Biology subjects

Iommarini, L.

Publications and source records attributed to Iommarini, L..

5 recordsLinked to original sources

bioRxiv2026

Abolishing respiratory complex I decreases in vivo growth of high grade serous ovarian cancer cells and sensitizes to anti-angiogenic therapy

Targeting mitochondrial Complex I (CI) is a currently emerging anti-cancer strategy, with several enzyme inhibitors entering clinical trials. Among others, aggressive high-grade serous tubo-ovarian cancer (HGSOC) may particularly benefit from this therapeutic approach due to the scarce response to first- and second-line treatments, with consequent high mortality, such as the anti-angiogenic bevacizumab. We here show that CI represents a vulnerability in HGSOC, which can be exploited for therapeutic intervention. Indeed, ablating CI function in OV-90 HGSOC cells led to significant in vivo tumor growth decrease, smaller masses, and lower KI-67 proliferative index. This was confirmed in a switch-off system in which CI deprivation was induced during tumor progression to mimic pharmacologic treatment, suggesting this result can be achieved in growing neoplasms. We also show that abolishing CI in HGSOC cells leads to failure in stabilizing the hypoxia inducible factor-1a and to respond to hypoxia through the transcriptional activation of its target genes, ultimately lowering vascular endothelial growth factor (VEGF) and generating an immature intratumor vascular system accompanied by a decreased blood flow. Last, we demonstrate that targeting CI sets the biological basis for increased sensitivity to anti-angiogenics, as CI-deprived tumors displayed growth arrest when bevacizumab was administered, unlike their CI-competent counterpart. Our findings point to CI inhibition as a booster for anti-VEGF therapies and pave the way for combined protocols in treatment of HGSOC.

cancer biology↗

bioRxiv2023

A computational study to assess the pathogenicity of single or combinations of missense variants on respiratory Complex I

Variants found in the respiratory complex I (CI) subunit genes encoded by mitochondrial DNA can cause severe genetic diseases. However, it is difficult to establish a priori whether a single or a combination of CI variants may impact oxidative phosphorylation. Here we propose a computational approach based on coarse-grained molecular dynamics simulations. One of the primary CI variants (m.14484T>C/MT-ND6) associated with the Leber hereditary optic neuropathy was used as a test case. This variant was investigated alone or in combination with two additional rare CI variants whose role remains uncertain. We found that the primary variant stiffens CI dynamics in the crucial E-channel region and that one of the other variants, located in the vicinity of the primary one, further worsens the stiffening. This approach may be extended to other variants candidate to exert a pathogenic impact on CI function, or to investigate the interaction of multiple variants. TeaserMolecular dynamics is able to predict the functional impact of variants hitting respiratory complex I mitochondrial genes.

biophysics↗

bioRxiv2021

Lipid droplets 3D full measurement by holographic in-flow tomography

The most recent discoveries in the biochemical field are highlighting the increasingly important role of lipid droplets (LDs) in several regulatory mechanisms in living cells. LDs are dynamic organelles and therefore their complete characterization in terms of number, size, spatial positioning and relative distribution in the cell volume can shed light on the roles played by LDs. Until now, fluorescence microscopy and transmission electron microscopy are assessed as the gold standard methods for identifying LDs due to their high sensitivity and specificity. However, such methods generally only provide 2D assays and partial measurements. Furthermore, both can be destructive and with low productivity, thus limiting analysis of large cell numbers in a sample. Here we demonstrate for the first time the capability of 3D visualization and the full LD characterization in high-throughput with a tomographic phase-contrast flow-cytometer, by using ovarian cancer cells and monocyte cell lines as models. A strategy for retrieving significant parameters on spatial correlations and LD 3D positioning inside each cell volume is reported. The information gathered by this new method could allow more in depth understanding and lead to new discoveries on how LDs are correlated to cellular functions.

biophysics↗

bioRxiv2020

Biogenesis of NDUFS3-less complex I indicates TMEM126A/OPA7 as an assembly factor of the ND4-module

Complex I (CI) is the largest enzyme of the mitochondrial respiratory chain and its defects are the main cause of mitochondrial disease. To understand the mechanisms regulating the extremely intricate biogenesis of this fundamental bioenergetic machine, we analyzed the structural and functional consequences of the ablation of NDUFS3, a non-catalytic core subunit. We prove that in diverse mammalian cell types a small amount of functional CI can still be detected in the complete absence of NDUFS3. In addition, we have determined the dynamics of CI disassembly when the amount of NDUFS3 is gradually decreased. The process of degradation of the complex occurs in a hierarchical and modular fashion where the ND4-module remains stable and bound to TMEM126A. We have thus, uncovered the function of TMEM126A, the product of a disease gene causing recessive optic atrophy, as a factor necessary for the correct assembly and function of CI.

biochemistry↗

bioRxiv2018

Mice harboring a SCA28 patient mutation in AFG3L2 develop late-onset ataxia associated with enhanced mitochondrial proteotoxicity.

Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but signs of ataxia were detectable by beam test at 18 months. Cerebellar pathology was negative; electrophysiological analysis showed increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls, although not statistically significant. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was also altered, in line with greatly reduced expression of Opa1 fusogenic protein L-isoforms. The mitochondrial alterations observed in MEFs were also detected in cerebella of 18-month-old heterozygous mutants, suggesting they may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.

genetics↗