ABL kinases regulate FGF signaling independent of CRK phosphorylation to prevent Peters anomaly type II

Nature Communications · 2026-05-13

Peters anomaly is an anterior segment dysgenesis and a leading cause of congenital corneal opacity. Here, we show that loss of ABL kinases restores lens induction in the absence of FGF signaling but induces Peters anomaly type II independently of ERK signaling, a phenotype also observed with elevated FGF–Ras activity. This defect is rescued by allelic deletion of the ABL substrates CRK and CRKL. Contrary to prevailing models, ABL kinases do not act through direct phosphorylation of CRK proteins; instead, they phosphorylate PTPN12, suppressing p130CAS phosphorylation and CRK recruitment required for RHO GTPase activation. ABL kinase deficiency reduces actomyosin contractility in the lens vesicle and genetically interacts with RHOA inhibition, whereas RAC1 inhibition ameliorates disease phenotypes. These findings define an ABL–PTPN12–p130CAS pathway that controls cytoskeletal tension during lens vesicle separation and suggest that modulation of this process may offer a therapeutic approach for Peters anomaly type II. Peters anomaly type II arises from failed lens vesicle separation. Here, the authors show that ABL kinases counterbalance FGF–RAS signaling via a PTPN12–p130CAS pathway to regulate cytoskeletal tension, ensuring proper lens detachment during development.

Abstract Fri095: Abl1 kinase-deficient mouse hearts exhibit conduction disturbance and arrhythmia vulnerability to oxidative stress that are typically associated with age-related proarrhythmic remodeling

Circulation Research · 2025-08-01

Background: Abl1 kinase has diverse roles in cell development, proliferation, cytoskeletal reorganization, and aging. Importantly, proarrhythmic complications are noted among cancer patients taking tyrosine kinase inhibitors, including AV block, atrial fibrillation, QTc prolongation, and tachycardia associated with heart failure. Goals: We investigated the roles of Abl1 kinase in aging and arrhythmias using a cardiac-specific Abl1 knockout (Abl1 CKO) mouse. Methods: Electrophysiology and arrhythmogenesis were studied using optical mapping with voltage-sensitive dye, di-4 ANEPPS. Results: Abl1 CKO resulted in sudden death (median survival 39 weeks, n=31). Abl1 CKO mouse hearts (mean age 31 weeks) showed significant APD prolongation (64±5 vs. 72±4 ms, p=0.001, Figure 1A), increased APD dispersion (14±2 vs. 21±8 ms, p=0.047) but conduction velocity was not changed (longitudinal CV=0.81±0.05 vs. 0.78±0.08 m/s p =0.51, transverse CV=0.5±0.10 vs. 0.5±0.06 m/s p = 0.32). Oxidative stress using perfusion of 10 µM paraquat for 90 minutes caused further APD prolongation (109±23 ms) and triggered frequent premature ventricular contractions (PVC) in Abl1 CKO hearts (Figure 1B). In atria, AV delay was significantly longer (55±3 vs. 63±8 ms, p=0.03, Figure 1C), associated with significantly longer rise time (4.1±0.7 vs. 5.3±0.5 ms, p=0.006) and increased conduction time between right and left atrium (6.3±1.7 vs. 9.2±1.6 ms, p=0.006). S1S2 stimulation caused frequent premature atrial contractions (n=0/7 in control vs. 5/8 hearts, Figure 1D). Conclusion: Abl1 CKO hearts demonstrate sudden death, APD prolongation, increased vulnerability to oxidative stress, conduction disorders such as increased AV delay and frequent AV block, and arrhythmia induction associated with slow atrial conduction, which are typical features of aging myocardium, suggesting that alteration in Abl1 kinase may be an important factor underlying age-associated electrical remodeling.

Vinculin Y822 phosphorylation regulates adhesion remodeling during cardiomyocyte maturation

