bims-meprid 2024-08-11 papers

Cell Mol Life Sci. 2024 Aug 09. 81(1): 340

Mitochondrial copper overload promotes renal fibrosis via inhibiting pyruvate dehydrogenase activity.

Saiya Zhu, Yangyang Niu, Wenqian Zhou, Yuqing Liu, Jing Liu, Xi Liu, Limin Lu, Chen Yu.

Copper is a trace element essential for numerous biological activities, whereas the mitochondria serve as both major sites of intracellular copper utilization and copper reservoir. Here, we investigated the impact of mitochondrial copper overload on the tricarboxylic acid cycle, renal senescence and fibrosis. We found that copper ion levels are significantly elevated in the mitochondria in fibrotic kidney tissues, which are accompanied by reduced pyruvate dehydrogenase (PDH) activity, mitochondrial dysfunction, cellular senescence and renal fibrosis. Conversely, lowering mitochondrial copper levels effectively restore PDH enzyme activity, improve mitochondrial function, mitigate cellular senescence and renal fibrosis. Mechanically, we found that mitochondrial copper could bind directly to lipoylated dihydrolipoamide acetyltransferase (DLAT), the E2 component of the PDH complex, thereby changing the interaction between the subunits of lipoylated DLAT, inducing lipoylated DLAT protein dimerization, and ultimately inhibiting PDH enzyme activity. Collectively, our study indicates that mitochondrial copper overload could inhibit PDH activity, subsequently leading to mitochondrial dysfunction, cellular senescence and renal fibrosis. Reducing mitochondrial copper overload might therefore serve as a strategy to rescue renal fibrosis.

Keywords: Copper; Mitochondria; Pyruvate dehydrogenase; Renal fibrosis; Tricarboxylic acid (TCA) cycle

DOI: https://doi.org/10.1007/s00018-024-05358-1

Dev Cell. 2024 Jul 30. pii: S1534-5807(24)00445-3. [Epub ahead of print]

Redox heterogeneity in mouse embryonic stem cells individualizes cell fate decisions.

Agnes Ulfig, Ursula Jakob.

Pluripotent embryonic stem cells (ESCs) can develop into any cell type in the body. Yet, the regulatory mechanisms that govern cell fate decisions during embryogenesis remain largely unknown. We now demonstrate that mouse ESCs (mESCs) display large natural variations in mitochondrial reactive oxygen species (mitoROS) levels that individualize their nuclear redox state, H3K4me3 landscape, and cell fate. While mESCs with high mitoROS levels (mitoROSHIGH) differentiate toward mesendoderm and form the primitive streak during gastrulation, mESCs, which generate less ROS, choose the alternative neuroectodermal fate. Temporal studies demonstrated that mesendodermal (ME) specification of mitoROSHIGH mESCs is mediated by a Nrf2-controlled switch in the nuclear redox state, triggered by the accumulation of redox-sensitive H3K4me3 marks, and executed by a hitherto unknown ROS-dependent activation process of the Wnt signaling pathway. In summary, our study explains how ESC heterogeneity is generated and used by individual cells to decide between distinct cellular fates.

Keywords: H3K4me3 epigenome; Nrf2 signaling; Wnt signaling pathway; cell fate decision; embryonic stem cells; mesendoderm; neuroectoderm; reactive oxygen species; redox; stem cell heterogeneity

DOI: https://doi.org/10.1016/j.devcel.2024.07.008

J Transl Med. 2024 Aug 05. 22(1): 738

Lactate dehydrogenase A (LDHA)-mediated lactate generation promotes pulmonary vascular remodeling in pulmonary hypertension.

Daiqian Wu, Shuo Wang, Fengxian Wang, Qing Zhang, Zhen Zhang, Xingbing Li.

BACKGROUND: High levels of lactate are positively associated with prognosis and mortality in pulmonary hypertension (PH). Lactate dehydrogenase A (LDHA) is a key enzyme for the production of lactate. This study is undertaken to investigate the role and molecular mechanisms of lactate and LDHA in PH.
METHODS: Lactate levels were measured by a lactate assay kit. LDHA expression and localization were detected by western blot and Immunofluorescence. Proliferation and migration were determined by CCK8, western blot, EdU assay and scratch-wound assay. The right heart catheterization and right heart ultrasound were measured to evaluate cardiopulmonary function.
RESULTS: In vitro, we found that lactate promoted proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) in an LDHA-dependent manner. In vivo, we found that LDHA knockdown reduced lactate overaccumulation in the lungs of mice exposed to hypoxia. Furthermore, LDHA knockdown ameliorated hypoxia-induced vascular remodeling and right ventricular dysfunction. In addition, the activation of Akt signaling by hypoxia was suppressed by LDHA knockdown both in vivo and in vitro. The overexpression of Akt reversed the inhibitory effect of LDHA knockdown on proliferation in PASMCs under hypoxia. Finally, LDHA inhibitor attenuated vascular remodeling and right ventricular dysfunction in Sugen/hypoxia mouse PH model, Monocrotaline (MCT)-induced rat PH model and chronic hypoxia-induced mouse PH model.
CONCLUSIONS: Thus, LDHA-mediated lactate production promotes pulmonary vascular remodeling in PH by activating Akt signaling pathway, suggesting the potential role of LDHA in regulating the metabolic reprogramming and vascular remodeling in PH.

Keywords: Glycolysis; Lactate; Lactate dehydrogenase A; Pulmonary hypertension; Vascular remodeling

DOI: https://doi.org/10.1186/s12967-024-05543-7

Nature. 2024 Aug 07.

Glycosphingolipid synthesis mediates immune evasion in KRAS-driven cancer.

Mariluz Soula, Gokhan Unlu, Rachel Welch, Aleksey Chudnovskiy, Beste Uygur, Vyom Shah, Hanan Alwaseem, Paul Bunk, Vishvak Subramanyam, Hsi-Wen Yeh, Artem Khan, Søren Heissel, Hani Goodarzi, Gabriel D Victora, Semir Beyaz, Kıvanç Birsoy.

Cancer cells frequently alter their lipids to grow and adapt to their environment1-3. Despite the critical functions of lipid metabolism in membrane physiology, signalling and energy production, how specific lipids contribute to tumorigenesis remains incompletely understood. Here, using functional genomics and lipidomic approaches, we identified de novo sphingolipid synthesis as an essential pathway for cancer immune evasion. Synthesis of sphingolipids is surprisingly dispensable for cancer cell proliferation in culture or in immunodeficient mice but required for tumour growth in multiple syngeneic models. Blocking sphingolipid production in cancer cells enhances the anti-proliferative effects of natural killer and CD8+ T cells partly via interferon-γ (IFNγ) signalling. Mechanistically, depletion of glycosphingolipids increases surface levels of IFNγ receptor subunit 1 (IFNGR1), which mediates IFNγ-induced growth arrest and pro-inflammatory signalling. Finally, pharmacological inhibition of glycosphingolipid synthesis synergizes with checkpoint blockade therapy to enhance anti-tumour immune response. Altogether, our work identifies glycosphingolipids as necessary and limiting metabolites for cancer immune evasion.

DOI: https://doi.org/10.1038/s41586-024-07787-1