Biology subjects

Facchinello, N.

Publications and source records attributed to Facchinello, N..

4 recordsLinked to original sources

bioRxiv2026

Endothelial RRM2B-dependent mitochondrial DNA signalling drives doxorubicin-cardiotoxicity

Doxorubicin remains a mainstay of cancer therapy, yet its clinical use is constrained by severe cardiotoxicity, classically attributed to cardiomyocyte death. Here, we identify endothelial inflammation driven by mitochondrial DNA (mtDNA) turnover and release as a critical mediator of doxorubicin-induced cardiac injury. In vivo, a standard doxorubicin regimen activates the cGAS-STING innate immune pathway in endothelial cells before cardiomyocyte dysfunction or death occurs. Mechanistically, doxorubicin recruits the stress-inducible ribonucleotide reductase subunit RRM2B (p53R2) that normally sustains the mitochondrial deoxyribonucleotide pool, to promote aberrant mtDNA turnover and release, fuelling sterile inflammation. The FDA-approved BAX inhibitor Eltrombopag suppresses mtDNA release, attenuates endothelial inflammation, and prevents doxorubicin cardiotoxicity in vivo without compromising anticancer efficacy. These findings reveal an unrecognized proinflammatory role of RRM2B and establish endothelial inflammation as a central driver of chemotherapy-related cardiac injury, identifying the cardiac endothelium as a tractable target for cardioprotection during cancer treatment.

cell biology↗

bioRxiv2025

Antxr2-mediated fine-tuning of Collagen VI ensures skeletal muscle function

Tissue function relies on the extracellular matrix (ECM) that surrounds cells, providing structural and biochemical support. The complex ECM composition depends on an adequately tuned balance between the deposition and degradation of each of its components. Disequilibrium may cause disease, as observed for Collagen VI (COL6), for which mutations lead to muscular dystrophy. Here, we investigated the role of Anthrax Toxin Receptor 2 (ANTXR2/CMG2), a receptor that controls the turnover of COL6, in skeletal muscle. We show that ANTXR2 is mostly expressed by fibro-adipogenic precursors and that its deficiency in ANTXR2 null (Antxr2-/-) mice leads to a premature and irregular COL6 accumulation in intramuscular connective tissue. This results in tissue stiffening and gradual, non-functional muscle hypertrophy, marked by impaired locomotion and myopathic signs. Our findings further indicate that COL6 accretion drives these alterations, as revealed by Antxr2-/-::Col6a1-/- double knockout mice, highlighting the essential role of ANTXR2-mediated COL6 remodeling in maintaining ECM homeostasis and muscle functionality. SIGNIFICANCE STATEMENTRemodelling of the extracellular matrix (ECM) was long thought to rely almost exclusively on extracellular proteases. Increasing evidence, however, indicates that some ECM components may undergo intracellular degradation following receptor-mediated endocytosis, as we have found for Collagen VI (COL6). Here, we identify the COL6 receptor ANTXR2 as a critical regulator of ECM turnover in skeletal muscle.. When ANTXR2 is absent, COL6 builds up, followed by the accumulation of fibrillar collagens, without changes in gene expression. These alterations in muscle ECM lead to increased stiffness, myofiber defects and impaired locomotor activity. Our findings establish ANTXR2 as a key regulator in ECM remodelling, offering new insights into potential treatments for conditions associated with defective ECM remodeling, such as aging and congenital muscular dystrophies.

cell biology↗

bioRxiv2020

Mitochondrial STAT3 regulates proliferation of tissue stem cells.

The STAT3 transcription factor, acting both in the nucleus and mitochondria, maintains embryonic stem cell pluripotency and promotes their proliferation. In this work, using zebrafish, we determined in vivo that mitochondrial STAT3 regulates mtDNA transcription in embryonic and larval stem cell niches and that this activity affects their proliferation rates. As a result, we demonstrated that STAT3 import inside mitochondria requires Y705 phosphorylation by Jak2, while its mitochondrial transcriptional activity, as well as its effect on proliferation, depends on the MAPK target S727. These data were confirmed using mouse embryonic stem cells: Y705 mutated STAT3 cannot enter the mitochondrion while the S727 mutation does not affect mitochondrial import of the protein. Surprisingly, STAT3-dependent increase of mitochondrial transcription seems independent from STAT3 binding to STAT3 responsive elements. Finally, loss of function experiments, with chemical inhibition of JAK/STAT3 pathway or genetic ablation of stat3 gene, demonstrated that STAT3 is also required for cell proliferation in the intestine of zebrafish.

developmental biology↗

bioRxiv2020

Latrophilin 2 controls vascular morphogenesis and function by inhibiting endothelial cell adhesion and YAP/TAZ mechanosignaling

Dynamic modulation of endothelial cell-to-cell and cell-to-extracellular matrix (ECM) adhesion is essential for blood vessel patterning and functioning. Yet, the molecular mechanisms involved in this process have not been completely deciphered. We identify the adhesion G protein-coupled receptor (ADGR) Latrophilin 2 (LPHN2) as a novel determinant of endothelial cell (EC) adhesion and barrier function. In cultured ECs, endogenous LPHN2 localizes at ECM contacts, signals through cAMP/Rap1, and inhibits focal adhesion (FA) formation and nuclear localization of YAP/TAZ transcriptional regulators, while promoting tight junction (TJ) assembly. ECs also express an endogenous LPHN2 ligand, fibronectin-leucine-rich transmembrane 2 (FLRT2), that prevents ECM-elicited EC behaviors in a LPHN2-dependent manner. Vascular ECs of lphn2a knock-out zebrafish embryos become abnormally stretched, display a hyperactive YAP/TAZ pathway, and lack proper intercellular TJs. Consistently, blood vessels are hyperpermeable and intravascularly injected cancer cells extravasate more easily in lphn2a null animals. Thus, LPHN2 ligands, such as FLRT2, may be therapeutically exploited to interfere with cancer metastatic dissemination. SUMMARYCamillo et al. show that the LPHN2 receptor, upon activation by FLRT2 ligand, inhibits focal adhesion formation and promotes tight junction assembly in endothelial cells. Blood vessels of lphn2a null animals are hyperpermeable and injected cancer cells extravasate more easily.

cell biology↗