Journal of Cell Science · 2024-12-15 · 1 citations

In the heart, cardiomyocyte cell-matrix and cell-cell adhesions reorganize in response to increased cardiac demand and growth. Vinculin (VCL), a mechanosensitive adaptor protein, links filamentous actin to cell-matrix and cell-cell adhesions. Yet how VCL regulates remodeling of the two adhesion systems is poorly understood. Here, we investigate the role of phosphorylation at VCL tyrosine residue 822 (pY822) in cardiomyocyte adhesion and heart function. VCL Y822 phosphorylation levels peaked during adhesion remodeling in the developing heart and were reduced as adhesions matured postnatally. VCL pY822 levels also increased in the adult heart following injury. We mutated Vcl Y822 to phenylalanine (Y822F) in the mouse to determine the in vivo function of pY822. Homozygous mutant Vcl Y822F mice were viable but exhibited cardiac dysfunction at 28 weeks. We found that VCL pY822 regulated cardiomyocyte cell-matrix and cell-cell adhesions during postnatal heart development. Defects in cell-cell adhesion organization were also observed in cultured Vcl Y822F cardiomyocytes. Our results demonstrate that VCL Y822 phosphorylation regulates adhesion organization in cardiomyocytes, highlighting the importance of post-translational modification in modulating VCL function in the heart.

Abstract 4142747: Role of Cardiomyocyte Mechanotransduction in Triggering Atrial Arrhythmias in Pulmonary Hypertension

Circulation · 2024-11-12

Introduction: Pulmonary arterial hypertension (PAH) is a chronic disease associated with atrial fibrillation (AF). Chronic pressure overload in right atria (RA) may disrupt cardiomyocyte mechanotransduction resulting in remodeling that triggers arrhythmias. The mechanosensitive adaptor protein, vinculin, interacts with Nav1.5 as well as indirectly stabilizing connexin-43 gap junctions. Goal: To show that the influence of chronic overload in RA under conditions of PAH disrupts mechanotransduction signaling and increases susceptibility to arrhythmias. Methods: We used the Sugen/Hypoxia (Su/Hx) rat model of PAH for optical mapping of action potentials in isolated right atria as well as immunohistochemistry of atrial tissue. Results: PAH rats have enlarged RA (82.2 ± 22.3 mg PAH vs. 38.5 ± 4.7 mg control, p=0.02, t-test). In comparison to controls, isolated RA of PAH rats show slower conduction velocity (CV) (0.4 ± 0.07 mm/ms PAH vs. 0.5 ± 0.06 mm/ms control, p=0.02, t-test) together with increased local heterogeneity, an increase in APD (Fig. 1A) and APD dispersion (11.2 ± 3.7 ms PAH vs. 5.6 ± 1.3 ms control, p=0.006, t-test). Traditionally, AF is usually associated with shorter APD, so the prolonged APD we recorded in PAH RA represents a unique electrophysiological change. This electrical remodeling in PAH rats promotes conduction block in the posteromedial RA and reentry formation (Fig. 1B). Immunohistochemistry shows that vinculin is reduced at N-cadherin cell-cell contacts and redistributed to the lateral membrane in PAH RA (Fig. 2) with a 2D FFT radial sum intensity major to minor peak ratio: 1.02 ± 0.002 vs 1.008 +/- 0.001 control, p=0.02, t-test. Conclusion: RA of PAH rats show high arrhythmia risks compared to controls. The unique electrophysiological changes could be a critical feature of AF in PAH. Vinculin redistribution may create a substrate for RA arrhythmias and may play an important role in regulating the electrical remodeling of RA in PAH.

Abl kinases regulate FGF signaling independent of Crk phosphorylation to prevent Peters anomaly

bioRxiv (Cold Spring Harbor Laboratory) · 2024-10-26 · 1 citations

Abstract Peters anomaly, the most common cause of congenital corneal opacity, stems from corneal-lenticular adhesion. Despite numerous identified mutations, a cohesive molecular framework of the disease’s etiology remains elusive. Here, we identified Abl kinases as pivotal regulators of FGF signaling, as genetic ablation of Abl kinases restores lens induction even in the absence of FGF signaling. Intriguingly, both Abl kinase deficiency and increased FGF-Ras activity result in Peters anomaly independent of ERK signaling, which can be rescued by allelic deletion of Abl substrate, Crk. However, contrary to the prevailing belief that Abl kinases regulate Crk proteins by direct phosphorylation, mutations at Abl kinase phosphorylation sites on Crk and CrkL did not yield any observable effects. Instead, our findings reveal that Abl kinases phosphorylate Ptpn12, which in turn inhibits p130Cas phosphorylation and Crk recruitment, crucial for Rho GTPases activation and cytoskeletal dynamics. Consequently, Abl kinase deficiency reduces actomyosin contractility within the lens vesicle and genetically interacts with RhoA inhibition. Conversely, Rac1 deletion mitigates Peters anomaly in models with aberrant FGF, Abl kinase and RhoA signaling. Our results demonstrate that Abl kinases regulate FGF signaling to balance RhoA and Rac1 activity via the Ptpn12-p130Cas pathway, suggesting that targeting tension-mediated lens vesicle separation could be a therapeutic strategy for Peters anomaly.

