Discovery of a small-molecule inhibitor for kidney ADP-ribosyl cyclase: Implication for intracellular calcium signal mediated by cyclic ADP-ribose

Tae-Sik Nam,Won Jang,Sung Hoon Choi,So-Young Rah,Seon-Young Kim,Uh-Hyun Kim,Ho Jeong Kwon,Mie-Jae Im

doi:10.1038/emm.2006.84

Abstract

ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca2+-mobilizing second messenger, cyclic ADP- ribose (cADPR), from beta-NAD+. A prototype of mammalian ADPR-cyclases is a lymphocyte antigen CD38. Accumulating evidence indicates that ADPR-cyclases other than CD38 are expressed in various cells and organs. In this study, we discovered a small molecule inhibitor of kidney ADPR-cyclase. This compound inhibited kidney ADPR-cyclase activity but not CD38, spleen, heart or brain ADPR-cyclase activity in vitro. Characterization of the compound in a cell-based system revealed that an extracellular calcium-sensing receptor (CaSR)- mediated cADPR production and a later long-lasting increase in intracellular Ca2+ concentration ([Ca2+]i) in mouse mesangial cells were inhibited by the pre-treatment with this compound. In contrast, the compound did not block CD3/TCR-induced cADPR production and the increase of [Ca2+]i in Jurkat T cells, which express CD38 exclusively. The long-lasting Ca2+ signal generated by both receptors was inhibited by pre-treatment with an antagonistic cADPR derivative, 8-Br-cADPR, indicating that the Ca2+ signal is mediated by the ADPR-cyclase metabolite, cADPR. Moreover, among structurally similar compounds tested, the compound inhibited most potently the cADPR production and Ca2+ signal induced by CaSR. These findings provide evidence for existence of a distinct ADPR-cyclase in the kidney and basis for the development of tissue specific inhibitors.

Highlights

ADP-ribosyl cyclase (ADPR-cyclase) is widely distributed and plays a critical role in regulation of intracellular Ca2+ concentration ([Ca2+]i) via cyclic ADP-ribose production (Guse et al, 1999; Galione et al, 2000; Lee, 2001)
The metabolite cyclic ADP-ribose (cADPR) is known to increase [Ca2+]i by releasing from intracellular Ca2+ stores or by Ca2+ influx through plasma membrane Ca2+ channels in a variety of cells (Guse et al, 1999; Galione et al, 2000; Lee, 2001; Partida-Sanchez et al, 2001)
Studies have indicated that a Zn2+-sensitive and reducing agent-insensitive ADPR-cyclase(s), which differs from CD38 or Aplysia californica ADPRcyclase, is present in brain, heart, kidney, arterial smooth muscle cells, and bone marrow cells (Hirata et al, 1994; de Toledo et al, 2000; Ceni et al, 2003; Zielinska et al, 2004; Xie et al, 2005)

Summary

Introduction

ADP-ribosyl cyclase (ADPR-cyclase) is widely distributed and plays a critical role in regulation of intracellular Ca2+ concentration ([Ca2+]i) via cyclic ADP-ribose (cADPR) production (Guse et al, 1999; Galione et al, 2000; Lee, 2001). We partially purified ADPR-cyclase from rat kidney, characterized, and screened a chemical library. Partial purification of ADPR-cyclase from rat kidney CADPR-hydrolase activity was determined by incubating cADPR with ADPR-cyclase or CD38 at 37oC for 20 min.

Results

Conclusion