SARAF and Orai1 Contribute to Endothelial Cell Activation and Angiogenesis

Isabel Galeano-Otero; Raquel Del Toro; Abdel-Majid Khatib; Juan Antonio Rosado; Antonio Ordóñez-Fernández; Tarik Smani

doi:10.3389/fcell.2021.639952

SARAF and Orai1 Contribute to Endothelial Cell Activation and Angiogenesis

Front Cell Dev Biol. 2021 Mar 4:9:639952. doi: 10.3389/fcell.2021.639952. eCollection 2021.

Authors

Isabel Galeano-Otero^{1

2

3}, Raquel Del Toro^{1

2

3}, Abdel-Majid Khatib⁴, Juan Antonio Rosado⁵, Antonio Ordóñez-Fernández^{2

3

6}, Tarik Smani^{1

2

3}

Affiliations

¹ Department of Medical Physiology and Biophysics, University of Seville, Seville, Spain.
² Group of Cardiovascular Pathophysiology, Institute of Biomedicine of Seville, University Hospital of Virgen del Rocío/University of Seville/CSIC, Seville, Spain.
³ CIBERCV, Madrid, Spain.
⁴ LAMC, INSERM U1029, Pessac, France.
⁵ Department of Physiology, University of Extremadura, Caceres, Spain.
⁶ Department of Surgery, University of Seville, Seville, Spain.

Abstract

Angiogenesis is a multistep process that controls endothelial cells (ECs) functioning to form new blood vessels from preexisting vascular beds. This process is tightly regulated by pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), which promote signaling pathways involving the increase in the intracellular Ca²⁺ concentration ([Ca²⁺]_i). Recent evidence suggests that store-operated calcium entry (SOCE) might play a role in angiogenesis. However, little is known regarding the role of SARAF, SOCE-associated regulatory factor, and Orai1, the pore-forming subunit of the store-operated calcium channel (SOCC), in angiogenesis. Here, we show that SOCE inhibition with GSK-7975A blocks aorta sprouting, as well as human umbilical vein endothelial cell (HUVEC) tube formation and migration. The intraperitoneal injection of GSK-7975A also delays the development of retinal vasculature assessed at postnatal day 6 in mice, since it reduces vessel length and the number of junctions, while it increases lacunarity. Moreover, we find that SARAF and Orai1 are involved in VEGF-mediated [Ca²⁺]_i increase, and their knockdown using siRNA impairs HUVEC tube formation, proliferation, and migration. Finally, immunostaining and in situ proximity ligation assays indicate that SARAF likely interacts with Orai1 in HUVECs. Therefore, these findings show for the first time a functional interaction between SARAF and Orai1 in ECs and highlight their essential role in different steps of the angiogenesis process.

Keywords: HUVEC; Orai1; SARAF; SOCE; angiogenesis.