Project description:To investigate the translatome change due to loss of MYSM1 in CD34+CD45RA-CD90+ cells We performed ribosome profiling followed by NGS sequencing where only ribosome protected RNA was extracted to make the library, which mostly are in active translation
Project description:The transcription factor RUNX1 is frequently mutated in myelodysplastic syndrome and leukemia. RUNX1 mutations can be early events, creating pre-leukemic stem cells that expand in the bone marrow. Here we show that, counter-intuitively, Runx1 deficient hematopoietic stem and progenitor cells (HSPCs) have a slow growth, low biosynthetic, small cell phenotype and markedly reduced ribosome biogenesis (Ribi). The reduced Ribi involves decreased levels of rRNA and many mRNAs encoding ribosome proteins. Runx1 appears to directly regulate Ribi; Runx1 is enriched on the promoters of genes encoding ribosome proteins, and binds the ribosomal DNA repeats. Runx1 deficient HSPCs have lower p53 levels, reduced apoptosis, an attenuated unfolded protein response, and accordingly are resistant to genotoxic and endoplasmic reticulum stress. The low biosynthetic activity and corresponding stress resistance provides a selective advantage to Runx1 deficient HSPCs, allowing them to expand in the bone marrow and outcompete normal HSPCs. Comparison of the phenotypic and molecular properties of normal (Runx1f/f, or WT) versus Runx1 deficient (Mut) hematopoietic stem cells.
Project description:Ferroptosis, an iron-dependent, non-apoptotic cell death program, is involved in a variety of degenerative diseases and represents a targetable vulnerability in certain cancers. The ferroptosis-susceptible cell-state can either preexist in cells arising from certain lineages or be acquired during cell-state transitions. Precisely how ferroptosis susceptibility is dynamically regulated remains poorly understood. Using genome-wide CRISPR/Cas9 suppressor screens, we identify a key role for peroxisome–ether phospholipid genes in driving ferroptosis susceptibility and evasion in ovarian cancer.
Project description:The selenoprotein glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid peroxides into nontoxic lipid alcohols. GPX4 has emerged as a promising therapeutic target for cancer treatment, but some cancer cells are resistant to ferroptosis triggered by GPX4 inhibition. Using a chemical-genetic screen, we identify LRP8 (also known as ApoER2) as a ferroptosis resistance factor that is upregulated in cancer. Loss of LRP8 decreases cellular selenium levels and the expression of a subset of selenoproteins. Counter to the canonical hierarchical selenoprotein regulatory program, GPX4 levels are strongly reduced due to impaired translation. Mechanistically, low selenium levels result in ribosome stalling at the inefficiently decoded GPX4 selenocysteine UGA codon, leading to ribosome collisions, early translation termination and proteasomal clearance of the N-terminal GPX4 fragment. These findings reveal rewiring of the selenoprotein hierarchy in cancer cells and identify ribosome stalling and collisions during GPX4 translation as ferroptosis vulnerabilities in cancer.