Age matters: Grading granule secretion in beta cells

Insulin is stored in secretory granules to facilitate rapid release in response to rising glucose levels, but the mechanisms by which these granules are identified and prioritized for secretion remains unclear. Using a fluorescent timer and flow cytometry–assisted organelle sorting, Yau et al. develop an elegant approach to assess insulin secretion as a function of granule age in pancreatic islet beta cells. Their findings supply quantitative evidence supporting the age-dependent release of different granule pools and confirm earlier models of preferential release of younger granules.

Download Full-text

Quantitative morphometric studies of pancreatic islets obtained from tolbutamide-treated rats.

Journal of Histochemistry & Cytochemistry ◽

10.1177/34.9.3525667 ◽

1986 ◽

Vol 34 (9) ◽

pp. 1195-1200 ◽

Cited By ~ 4

Author(s):

D E Yorde ◽

R K Kalkhoff

Keyword(s):

Pancreatic Islets ◽

Beta Cells ◽

Secretory Granules ◽

Total Cell ◽

Islet Beta Cells ◽

Physiological Conditions ◽

Pancreatic Islet Beta Cells ◽

Granule Density ◽

Treatment Data ◽

Computerized System

We have developed a computerized system for quantitative morphometric analysis of the number and position of secretory granules and organelles in pancreatic islet beta cells following tolbutamide treatment. Data from animals injected with tolbutamide for 1, 2, and 3 days were compared to tissues obtained from untreated control animals. Pancreatic islets removed by a collagenase technique were perfused with an appropriate medium to restore a basal state. After fixation and embedding, thick sections of beta cells were viewed by electron microscopy. Morphometric studies of randomly selected or serially cut cells were performed with computer programs for digitization, quantify, rotational, and perspective display. Tolbutamide treatment resulted in graded granule depletion which was maximal at 72 hr relative to control animals. Reduced granule density was associated with significant reduction in total cell area or cytoplasmic area, but was without effect on nuclear size. Since granule depletion improved visualization of subcellular structures, this will enable us to pursue studies of exocytosis under a variety of physiological conditions.

Download Full-text

Purification of age-distinct insulin secretory granules through antigen restriction using the CLIP-tag

10.1101/2020.06.03.103770 ◽

2020 ◽

Author(s):

Martin Neukam ◽

Katharina Ganß ◽

Jovana Vasiljević ◽

Johannes Broichhagen ◽

Kai Johnsson ◽

...

Keyword(s):

Plasma Membrane ◽

Insulin Secretion ◽

Beta Cells ◽

Solid Phase ◽

Secretory Granules ◽

Islet Beta Cells ◽

Temporal Variables ◽

Pancreatic Islet Beta Cells ◽

Insulin Granules ◽

Insulin Granule

AbstractPancreatic islet beta cells employ secretory granules for the storage and glucose-stimulated release of the hormone insulin. The competence of an insulin granule for exocytosis depends on spatial and temporal variables such as its proximity to the plasma membrane as well as its age, with newly-generated granules being preferentially released. The molecular underpinnings for the control of these variables remain largely unknown and their uncovering is of high relevance for the study of diabetes, which results from deficient insulin secretion. However, we still lack a comprehensive view about the molecular composition of the insulin granules and how this may change over their lifetime. Here we report a strategy for the background-free purification of insulin secretory granules of distinct age from insulinoma INS-1 cells. We show that utilization of an immuno-based affinity approach for pulse-chase labeled insulin secretory granules, produces a highly enriched granular fraction. Our approach precludes typical contaminants from the solid phase and may be designed to purify secretory granules of a distinct age.

Download Full-text

Faculty Opinions recommendation of Inhibition of Foxo1 protects pancreatic islet beta-cells against fatty acid and endoplasmic reticulum stress-induced apoptosis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1108809.564937 ◽

2008 ◽

Author(s):

Raghavendra Mirmira

Keyword(s):

Endoplasmic Reticulum ◽

Fatty Acid ◽

Endoplasmic Reticulum Stress ◽

Beta Cells ◽

Pancreatic Islet ◽

Islet Beta Cells ◽

Pancreatic Islet Beta Cells ◽

Induced Apoptosis

Download Full-text

Epigenetic Memory and Preferential Lineage-Specific Differentiation in Induced Pluripotent Stem Cells Derived from Human Pancreatic Islet Beta Cells

Cell Stem Cell ◽

10.1016/j.stem.2012.11.007 ◽

2012 ◽

Vol 11 (6) ◽

pp. 854

Author(s):

Ori Bar-Nur ◽

Holger A. Russ ◽

Shimon Efrat ◽

Nissim Benvenisty

Keyword(s):

Stem Cells ◽

Induced Pluripotent Stem Cells ◽

Beta Cells ◽

Pancreatic Islet ◽

Pluripotent Stem Cells ◽

Epigenetic Memory ◽

Islet Beta Cells ◽

Human Pancreatic Islet ◽

Pancreatic Islet Beta Cells ◽

Induced Pluripotent

Download Full-text

Selective expression of an arachidonate 12-lipoxygenase by pancreatic islet beta-cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1992.263.5.e828 ◽

1992 ◽

Vol 263 (5) ◽

pp. E828-E836 ◽

Cited By ~ 3

Author(s):

V. R. Shannon ◽

S. Ramanadham ◽

J. Turk ◽

M. J. Holtzman

Keyword(s):

Beta Cell ◽

Enzymatic Activity ◽

Beta Cells ◽

Pancreatic Islet ◽

Cell Populations ◽

Intense Staining ◽

Rat Pancreas ◽

Islet Beta Cells ◽

Pancreatic Islet Beta Cells ◽

12 Lipoxygenase

The immunohistochemical distribution of arachidonate lipoxygenases in rat pancreas was characterized with specific polyclonal anti-5-lipoxygenase and anti-12-lipoxygenase antibodies. Immunohistochemical analysis of formaldehyde-fixed paraffin-embedded rat pancreas using anti-12-lipoxygenase antibody and biotin-avidin-peroxidase detection demonstrated specific staining of islets and no staining of pancreatic exocrine tissue. Less intense staining of pancreatic vascular myocytes and endothelial cells was also observed. Immunoblotting of isolated pancreatic islet extracts with the anti-12-lipoxygenase antibody demonstrated immunoperoxidase staining of a single protein band which comigrated with purified 12-lipoxygenase (relative molecular weight = 72,000) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Dispersed cells prepared from isolated islets and then subjected to fluorescence-activated cell sorting and immunostaining exhibited 12-lipoxygenase antigen in beta-cell populations but not in non-beta-cell (predominantly alpha-cell) populations. Assays of enzymatic activity confirmed that the 12-lipoxygenase-catalyzed conversion of arachidonic acid to 12-hydroxyeicosatetraenoic acid methyl ester occurred only with purified beta-cells and not with islet non-beta-cells. No evidence of 5-lipoxygenase antigen or enzymatic activity was found in purified beta-cells or in islet non-beta-cells. We conclude that rat pancreatic islet beta-cells contain an arachidonate 12-lipoxygenase which shares antigenic epitopes with the homologous enzyme contained in tissues from other species. In addition, the selective localization of the 12-lipoxygenase to pancreatic beta-cells and its absence in pancreatic acinar cells and in islet non-beta-cells support observations suggesting that 12-lipoxygenase products may participate in glucose-induced insulin secretion from beta-cells.

Download Full-text