Project description:Tamoxifen-induced deletion of endogenous GlcCer-synthesizing enzyme UDP-glucose:ceramide glucosyltransferase (UGCG) in keratin K14-positive cells results in epidermal GlcCer depletion. We used microarrays to investigate the molecular consequences of Ugcg-depleted mouse epidermis.
Project description:Tamoxifen-induced deletion of endogenous GlcCer-synthesizing enzyme UDP-glucose:ceramide glucosyltransferase (UGCG) in keratin K14-positive cells results in epidermal GlcCer depletion. We used microarrays to investigate the molecular consequences of Ugcg-depleted mouse epidermis. Ugcgfl/fl K14CreERT2 vs. Ugcgfl/fl samples taken at day 21 post tamoxifen induction
Project description:The protein quality control sensors UDP-glucose: glycoprotein glucosyltransferase (UGGT) 1 and 2 are proposed to act as gatekeepers of the early secretory pathway. They initiate rebinding to the carbohydrate-dependent chaperones calnexin and calreticulin that associate with proteins possessing monoglucosylated glycans. The UGGTs control glycoprotein exit from the endoplasmic reticulum (ER) for trafficking to the Golgi or ER retention to provide additional folding opportunities. A quantitative glycoproteomics strategy was used to identify cellular glycoproteins modified by the UGGTs at endogenous levels and delineate the specificities of UGGT1 and UGGT2. UGGT substrates were comprised of seventy-one mainly large multidomain and heavily glycosylated proteins when compared to the general N-glycome. UGGT1 was the dominant glucosyltransferase with a preference towards large plasma membrane proteins whereas UGGT2 favored the modification of smaller, soluble lysosomal proteins. This study provides insight into the cellular secretory load that utilizes multiple rounds of carbohydrate-dependent chaperone intervention for proper maturation.
Project description:Glucose is essential for T cell proliferation and function, yet the metabolic fates of glucose critical for T cell responses in vivo remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as an essential arm of glucose metabolism that fuels CD8+ T cell expansion and cytotoxic function in vivo. Using stable isotope tracing, we show that CD8+ effector T (Teff) cells in vivo use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a common precursor for glycogen, glycan, and GSL biosynthesis. Blocking GSL production–by targeting the enzymes UDP-Glc pyrophosphorylase 2 (UGP2) or UDP-Glc ceramide glucosyltransferase (UGCG)–blunts CD8+ T cell expansion and cytotoxic activity without impacting glucose-dependent energy production. Mechanistically, we show that glucose-dependent GSL biosynthesis (via UGCG) maintains lipid integrity at the plasma membrane and is required for lipid raft aggregation following T cell receptor (TCR) stimulation. CD8+ T cells lacking UGCG display poor cytotoxic function and reduced tumor control in vivo. Together, our data highlight GSL biosynthesis as an essential metabolic fate for glucose–independent of energy production–required to maintain membrane lipid homeostasis and CD8+ T cell cytotoxic function in vivo.
Project description:Glucose is essential for T cell proliferation and function, yet the metabolic fates of glucose critical for T cell responses in vivo remain poorly defined. Here, we identify glycosphingolipid (GSL) biosynthesis as an essential arm of glucose metabolism that fuels CD8+ T cell expansion and cytotoxic function in vivo. Using stable isotope tracing, we show that CD8+ effector T (Teff) cells in vivo use glucose to synthesize uridine diphosphate-glucose (UDP-Glc), a common precursor for glycogen, glycan, and GSL biosynthesis. Blocking GSL production–by targeting the enzymes UDP-Glc pyrophosphorylase 2 (UGP2) or UDP-Glc ceramide glucosyltransferase (UGCG)–blunts CD8+ T cell expansion and cytotoxic activity without impacting glucose-dependent energy production. Mechanistically, we show that glucose-dependent GSL biosynthesis (via UGCG) maintains lipid integrity at the plasma membrane and is required for lipid raft aggregation following T cell receptor (TCR) stimulation. CD8+ T cells lacking UGCG display poor cytotoxic function and reduced tumor control in vivo. Together, our data highlight GSL biosynthesis as an essential metabolic fate for glucose–independent of energy production–required to maintain membrane lipid homeostasis and CD8+ T cell cytotoxic function in vivo.
Project description:UDP-glucose ceramide glucosyltransferase (UGCG) is an enzyme that glycosylates ceramide and blunts its pro-apoptotic activity in cancer cells. Targeting UGCG sensitizes solid cancer cells to chemotherapy. However, whether targeting UGCG can increase the sensitivity of AML cells to Venetoclax remains unclear. Here, we found that the inhibition of UGCG genetically or with its inhibitor Eliglustat efficiently suppressed growth and promoted apoptosis in AML cells. Moreover, Eliglustat in combination with Venetoclax increased apoptosis, reduced AML cell viability, and inhibited AML effectively both for primary AML cells and xenograft models. Mechanistically, the combination induced ceramide accumulation which activated the endoplasmic reticulum (ER) stress-GRP78/PERK/CHOP axis. Interestingly, combinatory treatment activated RAB32, which led to mitochondrial fission through ER-mitochondria communication and DRP1 activation. These findings demonstrate that targeting UGCG in combination with Venetoclax is a new combinatory strategy to treat AML, and provide new insights for ceramide-mediated cell death in anti-cancer therapies.
