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Biology subjects

Herfs, M.

Publications and source records attributed to Herfs, M..

3 recordsLinked to original sources

mTORC2 stabilizes HIF-1β to coordinate metabolic adaptation in lung cancer

Despite extensive genetic heterogeneity, lung tumors frequently converge on shared signaling dependencies that remain therapeutically underexploited. Here, we identify mTORC2 signaling as a convergent dependency across genetically distinct lung cancer subtypes and uncover HIF-1{beta} as a selective metabolic effector downstream of mTORC2 that promotes lung tumor progression. Elevated mTORC2 signaling in lung adenocarcinoma was associated with poor overall survival, metastatic dissemination and metabolic rewiring. Using complementary genetically engineered mouse models of Rictor deletion or overexpression in Kras-driven lung tumors, we show that mTORC2 activity is dispensable for normal lung homeostasis but required for tumor progression and metabolic adaptation in vivo. Mechanistically, mTORC2 stabilized HIF-1{beta} by preventing its ubiquitin-independent proteasomal degradation through a non-canonical PKC-CK2 signaling axis, independently of AKT. Integrated multi-omics analyses identified extensive metabolic rewiring downstream of the mTORC2-HIF-1{beta} axis, with sphingolipid metabolism emerging as a prominent and therapeutically exploitable vulnerability. Accordingly, pharmacological targeting of sphingolipid metabolism markedly impaired the growth of mTORC2-driven lung tumors in vivo. Together, our findings establish a non-canonical mTORC2-HIF-1{beta} signaling axis that couples oncogenic signaling to metabolic adaptation and defines therapeutically actionable metabolic vulnerabilities in lung cancer.

cancer biology↗

KDM6B interacts with nucleo-adhesome components CSRP2 and TGFB1I1 to regulate EMT

The methyltransferase EZH2 (Enhancer of Zest Homolog 2) and the demethylase KDM6B (Lysine Demethylase 6B) have been associated with epithelial to mesenchymal transition (EMT) and poor prognosis in various cancers. These enzymes methylate and demethylate H3K27me3 and regulate distinct sets of genes controlling EMT induction, despite having opposite catalytic activities. This could be due to their recruitment or the modulation of their activity by partner proteins on specific loci. This work sought to identify proteins associated with chromatin and interacting with EZH2 or with KDM6B during EMT. To do so, co-immunoprecipitation and mass spectroscopy was used under TGF{beta} (Tumor growth factor {beta}) and TNF (Tumor necrosis factor ) treatment to induce EMT in A549 lung cancer cells. Surprisingly, numerous proteins related to focal adhesions were identified to interact with EZH2 or KDM6B. These proteins are part of a nuclear protein interaction network previously described as nucleo-adhesome. Among these proteins, TGFB1I1 (transforming growth factor induced peptide 1) and CSRP2 (cysteine and glycine rich protein 2) were further confirmed to interact with KDM6B in the nucleus and even more so during EMT. The target genes of these complexes were then sought by knocking down KDM6B, TGFB1I1 or CSRP2. Three genes (coding Integrin alpha 5, Laminin y2 and Matrix Metalloproteinase 9) were confirmed to be regulated by KDM6B, TGFB1I1 and CSRP2. These findings may have clinical relevance, as immunohistochemistry analyses performed on a cohort of lung cancer patients revealed increased nuclear localization of TGFB1I1 and CSRP2 in cells undergoing EMT.

cell biology↗

Exostosin-1 Glycosyltransferase Regulates Endoplasmic Reticulum Architecture and Dynamics

The endoplasmic reticulum (ER) is a central eukaryotic organelle with a tubular network made of hairpin proteins linked by hydrolysis of GTP nucleotides. Among post-translational modifications initiated at the ER level, glycosylation is the most common reaction. However, our understanding of the impact of glycosylation on ER structure remains unclear. Here, we show that Exostosin-1 (EXT1) glycosyltransferase, an enzyme involved in N-glycosylation, is a key regulator of ER morphology and dynamics. We have integrated multi-omics data and super-resolution imaging to characterize the broad effect of EXT1 inactivation, including ER shape-dynamics-function relationships in mammalian cells. We have observed that, inactivating EXT1 induces cell enlargement and enhances metabolic switches such as protein secretion. In particular, suppressing EXT1 in mouse thymocytes causes developmental dysfunctions associated to ER network extension. Our findings suggest that EXT1 drives glycosylation reactions involving ER structural proteins and high-energy nucleotide sugars, which might also apply to other organelles.

cell biology↗