PB1260 - Importance of Erythrocyte Arginase-1 for Vascular Smooth Muscle Cell NO Signaling and Calcification

Tuesday, July 12, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Rajinikanth Gogiraju, PhD

Post-Doc
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany

Co-Author(s)

LR

Luisa Renner

graduate student
Department of Cardiology, University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
MB

Magdalena L. Bochenek, PhD

Post-Doc
Center for Thrombosis and Hemostasis, University Medical Center Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
Konstantinos Zifkos, MSc Eng

PhD student
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
MM

Michael Molitor

Postdoctoral Researcher
University Medical Center Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
Philip Wenzel, MD

Professor
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz
Mainz, Rheinland-Pfalz, Germany
Sven Danckwardt, MD

Univ.-Prof. Dr. med.
Center for Thrombosis and Hemostasis (CTH), University Medical Centre Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
TM

Thomas Münzel

Professor, Head of Cardiology I Department
Center for Cardiology - Cardiology I, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
Katrin Schäfer, MD

Professor
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany

Background: Erythrocytes (red blood cells, RBCs) actively participate in the control of vascular nitric oxide (NO) bioavailability. Increased expression of arginase-1 (ARG1), an important regulator of NO production by competing with endothelial NO synthase (eNOS) for L-arginine, is seen in erythrocytes of patients at risk for vascular dysfunction. Our group has previously shown that atherosclerotic plaque bleeding and erythrocyte extravasation promote vascular calcification by mechanisms involving NO.

Aims: To determine the significance of ARG1 in murine erythrocytes for vascular smooth muscle cell (VSMC) NO signaling, osteoblastic differentiation and calcification.

Methods: Atherosclerosis-prone mice lacking ARG1 in RBCs (apoE-/- RBC.ARG1 knockout, KO) were generated by crossing erythropoietin Cre recombinase transgenic mice into the apolipoprotein E-deficient background followed by intercrosses with ARG1flox/flox transgenic mice and feeding Western type diet.

Results: Conditional deletion of ARG1 increased the erythrocyte NO content in an eNOS-dependent manner, without affecting erythrocyte numbers, morphology or removal in the spleen. Vascular calcification was significantly enhanced in apoE-/- RBC.ARG1 knockout mice, as shown by molecular imaging of osteogenic activity using OsteoSense™ and verified by Alizarin staining of calcium phosphate deposits on cross-sections through the aortic root. Incubation of VSMCs with lysed RBC membranes from apoE-/- RBC.ARG1-KO mice also accelerated osteoblastic differentiation in vitro, and calcium deposits and osteogenic marker mRNA levels decreased in the presence of a NO scavenger or inhibition of NO signaling. Increased expression of the protein denitrosylase GSNOR (S-nitrosoglutathione reductase), degradation of S-nitrosoglutathione to glutathione and reduced protein S-nitrosation of ARG1 were identified as mechanisms leading to VSMC calcification in mice lacking ARG1 in erythrocytes.

Conclusion(s): Our findings suggest an important role of erythrocyte ARG1 in the control of vascular L-arginine metabolism, NO bioactivity and signaling and identify GSNOR and protein S-denitrosation of ARG1 as potential target to prevent vascular smooth muscle cell calcification.