in the best-studied species harbouring POUV proteins-zebrafish, Xenopus (anamniotes) and mammals (amniotes). Despite the broad diversity of their biological functions in vertebrates, POUV proteins exert a common feature related to their role in safeguarding the undifferentiated state of cells. Here we summarize numerous pieces of evidence for these specific functions of the POUV-class proteins and recap available loss-of-function data.

Oct4 differentially regulates chromatin opening and enhancer transcription in pluripotent stem cells

The transcription factor Oct4 is essential for the maintenance and induction of stem cell pluripotency, but its functional roles are not fully understood. Here, we investigate the functions of Oct4 by depleting and subsequently recovering it in mouse embryonic stem cells (ESCs) and conducting a time-resolved multiomics analysis. Oct4 depletion leads to an immediate loss of its binding to enhancers, accompanied by a decrease in mRNA synthesis from its target genes that are part of the transcriptional network that maintains pluripotency. Gradual decrease of Oct4 binding to enhancers does not immediately change the chromatin accessibility but reduces transcription of enhancers. Conversely, partial recovery of Oct4 expression results in a rapid increase in chromatin accessibility, whereas enhancer transcription does not fully recover. These results indicate different concentration-dependent activities of Oct4. Whereas normal ESC levels of Oct4 are required for transcription of pluripotency enhancers, low levels of Oct4 are sufficient to retain chromatin accessibility, likely together with other factors such as Sox2.

Long noncoding RNA OIP5-AS1 promotes the stemness of lung cancer cells through enhancing Oct4 mRNA stability

Long noncoding RNA (lncRNA) OIP5-AS1 was shown to facilitate drug resistance and metastasis in several tumors. As cancer stem cells (CSCs) have been elucidated as the origin of drug resistance and tumor progression, we speculate that lncRNA OIP5-AS1 holds critical roles in the CSC-like traits of lung cancer. Here, lncRNA OIP5-AS1 was found to be highly expressed in lung cancer cell spheres. Following experiments showed that OIP-AS1 knockdown reduced the CSC-like traits of lung cancer spheres, while overexpression of OIP-AS1 conferred the CSC-like traits in lung cancer cells by performing sphere-formation analysis, detecting stemness marker expression, and ALDH activity. Mechanistic studies revealed that lncRNA OIP5-AS1 could increase Oct4 expression by directly interacting with Oct4 mRNA and enhancing Oct4 mRNA stability. Finally, we found that the knockdown of Oct4 could rescue the promoting effects of OIP5-AS1 overexpression on the CSC-like traits of lung cancer. These results demonstrate that lncRNA OIP5-AS1 can confer lung cancer CSC-like traits by directly interacting with Oct4 mRNA and thus increasing Oct4 mRNA stability and expression.

Oct4 facilitates chondrogenic differentiation of mesenchymal stem cells by mediating CIP2A expression

Bone development and cartilage formation require strict modulation of gene expression for mesenchymal stem cells (MSCs) to progress through their differentiation stages. Octamer-binding transcription factor 4 (Oct4) expression is generally restricted to developing embryonic pluripotent cells, but its role in chondrogenic differentiation (CD) of MSCs remains unclear. We therefore investigated the role of Oct4 in CD using a microarray, quantitative real-time polymerase chain reaction, and western blotting. The expression of Oct4 was elevated when the CD of cultured MSCs was induced. Silencing Oct4 damaged MSC growth and proliferation and decreased CD, indicated by decreased cartilage matrix formation and the expression of Col2a1, Col10a1, Acan, and Sox9. We found a positive correlation between the expression of CIP2A, a natural inhibitor of protein phosphatase 2A (PP2A) and that of Oct4. Cellular inhibitor of PP2A (CIP2A) expression gradually increased after CD. Overexpression of CIP2A in MSCs with Oct4 depletion promoted cartilage matrix deposition as well as Col2a1, Col10a1, Acan, and Sox9 expression. The chondrogenic induction triggered c-Myc, Akt, ERK, and MEK phosphorylation and upregulated c-Myc and mTOR expression, which was downregulated upon Oct4 knockdown and restored by CIP2A overexpression. These findings indicated that Oct4 functions as an essential chondrogenesis regulator, partly via the CIP2A/PP2A pathway.

