Bioluminescence imaging of nuclear calcium oscillations in intact pancreatic islets of Langerhans from the mouse.
The stimulus-secretion coupling for insulin secretion by pancreatic beta cells in response to high glucose involves synchronic cytosolic calcium oscillations driven by bursting electrical activity. Calcium inside organelles can regulate additional functions, but analysis of subcellular calcium signals, specially at the single cell level, has been hampered for technical constrains. Here we have monitored nuclear calcium oscillations by bioluminescence imaging of targeted aequorin in individual cells within intact islets of Langerhans as well as in the whole islet. We find that glucose generates a pattern of nuclear calcium oscillations resembling those found in the cytosol. Some cells showed synchronous nuclear calcium oscillations suggesting that the islet of Langerhans may also regulate the activation of Ca(2+)-responsive nuclear processes, such as gene transcription, in a coordinated, synchronic manner. The nuclear Ca(2+) oscillations are due to bursting electrical activity and activation of plasma membrane voltage-gated Ca(2+) channels with little or no contribution of calcium release from the intracellular Ca(2+) stores. Irregularities in consumption of aequorins suggests that depolarization may generate formation of steep Ca(2+) gradients in both the cytosol and the nucleus, but further research is required to investigate the role of such high [Ca(2+)] microdomains.
Villalobos
Carlos
C
Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid and CSIC, Facultad de Medicina, Spain.
Nadal
Angel
A
Núñez
Lucía
L
Quesada
Iván
I
Chamero
Pablo
P
Alonso
María T
MT
García-Sancho
Javier
J
D000331:Aequorin / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D003600:Cytosol / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D015533:Transcriptional Activation / Q000502:physiology
D015220:Calcium Channels; D007328:Insulin; D008164:Luminescent Proteins; D000331:Aequorin; D005947:Glucose; D002118:Calcium