title: Plasticity and adaptation of Ca2+ signaling and Ca2+-dependent exocytosis in SERCA2(+/-) mice.
abstract: Darier's disease (DD) is a high penetrance, autosomal dominant mutation in the ATP2A2 gene, which encodes the SERCA2 Ca2+ pump. Here we have used a mouse model of DD, a SERCA2(+/-) mouse, to define the adaptation of Ca2+ signaling and Ca2+-dependent exocytosis to a deletion of one copy of the SERCA2 gene. The [Ca2+]i transient evoked by maximal agonist stimulation was shorter in cells from SERCA2(+/-) mice, due to an up-regulation of specific plasma membrane Ca2+ pump isoforms. The change in cellular Ca2+ handling caused approximately 50% reduction in [Ca2+]i oscillation frequency. Nonetheless, agonist-stimulated exocytosis was identical in cells from wild-type and SERCA2(+/-) mice. This was due to adaptation in the levels of the Ca2+ sensors for exocytosis synaptotagmins I and III in cells from SERCA2(+/-) mice. Accordingly, exocytosis was approximately 10-fold more sensitive to Ca2+ in cells from SERCA2(+/-) mice. These findings reveal a remarkable plasticity and adaptability of Ca2+ signaling and Ca2+-dependent cellular functions in vivo, and can explain the normal function of most physiological systems in DD patients.
authors.affiliation: Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040, USA.
authors.forename: X S
authors.initials: XS
authors.lastname: Zhao
authors.forename: D M
authors.initials: DM
authors.lastname: Shin
authors.forename: L H
authors.initials: LH
authors.lastname: Liu
authors.forename: G E
authors.initials: GE
authors.lastname: Shull
authors.forename: S
authors.initials: S
authors.lastname: Muallem
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002463:Cell Membrane Permeability; D007644:Darier Disease / Q000235:genetics; D005089:Exocytosis / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006579:Heterozygote; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051036:Large-Conductance Calcium-Activated Potassium Channels; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D010179:Pancreas / Q000201:enzymology / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology; D024681:Potassium Channels, Calcium-Activated; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D007527:Isoenzymes; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D012333:RNA, Messenger; D002217:Carbachol; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506946:ATP2A2 protein, human; C506947:Atp2a2 protein, mouse; D000252:Calcium-Transporting ATPases; D002118:Calcium