Oct4 dependent chromatin activation is required for chicken primordial germ cell migration

Primordial germ cells (PGCs) are the undifferentiated progenitors of the gametes. Unlike the poor maintenance of cultured mammalian PGCs, the avian PGCs can be expanded in vitro indefinitely while preserving pluripotency and germline competence. In mammals, the Oct4 is the master transcription factor that ensures the stemness of pluripotent cells such as PGCs, but the specific function of Oct4 in chicken PGCs remains unclear. As expected, the loss of Oct4 in chicken PGCs reduced the expression of key pluripotency factors and promoted the genes involved in endoderm and ectoderm differentiation. Furthermore, the global active chromatin was reduced as shown by the depletion of the H3K27ac upon Oct4 suppression. Interestingly, the de-activated chromatin caused the down-regulation of adjacent genes which are mostly known regulators of cell junction, chemotaxis and cell migration. Consequently, the Oct4-deficient PGCs show impaired cell migration and could not colonize the gonads when re-introduced into the bloodstream of the embryo. We propose that, in addition to maintaining pluripotency, the Oct4 mediated chromatin activation is dictating chicken PGC migration.

Metabolomics analysis reveals Oct4 overexpression drives metabolic reprogramming and enhanced glycolysis and pentose phosphate pathway in lung adenocarcinoma cells

Poor prognosis in the underlying mechanisms involved in lung adenocarcinoma and its treatment leads to low survival rates in patients. Emerging evidence indicates that cancer is primarily a metabolic disease and metabolic reprogramming is a well-established hallmark and driving force of cancer. Oct4, acting as an oncogene, is a major regulator of cell pluripotency. It can reprogram the differentiated cells into cancer stem cells (CSCs) and plays an oncogenic role when pathologically hijacked. However, data that Oct4, the genetic reprogramming factor, could induce metabolic reprogramming has been very limited and the direct evidence in metabolic level whether Oct4 reprograms metabolome is lacking. In the present study, integrated untargeted and targeted metabolomics analyses were utilized to investigate metabolic changes induced by Oct4 overexpression in lung adenocarcinoma cells. The results suggested that elevated expression levels of Oct4 drives metabolic reprogramming. Oct4 overexpression redirects glucose catabolism to glycolysis pathway and to the oxidative pentose phosphate pathway (PPP). This study identifies unique pathways that are candidate therapeutic targets for the treatment of lung adenocarcinoma. This study also aims to improve our understanding of the cancer-promoting activity of Oct4 and help identify novel diagnostic and therapeutic strategies for cancer treatment.

Partial epithelial-mesenchymal transition during enamel development

Objectives

We set out to investigate whether a hybrid stem‐like p‐EMT phenotype develops during murine molar enamel development in vivo.

Setting and Sample Population

Histology specimens incorporating molar tooth buds harvested from mice at post‐natal day 4 (P4) were included in our studies.

Materials and Methods

We employed double immunofluorescence staining to analyze the simultaneous expression of the epithelial marker E‐cadherin and the mesenchymal marker N‐cadherin in histology specimens with tooth buds harvested from P4 mice. Moreover, we evaluated the expression of the core master stem cell markers Oct4 and Sox2, as well as the mature ameloblast marker amelogenin.

Results

Here we document the co‐expression of E‐cadherin and N‐cadherin in a sub‐population of pre‐ameloblasts in the inner enamel epithelium suggestive of the presence of a hybrid epithelial/mesenchymal phenotype resulting from p‐EMT. Moreover, the core stem cell factors Oct4 and Sox2 colocalized with E‐cadherin expressing pre‐ameloblasts, whereas the mesenchymal marker N‐cadherin was expressed specifically by amelogenin–positive mature secretory ameloblasts.

Conclusions

The differentiation of E‐cadherin–positive pre‐ameloblasts towards N‐cadherin–positive mature secretory ameloblasts transition through a previously unidentified epithelial/mesenchymal stage derived through p‐EMT, co‐expressing the master transcription factors Oct4 and Sox2.

