Biology subjects

Liesa, M.

Publications and source records attributed to Liesa, M..

13 recordsLinked to original sources

bioRxiv2026

Pdk1-dependent metabolic heterogeneity promotes aggressive colorectal cancer through cell-intrinsic interferon signaling

Tumor heterogeneity is a major determinant of tumor progression and therapeutic resistance, yet the contribution of metabolism to intratumoral heterogeneity still remains poorly explored. Here, we find that pyruvate dehydrogenase kinase-1 (Pdk1) expression defines metabolically distinct cancer cell populations in colorectal tumors. Image-based spatial single-cell phenotyping shows that Pdk1-high cells are associated with tumor progression in orthotopic models of colorectal cancer (CRC). Genetic ablation experiments demonstrate the role of Pdk1-high cells in tumor growth, 5-fluorouracil chemoresistance and tumor relapse. Mechanistically, we identify a link between Pdk1-driven metabolic states and specific cell phenotypes, where Pdk1-high cancer cells exhibit an EMT, stem cell-like phenotype characterized by increased interferon (IFN) signaling. Mitochondrial remodeling in Pdk1-high cells leads to the release of mitochondrial DNA to the cytosol and activation of IFN pathways, promoting Pdk1-driven phenotypes. Inhibition of IFN signaling impairs the tumorigenic and aggressive features of Pdk1-high cancer cells, thus establishing a functional connection between metabolic heterogeneity, cell-intrinsic IFN signaling and aggressive CRC.

cancer biology↗

bioRxiv2026

Activation of the protective arm of renin-angiotensin system enhances mitochondrial turnover improving respiration and decreasing integrated stress response in a human Complex III deficiency model.

Primary mitochondrial diseases are clinically and genetically heterogeneous disorders, commonly caused by defects in the oxidative phosphorylation system. This heterogeneity presents major challenges for therapeutic development; however, a shared hallmark across these diseases is the accumulation of dysfunctional mitochondria. Enhancing mitochondrial turnover, by activating the selective degradation of dysfunctional mitochondria via mitophagy, concurrently with the activation of mitochondrial biogenesis, could represent a shared therapeutic strategy for mitochondrial diseases. Here, we describe a novel mitophagy inducer, CAP-1902. CAP-1902 is a new agonist of the MAS G-Protein Coupled Receptor (MasR). In fibroblasts from patients carrying a BCS1L mutation that impairs complex III (CIII) assembly, CAP-1902 increased mitochondrial turnover by promoting both mitophagy and biogenesis. Specifically, MasR activation triggered the AMPK/ULK1/FUNDC1 mitophagy pathway. Knockdown of FUNDC1 blocked mitophagy but not AMPK activation, confirming pathway specificity. Additionally, a decrease in the occurrence of depolarized mitochondria with treatment indicated the selective targeting of accumulated damaged mitochondria in the disease context. MasR activation by CAP-1902 also stimulated the nuclear translocation of PGC-1, promoting increased expression of transcripts associated with mitochondrial biogenesis, respiratory chain components, and mitochondrial translation. Remarkably, CAP-1902 was ultimately able to restore key defects in CIII-deficient fibroblasts by rescuing bioenergetics and correcting both the aberrant lysosomal distribution and the elevated integrated stress response markers, which is consistent with a shift toward a healthier mitochondrial population. In summary, we describe the first potential GPCR-mediated treatment of mitochondrial diseases and demonstrate that MasR activation by CAP-1902 induces mitochondrial turnover and improves mitochondrial function.

cell biology↗

bioRxiv2025

The malate aspartate shuttle supports thermogenic lipid mobilization in brown adipocytes

Brown adipose tissue (BAT) plays a central role in thermogenesis by coupling fatty acid oxidation to heat production. Efficient BAT thermogenic activity requires enhanced glycolytic flux, which in turn depends on continuous regeneration of cytosolic NAD to sustain glyceraldehyde-3-phosphate dehydrogenase activity. This regeneration is mediated by three main pathways: lactate dehydrogenase, the glycerol-3-phosphate shuttle, and the malate-aspartate shuttle (MASh). We previously showed that inhibition of the mitochondrial pyruvate carrier increases energy expenditure in brown adipocytes via MASh activation. However, the specific contribution of MASh to BAT energy metabolism remains poorly defined. Here, we show that MASh is functional and directly regulates lipid metabolism in BAT. Enzymatic activities of cytosolic and mitochondrial malate dehydrogenases and glutamic-oxaloacetic transaminases in BAT were comparable to those in the liver. Using a reconstituted system of isolated BAT mitochondria and cytosolic MASh enzymes, we demonstrated that extra-mitochondrial NADH is efficiently reoxidized in a glutamate-dependent manner via MASh. Genetic silencing of the mitochondrial carriers critical to MASh--namely the oxoglutarate carrier (OGC1) and aspartate-glutamate carrier (Aralar1) had no apparent effects on respiratory rates. However, silencing either OGC1 or Aralar1 led to the accumulation of small lipid droplets and impaired norepinephrine-induced lipolysis. Taken together, our data indicate a novel role of MASh in regulating BAT lipid homeostasis with potential implications to body energy expenditure and thermogenesis.

