Expression and Function of Ryanodine Receptors in Nonexcitable Cells

doi:10.1074/jbc.271.11.6356

Expression and Function of Ryanodine Receptors in Nonexcitable Cells (*)

From the (1)Babraham Institute Laboratory of Molecular Signalling, Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, United Kingdom and
(2)Katholieke Universiteit Leuven, Laboratorium voor Fysiologie, Campus Gasthuisberg, B-3000 Leuven, Belgium

^§Funded by the BBSRC and The Isaac Newton Trust. To whom correspondence should be addressed. Tel.: 44 1223 336674; Fax: 44 1223 324387; dlb15{at}mole.bio.cam.ac.uk.

Abstract

We have used reverse transcriptase-polymerase chain reaction to investigate the expression of ryanodine receptors in several excitable and nonexcitable cell types. Consistent with previous reports, we detected ryanodine receptor expression in brain, heart, and skeletal muscle. In addition, we detected ryanodine receptor expression in various other excitable cells including PC12 and A7r5 cells. Several muscle cell lines (BCH1, C2C12, L6, and Sol8) weakly expressed ryanodine receptor when undifferentiated but strongly expressed type 1 and type 3 ryanodine receptor isoforms when differentiated into a muscle phenotype. Only 2 (HeLa and LLC-PK1 cells) out of 11 nonexcitable cell types examined expressed ryanodine receptors. Expression of ryanodine receptors at the protein level in these cells was confirmed using [³H]ryanodine binding. We also investigated the function of ryanodine receptors in Ca signaling in HeLa cells using single-cell Fura-2 imaging. Neither caffeine nor ryanodine caused a detectable elevation of cytoplasmic Ca in single HeLa cells. However, ryanodine caused a significant decrease in the amplitude of Ca signals evoked by repetitive stimulation with ATP. These studies show that ryanodine receptors are expressed in some nonexcitable cell types and furthermore suggest that the ryanodine receptors may be involved in a subtle regulation of intracellular Ca responses.

Footnotes

↵^¶ Royal Society University Research Fellows.
↵** Senior Research Assistant of the Belgian National Fund for Scientific Research (NFWO).
↵* 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:

RyR

ryanodine receptor

PCR

polymerase chain reaction

RT-PCR

reverse transcription-PCR

bp

base pair(s).
↵²R. Bolt, P. Vegeli, and R. Fries(1992) Sus scrofa RyR1 gene for ryanodine receptor. Submitted 1992 to the EMBL/GenBank/DDBJ databases. Accession number Z15155. Unpublished data.
↵³V. Sorrentino, G. Giannini, P. Malzac, and M. G. Mattei(1993) Homo sapiens RyR3 gene for ryanodine receptor type 3 (partial). Submitted 1993 to the EMBL/GenBank/DDBJ databases. Accession number X74270. Unpublished data.
- Received November 29, 1995.
- Revision received January 4, 1996.