NBMA Promotes Spermatogenesis by Mediating Oct4 Pathway

Non-obstructive azoospermia is one of the most common causes of male infertility, but there is still no specific treatment drug. Given that the Oct4 (Octamer-binding transcription factor 4) has an important regulatory effect on spermatogenesis, activating it can effectively promote spermatogenesis, so it is of great value to develop Oct4-targeted drug design and elucidating its mechanism of action. Here, we screened out the Oct4-targeted drug molecule NBMA (N-benzyl-4-methoxy-2-(1-(4-(trifluoromethyl)phenyl)vinyl)aniline) by computer-assisted technology, and found that it has a significant promoting effect on spermatogenesis in the established mouse azoospermia model. Subsequently, through transcriptome sequencing and enrichment analysis, real-time fluorescent quantitative PCR (qPCR) and western blot experiments revealed that NBMA promotes the differentiation of spermatogonial stem cells by activating the Oct4 pathway, thereby promoting spermatogenesis. This study proves that NBMA is a molecule with great potential to be developed as a therapeutic drug for azoospermia. It also shows that computer-assisted, chemical and biological multidisciplinary methods play a very important role in innovative drug discovery.

Transcription factors specifically control change

Transcription factors are defined by their sequence-specific binding to DNA and by their selective impacts on gene expression, depending on specific binding sites. The factor binding motifs in the DNA should thus represent a blueprint of regulatory logic, suggesting that transcription factor binding patterns on the genome (e.g., measured by ChIP-seq) should indicate which target genes the factors are directly controlling. However, although genetic data confirm high impacts of transcription factor perturbation in embryology, transcription factors bind to far more sites than the number of genes they dynamically regulate, when measured by direct perturbation in a given cell type. Also, deletion of carefully chosen transcription factor binding sites often gives disappointingly weak results. In a new study in the previous issue of Genes & Development, Lo and colleagues (pp. 1079-1095) reconcile these contradictions by using an elegant experimental system to directly compare the roles of transcription factor-binding site interaction in gene regulation maintenance with roles of the same factor-site interactions in gene regulation through developmental change. They examine Oct4:Sox2 shared target genes under maintained versus reinduced pluripotency conditions within the same cell clone. The results show that the same factor-site interaction impacts can appear modest in assays in developmental steady-state but are far more important as regulatory catalysts of developmental change.

Distinguishing Between Endodermal and Pluripotent Stem Cell Lines During Somatic Cell Reprogramming

Mouse somatic cell reprogramming using Oct4, Sox2, Klf4 and c-Myc (OSKM) induces formation of two stem cell types: induced pluripotent stem (iPS) cells and induced extraembryonic endoderm stem (iXEN) cells. Since both stem cells types routinely arise alongside one another during reprogramming, it is critical to distinguish between both cell types to ensure that the desired cell population is selected and analyzed. This chapter details, from start to finish, how to reprogram mouse embryonic fibroblasts (MEFs) using retrovirus and how to distinguish between iXEN and iPS cells at the colony and single-cell levels.

Counterintuitive production of tumor-suppressive secretomes from Oct4- and c-Myc-overexpressing tumor cells and MSCs

Background: Advanced breast cancer frequently metastasizes to bone, but inhibiting tumor progression in chemotherapy may occasionally enhance tumorigenesis. Here, we employed a counterintuitive approach of overexpressing Yamanaka factors (Oct4, c-Myc, Sox2, and Klf4) and examined a conditioned medium (CM)-based treatment option with induced tumor-suppressing cells (iTSCs).

Methods:In vitro proliferation and migration assays were conducted using tumor cell lines derived from breast cancer, as well as prostate and pancreatic cancers, and osteosarcoma. The tumor-suppressing capability of iTSC-derived CM was evaluated using freshly isolated breast cancer tissues and a mouse model of mammary tumors and tumor-induced osteolysis. The regulatory mechanism was evaluated using Western blotting, immunoprecipitation, pull-down, gene overexpression, and RNA interference based on mass spectrometry-based proteomics data.

