Vesicular Ca2+ mediates granule motion and exocytosis

Cell Calcium ◽  
2012 ◽  
Vol 51 (3-4) ◽  
pp. 338-341 ◽  
Author(s):  
Ricardo Borges ◽  
Natalia Domínguez ◽  
Judith Estévez-Herrera ◽  
Daniel Pereda ◽  
José David Machado
Keyword(s):  
Granule Motion

Insulin exocytosis in Goto-Kakizaki rat β-cells subjected to long-term glinide or sulfonylurea treatment

2008 ◽  
Vol 412 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Junko Kawai ◽  
Mica Ohara-Imaizumi ◽  
Yoko Nakamichi ◽  
Tadashi Okamura ◽  
Yoshihiro Akimoto ◽  
...  
Keyword(s):  
Insulin Release ◽  
Β Cells ◽  
Gk Rats ◽  
Insulin Granules ◽  
Long Term Treatment ◽  
Insulin Granule ◽  
Granule Motion ◽  
Insulin Exocytosis ◽  
First Phase Insulin Release

Sulfonylurea and glinide drugs display different effects on insulin granule motion in single β-cells in vitro. We therefore investigated the different effects that these drugs manifest towards insulin release in an in vivo long-term treatment model. Diabetic GK (Goto-Kakizaki) rats were treated with nateglinide, glibenclamide or insulin for 6 weeks. Insulin granule motion in single β-cells and the expression of SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins were then analysed. Perifusion studies showed that decreased first-phase insulin release was partially recovered when GK rats were treated with nateglinide or insulin for 6 weeks, whereas no first-phase release occurred with glibenclamide treatment. In accord with the perifusion results, TIRF (total internal reflection fluorescence) imaging of insulin exocytosis showed restoration of the decreased number of docked insulin granules and the fusion events from them during first-phase release for nateglinide or insulin, but not glibenclamide, treatment; electron microscopy results confirmed the TIRF microscopy data. Relative to vehicle-treated GK β-cells, an increased number of SNARE clusters were evident in nateglinide- or insulin-treated cells; a lesser increase was observed in glibenclamide-treated cells. Immunostaining for insulin showed that nateglinide treatment better preserved pancreatic islet morphology than did glibenclamide treatment. However, direct exposure of GK β-cells to these drugs could not restore the decreased first-phase insulin release nor the reduced numbers of docked insulin granules. We conclude that treatment of GK rats with nateglinide and glibenclamide varies in long-term effects on β-cell functions; nateglinide treatment appears overall to be more beneficial.

scholarly journals Restriction of Secretory Granule Motion near the Plasma Membrane of Chromaffin Cells

2001 ◽  
Vol 153 (1) ◽  
pp. 177-190 ◽  
Author(s):  
Laura M. Johns ◽  
Edwin S. Levitan ◽  
Eric A. Shelden ◽  
Ronald W. Holz ◽  
Daniel Axelrod
Keyword(s):  
Plasma Membrane ◽  
Total Internal Reflection ◽  
Chromaffin Cells ◽  
Botulinum Toxin A ◽  
Secretory Granules ◽  
Internal Reflection ◽  
Snare Proteins ◽  
Bovine Chromaffin Cells ◽  
Heterogeneous Matrix ◽  
Granule Motion

We used total internal reflection fluorescence microscopy to study quantitatively the motion and distribution of secretory granules near the plasma membrane (PM) of living bovine chromaffin cells. Within the ∼300-nm region measurably illuminated by the evanescent field resulting from total internal reflection, granules are preferentially concentrated close to the PM. Granule motion normal to the substrate (the z direction) is much slower than would be expected from free Brownian motion, is strongly restricted over tens of nanometer distances, and tends to reverse directions within 0.5 s. The z-direction diffusion coefficients of granules decrease continuously by two orders of magnitude within less than a granule diameter of the PM as granules approach the PM. These analyses suggest that a system of tethers or a heterogeneous matrix severely limits granule motion in the immediate vicinity of the PM. Transient expression of the light chains of tetanus toxin and botulinum toxin A did not disrupt the restricted motion of granules near the PM, indicating that SNARE proteins SNAP-25 and VAMP are not necessary for the decreased mobility. However, the lack of functional SNAREs on the plasma or granule membranes in such cells reduces the time that some granules spend immediately adjacent to the PM.

scholarly journals The occurrence of actinlike filaments in association with migrating pigment granules in frog retinal pigment epithelium

1975 ◽  
Vol 64 (3) ◽  
pp. 705-710 ◽  
Author(s):  
RL Murray ◽  
MW Dubin
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Action Spectrum ◽  
Pigment Granule ◽  
Melanin Pigment ◽  
Photoreceptor Outer Segments ◽  
Outer Segments ◽  
Pigment Granules ◽  
Continuous Sheet ◽  
Granule Motion