biochemistry↗

bioRxiv2025

A cold-inducible phospholipid--protein interaction in brown fat mitochondria optimizes thermogenic capacity

Cold stress elicits dynamic remodeling of the mitochondrial lipidome in brown adipose tissue (BAT), marked by an increase in arachidonoyl-phosphatidylethanolamine (AA-PE). However, the function of membrane lipid rewiring in thermoregulatory physiology has been a longstanding mystery. Here, we identify LPCAT3 as a cold-regulated O-acyltransferase driving the highly selective accrual of AA-PE in BAT mitochondria. Lipid-based proteomics, molecular dynamics simulations, and bioenergetic analyses reveal that AA-PE partitions at the COX4I1 interface of the Cytochrome c oxidase complex, enhancing electron transport chain (ETC) efficiency. Accordingly, fat-specific Lpcat3-knockout mice have defects in respiratory-dependent BAT thermogenesis and cold tolerance, despite intact {beta}-adrenergic signaling and UCP1 function. Under cold acclimation, Lpcat3-/-BAT exhibits ETC dysfunction and activation of the integrated stress-response. Thus, our study illuminates a cold-regulated lipid-protein interaction as a gating factor in UCP1-dependent thermogenesis.

physiology↗

bioRxiv2022

Pharmacological activation of the mitochondrial stress protease OMA1 reveals a therapeutic liability in Diffuse Large B-Cell Lymphoma

Constitutive activation of the ATF4-mediated integrated stress response (ATF4-ISR) is common in cancer and buffers the metabolic challenges imposed by rapid proliferation. However, hyperactivation of the ISR can induce apoptosis. Here we demonstrate that novel pyrazolo-thiazole derivates activate the mitochondrial protease OMA1 which subsequently induces apoptosis in diffuse large B-cell lymphoma (DLBCL) cells. Apoptosis is dependent on the OMA1 mediated cleavage of DELE1 which leads to activation of HRI and induction of the ATF4 ISR. Screening in 406 cancer cell lines identified an inverse correlation between sensitivity to OMA1 activators and expression of the mitochondrial protein FAM210B. Ectopic overexpression of FAM210B specifically blocks OMA1 activation and apoptosis induction by pyrazolo-thiazole activators in DLBCL. OMA1 activators, including the preclinical candidate BTM-3566, selectively killed ABC, GCB, and double-hit DLBCL lines and induced complete tumor regression across a panel of DLBCL patient-derived xenografts. SignificanceHere we describe a novel class of small molecules that activate the mitochondrial protease OMA1 and induce therapeutic responses in DLBCL preclinical models in vitro and in vivo. OMA1 activation drives apoptosis through ATF4-ISR, an orthogonal mechanism to current therapies.

cancer biology↗

bioRxiv2022

Mitoquinone mesylate targets SARS-CoV-2 and associated lung inflammation through host pathways

To date, there is no effective oral antiviral against SARS-CoV-2 that is also anti-inflammatory. Herein, we show that the mitochondrial antioxidant mitoquinone/mitoquinol mesylate (Mito-MES), a dietary supplement, has potent antiviral activity against SARS-CoV-2 and its variants of concern in vitro and in vivo. Mito-MES had nanomolar in vitro antiviral potency against the Beta and Delta SARS-CoV-2 variants as well as the murine hepatitis virus (MHV-A59). Mito-MES given in SARS-CoV-2 infected K18-hACE2 mice through oral gavage reduced viral titer by nearly 4 log units relative to the vehicle group. We found in vitro that the antiviral effect of Mito-MES is attributable to its hydrophobic dTPP+ moiety and its combined effects scavenging reactive oxygen species (ROS), activating Nrf2 and increasing the host defense proteins TOM70 and MX1. Mito-MES was efficacious reducing increase in cleaved caspase-3 and inflammation induced by SARS-CoV2 infection both in lung epithelial cells and a transgenic mouse model of COVID-19. Mito-MES reduced production of IL-6 by SARS-CoV-2 infected epithelial cells through its antioxidant properties (Nrf2 agonist, coenzyme Q10 moiety) and the dTPP moiety. Given established safety of Mito-MES in humans, our results suggest that Mito-MES may represent a rapidly applicable therapeutic strategy that can be added in the therapeutic arsenal against COVID-19. Its potential long-term use by humans as diet supplement could help control the SARS-CoV-2 pandemic, especially in the setting of rapidly emerging SARS-CoV-2 variants that may compromise vaccine efficacy. One-Sentence SummaryMitoquinone/mitoquinol mesylate has potent antiviral and anti-inflammatory activity in preclinical models of SARS-CoV-2 infection.

