Biology subjects

Abu-Remaileh, M.

Publications and source records attributed to Abu-Remaileh, M..

24 records · Page 2Linked to original sources

bioRxiv2022

Proteomic profiling reveals lysosomal heterogeneity in association with longevity

Lysosomes are active sites to integrate cellular metabolism and signal transduction. A collection of proteins associated with the lysosome mediate these metabolic and signaling functions. Both lysosomal metabolism and lysosomal signaling have been linked to longevity regulation; however, how lysosomes adjust their protein composition to accommodate this regulation remains unclear. Using deep proteomic profiling, we systemically profiled lysosome-associated proteins linked with different longevity mechanisms. We further discovered the lysosomal recruitment of AMPK and nucleoporin proteins and their requirements for longevity in response to increased lysosomal lipolysis. Through comparative proteomic analyses of lysosomes from different tissues and labeled with different markers, we discovered lysosomal heterogeneity across tissues as well as the specific enrichment of the Ragulator complex on Cystinosin positive lysosomes. Together, this work uncovers lysosomal proteome heterogeneity at different levels and provides resources for understanding the contribution of lysosomal protein dynamics to signal transduction, organelle crosstalk and organism longevity.

cell biology↗

bioRxiv2022

Loss of tumor suppressor WWOX enhances RAS activity in pancreatic cancer

Pancreatic cancer is one of the most lethal cancers, owing to its late diagnosis and resistance to chemotherapy. The tumor suppressor WW domain-containing oxidoreductase (WWOX), one of the most active fragile sites in the human genome (FRA16D), is commonly altered in pancreatic cancer. However, the direct contribution of WWOX loss to pancreatic cancer development and progression remains largely unknown. Here, we report that combined conditional deletion of Wwox and activation of KRasG12D in Ptf1a-CreER-expressing mice results in accelerated formation of precursor lesions and pancreatic carcinoma. At the molecular level, we found that WWOX physically interacts with SMAD3 and BMP2, which are known activators of the TGF-{beta} signaling pathway. In the absence of WWOX, TGF{beta}/BMPs signaling was enhanced, leading to increased macrophage infiltration and enhanced cancer stemness. Finally, overexpression of WWOX in patient-derived xenografts led to diminished aggressiveness both in vitro and in vivo. Overall, our findings reveal an essential role of WWOX in pancreatic cancer development and progression and underscore its role as a bona fide tumor suppressor.

cancer biology↗

bioRxiv2021

Ferroptosis Regulation by the NGLY1/NFE2L1 Pathway

Ferroptosis is an oxidative form of non-apoptotic cell death whose transcriptional regulation is poorly understood. Capncollar (CNC) transcription factors including Nuclear Factor Erythroid-2 Related Factor 1 (NFE2L1/NRF1) and NFE2L2 (NRF2) are important regulators of oxidative stress responses. Here, we report that NFE2L1 expression inhibits ferroptosis, independent of NFE2L2. NFE2L1 inhibits ferroptosis by promoting expression of the key anti-ferroptotic lipid hydroperoxidase glutathione peroxidase 4 (GPX4). NFE2L1 abundance and function are regulated post-translationally by N-glycosylation. Functional maturation of NFE2L1 requires deglycosylation by cytosolic peptide:N-glycanase 1 (NGLY1). We find that loss of NGLY1 or NFE2L1 enhances ferroptosis sensitivity. Expression of wild-type NGLY1 but not a disease-associated NGLY1 mutant inhibits ferroptosis, and this effect is dependent on the presence of NFE2L1. Enhanced ferroptosis sensitivity in NFE2L1 and NFE2L2 knockout cells can be potently reverted by expression of an NFE2L1 mutant containing eight asparagine-to-aspartate protein sequence substitutions, which mimic NGLY1-catalyzed sequence editing. Enhanced ferroptosis sensitivity in NGLY1/NFE2L1 pathway mutants could also be reversed by overexpression of NFE2L2. These results suggest that ferroptosis sensitivity is regulated by NGLY1-catalyzed NFE2L1 deglycosylation, and highlight a broad role for CNC transcription factors in ferroptosis regulation. Significance StatementFerroptosis is an oxidative form of cell death whose biochemical regulation remains incompletely understood. NFE2L1/NRF1 is a capncollar (CNC) transcription factor whose role in ferroptosis regulation is unclear. Unlike the CNC family member NFE2L2/NRF2, NFE2L1 is an N-glycoprotein whose abundance is regulated by post-translational deglycosylation catalyzed by the enzyme peptide:N-glycanase 1 (NGLY1). Our results indicate that NGLY1-mediated NFE2L1 deglycosylation, resulting in editing of the NFE2L1 amino acid sequence, is necessary for NFE2L1 to inhibit ferroptosis. Mechanistically, NFE2L1 inhibits ferroptosis by via the anti-ferroptotic protein GPX4. This work demonstrates that CNC transcription factors beyond NFE2L2 can regulate ferroptosis. This work may suggest a role of misregulation of ferroptosis in NGLY1 deficiency, an ultrarare genetic disorder.

