Biology subjects

Molinar-Inglis, O.

Publications and source records attributed to Molinar-Inglis, O..

3 recordsLinked to original sources

bioRxiv2025

Activated protein C promotes beta-arrestin-2- and c-Src-dependent caveolin-1 (Cav1) phosphorylation and alters Cav1 association with PAR1 and GRK5

G protein-coupled receptors (GPCRs) display bias towards either G proteins or GPCR kinase (GRK)-mediated {beta}-arrestin signaling depending on the agonist stabilized receptor conformation and cellular context. The cellular location of GPCRs particularly within plasma membrane microdomains such as lipid rafts contributes to biased signaling through mechanisms that are not well understood. The protease-activated receptor-1 (PAR1) exhibits biased signaling in response to thrombin and activated protein C (APC). APC-induced {beta}-arrestin-2 ({beta}arr2) biased signaling requires PAR1 compartmentalization in caveolae, a subtype of lipid rafts, whereas thrombin-activated PAR1 G protein signaling does not. Caveolin-1 (Cav1) is the principal structural protein of caveolae and regulates signaling through protein-protein interactions. The mechanisms by which Cav1 contributes to APC/PAR1-induced {beta}arr2 biased signaling is not known. Here we report that APC-activated PAR1 modulates Cav1 phosphorylation via a {beta}arr2- and c-Src-dependent pathway. APC also regulates the dynamics of endogenous PAR1-Cav1 and GRK5-Cav1 co-localization examined by single molecule super-resolution stochastic optical reconstruction microscopy imaging in human cultured endothelial cells. We further demonstrate that GRK5 interacts with Cav1 in intact cells through an N-terminus aromatic-rich consensus Cav1 binding motif. Unlike wildtype GRK5, a GRK5 mutant defective in Cav1 binding localized predominantly to the cytoplasm rather than the plasma membrane and failed to promote {beta}arr2 recruitment to APC-activated PAR1. These studies suggest that Cav1 itself contributes to the regulation of APC-activated PAR1 {beta}arr2 biased signaling likely through multiple mechanisms that may converge on GRK5.

cell biology↗

bioRxiv2021

aPC/PAR1 confers endothelial anti-apoptotic activity via a discrete β-arrestin-2 mediated SphK1-S1PR1-Akt signaling axis

Endothelial dysfunction is associated with multiple vascular diseases and lacks effective treatments. Activated Protein C (aPC) is a promising biotherapeutic that signals via protease-activated receptor-1 (PAR1) to promote diverse cytoprotective responses, including endothelial barrier stabilization, anti-inflammatory and anti-apoptotic activities, which is facilitated by co-receptors. We showed that aPC-activated PAR1 signals preferentially via {beta}-arrestin-2 ({beta}-arr2) and dishevelled-2 (Dvl2) scaffolds rather than G proteins to enhance barrier protection. However, the mechanisms by which aPC/PAR1 promotes other cytoprotective responses are poorly understood. Here we define a novel {beta}-arr2-mediated sphingosine kinase-1 (SphK1)-sphingosine-1-phosphate receptor-1 (S1PR1)-Akt signaling axis that confers aPC/PAR1-mediated protection against cell death. We show that PAR1 and S1PR1 co-exist in caveolin-1-rich microdomains basally and aPC markedly increases S1PR1-caveolin-1 co-association. Moreover, aPC stimulates {beta}-arr2-dependent SphK1 activation independent of Dvl2, which is critical for S1PR1 transactivation. These studies reveal that different aPC/PAR1 cytoprotective responses are mediated by discrete {beta}-arr2-driven signaling pathways in caveolae.

cell biology↗

bioRxiv2019

Signaling Diversity Enabled by Rap1-Regulated Plasma Membrane ERK with Distinct Temporal Dynamics

A variety of different signals induce specific responses through a common, ERK-dependent kinase cascade. It has been suggested that signaling specificity can be achieved through precise temporal regulation of ERK activity. Given the wide distrubtion of ERK susbtrates across different subcellular compartments, it is important to understand how ERK activity is temporally regulated at specific subcellular locations. To address this question, we have expanded the toolbox of FRET-based ERK biosensors by creating a series of improved biosensors targeted to various subcellular regions via sequence specific motifs to measure spatiotemporal changes in ERK enzymatic activity. Using these sensors, we showed that EGF induces sustained ERK activity near the plasma membrane in sharp contrast to the transient activity observed in the cytopolasm and nucleus. Furthermore, EGF-induced plasma membrane ERK activity involves Rap1, a noncanonical activator, and controls cell morphology and EGF-induced membrane protrusion dynamics. Our work strongly supports that spatial and temporal regulation of ERK activity is integrated to control signaling specificity from a single extracellular signal to multiple cellular processes.

cell biology↗