microbiology↗

bioRxiv2022

Modeling of Alpha-1 Antitrypsin Deficiency with Syngeneic Human iPSC-Hepatocytes Reveals Metabolic Dysregulation and Cellular Heterogeneity in PiMZ and PiZZ Hepatocytes

Individuals homozygous for the pathogenic "Z" mutation in alpha-1 antitrypsin deficiency (AATD) are known to be at increased risk for chronic liver disease. That some degree of risk is similarly conferred by the heterozygous state, estimated to affect 2% of the US population, has also become clear. A lack of model systems that recapitulate heterozygosity in human hepatocytes has limited the ability to study the impact of expressing a single ZAAT allele on hepatocyte biology. Here, through the application of CRISPR-Cas9 editing, we describe the derivation of syngeneic induced pluripotent stem cells (iPSCs) engineered to determine the effects of ZAAT heterozygosity in iPSC-derived hepatocytes (iHeps) relative to homozygous mutant (ZZ) or corrected (MM) cells. We find that heterozygous MZ iHeps exhibit an intermediate disease phenotype and share with ZZ iHeps alterations in AAT protein processing and downstream perturbations in hepatic metabolic function including ER and mitochondrial morphology, reduced mitochondrial respiration, and branch-specific activation of the unfolded protein response in subpopulations of cells. Our cellular model of MZ heterozygosity thus provides evidence that expression of a single Z allele is sufficient to disrupt hepatocyte homeostatic function and suggest a mechanism underlying the increased risk of liver disease observed among MZ individuals.

cell biology↗

bioRxiv2020

High-Throughput Image Analysis of Lipid-Droplet-Bound Mitochondria

Changes to mitochondrial architecture are associated with various adaptive and pathogenic processes. However, quantification of changes to mitochondrial structures are limited by the yet unmet challenge of defining the borders of each individual mitochondrion within an image.. Here, we describe a novel method for segmenting Brown Adipose Tissue (BAT) images. We describe a granular approach to quantifying subcellular structures, particularly mitochondria in close proximity to lipid droplets, peri-droplet mitochondria. In addition, we lay out a novel machine-learning-based mitochondrial segmentation method that eliminates the bias of manual mitochondrial segmentation and improves object recognition compared to conventional thresholding analyses. By applying these methods, we discovered a significant difference between cytosolic and peridroplet BAT mitochondrial H2O2 production, and validated the machine learning algorithm in BAT via norepinephrine-induced mitochondrial fragmentation and comparing manual analyses to the automated analysis. This approach provides a higher-throughput analysis protocol to quantify ratiometric probes in subpopulations of mitochondria in adipocytes.

cell biology↗

bioRxiv2019

Blocking mitochondrial pyruvate import causes energy wasting via futile lipid cycling in brown fat

Futile lipid cycling is an ATP-wasting process proposed to participate in energy expenditure of mature fat-storing white adipocytes, given their inability to oxidize fat. The hallmark of activated brown adipocytes is to increase fat oxidation by uncoupling respiration from ATP synthesis. Whether ATP-consuming lipid cycling can contribute to BAT energy expenditure has been largely unexplored. Here we find that pharmacological inhibition of the mitochondrial pyruvate carrier (MPC) in brown adipocytes is sufficient to increase ATP-synthesis fueled by fatty acid oxidation, even in the absence of adrenergic stimulation. We find that elevated ATP-demand induced by MPC inhibition results from activation of futile lipid cycling. Furthermore, we identify that glutamine consumption and the Malate-Aspartate Shuttle are required for the increase in Energy Expenditure induced by MPC inhibition in Brown Adipocytes (MAShEEBA). These data demonstrate that futile energy expenditure through lipid cycling can be activated in BAT by altering fuel availability to mitochondria. Therefore, we identify a new mechanism to increase fat oxidation and energy expenditure in BAT that bypasses the need for adrenergic stimulation of mitochondrial uncoupling.

biochemistry↗

bioRxiv2019

Cristae undergo continuous cycles of fusion and fission in a MICOS-dependent manner