cell biology↗

bioRxiv2020

Lysosomal nucleotide metabolism regulates ER proteostasis through mTOR signaling

Organelles in eukaryotic cells are compartmentalized to carry out different functions, and require specific mechanisms governing their coordination. Two of these organelles, the lysosome and the endoplasmic reticulum (ER), play crucial roles in regulating cellular homeostasis and organismal health. The lysosome contains various enzymes devoted to the hydrolysis of specific substrates, and dysfunctions of these hydrolases and their related metabolic processes are implicated in many diseases 1. On the other hand, ER is essential for protein synthesis and utilizes quality control mechanisms to maintain proteostasis. The metabolic status of the lysosome is now known to actively influence nuclear transcription and mitochondrial signaling 2-4. However, whether and how mechanistically lysosomal metabolic activities regulate ER proteostasis remain unclear. Here, we reported that RSH-1, the Caenorhabditis elegans RelA/SpoT Homolog (RSH) protein, carries a lysosomal NADPH phosphatase activity and acts through the mammalian/mechanistic target of rapamycin (mTOR) signaling to regulate ER proteostasis. We discovered that RSH-1 is localized to the lysosome. Its mutation reduces NADPH hydrolysis by the lysosome, leading to a protection against ER stress-induced lethality. We further revealed that this ER stress tolerance requires lysosomal vacuolar-type H+-ATPase (v-ATPase), and Rag GTPases and ribosomal protein S6 kinase (S6K) in the mTOR signaling pathway. Through transcriptome analysis, we discovered that the S6K activation by the RSH-1 mutation increases the basal expression of X-box binding protein 1 (XBP-1) and peptidyl-prolyl cis-trans isomerases, which is necessary for improving ER proteostasis. Moreover, we demonstrated the lysosomal localization of RSH-1 mammalian homolog and its conserved role in regulating mTOR signaling. Together, our findings reveal the key role of a specific lysosomal nucleotide hydrolase in regulating organellar coordination and also signaling mechanisms underlying this active regulation, and suggest that diseases resulted from deficiency in lysosomal hydrolases may be attributed to the distortion of signal transduction and organelle homeostasis.

cell biology↗

bioRxiv2018

MITO-Tag Mice enable rapid isolation and multimodal profiling of mitochondria from specific cell types in vivo

Mitochondria are metabolic organelles that are essential for mammalian life, but the dynamics of mitochondrial metabolism within mammalian tissues in vivo remains incompletely understood. While whole-tissue metabolite profiling has been useful for studying metabolism in vivo, such an approach lacks resolution at the cellular and subcellular level. In vivo methods for interrogating organellar metabolites in specific cell-types within mammalian tissues have been limited. To address this, we built on prior work in which we exploited a mitochondrially-localized 3XHA epitope-tag (\"MITO-Tag\") for the fast isolation of mitochondria from cultured cells to now generate \"MITO-Tag Mice.\" Affording spatiotemporal control over MITO-Tag expression, these transgenic animals enable the rapid, cell-type-specific immunoisolation of mitochondria from tissues, which we verified using a combination of proteomic and metabolomic approaches. Using MITO-Tag Mice and targeted and untargeted metabolite profiling, we identified changes during fasted and refed conditions in a diverse array of mitochondrial metabolites in hepatocytes and found metabolites that behaved differently at the mitochondrial versus whole-tissue level. MITO-Tag Mice should have utility for studying mitochondrial physiology and our strategy should be generally applicable for studying other mammalian organelles in specific cell-types in vivo.

molecular biology↗

bioRxiv2018

Identification and characterization of a transporter complex responsible for the cytosolic entry of nitrogen-containing bisphosphonates

AbstractNitrogen-containing-bisphosphonates (N-BPs) are a class of drugs widely prescribed to treat osteoporosis and other bone-related diseases. Although previous studies have established that N-BPs function by inhibiting the mevalonate pathway in osteoclasts, the mechanism by which N-BPs enter the cytosol from the extracellular space to reach their molecular target is not understood. Here we implemented a CRISPRi-mediated genome-wide screen and identified SLC37A3 (solute carrier family 37 member A3) as a gene required for the action of N-BPs. We observed that SLC37A3 forms a complex with ATRAID (all-trans retinoic acid-induced differentiation factor), a previously identified genetic target of N-BPs. SLC37A3 and ATRAID localize to lysosomes and are required for releasing N-BP molecules that have trafficked to lysosomes through fluid-phase endocytosis into the cytosol. Our results elucidate the route by which N-BPs are delivered to their molecular target, addressing a key aspect of the mechanism of action of N-BPs that may have significant clinical relevance.

biochemistry↗