Nicotinate Adenine Dinucleotide Phosphate (NAADP) Triggers a Specific Calcium Release System in Sea Urchin Eggs

doi:10.1074/jbc.270.7.3216

Nicotinate Adenine Dinucleotide Phosphate (NAADP) Triggers a Specific Calcium Release System in Sea Urchin Eggs (*)

From the Nephrology Research Unit, Division of Nephrology and Internal Medicine, Departments of Medicine and Physiology, Mayo Clinic and Foundation, Mayo Medical School, Rochester, Minnesota 55905

** To whom correspondence and reprint requests should be addressed:
921B Guggenheim Bldg., Mayo Clinic, Rochester, MN 55905.
Tel.: 507-284-4343; Fax: 507-284-8566.

Abstract

Transient fluxes of intracellular ionized calcium (Ca) from intracellular stores are integral components of regulatory signaling pathways operating in numerous biological regulations, including in early stages of egg fertilization. Therefore, we explored whether NADP, which is rapidly generated by phosphorylation of NAD upon fertilization may, directly or indirectly, exert a regulatory role as a trigger of Ca release from intracellular stores in sea urchin eggs. NADP had no effect, but we found that the deamidated derivative of NADP, nicotinate adenine dinucleotide phosphate (β-NAADP), is a potent and specific stimulus (ED 16 nM) for Ca release in sea urchin egg homogenates. NAADP triggers the Ca release via a mechanism which is distinct from the well-known Ca release systems triggered either by inositol-1,4,5-triphosphate (IP₃) or by cyclic adenosine diphospho-ribose (cADPR). The NAADP-induced release of Ca is not blocked by heparin, an antagonist of IP₃, or by procaine or ruthenium red, antagonists of cADPR. However, it is selectively blocked by thionicotinamide-NADP which does not inhibit the actions of IP₃ or cADPR. NAADP produced by heating of NADP in alkaline (pH = 12) medium or synthetized enzymatically by nicotinic acid-NADP reaction catalyzed by NAD glycohydrolase have identical properties. The results presented herein thus describe a novel endocellular Ca-releasing system controlled by NAADP as a specific stimulus. The NAADP-controlled Ca release system may be an integral component of multiple intracellular regulations occurring in fertilized sea urchin eggs, which are mediated by intracellular Ca release, and may also have similar role(s) in other tissues.

Footnotes

↵^§ Research Fellow of the Mayo Foundation.
↵^¶ Recipient of a research training fellowship from NIH Renal Diseases Research Training Grant DK-07013.
↵* This research was supported by United States Public Health Service Grant DK-30579 from the National Institute of Diabetes and Digestive and Kidney Disease and by the Mayo Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

IP₃

inositol-1,4,5-trisphosphate

cADPR

cyclic ADP-ribose

TMB-8

3,4,5-trimethoxibenzoic acid 8-(diethylemine)octal ether)

thio-NADP

thionicotinamide-NADP

HPLC

high performance liquid chromatography

TLC

thin layer chromatography

2′P-ADPR

adenosine diphosphoribose 2′ phosphate.
- Received October 6, 1994.
- Revision received December 5, 1994.