ABSTRACT: During vertebrate retinogenesis, the precise balance between retinoblast proliferation and differentiation is spatially and temporally regulated through a number of intrinsic factors and extrinsic signaling pathways. Moreover, there are complex gene regulatory network interactions between these intrinsic factors and extrinsic pathways, which ultimately function to determine when retinoblasts exit the cell cycle and terminally differentiate. We recently uncovered a cell non-autonomous role for the intrinsic HLH factor, Id2a, in regulating retinoblast proliferation and differentiation, with Id2a-deficient retinae containing an abundance of proliferative retinoblasts and an absence of terminally differentiated retinal neurons and glia. Here, we report that Id2a function is necessary and sufficient to limit Notch pathway activity during retinogenesis. Id2a-deficient retinae possess elevated levels of Notch pathway component gene expression, while retinae overexpressing id2a possess reduced expression of Notch pathway component genes. Attenuation of Notch signaling activity by DAPT or by morpholino knockdown of Notch1a is sufficient to rescue both the proliferative and differentiation defects in Id2a-deficient retinae. In addition to regulating Notch pathway activity, through an RNA-Seq and differential gene expression analysis of Id2a-deficient retinae, we identify a number of additional intrinsic and extrinsic regulatory pathway components whose expression is regulated by Id2a. These data highlight the integral role played by Id2a in the gene regulatory network governing the transition from retinoblast proliferation to terminal differentiation during vertebrate retinogenesis. Two biological replicates for both Id2aMM and Id2aMO samples
Project description:During vertebrate retinogenesis, the precise balance between retinoblast proliferation and differentiation is spatially and temporally regulated through a number of intrinsic factors and extrinsic signaling pathways. Moreover, there are complex gene regulatory network interactions between these intrinsic factors and extrinsic pathways, which ultimately function to determine when retinoblasts exit the cell cycle and terminally differentiate. We recently uncovered a cell non-autonomous role for the intrinsic HLH factor, Id2a, in regulating retinoblast proliferation and differentiation, with Id2a-deficient retinae containing an abundance of proliferative retinoblasts and an absence of terminally differentiated retinal neurons and glia. Here, we report that Id2a function is necessary and sufficient to limit Notch pathway activity during retinogenesis. Id2a-deficient retinae possess elevated levels of Notch pathway component gene expression, while retinae overexpressing id2a possess reduced expression of Notch pathway component genes. Attenuation of Notch signaling activity by DAPT or by morpholino knockdown of Notch1a is sufficient to rescue both the proliferative and differentiation defects in Id2a-deficient retinae. In addition to regulating Notch pathway activity, through an RNA-Seq and differential gene expression analysis of Id2a-deficient retinae, we identify a number of additional intrinsic and extrinsic regulatory pathway components whose expression is regulated by Id2a. These data highlight the integral role played by Id2a in the gene regulatory network governing the transition from retinoblast proliferation to terminal differentiation during vertebrate retinogenesis.
Project description:Correct neural progenitor fate determination requires the coordination of extrinsic fate determinant signals with intrinsic responses. Post-translational modifications dynamically alter protein function and so are ideally situated to regulate development. Here we show that the deubiquitylaying enzyme, Usp9x modulates both intrinsic and extrinsic regulators of mouse neural progenitors. Nestin-cre mediated deletion of Usp9x from neural progenitors results in a transient disruption of cell adhesion and apical-basal polarity as well as the premature differentiation of intermediate neural progenitors. Ablation of Usp9x also significantly increased β-catenin protein levels, especially S33/S37/T41 phospho-β-catenin, and Wnt signalling. Usp9x was found to be part of the β-catenin destruction complex and loss of Usp9x affects destruction complex composition. Notch signalling was also increased in Usp9x ablated neural progenitors, coinciding with decreased Itch and Numb, and increased Notch intracellular domain protein levels. Usp9x co-localized and immunopreciptiated with Numb from neural progenitors suggesting it is required for Numb stabilisation. These data suggest Usp9x plays a role in coordinating intrinsic responses to extrinsic signals during neural development.
Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:The roles of retinal cis-regulatory landscape in controlling the expression of gene regulatory networks important for retinogenesis remain poorly understood. Vsx2 is a transcription factor essential for retinal proliferation and bipolar cell differentiation but the molecular mechanisms underlying its developmental roles are unclear. Here, we profiled VSX2 genomic occupancy during mouse retinogenesis, revealing extensive retinal gene regulatory networks associated with Vsx2 during development. We defined an autoregulatory loop in which VSX2 binds and transactivates its own enhancer in association with the transcription factor PAX6 . The Vsx2 regulatory landscape contains elements that are required for Vsx2 expression, retinal proliferation and proper cell type differentiation. We further show that retinae in which the Vsx2 enhancer landscape has been largely deleted suffer a bias toward photoreceptor production. Genomic data indicate that VSX2 occupies cis-regulatory elements nearby genes associated with photoreceptor differentiation and homeostasis in mouse and human retinae, including a conserved region nearby the rod-specifying factor Prdm1. We provide evidence that VSX2 associates with OTX2 and can act to suppress OTX2-dependent enhancer transactivation of Prdm1 enhancer. Taken together, our analyses illuminate important mechanistic insights on how VSX2 is engaged with gene regulatory networks that are essential for retinal proliferation and cell fate acquisition.
Project description:Appropriate neural initiation of the pluripotent stem cells in the early embryos is critical for the development of the central nervous system. This process is regulated by the coordination of extrinsic signals and intrinsic programs. However, how the coordination is achieved to ensure proper neural fate commitment is largely unknown. Here, taking advantage of genome-wide ChIP-sequencing (ChIP-seq) and RNA-sequencing (RNA-seq) analyses, we demonstrate that the transcriptional factor Pou3f1 is an upstream activator of neural-promoting genes, and it is able to repress neural-inhibitory signals as well. Further studies revealed that Pou3f1 could directly bind neural lineage genes like Sox2 and downstream targets of neural inhibition signaling such as BMP and Wnt. Our results thus identify Pou3f1 as a critical dual-regulator of the intrinsic transcription factors and the extrinsic cellular signals during neural fate commitment. ChIP-seq assay was ultilized to characterize the targets of Pou3f1 on ESC differentiation day 2.
Project description:Fibro adipogenic progenitors (FAPs) promote satellite cell differentiation in adult skeletal muscle regeneration. However, in pathological conditions, FAPs are responsible for fibrosis and fatty infiltrations. Here we show that the NOTCH pathway negatively modulates FAP differentiation both in vitro and in vivo. However, FAPs isolated from young dystrophin- deficient mdx mice are insensitive to this control mechanism. An unbiased mass spectrometry-based proteomic analysis of FAPs from muscles of wild type and mdx mice, suggest that the synergistic cooperation between NOTCH and inflammatory signals controls FAP differentiation. Remarkably, we demonstrated that factors released by hematopoietic cells restore the sensitivity to NOTCH adipogenic inhibition in mdx FAPs. These results offer a basis for rationalizing pathological ectopic fat infiltrations in skeletal muscle and may suggest new therapeutic strategies to mitigate the detrimental effects of fat depositions in muscles of dystrophic patients.
Project description:Generation of effective immune responses requires expansion of rare antigen-specific CD4+ T cells. The magnitude of the response is ultimately determined by proliferation and survival. Both processes are tightly controlled to limit responses to innocuous antigens. Sustained expansion occurs only when innate immune sensors are activated by microbial stimuli or by adjuvants, which has important implications for vaccination. The molecular identity of the signals controlling sustained T cell responses is not fully clear. Here we describe a prominent role for the Notch pathway in this process. Co-activation of Notch allows accumulation of far greater numbers of activated CD4+ T cells than stimulation via T cell receptor and classical co-stimulation alone. Notch does not overtly affect cell cycle entry or progression of CD4+ T cells. Instead, Notch protects activated CD4+ T cells against apoptosis after an initial phase of clonal expansion. Notch induces a broad anti-apoptotic gene expression program, which protects against intrinsic as well as extrinsic apoptosis pathways. Both Notch1 and Notch2 receptors and the canonical effector RBPJ are involved in this process. Correspondingly, CD4+ T cell responses to immunization with protein antigen are strongly reduced in mice lacking these components of the Notch pathway. Our findings therefore show that Notch controls the magnitude of CD4+ T cell responses by promoting cellular longevity. Naïve CD4+ T cells were activated for 1 day (1 control sample and 1 experimental sample) or 3 days (3 control samples and 3 experimental samples) with antibodies to CD3 soluble and CD28 in the presence of recombinant Delta4-Ig (experimental samples) or control Ig (control samples).
Project description:This randomized phase I/II clinical trial is studying the side effects and best dose of gamma-secretase/notch signalling pathway inhibitor RO4929097 when given together with vismodegib and to see how well they work in treating patients with advanced or metastatic sarcoma. Vismodegib may slow the growth of tumor cells. Gamma-secretase/notch signalling pathway inhibitor RO4929097 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving vismodegib together with gamma-secretase/notch signalling pathway inhibitor RO4929097 may be an effective treatment for sarcoma.