Signal transduction and gene expression regulated by calcium release from internal stores in excitable cells.
Calcium regulation of several transcription factors involves different calcium-dependent signaling cascades and engages cytoplasmic as well as nuclear calcium signals. The study of the specific sources of calcium signals involved in regulation of gene expression in skeletal muscle has been addressed only recently. In this tissue, most cytoplasmic and nuclear calcium signals originate from calcium release from internal stores, mediated either by ryanodine receptor (RyR) or IP3 receptor (IP3R) channels. The latter are located both in the sarcoplasmic reticulum (SR) and in the nuclear membrane, and their activation results in long-lasting nuclear calcium increase. The calcium signals mediated by RyR and IP3R are very different in kinetics, amplitude and subcellular localization; an open question is whether these differences are differentially sensed by transcription factors. In neurons, it is well established that calcium entry through L-type calcium channels and NMDA receptors plays a role in the regulation of gene expression. Increasing evidence, however, points to a role for calcium release from intracellular stores in this process. In this article, we discuss how RyR-mediated calcium release contributes to the activation of the calcium-dependent transcription factor CREB and the subsequent LTP generation. We present novel results from our laboratory showing ERK-mediated CREB activation by hydrogen peroxide. This activation takes place in the absence of extracellular calcium and is blocked by inhibitory ryanodine concentrations, suggesting it is caused by redox activation of RyR-mediated calcium release.
Carrasco
María Angélica
MA
FONDAP Center of Molecular Studies of the Cell, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Casilla 70005, Santiago 7, Chile. mcarras@med.uchile.cl
Jaimovich
Enrique
E
Kemmerling
Ulrike
U
Hidalgo
Cecilia
C
D015220:Calcium Channels / Q000378:metabolism / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D042541:Intracellular Space / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D011519:Proto-Oncogenes / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism / Q000502:physiology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
D015220:Calcium Channels; D017362:Cyclic AMP Response Element-Binding Protein; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D019837:Ryanodine Receptor Calcium Release Channel