Results: The overexpression of Oct4 and c-Myc in tumor cells and MSCs, but not Sox2 or Klf4, generated anti-tumor CM, which suppressed the progression of mammary tumors and tumor-induced bone loss. Notably, CM downregulated histone demethylase, and PDL-1, a blocker of T-cell-based immune responses. Whole-genome proteomics predicted enolase 1 (Eno1), Hsp90ab1, Eef2, and vinculin as extracellular tumor suppressors. Specifically, CD44 was co-immunoprecipitated with Eno1 and the silencing of CD44 suppressed Eno1's anti-tumor action. The overexpression of Oct4 and c-Myc also generated secretomes that inhibited the development of bone-resorbing osteoclasts.

Conclusions: In analogous to cell competition in which Myc-overexpressing cells in Drosophila and mouse embryos remove neighboring cells with a lower level of Myc, this study presented the possibility of eliminating tumor cells by the secretory proteomes derived from Myc/Oc4-overexpressing iTSCs.

Distinct role of histone chaperone Asf1a and Asf1b during fertilization and pre-implantation embryonic development in mice

Background

Asf1 is a well-conserved histone chaperone that regulates multiple cellular processes in different species. Two paralogous genes, Asf1a and Asf1b exist in mammals, but their role during fertilization and early embryogenesis remains to be investigated further.

Methods

We analyzed the dynamics of histone chaperone Asf1a and Asf1b in oocytes and pre-implantation embryos in mice by immunofluorescence and real-time quantitative PCR, and further investigated the role of Asf1a and Asf1b during fertilization and pre-implantation development by specific Morpholino oligos-mediated knock down approach.

Results

Immunofluorescence with specific antibodies revealed that both Asf1a and Asf1b were deposited in the nuclei of fully grown oocytes, accumulated abundantly in zygote and 2-cell embryonic nuclei, but turned low at 4-cell stage embryos. In contrast to the weak but definite nuclear deposition of Asf1a, Asf1b disappeared from embryonic nuclei at morula and blastocyst stages. The knockdown of Asf1a and Asf1b by specific Morpholino oligos revealed that Asf1a but not Asf1b was required for the histone H3.3 assembly in paternal pronucleus. However, knockdown of either Asf1a or Asf1b expression decreased developmental potential of pre-implantation embryos. Furthermore, while Asf1a KD severely reduced H3K56 acetylation level and the expression of Oct4 in blastocyst stage embryos, Asf1b KD almost eliminated nuclear accumulation of proliferating cell marker-PCNA in morula stage embryos. These results suggested that histone chaperone Asf1a and Asf1b play distinct roles during fertilization and pre-implantation development in mice.

Conclusions

Our data suggested that both Asf1a and Asf1b are required for pre-implantation embryonic development. Asf1a regulates H3K56ac levels and Oct4 expression, while Asf1b safeguards pre-implantation embryo development by regulating cell proliferation. We also showed that Asf1a, but not Asf1b, was necessary for the assembly of histone H3.3 in paternal pronuclei after fertilization.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13072-021-00430-7.

CCCTC-binding factor is an upstream regulator of the pluripotency factor Oct4 and functions in active transcription of linc1253 and linc1356 genes in pluripotent cells

The embryonic stem cell- (ESC) specific transcription factor Oct4 is a well-known master regulator of pluripotency. The aim of this study was to identify upstream regulators of Oct4 and explore their functional link in regulating lincRNA expression in ESCs. By quantitative real-time PCR (RT-qPCR) analysis upon CCCTC-binding factor (CTCF) or Oct4 knockdown, here, we found that the chromatin insulator CTCF transcriptionally controls Oct4 gene expression in mouse ES cells. Furthermore, co-immunoprecipitation assays showed that CTCF physically interacts with Oct4. By analyzing CTCF and Oct4 ChIP-seq datasets in mouse ES cells and investigating their genomic occupancies, we demonstrated that CTCF and Oct4 share overlapping regulatory functions and are required for active transcription of long intergenic non-coding RNAs (lincRNAs) linc1253 and linc1356, which were reported to repress cellular lineage programs and maintain a pluripotent state. In summary, we propose an integrated model of transcriptional control mediated by CTCF, the master weaver of the genome, for the upstream regulation of Oct4-and ESC-associated genes. These results connect the chromatin insulator CTCF and the pluripotency factor Oct4 in the regulation of lincRNAs in pluripotent cells.