In the retina of the frog and certain other animals, melanin pigment granules move in response to light so as to shield photoreceptor outer segments. The granules are contained within the cells of the pigment epithelium (PE) which lie as a continuous sheet between the neural retina and the choroid. Moderate illumination of the eye causes the melanin granules to move from a region within a PE cell body into numerous fingerlike extensions of the cell which interdigitate with the receptor outer segments. This migration takes many minutes and is reversed when the light falling on the eye increases in intensity. Several reviews are concerned with the early descriptions of this phenomenon (6,30) and with more recent experiments (1,5,19). The mechanism of the pigment granule motion is undetermined although there are studies concerning PE ultrastructure (8, 23, 31), scanning electron microscopy of the fingerlike extensions of the PE cells (27), the role of the PE in photoreceptor phagocytosis (32), the nature of the pigment granules (19), and the action spectrum of the light which induces the migration (16). This study reports the presence of a system of microfilaments associated with the pigment granules in the fingerlike extensions processes of the PE cells. We demonstrate by heavy meromyosin (HMM) labeling that the filaments are actinlike in character and suggest that these filaments could be responsible for the migration of the melanin pigment granules.

Arrest of pigment granule motion in erythrophores by quick-freezing

1984 ◽  
Vol 86 (2) ◽  
pp. 162-175 ◽  
Author(s):  
Ip Wallace ◽  
Douglas B. Murphy ◽  
John E. Heuser
Keyword(s):  
Pigment Granule ◽  
Quick Freezing ◽  
Granule Motion

scholarly journals Mechanism of insulin exocytosis in pancreatic B cells by analyzing single insulin granule motion with TIRF imaging system

2003 ◽  
Vol 43 (supplement) ◽  
pp. S5
Author(s):  
M. Ohara-Imaizumi ◽  
Y. Nakamichi ◽  
C. Nishiwaki ◽  
T. Kikuta ◽  
S. Nagai ◽  
...  
Keyword(s):  
B Cells ◽  
Imaging System ◽  
Pancreatic B Cells ◽  
Insulin Granule ◽  
Granule Motion ◽  
Insulin Exocytosis

scholarly journals TIRF imaging of docking and fusion of single insulin granule motion in primary rat pancreatic β-cells: different behaviour of granule motion between normal and Goto–Kakizaki diabetic rat β-cells

2004 ◽  
Vol 381 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Mica OHARA-IMAIZUMI ◽  
Chiyono NISHIWAKI ◽  
Toshiteru KIKUTA ◽  
Shintaro NAGAI ◽  
Yoko NAKAMICHI ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Release ◽  
Secretory Granules ◽  
Dynamic Change ◽  
Second Phase ◽  
Β Cells ◽  
Gk Rat ◽  
Pancreatic Β Cells ◽  
Insulin Granules ◽  
Granule Motion

We imaged and analysed the motion of single insulin secretory granules near the plasma membrane in live pancreatic β-cells, from normal and diabetic Goto–Kakizaki (GK) rats, using total internal reflection fluorescence microscopy (TIRFM). In normal rat primary β-cells, the granules that were fusing during the first phase originate from previously docked granules, and those during the second phase originate from ‘newcomers’. In diabetic GK rat β-cells, the number of fusion events from previously docked granules were markedly reduced, and, in contrast, the fusion from newcomers was still preserved. The dynamic change in the number of docked insulin granules showed that, in GK rat β-cells, the total number of docked insulin granules was markedly decreased to 35% of the initial number after glucose stimulation. Immunohistochemistry with anti-insulin antibody observed by TIRFM showed that GK rat β-cells had a marked decline of endogenous insulin granules docked to the plasma membrane. Thus our results indicate that the decreased number of docked insulin granules accounts for the impaired insulin release during the first phase of insulin release in diabetic GK rat β-cells.

The Analysis and Simulation of Granule Concentration Distribution in Cross Section of Spiral Slurry Pipeline

2012 ◽  
Vol 268-270 ◽  
pp. 1123-1127
Author(s):  
Yu Lin ◽  
Ping Lei ◽  
Xiao Dong Zhang
Keyword(s):  
Cross Section ◽  
Concentration Distribution ◽  
Pipe Wall ◽  
Spiral Flow ◽  
Cross Section Area ◽  
Movement Characteristics ◽  
Section Area ◽  
Peripheral Area ◽  
Fluent Software ◽  
Granule Motion

Through the analysis of force acting on granule in slurry spiral flow and movement characteristics of granules, the granule motion equation, the granule size distribution along radial direction, and distribution of granule concentration on cross section of the pipeline were established. By using computer simulation with FLUENT software for granule concentration distribution on cross section in slurry spiral flow of pipeline, the results of simulation revealed that the granule distribution in slurry spiral flow concentrated in peripheral area of cross section of pipeline, the concentration distribution of granule in center of the cross section area was smaller and more uniform, and the concentration of granule was minimum in pipe wall because of the effect of centrifugal force and circumferential velocity acting granules.

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