Biology subjects

Eischen, C. M.

Publications and source records attributed to Eischen, C. M..

3 recordsLinked to original sources

bioRxiv2023

C9orf72 poly(PR) mediated neurodegeneration is associated with nucleolar stress

The ALS/FTD-linked intronic hexanucleotide repeat expansion in the C9orf72 gene is translated into dipeptide repeat proteins, among which poly-proline-arginine (PR) displays the most aggressive neurotoxicity in-vitro and in-vivo. PR partitions to the nucleus when expressed in neurons and other cell types. Using drosophila and primary rat cortical neurons as model systems, we show that by lessening the nuclear accumulation of PR, we can drastically reduce its neurotoxicity. PR accumulates in the nucleolus, a site of ribosome biogenesis that regulates the cell stress response. We examined the effect of nucleolar PR accumulation and its impact on nucleolar function and determined that PR caused nucleolar stress and increased levels of the transcription factor p53. Downregulating p53 levels, either genetically or by increasing its degradation, also prevented PR-mediated neurotoxic phenotypes both in in-vitro and in-vivo models. We also investigated whether PR could cause the senescence phenotype in neurons but observed none. Instead, we found induction of apoptosis via caspase-3 activation. In summary, we uncovered the central role of nucleolar dysfunction upon PR expression in the context of C9-ALS/FTD.

neuroscience↗

bioRxiv2022

Systematic lncRNA mapping to genome-wide co-essential pathways uncovers cancer dependency on uncharacterized lncRNAs

Quantification of gene dependency across hundreds of cell lines using genome-scale CRISPR screens have revealed co-essential pathways/modules and critical functions of uncharacterized genes. In contrast to protein-coding genes, robust CRISPR-based loss-of-function screens are lacking for long non-coding RNAs (lncRNAs), which are key regulators of many cellular process, leaving many essential lncRNAs unidentified and uninvestigated. Integrating copy- number, epigenetic, and transcriptomic data of >800 cancer cell lines with CRISPR-derived co-essential pathways, our method recapitulates known essential lncRNAs and predicts proliferation/growth dependency of 289 poorly characterized lncRNAs. Analyzing lncRNA dependencies across ten cancer types and their expression alteration by diverse growth- inhibitors across cell types, we prioritize 30 high-confidence pan-cancer proliferation/growth- regulating lncRNAs. Further evaluating two previously uncharacterized top proliferation-suppressive lncRNAs (PSLR-1, PSLR-2) showed they are transcriptionally regulated by p53, induced by multiple cancer treatments, and significantly correlate to increased cancer patient survival. These lncRNAs modulate G2 cell cycle-regulating genes within the FOXM1 transcriptional network, inducing a G2 arrest and inhibiting proliferation and colony formation. Collectively, our results serve as a powerful resource for exploring lncRNA-mediated regulation of cellular fitness in cancer, circumventing current limitations in lncRNA research.

bioinformatics↗

bioRxiv2020

MYC regulates ribosome biogenesis and mitochondrial gene expression programs through interaction with Host Cell Factor-1

The oncoprotein transcription factor MYC is a major driver of malignancy and a highly-validated but challenging target for development of anti-cancer therapies. Novel strategies to inhibit MYC may come from understanding the co-factors it uses to drive pro-tumorigenic gene expression programs, providing their role in MYC activity is understood. Here, we interrogate how one MYC co-factor, Host Cell Factor (HCF)-1, contributes to MYC activity in a Burkitt lymphoma setting. We identify genes connected to mitochondrial function and ribosome biogenesis as direct MYC/HCF-1 targets, and demonstrate how modulation of the MYC-HCF-1 interaction influences cell growth, metabolite profiles, global gene expression patterns, and tumor growth in vivo. This work defines HCF-1 as a critical MYC co-factor, places the MYC-HCF-1 interaction in biological context, and highlights HCF-1 as a focal point for development of novel anti-MYC therapies.

cancer biology↗