Biology subjects

Martineau, S.

Publications and source records attributed to Martineau, S..

5 recordsLinked to original sources

bioRxiv2024

Exploring Integrin α5β1 as a Potential Therapeutic Target for Pulmonary Arterial Hypertension: Insights from Comprehensive Multicenter Preclinical Studies

Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling of the small pulmonary arteries (PA) and progressive increase in pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Although several drugs are approved for the treatment of PAH, mortality remains high. Accumulating evidence supports a pathological function of integrins in vessel remodeling, which are gaining renewed interest as drug targets. However, their role in PAH remains largely unexplored. We found that the arginine-glycine-aspartate (RGD)-binding integrin 5{beta}1 is upregulated in PA endothelial cells (PAEC) and PA smooth muscle cells (PASMC) from PAH patients and remodeled PAs from animal models. Blockade of the integrin 5{beta}1 or depletion of the 5 subunit resulted in mitotic defects and inhibition of the pro-proliferative and apoptosis-resistant phenotype of PAH cells. Using a novel small molecule integrin inhibitor and neutralizing antibodies, we demonstrated that 5{beta}1 integrin blockade attenuates pulmonary vascular remodeling and improves hemodynamics and RV function in multiple preclinical models. Our results provide converging evidence to consider 5{beta}1 integrin inhibition as a promising therapy for pulmonary hypertension. One sentence summaryThe 5{beta}1 integrin plays a crucial role in pulmonary vascular remodeling.

pathology↗

bioRxiv2024

RV-specific Targeting of Snai1 Rescues Pulmonary Hypertension-induced Right Ventricular Failure by Inhibiting EndMT and Fibrosis via LOXL2 Mediated Mechanism

BackgroundPulmonary hypertension (PH)-induced right ventricular (RV) failure (PH-RVF) is a significant prognostic determinant of mortality and is characterized by RV hypertrophy, endothelial-to-mesenchymal transition (EndMT), fibroblast-to-myofibroblast transition (FMT), fibrosis, and extracellular matrix (ECM)-remodeling. Despite the importance of RV function in PH, the mechanistic details of PH-RVF, especially the regulatory control of RV EndMT, FMT, and fibrosis, remain unclear. The action of transcription factor Snai1 is shown to be mediated through LOXL2 recruitment, and their co-translocation to the nucleus, during EndMT progression. We hypothesize that RV EndMT and fibrosis in PH-RVF are governed by the TGF{beta}1-Snai1-LOXL2 axis. Furthermore, targeting Snai1 could serve as a novel therapeutic strategy for PH-RVF. MethodsAdult male Sprague Dawley rats (250-300g) received either a single subcutaneous injection of Monocrotaline (MCT, 60mg/kg, n=9; followed for 30-days) or Sugen (SU5416 20mg/kg, n=9; 10% O2 hypoxia for 3-weeks followed by normoxia for 2-weeks) or PBS (CTRL, n=9). We performed secondary bioinformatics analysis on the RV bulk RNA-Seq data from MCT, SuHx, and PAB rats and human PH-PVF. We validated EndMT and FMT and their association with Snai1 and LOXL2 in the RVs of MCT and SuHx rat models and human PH-RVF using immunofluorescence, qPCR, and Western blots. For in vivo Snai1 knockdown (Snai1-KD), MCT-rats either received Snai1-siRNA (n=7; 5nM/injection every 3-4 days; 4-injections) or scramble (SCRM-KD; n=7) through tail vein from day 14-30 after MCT. Echocardiography and catheterization were performed terminally. Bulk RNASeq and differential expression analysis were performed on Snai1- and SCRM-KD rat RVs. In vitro Snai1-KD was performed on human coronary artery endothelial cells (HCAECs) and human cardiac fibroblasts (HCFs) under hypoxia+TGF{beta}1 for 72-hrs. ResultsPH-RVF had increased RVSP and Fulton index and decreased RV fractional area change (RVFAC %). RV RNASeq demonstrated EndMT as the common top-upregulated pathway between rat (MCT, SuHx, and PAB) and human PH-RVF. Immunofluorescence using EndMT- and FMT-specific markers demonstrated increased EndMT and FMT in RV of MCT and SuHx rats and PH-RVF patients. Further, RV expression of TGF{beta}1, Snai1, and LOXL2 was increased in MCT and SuHx. Nuclear co-localization and increased immunoreactivity, transcript, and protein levels of Snai1 and LOXL2 were observed in MCT and SuHx rats and human RVs. MCT rats treated with Snai1-siRNA demonstrated decreased Snai1 expression, RVSP, Fulton index, and increased RVFAC. Snai1-KD resulted in decreased RV-EndMT, FMT, and fibrosis via a LOXL2-dependent manner. Further, Snai1-KD inhibited hypoxia+TGF{beta}1-induced EndMT in HCAECs and FMT in HCFs in vitro by decreasing perinuclear/nuclear Snai1+LOXL2 expression and co-localization. ConclusionsRV-specific targeting of Snai1 rescues PH-RVF by inhibiting EndMT and Fibrosis via a LOXL2-mediated mechanism.

physiology↗

bioRxiv2024

ATP Citrate Lyase Drives Vascular Remodeling Diseases Development Through Metabolic-Epigenetic Reprograming.

