Ryanodine receptors in calcium signaling pathways

Calcium (Ca2+) plays an important role as a second messenger, transmitting the message of arrival of stimuli such as hormones and neurotransmitters to the intracellular system that carries out the cellular response to the stimulus. The universality of Ca2+ as an intracellular messenger depends on its enormous versatility. This versatility is exploited to control processes as diverse as fertilization, proliferation, development, learning and memory, contraction and secretion, and must be accomplished within the context of Ca2+ being highly toxic.Ryanodine receptors (RyRs) and inositol trisphosphate receptors (IP3Rs) are Ca2+ -release channels located on intracellular membranes of the endoplasmic reticulum (ER)/sarcoplasmic reticulum (SR) that perform essential functions as key targets of hormone/neurotransmitter action to initiate intracellular Ca2+ signals. The purpose of this project was to study the role of RyR2 in Ca2+ signaling in the NG115-401L neuronal cell line. siRNA transfection methods were employed to knockdown RyR2 expression levels in NG115-401L cells. We used reverse transcription and real-time PCR to evaluate RyR2 gene expression in transfected/untransfected cells. We also evaluated cytosolic Ca2+ changes induced by RyR activators or regulators, using fura-2 AM as the Ca2+ indicator. Successful RyR2 gene knockdown allowed us to carry out some initial experiments to characterize the specific roles played by the RyR2 receptor isoform. We examined cell responses to FK-506 under the condition of RyR2 knockdown, finding that RyR2 appears to confer selectivity to this response. Finally, the effects of siRNA transfection and FK-506 treatment on NG115-401L cell growth were evaluated. These experimental results may contribute to future studies of RyR2, and help develop novel treatments for RyR2-base d dysfunctional diseases.