Ikaros family proteins regulate developmental windows in the mouse retina through convergent and divergent transcriptional programs

ABSTRACTTemporal identity factors regulate the competence of neural progenitors to generate specific cell types in a time-dependent manner, but how they operate remains poorly defined. In the developing mouse retina, the Ikaros zinc finger transcription factor Ikzf1 regulates the production of early-born cell types, except cone photoreceptors. In this study we show that Ikzf4, another Ikaros family protein, cooperates with Ikzf1 to control cone photoreceptor production during early stages of retinal development, whereas at late stages, when Ikzf1 is no longer expressed in progenitors, Ikzf4 is instead required for Müller glia production. Using CUT&RUN sequencing, we find that both Ikzf1 and Ikzf4 generally bind to the same genes involved in cone development and other early-born fates, but at different cis-regulatory elements. In late-stage progenitors, Ikzf4 re-localizes to bind target genes involved in Müller glia development and regulate their expression. Specifically, we show that Ikzf4 maintains Hes1 expression in differentiating cells using two Ikzf GGAA binding sites at the Hes1 promoter, thereby favouring Müller glia fate commitment. These results uncover a combinatorial role for Ikaros family members in nervous system development and provide mechanistic insights on how they temporally regulate cell fate output.

HES1 expression associates with survival in triple negative breast cancer.

We mined published microarray data (1) to understand the most significant gene expression differences in the tumors of triple negative breast cancer patients based on survival following treatment: dead or alive. We observed significant transcriptome-wide differential expression of hairy and enhancer of split 1, encoded by HES1 when comparing the primary tumors of triple negative breast cancer patients dead or alive. Importantly, HES1 expression was significantly correlated with overall survival in basal subtype breast cancer, a molecular subtype sharing significant overlap with triple negative breast cancer. HES1 may be of relevance as a biomarker or as a molecule of interest in understanding the etiology or progression of triple negative breast cancer.

Bone marrow mesenchymal stem cells promote remyelination in spinal cord by driving oligodendrocyte progenitor cell differentiation via TNFα/RelB-Hes1 pathway: a rat model study of 2,5-hexanedione-induced neurotoxicity

Background N-hexane, with its metabolite 2,5-hexanedine (HD), is an industrial hazardous material. Chronic hexane exposure causes segmental demyelination in the peripheral nerves, and high-dose intoxication may also affect central nervous system. Demyelinating conditions are difficult to treat and stem cell therapy using bone marrow mesenchymal stem cells (BMSCs) is a promising novel strategy. Our previous study found that BMSCs promoted motor function recovery in rats modeling hexane neurotoxicity. This work aimed to explore the underlying mechanisms and focused on the changes in spinal cord. Methods Sprague Dawley rats were intoxicated with HD (400 mg/kg/day, i.p, for 5 weeks). A bolus of BMSCs (5 × 107 cells/kg) was injected via tail vein. Demyelination and remyelination of the spinal cord before and after BMSC treatment were examined microscopically. Cultured oligodendrocyte progenitor cells (OPCs) were incubated with HD ± BMSC-derived conditional medium (BMSC-CM). OPC differentiation was studied by immunostaining and morphometric analysis. The expressional changes of Hes1, a transcription factor negatively regulating OPC-differentiation, were studied. The upstream Notch1 and TNFα/RelB pathways were studied, and some key signaling molecules were measured. The correlation between neurotrophin NGF and TNFα was also investigated. Statistical significance was evaluated using one-way ANOVA and performed using SPSS 13.0. Results The demyelinating damage by HD and remyelination by BMSCs were evidenced by electron microscopy, LFB staining and NG2/MBP immunohistochemistry. In vitro cultured OPCs showed more differentiation after incubation with BMSC-CM. Hes1 expression was found to be significantly increased by HD and decreased by BMSC or BMSC-CM. The change of Hes1 was found, however, independent of Notch1 activation, but dependent on TNFα/RelB signaling. HD was found to increase TNFα, RelB and Hes1 expression, and BMSCs were found to have the opposite effect. Addition of recombinant TNFα to OPCs or RelB overexpression similarly caused upregulation of Hes1 expression. The secretion of NGF by BMSC and activation of NGF receptor was found important for suppression of TNFα production in OPCs. Conclusions Our findings demonstrated that BMSCs promote remyelination in the spinal cord of HD-exposed rats via TNFα/RelB-Hes1 pathway, providing novel insights for evaluating and further exploring the therapeutical effect of BMSCs on demyelinating neurodegenerative disease.