Vinculin Y822 phosphorylation regulates cardiomyocyte adhesion dynamics and adherens junction maturation in the heart

bioRxiv (Cold Spring Harbor Laboratory) · 2024-11-03 · 1 citations

In the heart, cell-matrix and cell-cell adhesions reorganize in response to increased cardiac demand and growth to promote cardiomyocyte maturation. Vinculin, a mechanosensitive adaptor protein, links filamentous actin to cell-matrix and cell-cell adhesions and is thus positioned to regulate adhesion reorganization. However, how the two adhesion systems are coordinated in the heart, and the role of vinculin in this process is poorly understood. Here, we define the role of vinculin phosphorylation at tyrosine residue 822 (pY822) in cardiomyocyte adhesion and heart function. We found that pY822 correlated with dynamic junction remodeling in the developing heart but was lost as junctions matured postnatally. We then mutated Y822 to phenylalanine (Y822F) in the mouse to determine pY822 function in vivo. Homozygous mutant Vcl Y822F mice were viable and exhibited normal cardiac function at ten weeks of age; however, cardiac dysfunction was observed at 28 weeks. Vinculin and adherens junction proteins were reduced at cardiomyocyte junctions in Y822F hearts. In contrast, α5/β1 integrin and fibronectin increased along the lateral border of Y822F cardiomyocytes. Our results demonstrate that vinculin Y822 phosphorylation regulates the balance between cadherin and integrin adhesion organization, highlighting the importance of post-translational modification in modulating vinculin function in heart physiology.

Cadherin-dependent adhesion is required for muscle stem cell niche anchorage and maintenance

Development · 2024-03-08 · 13 citations

Adhesion between stem cells and their niche provides stable anchorage and signaling cues to sustain properties such as quiescence. Skeletal muscle stem cells (MuSCs) adhere to an adjacent myofiber via cadherin-catenin complexes. Previous studies on N- and M-cadherin in MuSCs revealed that although N-cadherin is required for quiescence, they are collectively dispensable for MuSC niche localization and regenerative activity. Although additional cadherins are expressed at low levels, these findings raise the possibility that cadherins are unnecessary for MuSC anchorage to the niche. To address this question, we conditionally removed from MuSCs β- and γ-catenin, and, separately, αE- and αT-catenin, factors that are essential for cadherin-dependent adhesion. Catenin-deficient MuSCs break quiescence similarly to N-/M-cadherin-deficient MuSCs, but exit the niche and are depleted. Combined in vivo, ex vivo and single cell RNA-sequencing approaches reveal that MuSC attrition occurs via precocious differentiation, re-entry to the niche and fusion to myofibers. These findings indicate that cadherin-catenin-dependent adhesion is required for anchorage of MuSCs to their niche and for preservation of the stem cell compartment. Furthermore, separable cadherin-regulated functions govern niche localization, quiescence and MuSC maintenance.

Abstract 4143048: Role of Inflammatory Cytokines in Triggering Ventricular Arrhythmias in Pulmonary Hypertension

Circulation · 2024-11-12

Introduction: Pulmonary hypertension (PH) is a deadly disease, and the corresponding survival rates are estimated at 50% over 5 years. Most patients with severe PH die of right heart failure or sudden cardiac death from arrhythmias. There are strong indications supporting inflammation as a major proarrhythmic factor in PH. Goal: To investigate whether and how inflammatory cytokines promote cardiac arrhythmias in PH rat model. Methods: We used rat models of PH: 1) decompensated PH using Su5416 injection (SU) and 3 weeks of hypoxia (Hx) (Su/Hx, n=7), 2) compensated PH using Hx alone (n=3), 3) sham control (CTR, n=8). Interleukin 1b (IL-1b) and IL-18 were perfused (5 ng/ml for 90 min) and action potentials (AP) were mapped using optical mapping with voltage sensitive dye. Results: APDs in the right ventricle (RV) were significantly increased in Su/Hx (86±9 ms, p=0.014) vs. Hx (75±10 ms) and CTR (74±8 ms). APD dispersion is also increased in Su/Hx (23±3 ms, p=0.011) vs. Hx (8±3 ms) and CTR (9±4 ms), leading to conduction block and reentry formation around RVOT in Su/Hx during S1S2 programmed stimulation (Fig-A). Longitudinal conduction velocity (CV) is significantly slower in Su/Hx (0.58±0.08 m/s, p=0.01) vs. Hx (0.78±0.12 m/s) and CTR (0.84±0.10 m/s). Perfusion of IL-1b/IL-18 significantly prolongs APDs in the Su/Hx model (Fig-B, APD=109±19 ms, p=0.003) but not in Hx (78±13 ms) and CTR (83±7 ms), associated with frequent PVCs in Su/Hx model (Fig-C.D, n=5/7 hearts in Su/Hx vs. 0/3 in Hx only and 2/8 hearts in CTR), indicating that inflammatory cytokines increase arrhythmia risks in decompensated PH. Conclusion: More severe form of PH (Su/Hx) showed the highest arrhythmia risks compared to the compensated PH model (Hx) and control under IL-1b/IL-18 perfusion, supporting the idea that inflammation in PH may play key roles promoting electrical remodeling and arrhythmias.

