Uncoupling Caveolae From Intracellular Signaling In Vivo

Abstract

Rationale Caveolin-1 negatively regulates eNOS derived NO production and this has been mapped to several residues on Cav-1 including F92. Herein, we reasoned that endothelial expression of an F92ACav-1 transgene would let us decipher the mechanisms and relationships between caveolae structure and intracellular signaling. Objective This study was designed to separate caveolae formation from its downstream signaling effects. Methods and Results An endothelial-specific doxycycline-regulated mouse model for the expression of Cav-1-F92A was developed. Blood pressure by telemetry and nitric oxide bioavailability by electron paramagnetic resonance and phosphorylation of VASP were determined. Caveolae integrity in the presence of Cav-1-F92A was measured by stabilization of Cav-2, sucrose gradient and electron microscopy. Histological analysis of heart and lung, echocardiography and signaling were performed. Conclusions This study shows that mutant Cav-1-F92A forms caveolae structures similar to WT but leads to increases in NO bioavailability in vivo thereby demonstrating that caveolae formation and downstream signaling events occur through independent mechanisms.

Contemporary Approaches to Modulating the Nitric Oxide–cGMP Pathway in Cardiovascular Disease

“…These two studies imply that cavnoxin can reduce the inhibitory effect of caveolin on eNOS function, allowing for enhancement of endogenous NO biosynthesis. Recent genetic data using an endothelial specific transgenic mouse expressing F92A CAV1 documents that regulated expression of the transgene is sufficient to increase NO bioavailability, resulting in a significantly lower systolic blood pressure 63 . Future work examining the spectrum of actions of cavtratin in a variety of models will yield insight into whether this strategy will improve endothelial dysfunction and reduce disease progression.…”

Caveolins and caveolae in ocular physiology and pathophysiology

“…Although the overarching hypothesis that the CSD is a general regulator of signal transduction has recently been challenged (Collins et al, 2012), there is clear evidence that the CSD is involved in endogenous inhibition of endothelial nitric oxide synthase (eNOS) in vascular endothelium and that mechanical uncoupling of eNOS from Cav-1 results in NO production (García-Cardeña et al, 1997; Yu et al, 2006). Recent evidence using an eNOS-activating CSD mutant (Bernatchez et al, 2011) has allowed for the separation of this CSD signal regulation from the formation of caveolae domains (Kraehling et al, 2015). Besides the CSD, the originally-identified phosphotyrosine modification at Tyr14 provides an additional means for Cav-1 to modulate signaling (Glenney and Zokas, 1989; Li et al, 1996b).…”

EphB1 in Endothelial Cells Regulates Caveolae Formation and Endocytosis

“…Multiple signaling proteins have been shown to bind CSD like EphB1 described in the present study (24)(25)(26)(27)(28)(29)(30)(31)(32)(33). However, it is argued on the basis of structural and bioinformatic analysis that physical interactions between CSD and CSDBM may be less common than believed since CSDBM is buried in many of the CSDBM containing proteins and thus inaccessible to bind CSD (45).…”

“…1A). Several of these key binding proteins have been identified including Src tyrosine kinases, eNOS (endothelial nitric oxide synthase), and trimeric G protein subunits, Ras, and PPARg (24)(25)(26)(27)(28)(29)(30)(31)(32)(33). Interestingly, in a study using CHO cells, it was shown that EphB1 can also bind CSD via its CSDBM ( 808 WSYGIVMW 815 ) and target the plasma membrane (34); however, while this study raised the potential for this interaction it did not address the mechanism of this interaction and in functional significance in the endothelium.…”