The mitochondrial inner membrane can reshape under different physiological conditions. How and at which frequency this occurs in vivo and what are the molecular players involved is unknown. Here we show using state-of-the-art live-cell stimulated emission depletion (STED) super-resolution nanoscopy that crista junctions (CJs) are dynamically fusing and dividing in a reversible and balanced manner at a timescale of seconds. CJ dynamics is strongly reduced in the absence of the MICOS subunit MIC13. Staining of the cristae membrane using different protein markers or two inner mitochondrial membrane-specific dyes revealed that cristae also undergo continuous cycles of fusion and fission. These processes are dependent on MIC13 and occur at a timescale of seconds, resembling CJ dynamics. Our data further suggest that MIC60 acts as a docking platform pioneering CJ formation. Overall, by employing a variety of advanced imaging techniques including FRAP (Fluorescence-Recovery-After Photobleaching), SPT (Single-Particle-Tracking), live-cell STED and confocal Airyscan microscopy we demonstrate that cristae undergo continuous cycles of fusion and fission in a manner that is mechanistically linked to CJ formation and dynamics.

cell biology↗

bioRxiv2019

Single cell profiling of the VMH reveals a sexually dimorphic regulatory node of energy expenditure

Estrogen signaling in the central nervous system promotes weight loss by increasing thermogenesis and physical activity in the ventromedial hypothalamus (VMH), but the precise neuronal populations regulating these aspects of energy expenditure remain unclear. Here we define the molecular and functional heterogeneity of the VMH using single cell RNA sequencing, in situ hybridization, chemogenetic activation, and targeted gene knockdown. We describe six molecularly distinct neuron clusters in the VMH. In females, estrogen receptor alpha (ER) is restricted to neurons expressing tachykinin-1 (Tac1) or reprimo (Rprm). Further, Tac1 and Rprm expression is enriched in females, a sex difference that is established by permanent effects of gonadal hormones early in life. Finally, while Tac1 ablation selectively impairs movement, here we show that silencing Rprm selectively dysregulates temperature without affecting physical activity. Together this work provides a novel architectural framework whereby distinct and sexually differentiated neuron populations within the VMH mediate sex-specific aspects of metabolic homeostasis.

neuroscience↗

bioRxiv2018

NCLX prevents cell death during adrenergic activation of the brown adipose tissue

A sharp increase in mitochondrial Ca2+ marks the activation of the brown adipose tissue (BAT) thermogenesis, yet the mechanisms preventing Ca2+ deleterious effects are poorly understood. Here, we show that adrenergic stimulation of BAT activates a PKA-dependent mitochondrial Ca2+ extrusion via the mitochondrial Na+/Ca2+ exchanger, NCLX. Adrenergic stimulation of NCLX-ablated brown adipocytes (BA) induces a profound mitochondrial Ca2+ overload and impaired uncoupled respiration. Core body temperature, PET imaging and VO2 measurements confirm a BAT specific thermogenic defect in NCLX-null mice.\n\nWe show that mitochondrial Ca2+ overload induced by adrenergic stimulation of NCLX-null BAT, triggers the opening of the mitochondrial permeability transition pore (mPTP), leading to remarkable mitochondrial swelling, Cytochrome c release and cell death in BAT. However, treatment with mPTP inhibitors rescue mitochondrial respiratory function and thermogenesis in NCLX-null BA, in vitro and in vivo.\n\nOur findings identify a novel pathway enabling non-lethal mitochondrial Ca2+ elevation during adrenergic stimulation of uncoupled respiration. Deletion of NCLX transforms the adrenergic pathway responsible for the stimulation of thermogenesis into a death pathway.

physiology↗

bioRxiv2017

GPS2 regulates mitochondria biogenesis via mitochondrial retrograde signaling and chromatin remodeling of nuclear-encoded mitochondrial genes

As most of the mitochondrial proteome is encoded in the nucleus, mitochondrial functions critically depend on nuclear gene expression and bidirectional mito-nuclear communication. However, mitochondria-to-nucleus communication pathways are incompletely understood. Here, we identify G-Protein Pathway Suppressor 2 (GPS2) as a mediator of mitochondrial retrograde signaling and a key transcriptional activator of nuclear-encoded mitochondrial genes in mammals. GPS2 regulated translocation from mitochondria to nucleus is essential for the transcriptional activation of the nuclear stress response to mitochondrial depolarization and for supporting basal mitochondrial biogenesis in differentiating adipocytes and in brown adipose tissue from mice. In the nucleus, GPS2 recruitment to target gene promoters regulates histone H3K9 demethylation and RNA Polymerase II (POL2) activation through inhibition of Ubc13-mediated ubiquitination. Together, these findings reveal an unexpected layer of regulation of mitochondrial gene transcription as they uncover a novel mitochondria-nuclear communication pathway.

molecular biology↗