Localization of the Cyclic ADP-ribose-dependent Calcium Signaling Pathway in Hepatocyte Nucleus

doi:10.1074/jbc.M908231199

Localization of the Cyclic ADP-ribose-dependent Calcium Signaling Pathway in Hepatocyte Nucleus*

From the ^‡Clinical Research Unit, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, S308433, Singapore, the ^§Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, S119260, Singapore, the ^¶Department of Biochemistry, Institute of Medical Sciences, the ^‖Department of Pharmacology, Institute of Cardiovascular Research, Chonbuk National University Medical School, Chonju 561-182 Korea, the ^**Department of Physiology, University of Minnesota, Minneapolis, Minnesota 55455, and the ^‡Department of Anatomy, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, S119260, Singapore

Abstract

CD38 is a type II transmembrane glycoprotein found on both hematopoietic and non-hematopoietic cells. It is known for its involvement in the metabolism of cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate, two nucleotides with calcium mobilizing activity independent of inositol trisphosphate. It is generally believed that CD38 is an integral protein with ectoenzymatic activities found mainly on the plasma membrane. Here we show that enzymatically active CD38 is present intracellularly on the nuclear envelope of rat hepatocytes. CD38 isolated from rat liver nuclei possessed both ADP-ribosyl cyclase and NADase activity. Immunofluorescence studies on rat liver cryosections and isolated nuclei localized CD38 to the nuclear envelope of hepatocytes. Subcellular localization via immunoelectron microscopy showed that CD38 is located on the inner nuclear envelope. The isolated nuclei sequestered calcium in an ATP-dependent manner. cADPR elicited a rapid calcium release from the loaded nuclei, which was independent of inositol trisphosphate and was inhibited by 8-amino-cADPR, a specific antagonist of cADPR, and ryanodine. However, nicotinic acid adenine dinucleotide phosphate failed to elicit any calcium release from the nuclear calcium stores. The nuclear localization of CD38 shown in this study suggests a novel role of CD38 in intracellular calcium signaling for non-hematopoietic cells.

Footnotes

↵* This work was supported by the National University of Singapore Academic Research Grants RP960325 and RP960376. The work on the three-dimensional reconstruction was supported by a National Institutes of Health Grant HD17484 (to H. C. L.). The calcium mobilization work and funds for K. M. Khoo's stay in Korea to perform the initial part of that work was supported by a Genetic Engineering Research Grant from the Korean Ministry of Education (to U. H. K.) and a Korean STEPI Grant 97-N1-02-02-A-04 (to U.-H. K. and S. W. C.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵§§ To whom correspondence should be addressed: National University of Singapore, Dept. of Biochemistry, Faculty of Medicine, National University of Singapore, 10, Kent Ridge Crescent, Singapore 119260. Tel.: 65-8743681; Fax: 65-7791453; E-mail: bchccf@nus.edu.sg.
Published, JBC Papers in Press, May 18, 2000, DOI 10.1074/jbc.M908231199
↵2 C. F. Chang, unpublished observations.
Abbreviations:

cADPR

cADP-ribose

NGD⁺

nicotinamide-guanine-dinucleotide

cGDPR

cGDP-ribose

GDPR

GDP-ribose

IP₃

inositol trisphosphate

RyR

ryanodine receptor

PAGE

polyacrylamide gel electrophoresis

PBS

phosphate-buffered saline

BSA

bovine serum albumin

NAADP

nicotinic acid adenine dinucleotide phosphate

ConA

concanavalin A
- Received October 8, 1999.
- Revision received May 15, 2000.
The American Society for Biochemistry and Molecular Biology, Inc.