Insulin-Increased L-Arginine Transport Requires A(2A) Adenosine Receptors Activation in Human Umbilical Vein Endothelium

Guzman-Gutierrez, E; Westermeier, F; Salomon, C; Gonzalez, M.; Pardo F.; Leiva A.; Sobrevia L.

Abstract

Adenosine causes vasodilation of human placenta vasculature by increasing the transport of arginine via cationic amino acid transporters 1 (hCAT-1). This process involves the activation of A2A adenosine receptors (A2AAR) in human umbilical vein endothelial cells (HUVECs). Insulin increases hCAT-1 activity and expression in HUVECs, and A2AAR stimulation increases insulin sensitivity in subjects with insulin resistance. However, whether A2AAR plays a role in insulin-mediated increase in L-arginine transport in HUVECs is unknown. To determine this, we first assayed the kinetics of saturable L-arginine transport (1 minute, 37°C) in the absence or presence of nitrobenzylthioinosine (NBTI, 10 μmol/L, adenosine transport inhibitor) and/or adenosine receptors agonist/antagonists. We also determined hCAT-1 protein and mRNA expression levels (Western blots and quantitative PCR), and SLC7A1 (for hCAT-1) reporter promoter activity. Insulin and NBTI increased the extracellular adenosine concentration, the maximal velocity for L-arginine transport without altering the apparent Km for L-arginine transport, hCAT-1 protein and mRNA expression levels, and SLC7A1 transcriptional activity. An A2AAR antagonist ZM-241385 blocked these effects. ZM241385 inhibited SLC7A1 reporter transcriptional activity to the same extent in cells transfected with pGL3-hCAT-1-1606 or pGL3-hCAT-1-650 constructs in the presence of NBTI + insulin. However, SLC7A1 reporter activity was increased by NBTI only in cells transfected with pGL3-hCAT-1-1606, and the ZM-241385 sensitive fraction of the NBTI response was similar in the absence or in the presence of insulin. Thus, insulin modulation of hCAT-1 expression and activity requires functional A2AAR in HUVECs, a mechanism that may be applicable to diseases associated with fetal insulin resistance, such as gestational diabetes. © 2012 Guzmán-Gutiérrez et al.

Más información

Título según WOS: Insulin-Increased L-Arginine Transport Requires A(2A) Adenosine Receptors Activation in Human Umbilical Vein Endothelium
Título según SCOPUS: Insulin-increased L-arginine transport requires A2A adenosine receptors activation in human umbilical vein endothelium
Título de la Revista: PLOS ONE
Volumen: 7
Número: 7
Editorial: PUBLIC LIBRARY SCIENCE
Fecha de publicación: 2012
Idioma: English
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-84864231326&partnerID=40&md5=d744a2608c6d9d8a8221e4fb5a7e7a02
DOI:

10.1371/journal.pone.0041705

Notas: ISI, SCOPUS