Project description:<p>This study investigates the dual role of the Streptomyces-derived nucleoside Guvermectin (GV) in promoting plant growth and enhancing disease resistance. Multiomics analysis revealed that GV reprograms phenylalanine metabolism, leading to the accumulation of antimicrobial flavonoids. A key UDP-glucosyltransferase (StGTR) and transcription factor (StMYB5) were identified as essential for GV-induced flavonoid production and late blight resistance. Genetic and field experiments confirmed that GV-triggered immunity and growth promotion depend on BAK1 and outperform commercial fungicides in suppressing Phytophthora infestans while improving potato yield. These findings highlight GV’s potential as a natural compound for sustainable crop protection.</p>
Project description:Kelch-like ECH associated protein 1 (KEAP1) is the third most commonly mutated gene in non-small cell lung cancer (NSCLC) and is associated with poor prognosis. Here, we investigated synthetic lethal interaction genes in KEAP1-mutated cancer cells and identified a dependency on UDP xylose synthase 1 (UXS1), which converts UDP-glucuronic acid (UDP-GlcA) to UDP- xylose in the proteoglycan synthetic pathway. UDP glucose dehydrogenase (UGDH), a transcriptional target of NRF2 that converts UDP-glucose to UDP-GlcA, was highly expressed in KEAP1-mutant tumors. Upon UXS1 knockdown, depletion of UDP-xylose occurred in both KEAP1-mutant and wildtype (WT) cells, whereas UDP-GlcA accumulated to a greater extent in the KEAP1-mutant setting. The resulting shortage of available UDP and other pyrimidines slowed S-phase progression and stalled DNA replication fork marks, causing cells to undergo prolonged cell-cycle exit or apoptosis. Dependency on UXS1 was rescued by knocking out UGDH to prevent UDP-GlcA accumulation and UDP depletion. DNA replication stress in UXS1-depleted cells sensitized them to clinical cell-cycle checkpoint inhibitors. Further, CRISPR screening experiments identified genes that modulate UXS1 dependency. While liver had the highest normal tissue expression of UGDH, UXS1 knockout in the liver did not result in hepatotoxicity. Taken together, these data demonstrate that UXS1 is a selective dependency in KEAP1-mutant tumors and loss of UXS1 creates additional therapeutically exploitable vulnerabilities in KEAP1-mutant tumors.
Project description:Kelch-like ECH associated protein 1 (KEAP1) is the third most commonly mutated gene in non-small cell lung cancer (NSCLC) and is associated with poor prognosis. Here, we investigated synthetic lethal interaction genes in KEAP1-mutated cancer cells and identified a dependency on UDP xylose synthase 1 (UXS1), which converts UDP-glucuronic acid (UDP-GlcA) to UDP- xylose in the proteoglycan synthetic pathway. UDP glucose dehydrogenase (UGDH), a transcriptional target of NRF2 that converts UDP-glucose to UDP-GlcA, was highly expressed in KEAP1-mutant tumors. Upon UXS1 knockdown, depletion of UDP-xylose occurred in both KEAP1-mutant and wildtype (WT) cells, whereas UDP-GlcA accumulated to a greater extent in the KEAP1-mutant setting. The resulting shortage of available UDP and other pyrimidines slowed S-phase progression and stalled DNA replication fork marks, causing cells to undergo prolonged cell-cycle exit or apoptosis. Dependency on UXS1 was rescued by knocking out UGDH to prevent UDP-GlcA accumulation and UDP depletion. DNA replication stress in UXS1-depleted cells sensitized them to clinical cell-cycle checkpoint inhibitors. Further, CRISPR screening experiments identified genes that modulate UXS1 dependency. While liver had the highest normal tissue expression of UGDH, UXS1 knockout in the liver did not result in hepatotoxicity. Taken together, these data demonstrate that UXS1 is a selective dependency in KEAP1-mutant tumors and loss of UXS1 creates additional therapeutically exploitable vulnerabilities in KEAP1-mutant tumors.
Project description:UDP-glucuronic acid (UDP-GlcUA) is a nucleotide sugar that plays important roles in many organisms and excessive UDP-GlcUA in the cell causes many defects in the cellular processes. In Cryptococcus spp., mutations in the UXS1 gene which encodes an enzyme that converts UDP-GlcUA into UDP-xylose trigger high level accumulation of UDP-GlcUA and effectuate resistance to the antifungal drug 5-fluorocytosine. Here, we show that elevation of UDP-GlcUA affects several cellular processes including growth rate, ability to grow at various stress conditions, and resistance to fluorine containing analogs. RNA-seq analyses reveal that UXS1 deletion leads to the identification of three differentially expressed endopeptidase genes, notably PEP401. Lack of PEP401 from the uxs1 mutant background reduces the UDP-GlcUA levels and reverts all the phenotypes of the uxs1 mutant toward the wild-type characteristics. Particularly, high levels of UDP-GlcUA not only regulate expression of PEP401 at RNA and protein levels, but it also enhances the proteolytic activity of total protein extracts in a PEP401-dependent manner, establishing a functional link between nucleotide sugar metabolism and proteolytic regulation. Moreover, the UDP-GlcUA transporter gene, UUT1, can further modulate the levels of UDP-GlcUA in the uxs1 pep401 double mutant and manifests the drug resistance phenotypes observed in the uxs1 mutant. Taken together, these findings reveal a previously unrecognized regulatory network that connects UDP-GlcUA metabolism to protease-mediated cellular processes and to the transportation of UDP-GlcUA. This newly identified interplay provides a foundation for targeting nucleotide sugar metabolism and protease regulation in the development of improved therapeutic strategies against cryptococcosis.