The Prognostic Value of Cancer Stem Cell Markers in Cervical Cancer: A Systematic Review and Meta-Analysis

OBJECTIVES

Prognostic biomarkers in cervical cancer are widely investigated, including cancer stem cell (CSC) markers. However, their significance remains uncertain. This study aimed to determine the role of cervical cancer stem cell (CCSC) markers for survival.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis (PROSPERO CRD42021237072) of studies reporting CCSC markers as the prognostic predictor based on PRISMA guidelines. We included English articles investigating associations of CCSCs expression in tissue tumor with overall survival (OS) or disease-free survival (DFS) from PubMed, EBSCO, and The Cochrane Library databases. The quality of studies was analyzed based on Newcastle-Ottawa Quality Assessment Scale.

RESULTS

From 413 publications, after study selection with inclusion and exclusion criteria, 22 studies were included. High expressions of CCSC markers were associated with poor OS and DFS (HR= 1.05, 95% CI: 1.03 - 1.07, P <0.0001; HR= 1.31, 95% CI: 1.09 - 1.17, P <0.00001; respectively). Sub-analysis of individual CCSC markers indicated significant correlations between CD44 (HR= 1.14, 95% CI: 1.07 - 1.22, P 0.0001), SOX2 (HR= 1.58, 95% CI: 1.17 - 2.14, P 0.003), OCT4 (HR= 1.03, 95% CI: 1.01 - 1.06, P 0.008), ALDH1 (HR= 1.36, 95% CI: 1.13 - 1.64, P 0.001), and CD49f (HR= 3.02, 95% CI: 1.37 - 6.64, P 0.006) with worse OS; OCT4 (HR= 1.14, 95% CI 1.06 - 1.22, P 0.0003), SOX2 (HR= 1.11, 95% CI: 1.06 - 1.16, P <0.0001), and ALDH1 (HR= 1.22, 95% CI: 1.10 - 1.35, P 0.0002) with poor DFS. We did not conduct a meta-analysis for MSI-1 and CK17 because only one study investigated those markers.

CONCLUSION

Expressions of OCT4, SOX2, and ALDH1 were associated with poor OS and DFS in cervical cancer tissue. These markers might have potential roles as prognostic biomarkers to predict unfavorable survival.

Oct4 downregulation-induced inflammation increases the migration and invasion rate of oral squamous cell carcinoma

Inflammatory changes are involved in tumor cell proliferation, migration, and invasion. Tumor necrosis factor-α (TNF-α) and lipopolysaccharide (LPS) play important roles in inflammatory regulation during tumor development. Oct4 acts as a transcription factor that modulates inflammatory changes in mesenchymal stem cells. In this study, we explored the role of Oct4 in the invasion and migration of oral squamous cell carcinoma (OSCC) cells. LPS and TNF-α were used to treat the OSCC cell lines HN4 and CAL27 to induce inflammation. The generation of inflammatory cytokines, including TNF-α, interleukin (IL)-1β, and IL-6, was evaluated by enzyme-linked immunosorbent assay and real-time quantitative PCR. Western blot analysis was employed to detect the expression and phosphorylation of JNK1, p65, and STAT3, which are key modulators of inflammation. Wound scratch healing and transwell invasion assays were further used to determine the role of inflammation in the invasion and migration of OSCC cells. Robust inflammation was observed in HN4 and CAL27 cells treated with LPS and TNF-α. A marked increase in JNK1, p65, and STAT3 phosphorylation levels in OSCC cells was also detected after LPS and TNF-α treatment. The migration and invasion of HN4 and CAL27 cells were significantly boosted by stimulation with LPS and TNF-α. Furthermore, Oct4 mRNA and protein levels were significantly upregulated by stimulation with LPS and TNF-α. Silencing of Oct4 led to reduced inflammation and decreased levels of phosphorylated JNK1, p65, and STAT3 and impaired invasion and migration in LPS- and TNF-α-stimulated OSCC cells. Overall, LPS- and TNF-α-induced inflammation suppressed the migration and invasion of OSCC cells by upregulating Oct4 expression.