Bone Marrow Mesenchymal Stem Cells Promote Remyelination in Spinal Cord by Driving Oligodendrocyte Progenitor Cell Differentiation Via Tnfα/Relb-Hes1 Pathway: A Rat Model Study of 2,5-Hexanedione-Induced Neurotoxicity

Background: N-hexane, with its metabolite 2,5-hexanedine (HD), is a hazardous material widely used in industry and chronic exposure causes nerve demyelination. Demyelinating conditions are difficult to treat and frequently cause disabilities. Stem cell therapy using bone marrow mesenchymal stem cells (BMSCs) is a promising novel strategy. Our previous study found that BMSCs promoted significant recovery of motor dysfunction in rats modelling N-hexane neurotoxicity. The present study aimed to explore the underlying mechanisms and focused on the changes in spinal cord. Methods: Sprague Dawley rats were intoxicated with HD (400 mg/kg/day, i.p, for 5 weeks). BMSCs (5×107cells/kg) were administrated by tail vein injection. Demyelination and remyelination of the spinal cord before and after BMSC treatment were examined microscopically. Cultured oligodendrocyte progenitor cells (OPCs) were incubated with HD +/- BMSCs-derived conditional medium (BMSC-CM). OPC differentiation was studied by immunostaining and quantitative imaging analysis. The expressional changes of Hes1, a key transcription factor negatively regulating OPC-differentiation, were studied. The upstream Notch1 and TNFα/RelB pathways were studied and some key signaling molecules in these pathways were measured. The correlation between neurotrophin NGF and TNFα was also investigated. Statistical significance was evaluated using one-way ANOVA test and performed using SPSS 13.0. Results: The demyelinating damage by HD and remyelination by BMSCs were evidenced by electron microscopy, LFB staining and NG2/MBP immunohistochemistry. In vitro cultured OPCs showed more differentiation after incubation with BMSC-CM. Hes1 expression was found to be significantly increased by HD and decreased by BMSC or BMSC-CM. The change of Hes1 was found, however, independent on Notch1 activation, but dependent on TNFα/RelB signaling. HD was found to increase TNFα, RelB and Hes1 expression and BMSCs was found to have the opposite effect. Addition of recombinant TNFα to OPCs or RelB overexpression similarly caused upregulation of Hes1 expression. The secretion of NGF by BMSC and activation of NGF receptor was found important for suppression of TNFα production in OPCs. Conclusions: Our findings demonstrated that BMSCs promote remyelination in the spinal cord of HD-exposed rats via TNFα/RelB-Hes1 pathway, providing novel insights for evaluating and further exploring the therapeutical effect of BMSCs on demyelinating neurodegenerative disease.

miR-449a Repression Leads to Enhanced NOTCH Signaling in TMPRSS2:ERG Fusion Positive Prostate Cancer Cells

About 50% of prostate cancer (PCa) tumors are TMPRSS2:ERG (T2E) fusion-positive (T2E+), but the role of T2E in PCa progression is not fully understood. We were interested in investigating epigenomic alterations associated with T2E+ PCa. Using different sequencing cohorts, we found several transcripts of the miR-449 cluster to be repressed in T2E+ PCa. This repression correlated strongly with enhanced expression of NOTCH and several of its target genes in TCGA and ICGC PCa RNA-seq data. We corroborated these findings using a cellular model with inducible T2E expression. Overexpression of miR-449a in vitro led to silencing of genes associated with NOTCH signaling (NOTCH1, HES1) and HDAC1. Interestingly, HDAC1 overexpression led to the repression of HES6, a negative regulator of the transcription factor HES1, the primary effector of NOTCH signaling, and promoted cell proliferation by repressing the cell cycle inhibitor p21. Inhibition of NOTCH as well as knockdown of HES1 reduced the oncogenic properties of PCa cell lines. Using tissue microarray analysis encompassing 533 human PCa cores, ERG-positive areas exhibited significantly increased HES1 expression. Taken together, our data suggest that an epigenomic regulatory network enhances NOTCH signaling and thereby contributes to the oncogenic properties of T2E+ PCa.

Hes1 overexpression leads to expansion of embryonic neural stem cell pool and stem cell reservoir in the postnatal brain

ABSTRACTNeural stem cells (NSCs) gradually alter their characteristics during mammalian neocortical development, resulting in the production of various neurons and glial cells, and remain in the postnatal brain as a source of adult neurogenesis. Notch-Hes signaling is a key regulator of stem cell properties in the developing and postnatal brain, and Hes1 is a major effector that strongly inhibits neuronal differentiation and maintains NSCs. To manipulate Hes1 expression levels in NSCs, we generated transgenic (Tg) mice using the Tet-On system. In Hes1-overexpressing Tg mice, NSCs were maintained in both embryonic and postnatal brains, and generation of later-born neurons was prolonged until later stages in the Tg neocortex. Hes1 overexpression inhibited the production of Tbr2+ intermediate progenitor cells but instead promoted the generation of basal radial glia-like cells in the subventricular zone (SVZ) at late embryonic stages. Furthermore, Hes1-overexpressing Tg mice exhibited the expansion of NSCs and enhanced neurogenesis in the SVZ of adult brain. These results indicate that Hes1 overexpression expanded the embryonic NSC pool and led to the expansion of the NSC reservoir in the postnatal and adult brain.

