EIF3D Safeguards the Homeostasis of Key Signaling Pathways in Human Primed Pluripotency [RNA-seq]
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ABSTRACT: Pluripotent stem cell identities such as differentiation and infinite proliferation have long been decoded in the frameworks of transcription factor networks, epigenomes, and signal transduction, yet unclear and fragmented. However, directing attention toward translation regulation, the bridge between these events promises to provide new insights into previously unexplained mechanisms. Functional screening led to the discovery that EIF3D maintains primed pluripotency via selective translation regulation. The loss of EIF3D unbalanced the pluripotency-associated signaling pathways, disrupting primed pluripotency. Furthermore, we found that EIF3D safeguards robust proliferation by managing the translation of multiple p53 regulators that maintain low p53 activity in the undifferentiated state. Therefore, this study provides a paradigm for selective translation regulation that defines the primed pluripotent stem cell identity.
Project description:Pluripotent stem cell identities such as differentiation and infinite proliferation have long been decoded in the frameworks of transcription factor networks, epigenomes, and signal transduction, yet unclear and fragmented. However, directing attention toward translation regulation, the bridge between these events promises to provide new insights into previously unexplained mechanisms. Functional screening led to the discovery that EIF3D maintains primed pluripotency via selective translation regulation. The loss of EIF3D unbalanced the pluripotency-associated signaling pathways, disrupting primed pluripotency. Furthermore, we found that EIF3D safeguards robust proliferation by managing the translation of multiple p53 regulators that maintain low p53 activity in the undifferentiated state. Therefore, this study provides a paradigm for selective translation regulation that defines the primed pluripotent stem cell identity.
Project description:Pluripotent stem cell identities such as differentiation and infinite proliferation have long been decoded in the frameworks of transcription factor networks, epigenomes, and signal transduction, yet unclear and fragmented. However, directing attention toward translation regulation, the bridge between these events promises to provide new insights into previously unexplained mechanisms. Functional screening led to the discovery that EIF3D maintains primed pluripotency via selective translation regulation. The loss of EIF3D unbalanced the pluripotency-associated signaling pathways, disrupting primed pluripotency. Furthermore, we found that EIF3D safeguards robust proliferation by managing the translation of multiple p53 regulators that maintain low p53 activity in the undifferentiated state. Therefore, this study provides a paradigm for selective translation regulation that defines the primed pluripotent stem cell identity.
Project description:Pluripotent stem cell identities such as differentiation and infinite proliferation have long been decoded in the frameworks of transcription factor networks, epigenomes, and signal transduction, yet unclear and fragmented. However, directing attention toward translation regulation, the bridge between these events promises to provide new insights into previously unexplained mechanisms. Functional screening led to the discovery that EIF3D maintains primed pluripotency via selective translation regulation. The loss of EIF3D unbalanced the pluripotency-associated signaling pathways, disrupting primed pluripotency. Furthermore, we found that EIF3D safeguards robust proliferation by managing the translation of multiple p53 regulators that maintain low p53 activity in the undifferentiated state. Therefore, this study provides a paradigm for selective translation regulation that defines the primed pluripotent stem cell identity.
Project description:Shutoff of global protein synthesis is a conserved response to cellular stresses. This general phenomenon is accompanied by induction of distinct gene programs tailored to each stress condition. Although the mechanisms that lead to general repression of protein synthesis are well characterized, how cells reprogram the translation machinery for selective gene expression remains poorly understood. Here we show that the noncanonical 5′ cap-binding protein eIF3d is specifically activated in response to metabolic stress, due to loss of CK2-mediated phosphorylation near the eIF3d cap-binding pocket. Activated eIF3d controls a gene program enriched in factors important for glucose homeostasis, including members of the mTOR pathway, and eIF3d-mediated translation adaptation is essential for cell survival during chronic glucose deprivation. Our findings reveal a new mechanism of translation reprogramming engaged in response to metabolic stress.
Project description:All cells respond to intrinsic and extrinsic stresses by reducing global protein synthesis and activating select gene programs necessary for survival. Here, we show the fundamental integrated stress response (ISR) is driven by the non-canonical cap-binding protein eIF3d which acts as a master effector to control core stress response orchestrators, the translation factor eIF2ɑ and the transcription factor ATF4. We find that during persistent stress, eIF3d activates translation of the protein kinase GCN2, inducing eIF2ɑ phosphorylation and inhibiting global protein synthesis. In parallel, eIF3d upregulates the m6A demethylase enzyme ALKBH5 to drive 5′ UTR-specific demethylation of stress response genes, including ATF4. Ultimately, this cascade converges on ATF4 expression by increasing mRNA engagement of translation machinery and enhancing ribosome bypass of upstream open reading frames. Our results reveal that eIF3d acts as a critical life-or-death decision point during adaptation to chronic stress and uncover a synergistic signaling mechanism in which translational cascades dynamically complement transcriptional amplification to control essential cellular processes.