Hydroquinone 5-O-Cinnamoyl Ester of Renieramycin M Suppresses Lung Cancer Stem Cells by Targeting Akt and Destabilizes c-Myc

Cancer stem cells (CSCs) are distinct cancer populations with tumorigenic and self-renewal abilities. CSCs are drivers of cancer initiation, progression, therapeutic failure, and disease recurrence. Thereby, novel compounds targeting CSCs offer a promising way to control cancer. In this study, the hydroquinone 5-O-cinnamoyl ester of renieramycin M (CIN-RM) was demonstrated to suppress lung cancer CSCs. CIN-RM was toxic to lung cancer cells with a half-maximal inhibitory concentration of around 15 µM. CIN-RM suppressed CSCs by inhibiting colony and tumor spheroid formation. In addition, the CSC population was isolated and treated and the CSCs were dispatched in response to CIN-RM within 24 h. CIN-RM was shown to abolish cellular c-Myc, a central survival and stem cell regulatory protein, with the depletion of CSC markers and stem cell transcription factors ALDH1A1, Oct4, Nanog, and Sox2. For up-stream regulation, we found that CIN-RM significantly inhibited Akt and consequently decreased the pluripotent transcription factors. CIN-RM also inhibited mTOR, while slightly decreasing p-GSK3β (Ser9) but rarely affected the protein kinase C (PKC) signal. Inhibiting Akt/mTOR induced ubiquitination of c-Myc and promoted degradation. The mechanism of how Akt regulates the stability of c-Myc was validated with the Akt inhibitor wortmannin. The computational analysis further confirmed the strong interaction between CIN-RM and the Akt protein with a binding affinity of −10.9 kcal/mol at its critical active site. Taken together, we utilized molecular experiments, the CSC phenotype, and molecular docking methods to reveal the novel suppressing the activity of this compound on CSCs to benefit CSC-targeted therapy for lung cancer treatment.

Key features of the POU transcription factor Oct4 from an evolutionary perspective

Oct4, a class V POU-domain protein that is encoded by the Pou5f1 gene, is thought to be a key transcription factor in the early development of mammals. This transcription factor plays indispensable roles in pluripotent stem cells as well as in the acquisition of pluripotency during somatic cell reprogramming. Oct4 has also been shown to play a role as a pioneer transcription factor during zygotic genome activation (ZGA) from zebrafish to human. However, during the past decade, several studies have brought these conclusions into question. It was clearly shown that the first steps in mouse development are not affected by the loss of Oct4. Subsequently, the role of Oct4 as a genome activator was brought into doubt. It was also found that the reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) could proceed without Oct4. In this review, we summarize recent findings, reassess the role of Oct4 in reprogramming and ZGA, and point to structural features that may underlie this role. We speculate that pluripotent stem cells resemble neural stem cells more closely than previously thought. Oct4 orthologs within the POUV class hold key roles in genome activation during early development of species with late ZGA. However, in Placentalia, eutherian-specific proteins such as Dux overtake Oct4 in ZGA and endow them with the formation of an evolutionary new tissue-the placenta.

The Pro-Survival Oct4/Stat1/Mcl-1 Axis Is Associated with Poor Prognosis in Lung Adenocarcinoma Patients

