Fosl2 facilitates chromatin accessibility to determine developmental events during follicular maturation [RNA-seq]
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ABSTRACT: Granulosa cells (GCs) are the most dynamically responsive cell lineage to encourage continuous folliculogenesis; however, developmental dynamics and interplay with downstream transcription circuitry remain unclear. Here, we unravel the redistribution of genome-wide chromatin areas that drive broad developmental-related transcriptomic alterations during follicular maturation in murine and porcine GCs. Distinct GC-activated accessibility regions (GAAs) at the ovulatory phase are responsible for augmenting flanking GC-involved developmental gene (GDG) expression, which are essential for transcriptional responses to developmental cues. Mechanistically, the transcription factor (TF) Fosl2 is strongly recruited to GAAs, facilitating chromatin accessibility state transition. Elevated GAA signals driven by Fosl2 loading induce a significant upregulation of adjacent GDG expression. Additionally, GC-specific Fosl2 deletion in mice perturbs GC cellularity, leading to subfertility related to reproductive aging. Together, we highlight a dynamic chromatin accessibility landscape during follicular maturation, revealing the indispensable Fosl2 function not only controls transcriptional activation via a reconfigured chromatin state, but also orchestrates intricate signaling pathways that are fundamental for ovulation and reproduction.
Project description:Granulosa cells (GCs) are the most dynamically responsive cell lineage to encourage continuous folliculogenesis; however, developmental dynamics and interplay with downstream transcription circuitry remain unclear. Here, we unravel the redistribution of genome-wide chromatin areas that drive broad developmental-related transcriptomic alterations during follicular maturation in murine and porcine GCs. Distinct GC-activated accessibility regions (GAAs) at the ovulatory phase are responsible for augmenting flanking GC-involved developmental gene (GDG) expression, which are essential for transcriptional responses to developmental cues. Mechanistically, the transcription factor (TF) Fosl2 is strongly recruited to GAAs, facilitating chromatin accessibility state transition. Elevated GAA signals driven by Fosl2 loading induce a significant upregulation of adjacent GDG expression. Additionally, GC-specific Fosl2 deletion in mice perturbs GC cellularity, leading to subfertility related to reproductive aging. Together, we highlight a dynamic chromatin accessibility landscape during follicular maturation, revealing the indispensable Fosl2 function not only controls transcriptional activation via a reconfigured chromatin state, but also orchestrates intricate signaling pathways that are fundamental for ovulation and reproduction.
Project description:Granulosa cells (GCs) are the most dynamically responsive cell lineage to encourage continuous folliculogenesis; however, developmental dynamics and interplay with downstream transcription circuitry remain unclear. Here, we unravel the redistribution of genome-wide chromatin areas that drive broad developmental-related transcriptomic alterations during follicular maturation in murine and porcine GCs. Distinct GC-activated accessibility regions (GAAs) at the ovulatory phase are responsible for augmenting flanking GC-involved developmental gene (GDG) expression, which are essential for transcriptional responses to developmental cues. Mechanistically, the transcription factor (TF) Fosl2 is strongly recruited to GAAs, facilitating chromatin accessibility state transition. Elevated GAA signals driven by Fosl2 loading induce a significant upregulation of adjacent GDG expression. Additionally, GC-specific Fosl2 deletion in mice perturbs GC cellularity, leading to subfertility related to reproductive aging. Together, we highlight a dynamic chromatin accessibility landscape during follicular maturation, revealing the indispensable Fosl2 function not only controls transcriptional activation via a reconfigured chromatin state, but also orchestrates intricate signaling pathways that are fundamental for ovulation and reproduction.
Project description:Granulosa cells (GCs) are the most dynamically responsive cell lineage to encourage continuous folliculogenesis; however, developmental dynamics and interplay with downstream transcription circuitry remain unclear. Here, we unravel the redistribution of genome-wide chromatin areas that drive broad developmental-related transcriptomic alterations during follicular maturation in murine and porcine GCs. Distinct GC-activated accessibility regions (GAAs) at the ovulatory phase are responsible for augmenting flanking GC-involved developmental gene (GDG) expression, which are essential for transcriptional responses to developmental cues. Mechanistically, the transcription factor (TF) Fosl2 is strongly recruited to GAAs, facilitating chromatin accessibility state transition. Elevated GAA signals driven by Fosl2 loading induce a significant upregulation of adjacent GDG expression. Additionally, GC-specific Fosl2 deletion in mice perturbs GC cellularity, leading to subfertility related to reproductive aging. Together, we highlight a dynamic chromatin accessibility landscape during follicular maturation, revealing the indispensable Fosl2 function not only controls transcriptional activation via a reconfigured chromatin state, but also orchestrates intricate signaling pathways that are fundamental for ovulation and reproduction.
Project description:Comparison of follicular dendritic cell-enriched versus -depleted splenocytes. Affinity maturation and Ab class switches occur in lymphoid germinal centers (GCs), in which differentiation and maintenance depend on lymphotoxin (LT) signaling and include differentiation of follicular dendritic cells (FDCs). The events leading to FDC and GC maturation are poorly defined. Using several approaches of functional genomics, we enumerated transcripts affected in mice by suppressing LT receptor (LTR) signaling and/or overrepresented in FDC-enriched GC isolates. Protein expression analysis of 3 of 12 genes both enriched in FDCs and down-regulated by LTR signaling suppression validated them as FDC markers. Functional analysis of one of these three, clusterin, suggests a role as an FDC-derived trophic factor for GC B cells. Hence, the set of genes presented in this study includes markers emanating from LTR signaling and transcripts relevant to GC and FDC function.
Project description:Germinal centers (GCs) are the site of immunoglobulin somatic hypermutation and affinity maturation, processes essential to an effective antibody response. The formation of GCs has been studied in detail, but less is known about what leads to their regression and eventual termination, factors that ultimately limit the extent to which antibodies mature within a single reaction. We show that contraction of immunization-induced GCs is immediately preceded by an acute surge in GC-resident Foxp3+ T cells, attributed at least partly to upregulation of the transcription factor Foxp3 by T follicular helper (Tfh) cells. Ectopic expression of Foxp3 in Tfh cells is sufficient to decrease GC size, implicating the natural upregulation of Foxp3 by Tfh cells as a potential regulator of GC lifetimes.