Zonghua Luo1, Qianwa Liang1, Hui Liu1, Joshi Sumit1, Hao Jiang1, Robyn S Klein2, Zhude Tu3. 1. Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA. 2. Departments of Medicine, Neuroscience, Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. 3. Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address: tuz@mir.wustl.edu.
Abstract
INTRODUCTION: Sphingosine-1-phosphate receptor 2 (S1PR2) activation exerts a critical role in biological abnormalities and diseases. A suitable radiotracer will advance our understanding of S1PR2 pathophysiology of diseases. The objective of this study is to evaluate the potential of iodine-125 labeled [125I]TZ6544 to be used for screening new compounds binding toward S1PR2, and assessing the changes of S1PR2 expression in the kidney of streptozotocin-induced diabetic rats. METHODS: [125I]TZ6544 was synthesized from borate precursor by copper (II)-catalyzed iodization reaction with [125I]NaI. [125I]TZ6544 was characterized using human recombinant S1PR2 cell membrane and biodistribution studies of [125]TZ6544 were performed on Wistar rats that were euthanized at 5 and 30 min post-injection. A rat model of diabetes was induced by IV injection of streptozotocin (55 mg/kg). In vitro autoradiography studies, immunostaining, and enzyme-linked immunosorbent assay (ELISA) analysis were performed in both diabetic and control rats. RESULTS: Radiosynthesis of [125I]TZ6544 was achieved successfully with good radiochemical yields of ~47% and high radiochemical purity of >99%. [125I]TZ6544 is a potent ligand in vitro for S1PR2 with Kd value of 4.31 nM. [125I]TZ6544 and [32P]-labeled endogenous S1P provided comparable IC50 values in radioactive competitive binding assays against known S1PR2 ligands. Compared to control, the kidney of diabetic rats had increased uptake of [125I]TZ6544, which could be reduced by a S1PR2 antagonist, JTE-013. Immunostaining and ELISA analysis confirmed that the diabetic rat had increased S1PR2 expression in the kidney. CONCLUSIONS: [125I]TZ6544 was synthesized successfully in high yields, and in vitro evaluation suggested [125I]TZ6544 has high potential to be used for screening new S1PR2 compounds and investigating the pathophysiology of S1PR2 functions. The availability of [125I]TZ6544 may facilitate the development of therapeutics and imaging agents targeting S1PR2. ADVANCES IN KNOWLEDGE: [125I]TZ6544 showed increased expression of S1PR2 in diabetic rat kidney and can be used to determine binding potency of S1PR2 compounds.
INTRODUCTION: Sphingosine-1-phosphate receptor 2 (S1PR2) activation exerts a critical role in biological abnormalities and diseases. A suitable radiotracer will advance our understanding of S1PR2 pathophysiology of diseases. The objective of this study is to evaluate the potential of iodine-125 labeled [125I]TZ6544 to be used for screening new compounds binding toward S1PR2, and assessing the changes of S1PR2 expression in the kidney of streptozotocin-induced diabetic rats. METHODS: [125I]TZ6544 was synthesized from borate precursor by copper (II)-catalyzed iodization reaction with [125I]NaI. [125I]TZ6544 was characterized using human recombinant S1PR2 cell membrane and biodistribution studies of [125]TZ6544 were performed on Wistar rats that were euthanized at 5 and 30 min post-injection. A rat model of diabetes was induced by IV injection of streptozotocin (55 mg/kg). In vitro autoradiography studies, immunostaining, and enzyme-linked immunosorbent assay (ELISA) analysis were performed in both diabetic and control rats. RESULTS: Radiosynthesis of [125I]TZ6544 was achieved successfully with good radiochemical yields of ~47% and high radiochemical purity of >99%. [125I]TZ6544 is a potent ligand in vitro for S1PR2 with Kd value of 4.31 nM. [125I]TZ6544 and [32P]-labeled endogenous S1P provided comparable IC50 values in radioactive competitive binding assays against known S1PR2 ligands. Compared to control, the kidney of diabetic rats had increased uptake of [125I]TZ6544, which could be reduced by a S1PR2 antagonist, JTE-013. Immunostaining and ELISA analysis confirmed that the diabetic rat had increased S1PR2 expression in the kidney. CONCLUSIONS: [125I]TZ6544 was synthesized successfully in high yields, and in vitro evaluation suggested [125I]TZ6544 has high potential to be used for screening new S1PR2 compounds and investigating the pathophysiology of S1PR2 functions. The availability of [125I]TZ6544 may facilitate the development of therapeutics and imaging agents targeting S1PR2. ADVANCES IN KNOWLEDGE: [125I]TZ6544 showed increased expression of S1PR2 in diabetic rat kidney and can be used to determine binding potency of S1PR2 compounds.
Authors: H Okazaki; N Ishizaka; T Sakurai; K Kurokawa; K Goto; M Kumada; Y Takuwa Journal: Biochem Biophys Res Commun Date: 1993-02-15 Impact factor: 3.575
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