Biology subjects

Villar, M.

Publications and source records attributed to Villar, M..

3 recordsLinked to original sources

bioRxiv2026

Elevated cholesterol in APOE4 astrocytes drives mitochondrial cristae collapse and ATP synthase dysfunction

Cholesterol imbalance is a hallmark of major human diseases, including atherosclerosis and Alzheimers disease, both of which are also associated with mitochondrial dysfunction, yet the mechanistic links between cholesterol and mitochondria remain poorly understood. Here we show that elevated intracellular cholesterol in murine astrocytes expressing the Alzheimers disease risk variant APOE4 disrupts the inner mitochondrial membrane, manifesting as sparse, truncated cristae alongside an excess of cristae junction complexes. These structural abnormalities are accompanied by loss of respiratory chain complexes I and IV, and reduced respiration; nevertheless, low proton leak and reverse ATP synthase activity combine to generate an elevated mitochondrial membrane potential. Strikingly, APOE4 astrocytes are hypersensitive to the ATP synthase inhibitor oligomycin, demonstrating a profound dysfunction of the enzyme, and cholesterol sequestration with methyl-{beta}-cyclodextrin abrogates this toxicity, establishing elevated cholesterol as its proximate cause. Another method of targeting ATP synthase, epicatechin, which prevents the enzyme operating in reverse, attenuated both cholesterol- and respiratory chain inhibitor-induced cell death. Reciprocally, reducing intracellular cholesterol via nutrient restriction restored cristae architecture and partially rescued respiratory chain complex abundance. These findings identify mitochondrial cholesterol as a critical determinant of cristae architecture and ATP synthase function and suggest that cholesterol-driven mitochondrial dysfunction may be a unifying feature of cholesterol-related disorders from neurodegeneration to atherosclerosis. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/742391v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@2e80a1org.highwire.dtl.DTLVardef@fecd32org.highwire.dtl.DTLVardef@51ba3corg.highwire.dtl.DTLVardef@199f3c6_HPS_FORMAT_FIGEXP M_FIG Elevated intracellular cholesterol in APOE4 astrocytes disrupts the inner mitochondrial membrane and ATP synthase, resulting in sparse cristae, increased ATP hydrolysis and heightened oligomycin sensitivity. The vulnerability to oligomycin is abrogated by cholesterol sequestration with cyclodextrin, indicating causality. These findings position cholesterol as a key determinant of the cristae landscape and ATP synthase function, highlighting the importance of the emerging field of mitochondrial-cholesterol crosstalk. C_FIG

cell biology↗

bioRxiv2024

Multi-Omics after O-GlcNAc Alteration Identifies Cellular Processes Working Synergistically to Promote Aneuploidy

Pharmacologic or genetic manipulation of O-GlcNAcylation, an intracellular, single sugar post-translational modification, are difficult to interpret due to the pleotropic nature of O-GlcNAc and the vast signaling pathways it regulates. To address this issue, we employed either OGT (O-GlcNAc transferase), OGA (O-GlcNAcase) liver knockouts, or pharmacological inhibition of OGA coupled with multi-Omics analysis and bioinformatics. We identified numerous genes, proteins, phospho-proteins, or metabolites that were either inversely or equivalently changed between conditions. Moreover, we identified pathways in OGT knockout samples associated with increased aneuploidy. To test and validate these pathways, we induced liver growth in OGT knockouts by partial hepatectomy. OGT knockout livers showed a robust aneuploidy phenotype with disruptions in mitosis, nutrient sensing, protein metabolism/amino acid metabolism, stress response, and HIPPO signaling demonstrating how OGT is essential in controlling aneuploidy pathways. Moreover, these data show how a multi-Omics platform can discern how OGT can synergistically fine-tune multiple cellular pathways.

cell biology↗

bioRxiv2020

The antibody response to the glycan α-Gal correlates with COVID-19 disease symptoms

The coronavirus disease 19 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected millions of people worldwide. The characterization of the immunological mechanisms involved in disease symptomatology and protective response is important to advance in disease control and prevention. Humans evolved by losing the capacity to synthesize the glycan Gal1-3Gal{beta}1-(3)4GlcNAc-R (-Gal), which resulted in the development of a protective response against pathogenic viruses and other microorganisms containing this modification on membrane proteins mediated by anti--Gal IgM/IgG antibodies produced in response to bacterial microbiota. In addition to anti--Gal antibody-mediated pathogen opsonization, this glycan induces various immune mechanisms that have shown protection in animal models against infectious diseases without inflammatory responses. In this study, we hypothesized that the immune response to -Gal may contribute to the control of COVID-19. To address this hypothesis, we characterized the antibody response to -Gal in patients at different stages of COVID-19 and in comparison with healthy control individuals. The results showed that while the inflammatory response and the anti-SARS-CoV-2 (Spike) IgG antibody titers increased, reduction in anti--Gal IgE, IgM and IgG antibody titers and alteration of anti--Gal antibody isotype composition correlated with COVID-19 severity. The results suggested that the inhibition of the -Gal-induced immune response may translate into more aggressive viremia and severe disease inflammatory symptoms. These results support the proposal of developing interventions such as probiotics based on commensal bacteria with -Gal epitopes to modify the microbiota and increase the -Gal-induced protective immune response and reduce the severity of COVID-19.

immunology↗