Expression of the Ryanodine Receptor Isoforms in Immune Cells

Abstract

Ryanodine receptor (RYR) is a Ca2+ channel that mediates Ca2+ release from intracellular stores. We have used RT-PCR analysis and examined its expression in primary peripheral mononuclear cells (PBMCs) and in 164 hemopoietic cell lines. In PBMCs, type 1 RYR (RYR1) was expressed in CD19+ B lymphocytes, but less frequently in CD3+ T lymphocytes and in CD14+ monocytes. Type 2 RYR (RYR2) was mainly detected in CD3+ T cells. Induction of RYR1 and/or RYR2 mRNA was found after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1α (MIP1α) or TGF-β. Type 3 RYR (RYR3) was not detected in PBMCs. Many hemopoietic cell lines expressed not only RYR1 or RYR2 but also RYR3. The expression of the isoforms was not associated with specific cell lineage. We showed that the RYR-stimulating agent 4-chloro-m-cresol (4CmC) induced Ca2+ release and thereby confirmed functional expression of the RYR in the cell lines expressing RYR mRNA. Moreover, concordant induction of RYR mRNA with Ca2+ channel function was found in Jurkat T cells. In untreated Jurkat T cells, 4CmC (>1 mM) had no effect on Ca2+ release, whereas 4CmC (<400 μM) caused Ca2+ release after the induction of RYR2 and RYR3 that occurred after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1α, or TGF-β. Our results demonstrate expression of all three isoforms of RYR mRNA in hemopoietic cells. Induction of RYRs in response to chemokines and TGF-β suggests roles in regulating Ca2+-mediated cellular responses during the immune response.