Sox2, a key factor in the regulation of pluripotency and neural differentiation

Human neural rosettes secrete bioactive extracellular vesicles enriched in neuronal and glial cellular components

Extracellular vesicles (EVs) play a critical role in the development of neural cells in the central nervous system (CNS). Human neural rosettes (hNRs) are radial cell structures that assemble from induced pluripotent stem cells (hiPSCs) and recapitulate some stages of neural tube morphogenesis. Here we show that hiPSCs and hNRs secrete EVs (hiPSC-EVs and hNR-EVs) with distinctive protein cargoes. Remarkably, hNR-EVs carry neuronal and glial cellular components involved in human CNS development. Importantly, hNR-EVs stimulate stem cells to change their cellular morphology and promote neurite growth in human and murine neurons with a significant dysregulation of SOX2 levels. This transcription factor modulates both neural differentiation and pluripotency. Interestingly, these effects were inhibited by antibodies against an unexpected neuroglial cargo of hNR-EVs: the major proteolipid protein (PLP). These findings show that hNRs secrete bioactive EVs containing neural components and might contribute as trophic factors during human neurodevelopment.

Neuroendocrine prostate cancer drivers SOX2 and BRN2 confer differential responses to imipridones ONC201, ONC206, and ONC212 in prostate cancer cell lines

OBJECTIVES

Prostate cancer (PCa) is a leading cause of cancer death in men worldwide. Approximately 30% of castrate-resistant PCa becomes refractory to therapy due to neuroendocrine differentiation (NED) that is present in <1% of de-novo tumors. First-in-class imipridone ONC201/TIC10 therapy has shown clinical activity against midline gliomas, neuroendocrine tumors, and PCa. We explored whether NED promotes sensitivity to imipridones ONC201 and ONC206 by inducibly overexpressing SOX2 and BRN2, well-known neuroendocrine drivers.

METHODS

Inducible SOX2 or BRN2 systems were cloned into human PCa cell lines LNCaP and DU145. Inducible cell lines were characterized based on protein expression, morphology, and migration. The sensitivity of the inducible cell lines to imipridone therapy was determined by viability, cell growth, or clonogenic assays.

RESULTS

Slight protection from ONC201 or ONC206 with SOX2 and BRN2 overexpression was observed in the inducible LNCaP cells but not in the DU145 cells. At 2 months, there was an apparent increase in CLpP expression in LNCaP SOX2-overexpressing cells, though this did not confer enhanced sensitivity to ONC201. DU145 SOX2-overexpressing cells had a significantly reduced ONC201 sensitivity than DU145 control cells.

CONCLUSIONS

The results suggest that treatment of castrate-resistant prostate cancer by imipridones may not be substantially affected by neuroendocrine differentiation as a therapy-resistance mechanism. The results support further testing of imipridones across subtypes of androgen-sensitive and castrate-resistant prostate cancer.

Synthetic organizer cells guide development via spatial and biochemical instructions

In vitro development relies primarily on treating progenitor cells with media-borne morphogens and thus lacks native-like spatial information. Here, we engineer morphogen-secreting organizer cells programmed to self-assemble, via cell adhesion, around mouse embryonic stem (ES) cells in defined architectures. By inducing the morphogen WNT3A and its antagonist DKK1 from organizer cells, we generated diverse morphogen gradients, varying in range and steepness. These gradients were strongly correlated with morphogenetic outcomes: the range of minimum-maximum WNT activity determined the resulting range of anterior-to-posterior (A-P) axis cell lineages. Strikingly, shallow WNT activity gradients, despite showing truncated A-P lineages, yielded higher-resolution tissue morphologies, such as a beating, chambered cardiac-like structure associated with an endothelial network. Thus, synthetic organizer cells, which integrate spatial, temporal, and biochemical information, provide a powerful way to systematically and flexibly direct the development of ES or other progenitor cells in different directions within the morphogenetic landscape.