Phase register of Hes1 oscillations with mitoses underlies cell-cycle heterogeneity in ER+ breast cancer cells

Here, we study the dynamical expression of endogenously labelled Hes1, a transcriptional repressor implicated in controlling cell proliferation, to understand how cell-cycle length heterogeneity is generated in ER+ breast cancer cells. We find that Hes1 shows oscillatory expression and during the cell-cycle has a variable peak in G1, a trough around G1-S transition and a less variable second peak in G2/M. Compared to other subpopulations, the cell-cycle in CD44HighCD24Low cancer stem cells is longest and most variable. Most cells divide around the peak of the Hes1 expression wave but mitoses in slow dividing CD44HighCD24Low cells appear phase-shifted, resulting in a late-onset Hes1 peak in G1. The position, duration and shape of this peak, rather than the Hes1 expression levels, are good predictors of cell-cycle length. Diminishing Hes1 oscillations impairs proliferation, indicating their functional importance for efficient cell-cycle progression. We propose that the position of mitosis in relation to the Hes1 wave underlies cell-cycle length heterogeneity in cancer cell subpopulations.Significance statementTumours exhibit heterogeneities that are not due to mutations, including Cancer Stem Cells with different potencies. We show that the cancer stem cell state predisposed to dormancy in vivo has a highly variable and long cell-cycle. Using single-cell live-imaging for the transcriptional repressor Hes1 (a key molecule in cancer), we show a new type of oscillatory expression of Hes1 in all cells in the population. The most potent cancer stem cells tend to divide around the trough of the Hes1 oscillatory wave, a feature predictive of a long cell-cycle. A novel concept proposed here is that the position that a cell is with respect to the Hes1 wave when it divides is predictive of its prospective cell-cycle length and characteristic of its cellular sub-state.Abstract in picture

Nestin +/CD31 + Cells in the Hypoxic Perivascular Niche Regulate Glioblastoma Chemoresistance by Upregulating JAG1 and DLL4

Background Failure of glioblastoma (GBM) therapy is often ascribed to different types of glioblastoma stem-like cells (GSLCs) niche, in particularly, a hypoxic perivascular niche (HPVN) is involved in GBM progression. However, the responsible cells for HPVN remained unclear. Methods Immunostaining was performed to determine the cells that are responsible for HPVN. A hypoxic chamber and 3D microfluidic chips were designed to simulate HPVN based on the pathological features of GBM. The phenotype of GSLCs was evaluated by fluorescence scanning in real-time and proliferation and apoptotic assays. The expression of JAG1, DLL4 and Hes1 was determined by immunostaining, ELISA, western-blotting, and q-PCR. Their clinical progonostic significance in GBM HPVN and total tumor tissues were verified by clinical data and TCGA databases. Results Nestin +/CD31 + cells and pericytes constitute the major part of microvessels in HPVN and high ratio of nestin +/CD31 + cells rather than pericytes were responsible for poor prognosis of GBM. A more real HPVN was simulated by hypoxic coculture system in vitro, which was assembled by 3D microfluidic chips and hypoxic chamber. Nestin +/CD31 + cells in HPVN were derived from GSLCs transdifferentiation and could promote GSLCs chemoresistance by providing more JAG1 and DLL4 to induce down-stream Hes1 overexpression. Poor prognosis of GBM was correlated to Hes1 expression of tumor cells in GBM HPVN, and not correlated with total Hes1 expression in GBM tissues. Conclusion These results hightlighted the critical role of nestin +/CD31 + cells in HPVN that acts in GBM chemoresistance and revealed the distinctive prognostic value of these molecular markers in HPVN.

Crosstalk between Androgen-ZIP9 Signaling and Notch Pathway in Rodent Sertoli Cells

Our recent study demonstrated altered expression of Notch ligands, receptors, and effector genes in testes of pubertal rats following reduced androgen production or signaling. Herein we aimed to explore the role of nuclear androgen receptor (AR) and membrane androgen receptor (Zrt- and Irt-like protein 9; ZIP9) in the regulation of Notch pathway activation in rodent Sertoli cells. Experiments were performed using TM4 and 15P-1 Sertoli cell lines and rat primary Sertoli cells (PSC). We found that testosterone (10−8 M–10−6 M) increased the expression of Notch1 receptor, its active form Notch1 intracellular domain (N1ICD) (p < 0.05, p < 0.01, p < 0.001), and the effector genes Hey1 (p < 0.05, p < 0.01, p < 0.001) and Hes1 (p < 0.05, p < 0.001) in Sertoli cells. Knockdown of AR or ZIP9 as well as antiandrogen exposure experiments revealed that (i) action of androgens via both AR and ZIP9 controls Notch1/N1ICD expression and transcriptional activity of recombination signal binding protein (RBP-J), (ii) AR-dependent signaling regulates Hey1 expression, (iii) ZIP9-dependent pathway regulates Hes1 expression. Our findings indicate a crosstalk between androgen and Notch signaling in Sertoli cells and point to cooperation of classical and non-classical androgen signaling pathways in controlling Sertoli cell function.