Biology subjects

Beerens, M.

Publications and source records attributed to Beerens, M..

7 recordsLinked to original sources

bioRxiv2026

Septins promote breast cancer cell invasion in 3D collagen gels by influencing actin-based protrusion formation

Septins are cytoskeletal proteins that contribute to essential cellular processes such as cell migration and cell division through interactions with the cell membrane and the cytoskeleton. High expression of septins is correlated with breast cancer malignancy and promotes cell invasion, but the molecular complexity of septins interactions has made it challenging to dissect the underlying molecular mechanisms. Here, we used a conditional knockout approach to deplete SEPT7 in the metastatic triple-negative breast cancer cell line Hs578T and examined the role of septin in 3D-matrix invasion of breast cancer cells. We show by spheroid assays that SEPT7 deletion strongly impairs breast cancer cell invasion into collagen gels. Additional single-cell migration studies using 3D collagen gels and microfluidic pillar devices that mimic the pores present in collagen matrices showed that SEPT7 expression regulates confined cell migration through control of cell shape and actin-based protrusions.

cancer biology↗

bioRxiv2024

Cyclooxygenase-2 disruption predisposes to heart failure with preserved ejection fraction

Heart failure (HF) is one of the most strongly associated adverse cardiovascular events linked to the use of cyclooxygenase (COX)-2 selective and non-selective nonsteroidal anti-inflammatory drug (NSAID). Nevertheless, it remains uncertain whether NSAID exposure is more likely to lead to heart failure with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF). In adult mice, postnatal genetic deletion or pharmacological inhibition of COX-2 did not affect cardiac function. In contrast, aged female inducible COX-2 (iCOX-2) knockout (KO) mice displayed diastolic dysfunction, cardiac hypertrophy, pulmonary congestion, and elevated levels of plasma N-terminal pro B-type natriuretic peptide (BNP) when compared to age- and sex- matched controls, while their ejection fraction (EF) remained preserved ([≥] 50%). No such phenotype was observed in aged male iCox-2 KO mice. Aged female iCox-2 KO mice showed a shift from prostanoid to leukotriene biosynthesis, along with changes in the expression of mitochondrial genes and calcium-handling proteins in the myocardium. The ratio of phospholamban to SERCA2a was increased, indicating an inhibitory effect on SERCA2a activity, which may contribute to impaired myocardial relaxation. In larval zebrafish, COX-2 inhibition by celecoxib caused a modest yet significant reduction in heart rate and diastolic function, while EF was preserved. Additionally, celecoxib increased BNP expression and ventricular calcium transient amplitude. Diabetic patients in the Harvard-Partners electronic medical record exposed to NSAIDs selective for COX-2 inhibition were more strongly associated with an increased risk of HFpEF compared to HFrEF. Collectively, these findings indicate that COX-2 deletion or inhibition does not impair systolic cardiac function but instead leads to an HFpEF phenotype in mice, zebrafish, and humans. An imbalance in calcium handling may mediate the impairment of myocardial relaxation following COX-2 suppression. SummaryGenetic deletion or pharmacological inhibition of COX-2 results in heart failure with preserved ejection fraction across zebrafish, mice, and humans.

pharmacology and toxicology↗

bioRxiv2024

Sepsis-induced NET formation requires MYD88 but is independent of GSDMD and PAD4

Neutrophils are peripheral blood-circulating leukocytes that play a pivotal role in host defense against bacterial pathogens which upon activation, they release web-like chromatin structures called neutrophil extracellular traps (NETs). Here, we analyzed and compared the importance of myeloid differentiation factor 88 (MYD88), peptidyl arginine deiminase 4 (PAD4), and gasdermin D (GSDMD) for NET formation in vivo following sepsis and neutrophilia challenge. Injection of lipopolysaccharide (LPS)/E. coli or the transgenic expression of granulocyte colony-stimulating factor (G-CSF), each induced NET-mediated lethal vascular occlusions in mice with combined genetic deficiency in Dnase1 and Dnase1l3 (D1/D1l3-/-). In accordance with the signaling of toll-like receptors, Myd88/D1/D1l3-/- animals were protected from the formation of lethal intravascular NETs during septic conditions. However, this protection was not observed during neutrophilia. It was unexpected to find that both Gsdmd/D1/D1l3-/- and Pad4/D1/D1l3-/- mice were fully capable of forming NETs upon LPS/E.coli challenge. Sepsis equally triggered a similar inflammatory response in these mice characterized by formation of DNA-rich thrombi, vessel occlusions, and mortality from pulmonary embolism, compared to D1/D1l3-/- mice. Pharmacologic GSDMD inhibitors did not reduce PMA-stimulated NET formation in ex vivo models either. Similarly, neither Pad4 nor GSDMD deficiency affected intravascular occlusive NET formation upon neutrophilia challenge. The magnitude of NET production, multi-organ damage, and lethality were comparable to those observed in challenged control mice. In conclusion, our data indicate that NET formation during experimental sepsis and neutrophilia is regulated by distinct stimulus-dependent pathways that may be independent of canonical PAD4 and GSDMD. Key points- Sepsis triggers vaso-occlusive NET formation in Dnase1/Dnase1l3-deficient mice in a myeloid differentiation factor 88-dependent manner - Peptidyl arginine deiminase 4 and gasdermin D are dispensable for NET formation in sepsis and neutrophilia models - Myeloid differentiation factor 88, peptidyl arginine deiminase 4 and gasdermin D differ in their importance for NET formation in vivo

immunology↗

bioRxiv2023

The phosphodiesterase 2A regulates lymphatic endothelial development via cGMP-mediated control of Notch signaling

