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Biology subjects

Labelle, M.

Publications and source records attributed to Labelle, M..

3 recordsLinked to original sources

ER-to-Golgi Trafficking is a Nutrient-Sensitive Checkpoint Linking Glucose Starvation to Cell Surface Remodeling

Cancer cells adapt to nutrient stress by remodeling the repertoire of proteins on their surface, enabling survival and progression under starvation conditions. However, the molecular mechanisms by which nutrient cues reshape the cell surface proteome to influence cell behavior remain largely unresolved. Here, we show that acute glucose starvation, but not amino acid deprivation or mTOR inhibition, selectively impairs ER-to-Golgi export of specific cargoes, such as E-cadherin, in a SEC24C-dependent manner. Quantitative cell surface proteomics reveal that glucose deprivation remodels the cell surface proteome, notably reducing surface expression of key adhesion molecules. This nutrient-sensitive reprogramming enhances cell migration in vitro and promotes metastasis in vivo. Mechanistically, we show that AMPK and ULK1 signaling orchestrate this process independent of autophagy, with ULK1-mediated phosphorylation of SEC31A driving SEC24C-dependent COPII reorganization. These findings establish ER-to-Golgi trafficking as a nutrient-sensitive regulatory node that links metabolic stress to cell surface remodeling and metastatic potential.

cell biology↗

Characterization of a KDM5 Small Molecule Inhibitor with Antiviral Activity against Hepatitis B Virus

Chronic hepatitis B (CHB) is a global health care challenge and a major cause of liver disease. To find new therapeutic avenues with a potential to functionally cure chronic Hepatitis B virus (HBV) infection, we performed a focused screen of epigenetic modifiers to identify replication inhibitors. From this work we identified isonicotinic acid inhibitors of the histone lysine demethylase 5 (KDM5) with potent anti-HBV activity. To enhance the cellular permeability and liver accumulation of the most potent KDM5 inhibitor identified (GS-080) an ester prodrug was developed (GS-5801) that resulted in improved bioavailability and liver exposure as well as an increased H3K4me3:H3 ratio on chromatin. GS-5801 treatment of HBV-infected primary human hepatocytes inhibited HBV replication and antigen levels. Evaluation of GS-5801 antiviral activity in a humanized mouse model of HBV infection, however, did not result in antiviral efficacy, despite achieving pharmacodynamic levels of H3K4me3:H3 predicted to be efficacious from the in vitro model. Here we discuss potential reasons for the disconnect between in vitro and in vivo efficacy, which highlight the translational difficulties of epigenetic targets for viral diseases.

pharmacology and toxicology↗

Platelet counts predict prognosis in IPF, but are not the main source of pulmonary TGFβ1

Transforming growth factor-{beta}1 (TGF{beta}1) is the key pro-fibrotic cytokine implicated in the interstitial lung diseases (ILD), including idiopathic pulmonary fibrosis (IPF), but the primary source of TGF{beta}1 in these diseases is unknown. Platelets have abundant TGF{beta}1 stores, however their role in IPF is ill-defined. We sought to investigate whether platelets or platelet-derived TGF{beta}1 mediate IPF disease progression. ILD/IPF and non-ILD patients were recruited to determine platelet reactivity and followed for mortality. To study whether platelet-derived TGF{beta}1 modulates pulmonary fibrosis, mice with a targeted deletion of TGF{beta}1 in megakaryocytes and platelets (TGF{beta}1fl/fl.PF4-Cre) were used in the bleomycin-induced PF model. We found a significantly higher mortality in IPF patients with elevated platelet counts, along with significantly increased platelets, neutrophils, TGF{beta}1 and CCL5 in the lung and bronchoalveolar lavage (BAL) of ILD patients. Despite platelets being readily detected within the lungs of bleomycin-treated mice, neither the degree of pulmonary inflammation or fibrosis were significantly different between TGF{beta}1fl/fl.PF4-Cre and control mice. Our results demonstrate for the first-time that platelet-derived TGF{beta}1 is redundant in driving pulmonary fibrosis in an animal model. However, platelets can predict mortality in IPF implicating other platelet-derived mediators, such as CCL5, in promoting human IPF disease.

cell biology↗