FoxO maintains a genuine quiescent muscle stem-cell state until geriatric age (ATAC-seq)
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ABSTRACT: We identify two quiescent stem-cell states through relative CD34 expression: CD34High, with stemness properties (genuine state), and CD34Low, more committed to myogenic differentiation (primed state). The genuine-quiescent state is preserved into later life succumbing only in extreme old age due to acquisition of primed-state traits. We identified niche-derived IGF1-dependent Akt activation as detrimental to the genuine stem-cell state by imposing primed-state features via FoxO inhibition. Interventions to neutralize Akt and promote FoxO activity drive primed-to-genuine state conversion, while FoxO inactivation deteriorates the genuine state at young age, causing muscle regenerative failure, as in geriatric mice.
Project description:We identify two quiescent stem-cell states through relative CD34 expression: CD34High, with stemness properties (genuine state), and CD34Low, more committed to myogenic differentiation (primed state). The genuine-quiescent state is preserved into later life succumbing only in extreme old age due to acquisition of primed-state traits. We identified niche-derived IGF1-dependent Akt activation as detrimental to the genuine stem-cell state by imposing primed-state features via FoxO inhibition. Interventions to neutralize Akt and promote FoxO activity drive primed-to-genuine state conversion, while FoxO inactivation deteriorates the genuine state at young age, causing muscle regenerative failure, as in geriatric mice.
Project description:Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with aging. Here we report that geriatric satellite cells, compared to old cells, are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and this irreversibly affects their intrinsic regenerative and self-renewal capacities.
Project description:Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with aging. Here we report that geriatric satellite cells, compared to old cells, are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and this irreversibly affects their intrinsic regenerative and self-renewal capacities. We analyzed the global changes in gene expression occurring within muscle stem cells (satellite cells) in homeostatic conditions during physiological aging. Pure satellite cell populations from dissociated skeletal muscle from Young (2-3 months) and Geriatric (28-32 months) mice were isolated using a well-established flow cytometry protocol gating on integrin a7(+)/CD34(+) (positive selection) and Lin- (CD31, CD45, CD11b, Sca1) (negative selection).
Project description:Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with aging and in progeric conditions. Here we report that geriatric satellite cells, compared to old cells, are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and this irreversibly affects their intrinsic regenerative and self-renewal capacities.
Project description:Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with aging and in progeric conditions. Here we show that geriatric satellite cells, compared to old cells, are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and this irreversibly affects their intrinsic regenerative and self-renewal capacities.
Project description:Naïve pluripotency is sustained by a self-reinforcing gene regulatory network (GRN) comprising core and naïve pluripotency-specific transcription factors (TFs). Upon exiting naïve pluripotency, ES cells transition through a formative post-implantation-like pluripotent state. However, the mechanisms underlying disengagement from the naïve GRN and initiation of the formative GRN remain unclear. Here, we demonstrate that phosphorylated AKT acts as a gatekeeper that prevents nuclear localization of FoxO TFs in naïve ESCs. PTEN-mediated reduction of AKT activity allows nuclear entry by FoxO TFs, enforcing a cell fate transition by binding and activating formative pluripotency-specific enhancers. Indeed, FoxO TFs are necessary and sufficient for transition from the naïve to the formative pluripotent state. Our work uncovers a pivotal role for FoxO TFs and AKT signalling in mechanisms underlying the exit from naïve pluripotency, a critical early embryonic cell fate transition.
Project description:Naïve pluripotency is sustained by a self-reinforcing gene regulatory network (GRN) comprising core and naïve pluripotency-specific transcription factors (TFs). Upon exiting naïve pluripotency, ES cells transition through a formative post-implantation-like pluripotent state. However, the mechanisms underlying disengagement from the naïve GRN and initiation of the formative GRN remain unclear. Here, we demonstrate that phosphorylated AKT acts as a gatekeeper that prevents nuclear localization of FoxO TFs in naïve ESCs. PTEN-mediated reduction of AKT activity allows nuclear entry by FoxO TFs, enforcing a cell fate transition by binding and activating formative pluripotency-specific enhancers. Indeed, FoxO TFs are necessary and sufficient for transition from the naïve to the formative pluripotent state. Our work uncovers a pivotal role for FoxO TFs and AKT signalling in mechanisms underlying the exit from naïve pluripotency, a critical early embryonic cell fate transition.