Kinesin I and cytoplasmic dynein orchestrate glucose-stimulated insulin-containing vesicle movements in clonal MIN6 beta-cells.
Glucose-stimulated mobilization of large dense-core vesicles (LDCVs) to the plasma membrane is essential for sustained insulin secretion. At present, the cytoskeletal structures and molecular motors involved in vesicle trafficking in beta-cells are poorly defined. Here, we describe simultaneous imaging of enhanced green fluorescent protein (EGFP)-tagged LDCVs and microtubules in beta-cells. Microtubules exist as a tangled array, along which vesicles describe complex directional movements. Whilst LDCVs frequently changed direction, implying the involvement of both plus- and minus-end directed motors, inactivation of the minus-end motor, cytoplasmic dynein, inhibited only a small fraction of all vesicle movements which were involved in vesicle recovery after glucose-stimulated exocytosis. By contrast, selective silencing of the plus-end motor, kinesin I, with small interfering RNAs substantially inhibited all vesicle movements. We conclude that the majority of LDCV transport in beta-cells is mediated by kinesin I, whilst dynein probably contributes to the recovery of vesicles after rapid kiss-and-run exocytosis.
Henry Wellcome Laboratories for Integrated Cell Signaling, Department of Biochemistry, School of Medical Sciences, University Walk, University of Bristol, Bristol BS8 1TD, UK.
Aniko
A
Varadi
Takashi
T
Tsuboi
Linda I
LI
Johnson-Cadwell
Victoria J
VJ
Allan
Guy A
GA
Rutter
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D002999:Clone Cells; D003593:Cytoplasm / Q000378:metabolism; D004398:Dyneins / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000502:physiology*; D016547:Kinesins / Q000502:physiology*; D008870:Microtubules / Q000502:physiology* / Q000648:ultrastructure; D020409:Molecular Motor Proteins / Q000502:physiology*; D022142:Secretory Vesicles / Q000502:physiology* / Q000648:ultrastructure
D007328:Insulin; D020409:Molecular Motor Proteins; D004398:Dyneins; D016547:Kinesins; D005947:Glucose