During vascular development endothelial junctions mature and vessel integrity is established to form the endothelial barrier. The molecular mechanisms by which lymphatic vessels induce cell contact inhibition are not understood. Here, we uncover the cGMP-dependent phosphodiesterase 2A (PDE2A) as a selective regulator of lymphatic, but not blood endothelial contact inhibition. Conditional deletion of Pde2a in mouse embryos reveals severe lymphatic dysplasia, while large blood vessel architecture remains unaltered. In the absence of PDE2A, human lymphatic endothelial cells fail to induce mature junctions and cell cycle arrest, while cGMP levels, but not cAMP levels, are increased. Loss of PDE2A-mediated cGMP hydrolysis leads to downregulation of NOTCH signaling. Vice versa, DLL4-induced NOTCH activation restores junctional maturation in PDE2A-deficient lymphatic endothelial cells. Our data demonstrate that PDE2A selectively modulates a crosstalk between cGMP and NOTCH signaling to finetune lymphatic development and suggest that PDE2A may be a druggable target to control lymphatic leakage and regeneration.

developmental biology↗

bioRxiv2022

Nr2f1a maintains atrial nkx2.5 expression to repress pacemaker identity within venous atrial cardiomyocytes

Maintenance of cardiomyocyte identity is vital for normal heart development and function. However, our understanding of cardiomyocyte plasticity remains incomplete. Here, we show that sustained expression of the zebrafish transcription factor (TF) Nr2f1a prevents the progressive acquisition of ventricular cardiomyocyte (VC) and pacemaker cardiomyocyte (PC) identities within distinct regions of the atrium. Transcriptomic analysis of isolated atrial cardiomyocytes (ACs) from nr2f1a mutant zebrafish embryos showed increased VC marker gene expression and altered expression of core PC regulatory genes, including decreased expression of nkx2.5, a critical repressor of PC differentiation. At the arterial pole of the atrium in nr2f1a mutants, cardiomyocytes resolve to VC identity within the expanded atrioventricular canal. However, at the venous pole, there is a progressive wave of AC transdifferentiation into PCs across the atrium toward the arterial pole. Restoring Nkx2.5 is sufficient to repress PC identity in nr2f1a mutant atria and analysis of chromatin accessibility identified a Nr2f1a-dependent nkx2.5 enhancer expressed in the atrial myocardium directly adjacent to PCs, supporting that Nr2f1a limits PC differentiation within venous ACs via maintaining nkx2.5 expression. The Nr2f-dependent maintenance of AC identity within discrete atrial compartments may provide insights into the molecular etiology of concurrent structural congenital heart defects and associated arrhythmias.

developmental biology↗

bioRxiv2021

Prdm16 and Notch functionally and physically interact during artery development

Proper arterial versus venous endothelial lineage identity is required to establish a hierarchical network of arteries and veins and prevent the occurrence of life-threatening arteriovenous malformations. The molecular mechanisms that govern arteriovenous lineage specification remain however incompletely understood. Here, we demonstrate that the transcription factor Prdm16 is expressed in arterial but not venous endothelial cells (ECs) from the earliest stages of development, where it actively promotes arterial EC identity by enhancing canonical Notch activity, while simultaneously suppressing the alternative venous cell fate. Concordantly, our results in zebrafish show that Prdm16 coordinates proper arterial development and arteriovenous lineage specification together with canonical Notch signaling, as combined loss of prdm16 and notch in zebrafish invariably leads to arteriovenous malformations (AVMs). Although the arterializing effect of Prdm16 in human ECs is dependent on the absolute levels of the cleaved intracellular domain of the Notch receptors (NICD), Prdm16 does not increase NICD levels per se. Rather, Prdm16 physically and functionally interacts with NICD to potentiate its effect. Prdm16 further finetunes Notch signaling and arterial development by complexing with the Notch downstream effector Hey2, which regulates arterial lineage specification and development across species. Together, our data demonstrate that Prdm16 act as a rheostat for endothelial Notch activity and suggest that Prdm16 signaling may constitute a novel therapeutic target for AVMs.

developmental biology↗

bioRxiv2021

RBPMS2 is a conserved regulator of alternative splicing that promotes myofibrillar organization and optimal calcium handling in cardiomyocytes

RationaleThe identification of novel cardiomyocyte-intrinsic factors that support heart function will expand the number of candidate genes and therapeutic options for heart failure, a leading cause of death worldwide. ObjectiveTo identify and characterize conserved regulators of cardiomyocyte function. Methods and ResultsWe report that the RNA-binding protein RBPMS2 is required for myofibril organization and the regulation of intracellular calcium dynamics in both zebrafish embryos and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). A differential expression screen in zebrafish uncovered enrichment of rbpms2 paralogs, rbpms2a and rbpms2b, in the myocardium. Double knock-out (rbpms2-null) embryos suffer from compromised ventricular filling during the relaxation phase of the cardiac cycle, which significantly reduces cardiac output. Whole transcriptome sequencing and validation studies revealed differential alternative splicing of several genes linked to cardiomyopathies in humans, including myosin binding protein C3 (mybpc3) and phospholamban (pln), consistent with a role in causing the observed ventricular deficiencies. Further, RBPMS2-null hiPSC-CMs exhibit myofibril and calcium handling defects that are highly analogous to those observed in the rbpms2-null zebrafish ventricle. ConclusionsTaken together, our data identify RBPMS2 as a conserved and essential regulator of alternative splicing that is required for myofibrillar organization and optimal calcium handling from zebrafish to humans.

developmental biology↗