Cruickshanks, N. | bioRxiv Science

bioRxiv2025

ATF4 activates a transcriptional program that chronically suppresses mTOR activity promoting neurodegeneration in Parkinson's disease models

The Integrated Stress Response (ISR) is a cell signaling pathway that enables cells to adapt to diverse cellular stresses. Conversely, during chronic/unmitigated cellular stress the ISR becomes maladaptive and has been implicated in a range of neurodegenerative conditions including Parkinsons Disease (PD). However, the mechanisms by which maladaptive ISR/ATF4 signaling contributes to neurodegeneration have not been elucidated. In this study we establish a critical mechanism by which chronic ISR activation becomes maladaptive and promotes neurodegeneration in neurotoxin and - synucleinopathy models of PD in vitro and in vivo. Specifically, we demonstrate that chronic activation of ATF4, the central transcription factor of the ISR, promotes neurodegeneration by regulating the transcriptional induction of SESN2, DDIT4 and Trib3 that co-operate to suppress both mTORC1 and mTORC2 activity. Furthermore, we demonstrate that ATF4-mediated suppression of mTORC1/2 activity promotes dopaminergic neuronal death in PD models by facilitating the activation of the pro- apoptotic BCL-2 family protein PUMA. Taken together, we have discovered a novel maladaptive ISR/ATF4 signaling pathway leading to chronic suppression of mTORC1/2 activity resulting in PUMA-mediated neuronal death that may have therapeutic implications in a range of neurodegenerative conditions that exhibit chronic ISR activation. O_FIG O_LINKSMALLFIG WIDTH=125 HEIGHT=200 SRC="FIGDIR/small/658667v1_ufig1.gif" ALT="Figure 1000"> View larger version (36K): org.highwire.dtl.DTLVardef@4fa02forg.highwire.dtl.DTLVardef@19d9f0forg.highwire.dtl.DTLVardef@13597beorg.highwire.dtl.DTLVardef@17d47e0_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Discovery and therapeutic exploitation of Master Regulatory miRNAs in Glioblastoma

Glioblastoma is a fatal primary malignant brain tumor, with an average survival of only 15 months despite surgical resection, chemotherapy, and radiation therapy. Due to the concurrent deregulation of numerous genes in glioblastoma, molecular monotherapies have not improved clinical outcomes. Evidence suggests that effectively targeting multiple deregulated molecules is essential for better therapies; however, this is limited by the lack of suitable drugs and the increased toxicity of combination therapies. To address this, we hypothesized that miRNAs, small gene-regulatory RNAs that suppress multiple target genes via sequence complementarity, could be developed to inhibit multiple deregulated genes simultaneously, leading to more effective treatments. We identified master regulatory miRNAs--those that target several deregulated genes in glioblastoma--using PAR-CLIP screenings in glioblastoma cells and analyzed TCGA tumor data to find which targets were deregulated. An algorithm ranked these targets based on their significance in glioblastoma malignancy. We selected two tumor suppressor master regulatory miRNAs, miR-340 and miR-382, and one oncogenic miRNA, miR-17. Validation showed that these miRNAs target critical glioblastoma pathways and significantly inhibit cell growth, survival, invasion, and tumor growth in vivo. We developed an innovative therapeutic delivery approach using Brain Penetrating Nanoparticles in combination with MRI-guided focused ultrasound and microbubbles, resulting in reduced tumor volume and extended survival in glioblastoma-bearing mice. This strategy offers a promising pathway for translating miRNA-based therapies into clinical trials for glioblastoma and other cancers. One Sentence SummaryWe developed and used new computational, experimental, and therapeutic approaches to identify and therapeutically deliver master regulatory miRNAs to inhibit the growth of glioblastoma, the most common and deadly primary brain tumor.

cancer biology↗