The embryonic stem cell marker Oct4 is expressed in several human cancers and is positively correlated with a poor outcome in cancer patients. However, its physiological role in cancer progression remains poorly understood. Tumor cells block apoptosis to escape cell death so that they can proliferate indefinitely, leading to ineffective therapy for cancer patients. In this study, we investigated whether Oct4 regulates the apoptosis pathway and contributes to poor prognosis in patients with lung adenocarcinoma. Our results revealed that Oct4 expression is correlated with Stat1 expression in lung adenocarcinoma patients and Oct4 is directly bound to the Stat1 promoter to transactivate Stat1 in lung adenocarcinoma cells. Expression of the Stat1 downstream gene Mcl-1 increased in Oct4-overexpressing cancer cells, while Stat1 knockdown in Oct4-overexpressing cancer cells sensitized them to cisplatin-induced apoptosis. Furthermore, Oct4 promoted Stat1 expression and tumor growth, whereas silencing of Stat1 reduced Oct4-induced tumor growth in human lung tumor xenograft models. Taken together, we demonstrate that Oct4 is a pro-survival factor by inducing Stat1 expression and that the Oct4/Stat1/Mcl-1 axis may be a potential therapeutic target for lung adenocarcinoma.

Cell-Permeable Oct4 Gene Delivery Enhances Stem Cell-like Properties of Mouse Embryonic Fibroblasts

Direct conversion of one cell type into another is a trans-differentiation process. Recent advances in fibroblast research revealed that epithelial cells can give rise to fibroblasts by epithelial-mesenchymal transition. Conversely, fibroblasts can also give rise to epithelia by undergoing a mesenchymal to epithelial transition. To elicit stem cell-like properties in fibroblasts, the Oct4 transcription factor acts as a master transcriptional regulator for reprogramming somatic cells. Notably, the production of gene complexes with cell-permeable peptides, such as low-molecular-weight protamine (LMWP), was proposed to induce reprogramming without cytotoxicity and genomic mutation. We designed a complex with non-cytotoxic LMWP to prevent the degradation of Oct4 and revealed that the positively charged cell-permeable LMWP helped condense the size of the Oct4-LMWP complexes (1:5 N:P ratio). When the Oct4-LMWP complex was delivered into mouse embryonic fibroblasts (MEFs), stemness-related gene expression increased while fibroblast intrinsic properties decreased. We believe that the Oct4-LMWP complex developed in this study can be used to reprogram terminally differentiated somatic cells or convert them into stem cell-like cells without risk of cell death, improving the stemness level and stability of existing direct conversion techniques.

Oct4-dependent FoxC1 activation improves the survival and neovascularization of mesenchymal stem cells under myocardial ischemia

Background

The administration of mesenchymal stem cells (MSCs) remains the most promising approach for cardiac repair after myocardial infarct (MI). However, their poor survival and potential in the ischemic environment limit their therapeutic efficacy for heart repair after MI. The purpose of this study was to investigate the influence of FoxC1-induced vascular niche on the activation of octamer-binding protein 4 (Oct4) and the fate of MSCs under hypoxic/ischemic conditions.

Methods

Vascular microenvironment/niche was induced by efficient delivery of FoxC1 transfection into hypoxic endothelial cells (ECs) or infarcted hearts. MSCs were cultured or injected into this niche by utilizing an in vitro coculture model and a rat MI model. Survival and neovascularization of MSCs regulated by Oct4 were explored using gene transfer and functional studies.

Results

Here, using gene expression heatmap, we demonstrated that cardiac ECs rapidly upregulated FoxC1 after acute ischemic cardiac injury, contributing to an intrinsic angiogenesis. In vitro, FoxC1 accelerated tube-like structure formation and increased survival of ECs, resulting in inducing a vascular microenvironment. Overexpression of FoxC1 in ECs promoted survival and neovascularization of MSCs under hypoxic coculture. Overexpression of Oct4, a FoxC1 target gene, in MSCs enhanced their mesenchymal-to-endothelial transition (MEndoT) while knockdown of Oct4 by siRNA altering vascularization. In a rat MI model, overexpression of FoxC1 in ischemic hearts increased post-infarct vascular density and improved cardiac function. The transplantation of adOct4-pretreated MSCs into these ischemic niches augments MEndoT, enhanced vascularity, and further improved cardiac function. Consistently, these cardioprotective effects of FoxC1 was abrogated when Oct4 was depleted in the MSCs and was mimicked by overexpression of Oct4.

Conclusions

Together, these studies demonstrate that the FoxC1/Oct4 axis is an essential aspect for survival and neovascularization of MSCs in the ischemic conditions and represents a potential therapeutic target for enhancing cardiac repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02553-w.