Cellular trafficking and fate mapping of cells within the nervous system after in utero hematopoietic cell transplantation

In utero hematopoietic cell transplantation (IUHCT) utilizes fetal immune tolerance to achieve durable chimerism without conditioning or immunosuppression during a unique window in fetal development. Though donor cells have been observed within the nervous system following in utero injection, the timeline and distribution of cellular trafficking across the blood-brain barrier following IUHCT is not well understood. We injected 20 × 106 adult bone marrow mononuclear cells intravenously at gestational age (GA) 12-17 days and found that donor cells were maximally concentrated in the brain with treatment between GA 13-14. Donor cell engraftment persisted within the brain at every timepoint analyzed and concentrated within the hindbrain with significantly more grafted cells than in the forebrain. Additionally, transplanted cells terminally differentiated into various nervous system cellular morphologies and also populated the enteric nervous system. This study is the first to document the timeline and distribution of donor cell trafficking into the immune-protected nervous system and serves as a foundation for the application of IUHCT to treat neurogenetic diseases.

Single-cell transcriptomics reveals the molecular basis of human iPS cell differentiation into ectodermal ocular lineages

The generation of a self-formed, ectodermal, autonomous multi-zone (SEAM) from human induced pluripotent stem cells (hiPSCs) offers a unique perspective to study the dynamics of ocular cell differentiation over time. Here, by utilising single-cell transcriptomics, we have (i) identified, (ii) molecularly characterised and (iii) ascertained the developmental trajectories of ectodermally-derived ocular cell populations which emerge within SEAMs as they form. Our analysis reveals interdependency between tissues of the early eye and delineates the sequential formation and maturation of distinct cell types over a 12-week period. We demonstrate a progression from pluripotency through to tissue specification and differentiation which encompasses both surface ectodermal and neuroectodermal ocular lineages and the generation of iPSC-derived components of the developing cornea, conjunctiva, lens, and retina. Our findings not only advance the understanding of ocular development in a stem cell-based system of human origin, but also establish a robust methodological paradigm for exploring cellular and molecular dynamics during SEAM formation at single-cell resolution and highlight the potential of hiPSC-derived systems as powerful platforms for modelling human eye development and disease.

IMPA1-derived inositol maintains stemness in castration-resistant prostate cancer via IMPDH2 activation

Acquisition of prostate cancer stem cells (PCSCs) manifested during androgen ablation therapy (ABT) contributes to castration-resistant prostate cancer (CRPC). However, little is known about the specific metabolites critically orchestrating this process. Here, we show that IMPA1-derived inositol enriched in PCSCs is a key metabolite crucially maintaining PCSCs for CRPC progression and ABT resistance. Notably, conditional Impa1 knockout in the prostate abrogates the pool and properties of PCSCs to orchestrate CRPC progression and prolong the survival of TRAMP mice. IMPA1-derived inositol serves as a cofactor that directly binds to and activates IMPDH2, which synthesizes guanylate nucleotides for maintaining PCSCs with ARlow/- features leading to CRPC progression and ABT resistance. IMPA1/inositol/IMPDH2 axis is upregulated in human prostate cancer, and its overexpression predicts poor survival outcomes. Genetically and pharmacologically targeting the IMPA1/inositol/IMPDH2 axis abrogates CRPC and overcomes ABT resistance in various CRPC xenografts, patient-derived xenograft (PDX) tumor models, and TRAMP mouse models. Our study identifies IMPDH2 as an inositol sensor whose activation by inositol represents a key mechanism for maintaining PCSCs for CRPC and ABT resistance.

An integrated view of the structure and function of the human 4D nucleome

The dynamic three-dimensional (3D) organization of the human genome (the "4D Nucleome") is closely linked to genome function. Here, we integrate a wide variety of genomic data generated by the 4D Nucleome Project to provide a detailed view of human 3D genome organization in widely used embryonic stem cells (H1-hESCs) and immortalized fibroblasts (HFFc6). We provide extensive benchmarking of 3D genome mapping assays and integrate these diverse datasets to annotate spatial genomic features across scales. The data reveal a rich complexity of chromatin domains and their sub-nuclear positions, and over one hundred thousand structural loops and promoter-enhancer interactions. We developed 3D models of population-based and individual cell-to-cell variation in genome structure, establishing connections between chromosome folding, nuclear organization, chromatin looping, gene transcription, and DNA replication. We demonstrate the use of computational methods to predict genome folding from DNA sequence, uncovering potential effects of genetic variants on genome structure and function. Together, this comprehensive analysis contributes insights into human genome organization and enhances our understanding of connections between the regulation of genome function and 3D genome organization in general.