Selective labeling of IRAP by the tritiated AT receptor ligands [H]Angiotensin IV and its stable analog [H]AL-11

Heidi Demaegdt (1) , Aneta Lukaszuk (2) , Evi de Buyser (1) , Jean-Paul de Backer (1) , Erzsébet Szemenyei (3) , Géza Tóth (3) , Sridhara Chakravarthy (4) , Mitradas Panicker (4) , Yvette Michotte (5) , Dirk Tourwé (2) , Georges Vauquelin (1)

1 Department of Molecular and Biochemical Pharmacology
2 VUB - Vrije Universiteit Brussel
3 MTA - Hungarian Academy of Sciences
4 Departement of Neurobiology [NCBS-TIFR]
5 Department of Pharmaceutical Chemistry

‘AT receptors' through which angiotensin IV (Ang IV) improves memory acquisition, were recently identified as insulin regulated aminopeptidase (IRAP). Radioligand binding studies have hitherto been performed with iodinated Ang IV in the presence of divalent cation chelators EDTA and 1,10-phenanthrolin. Hence, they referred to the apo-form of IRAP. Presently, binding of [H]Ang IV and [H]AL-11, a stable Ang IV analog, was compared on Chinese hamster ovary (CHO-K1) and mouse hippocampal (P40H1) cell membranes. With chelators, their high affinity sites showed the same pharmacological profile as for [I]Ang IV binding. Without chelators, only high affinity binding was perceived for [H]AL-11. The same pharmacological profile was recorded in both membrane preparations; it was different from the one in presence of chelators and corresponded to catalytically active IRAP (despite the concurrent presence aminopeptidase N (APN) in P40H1 cell membranes). This confirms that the active and apo-forms of IRAP have a distinct pharmacological profile.

Mots clés: Ang; APN; CHO-K1; EDTA; GLUT4; HEK; IRAP; L-Leu-pNA; LVV-H7; 10-Phe; P40H1; Ang IV; AL-11

Heidi Demaegdt, Aneta Lukaszuk, Evi de Buyser, Jean-Paul de Backer, Erzsébet Szemenyei, et al.. Selective labeling of IRAP by the tritiated AT receptor ligands [H]Angiotensin IV and its stable analog [H]AL-11. Molecular and Cellular Endocrinology, 2009, 311 (1-2), pp.77. ⟨10.1016/j.mce.2009.07.020⟩. ⟨hal-00521552⟩