Abstract P2074: Site-specific Phosphorylation Of Vinculin Regulates N-cadherin Junction Assembly

Circulation Research · 2023-08-04

Introduction: During physiological and pathological growth, cardiomyocytes adapt and remodel in response to changes in mechanical load. The cytoskeleton plays a central role in tissue remodeling as it both senses mechanical stress and mediates structural remodeling which affects the functional response within the cardiomyocyte. Abl kinase-dependent vinculin (VCL) phosphorylation at tyrosine (Y) residue 822 (pVCL-Y822) has been implicated in force-induced cytoskeletal remodeling and adhesion strengthening at cadherin junctions. However, the functional significance of VCL phosphorylation in the working myocardium remains unknown. Objective: To determine the role of vinculin-mediated mechanotransduction in cardiac development, homeostasis, and disease. Methods and Results: Using a phospho-specific antibody, we found that pVCL-Y822 correlates with dynamic junction remodeling in embryonic cardiomyocytes which declines in the postnatal heart when N-cadherin junctions assemble at the intercalated disc. Notably, pVCL-Y822 is upregulated in border zone cardiomyocytes following myocardial infarction. To investigate VCL-mediated mechanotransduction in the heart, CRISPR-mediated genome editing was used to mutate the tyrosine at position 822 to a non-phosphorylatable phenylalanine (F) in the mouse Vcl gene. Vcl Y822F mice were born in the expected Mendelian frequency and are viable. Blocking VCL phosphorylation causes a preferential reduction of mutant VCL protein at the myocyte termini together with the N-cadherin-catenin adhesion complex. Whereas, α5/β1 integrin and fibronectin are both increased along the lateral border of the Vcl Y822F postnatal cardiomyocytes. Vcl Y822F mice exhibit reduced cardiac function with age; however, cardiac remodeling is attenuated in the mutant hearts. Conclusion: This novel animal model demonstrates how blocking vinculin Y822 phosphorylation affects the balance between cadherin adhesions and integrin adhesions and thereby highlights the importance of understanding the crosstalk between the two adhesion systems and its implications for disease pathogenesis.

Actomyosin-mediated cellular tension promotes Yap nuclear translocation and myocardial proliferation through α5 integrin signaling

Development · 2023-01-09 · 14 citations

The cardiomyocyte phenotypic switch from a proliferative to terminally differentiated state results in the loss of regenerative potential of the mammalian heart shortly after birth. Nonmuscle myosin IIB (NM IIB)-mediated actomyosin contractility regulates cardiomyocyte cytokinesis in the embryonic heart, and NM IIB levels decline after birth, suggesting a role for cellular tension in the regulation of cardiomyocyte cell cycle activity in the postnatal heart. To investigate the role of actomyosin contractility in cardiomyocyte cell cycle arrest, we conditionally activated ROCK2 kinase domain (ROCK2:ER) in the murine postnatal heart. Here, we show that α5/β1 integrin and fibronectin matrix increase in response to actomyosin-mediated tension. Moreover, activation of ROCK2:ER promotes nuclear translocation of Yap, a mechanosensitive transcriptional co-activator, and enhances cardiomyocyte proliferation. Finally, we show that reduction of myocardial α5 integrin rescues the myocardial proliferation phenotype in ROCK2:ER hearts. These data demonstrate that cardiomyocytes respond to increased intracellular tension by altering their intercellular contacts in favor of cell-matrix interactions, leading to Yap nuclear translocation, thus uncovering a function for nonmuscle myosin contractility in promoting cardiomyocyte proliferation in the postnatal heart.