Our study explores the previously uncharted role of ATP-citrate lyase (ACLY) in vascular remodeling within the pulmonary and coronary arteries, providing novel insights into the pathogenesis of pulmonary hypertension and coronary artery diseases. ACLY, involved in de novo lipid synthesis and histone acetylation, has emerged as a key regulator in sustaining vascular smooth muscle cell (VSMC) proliferation and survival. Utilizing human coronary and pulmonary artery tissues, our findings reveal an upregulation of ACLY expression during vascular remodeling processes. Inhibition of ACLY, achieved through pharmacological and molecular interventions in humans primary cultured VSMCs, leads to decreased proliferation, migration, and resistance to apoptosis. Mechanistically, these effects are associated with diminished glycolysis, lipid synthesis, GCN5-dependent histone acetylation, and FOXM1 activation. In vivo experiments, combining pharmacological and VSMC-specific ACLY knockout mice, ACLY inhibition demonstrates its efficacy in mitigating coronary artery remodeling and reducing pulmonary hypertension. Notably, initiating ACLY inhibition post-disease onset reverses pathological conditions, positioning ACLY as a promising therapeutic target. Human ex vivo tissue culture further supports our findings, showing reduced vascular remodeling in cultured human coronary artery rings and a reversal of pulmonary artery remodeling in precision-cut lung slices upon ACLY inhibition. This study introduces a groundbreaking concept, linking disparate abnormalities in vascular diseases to a common pathogenetic denominator, ACLY. The identified "multiple hit" therapeutic approach presents potential targets for addressing complex vascular diseases, offering avenues for future clinical interventions. ONE SENTENCE SUMMARYOur study delineates the pivotal role of ATP-citrate lyase in orchestrating vascular remodeling, establishing it as a compelling translational target for therapeutic interventions in pulmonary hypertension and coronary artery disease.

physiology↗

bioRxiv2023

53BP1 interacts with the RNA primer from Okazaki fragments to support their processing during unperturbed DNA replication

RNA-binding proteins are found at replication forks, but their direct interaction with DNA-embedded RNA species that inevitably shape physiological DNA replication remains unexplored. Here we report that 53BP1, involved in the DNA damage and replication stress response, is an RNA-binding protein that directly interacts with Okazaki fragments, in the absence of any external stress. The bulk chromatin association of 53BP1 shows dramatic dependence on PRIM1, which synthesizes the RNA primer of Okazaki fragments. The direct recruitment of 53BP1 to nascent DNA shows susceptibility to in situ ribonuclease A treatment. Conversely, depletion of FEN1, which results in the accumulation of uncleaved RNA primers, leads to an upregulation of 53BP1 levels at the replication forks, suggesting that RNA primers contribute to the recruitment of 53BP1 at the lagging DNA strand. 53BP1 depletion induces an accumulation of S phase poly(ADP-ribose), which constitutes a sensor of unligated Okazaki fragments. Collectively, our data indicate that 53BP1, distinct from its canonical mode of chromatin-binding, is anchored at the replication fork through its RNA-binding activity, highlighting the role of an RNA-protein interaction at DNA replication forks.

molecular biology↗

bioRxiv2023

MET functions in tumour progression and therapy resistance are repressed by intronic polyadenylation

Intronic polyadenylation (IPA) leads to the production of transcript isoforms with alternative last exons in thousands of mammalian genes. Widespread regulation of IPA isoforms was observed during oncogenic transformation and in tumours versus healthy tissues, and several IPA isoforms were involved in oncogenesis. However, little is known about the potential involvement of IPA in tumour progression, such as cancer cell invasiveness and metastasis, and in resistance to anticancer therapies. Here, we show that an IPA isoform of MET (short MET) whose production is inhibited by U1 snRNP (U1), an essential ribonucleoprotein complex that recognizes the 5 exon-intron junction of pre-mRNA, is associated with better prognosis in breast cancer. Induction of the short MET isoform, using a steric-blocking antisense oligonucleotide targeting the U1 binding site in the vicinity of the short MET alternative polyadenylation site, antagonizes cell invasiveness. U1 blockade with an antisense oligonucleotide targeting the U1 snRNA also decreases breast cancer cell invasiveness, in both human and mouse cancer cell models, and this effect involves IPA induction in MET and several genes belonging to the RAS/RAF/MAPK signalling pathway. Finally, short MET relieves melanoma cell resistance to MAPK cascade-targeted therapy in vitro and in vivo. IPA isoform levels of MET and a few other genes (mTOR, EGFR and CTNNA1) help predict such resistance in patients. Altogether, our findings provide evidence for a role of IPA in both cancer cell invasiveness and resistance to therapy. This suggests that IPA isoforms can be exploited as biomarkers and therapeutic targets to combat tumour progression.

molecular biology↗