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Related Concept Videos

Insulin Secretory Vesicles01:05

Insulin Secretory Vesicles

Insulin secretory vesicles release insulin to stimulate blood glucose uptake and regulate carbohydrate metabolism. When the blood glucose levels increase, glucose enters the pancreatic β-islet cells through glucose transporters. Once inside, glucose is metabolized through glycolysis, the citric acid cycle, and the electron transport chain, producing ATP. This increase in ATP concentration closes ATP-sensitive potassium channels, leading to depolarization of the membrane and the opening of...
Overview of Secretory Vesicles01:33

Overview of Secretory Vesicles

Secretory vesicles, also known as dense core vesicles (DCVs), are membrane-bound vesicles that transport secretory proteins, such as hormones or neurotransmitters. Regulated secretory vesicles transport proteins from the trans-Golgi network to the exterior of the cell. Proteins present in regulated secretory vesicles are required to be rapidly exocytosed in large amounts upon a specific stimulus.
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Glucose Homeostasis: Pancreatic Islets and Insulin Secretion01:27

Glucose Homeostasis: Pancreatic Islets and Insulin Secretion

The pancreatic islets comprising only 1%-2% of the volume are highly vascularized and innervated mini-organs. They contain five endocrine cell types, including β cells that secrete insulin, which is synthesized as a single polypeptide chain, preproinsulin, processed to proinsulin, and finally to insulin and C-peptide. This process is complex and regulated, involving the Golgi complex, the endoplasmic reticulum, and the secretory granules of the β cell.
Insulin and C-peptide are co-secreted in...
Production of Pharmaceuticals01:30

Production of Pharmaceuticals

Industrial insulin production uses genetically engineered E. coli expressing a proinsulin gene controlled by a tryptophan promoter and containing a methionine linker for later cleavage. The cells also carry ampicillin resistance for selective growth. Seed cultures are stored at −80 °C and production begins by thawing a small amount to inoculate starter cultures, which are progressively scaled to a 50,000-L bioreactor. In the bioreactor, E. coli grow in nutrient-rich media under sterile, tightly...
Insulin: Biosynthesis, Chemistry, and Preparation01:25

Insulin: Biosynthesis, Chemistry, and Preparation

The endoplasmic reticulum (ER) of pancreatic β-cells synthesizes preproinsulin, which consists of a signal peptide, A and B chains, and a C-peptide. Preproinsulin is then cleaved and folded into proinsulin, which translocates to the Golgi apparatus for sorting and packaging into secretory granules. In these granules, enzymatic clipping generates insulin and C-peptide.
Damage or functional impairment of β-cells inhibits insulin production, leading to diabetes. Diabetes treatment primarily uses...
Intralumenal Vesicles and Multivesicular Bodies01:38

Intralumenal Vesicles and Multivesicular Bodies

Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...

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Related Experiment Video

Updated: Jul 16, 2026

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles
08:04

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles

Published on: November 3, 2023

Human insulin vesicle dynamics during pulsatile secretion.

Darren J Michael1, Wenyong Xiong, Xuehui Geng

  • 1Department of Physiology and Biophysics, Keck School of Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90089, USA.

Diabetes
|February 24, 2007
PubMed
Summary

Human pancreatic beta-cells secrete insulin in rhythmic bursts, not randomly. Young insulin vesicles are preferentially released first, followed by older vesicles during glucose stimulation.

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Measuring Relative Insulin Secretion using a Co-Secreted Luciferase Surrogate
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Measuring Relative Insulin Secretion using a Co-Secreted Luciferase Surrogate

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Glucose-Stimulated Insulin Secretion via Perfusion through the Mice Vasculature with an Intact Pancreas
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Glucose-Stimulated Insulin Secretion via Perfusion through the Mice Vasculature with an Intact Pancreas

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Related Experiment Videos

Last Updated: Jul 16, 2026

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles
08:04

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles

Published on: November 3, 2023

Measuring Relative Insulin Secretion using a Co-Secreted Luciferase Surrogate
05:58

Measuring Relative Insulin Secretion using a Co-Secreted Luciferase Surrogate

Published on: June 25, 2019

Glucose-Stimulated Insulin Secretion via Perfusion through the Mice Vasculature with an Intact Pancreas
04:41

Glucose-Stimulated Insulin Secretion via Perfusion through the Mice Vasculature with an Intact Pancreas

Published on: July 25, 2025

Area of Science:

  • Endocrinology
  • Cell Biology
  • Metabolic Regulation

Background:

  • Plasma insulin levels oscillate in healthy individuals during fasting and fed states.
  • Previous studies suggested insulin oscillations stem from pancreatic islet secretion patterns, but individual beta-cell secretion dynamics remained unobserved.
  • The precise mechanism of insulin secretion oscillation at the single-cell level requires elucidation.

Purpose of the Study:

  • To investigate the temporal dynamics of insulin secretion from individual human pancreatic beta-cells.
  • To determine if insulin secretion occurs in a regulated, non-random pattern.
  • To explore the dynamics of insulin vesicle release and recruitment during glucose stimulation.

Main Methods:

  • Utilized expressed fluorescent vesicle cargo proteins and total internal reflection fluorescence (TIRF) microscopy to visualize insulin vesicle secretion.
  • Applied randomization tests and spectral analysis to assess the temporal patterns of secretion.
  • Performed simultaneous membrane capacitance measurements and TIRF imaging during controlled depolarization to study vesicle dynamics.

Main Results:

  • Demonstrated that glucose stimulates human pancreatic beta-cells to secrete insulin in coordinated bursts of approximately 70 vesicles.
  • Confirmed non-random temporal patterns of secretion with statistically significant periods of 15-45 seconds, indicating alternating secretion and rest phases.
  • Observed that young fluorescent insulin vesicles were preferentially secreted first, followed by older vesicles in subsequent stimulation phases, despite total secretion remaining constant.

Conclusions:

  • Insulin secretion in human pancreatic beta-cells is an oscillatory process occurring in discrete, non-random bursts.
  • Younger insulin vesicles are preferentially secreted before older vesicles during glucose-stimulated insulin release.
  • These findings provide novel insights into the regulation of insulin secretion at the single-cell level, relevant for understanding metabolic control.