Insulin is produced by the
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Insulin Production: Key Sources and Mechanisms
Pancreatic Beta Cells: Primary Insulin Producers
The primary source of insulin in the body is the pancreatic beta cells. These cells are located in the islets of Langerhans within the pancreas. Insulin production in beta cells begins with the synthesis of preproinsulin, which is then converted to proinsulin. Proinsulin undergoes further proteolytic processing to produce mature insulin and C-peptide, which are stored in secretory granules and released in response to glucose levels in the blood .
Insulin Production in the Brain: Choroid Plexus and Neurons
Recent research has revealed that insulin is also produced in the brain, specifically by the epithelial cells of the choroid plexus (EChP). This production is regulated by serotonergic signaling rather than glucose. Insulin mRNA and protein, including C-peptide, have been detected in EChP at higher levels than in other brain regions and non-pancreatic tissues. The release of insulin from EChP is modulated by serotonin through the activation of 5HT2C receptors, which leads to intracellular calcium mobilization.
Additionally, a subpopulation of neurons in the cerebral cortex and neural progenitor cells in the hippocampus have been found to synthesize insulin. This locally produced insulin helps regulate synaptic transmission and energy homeostasis within neural networks, providing a rapid response mechanism that supplements the slower supply of insulin from pancreatic beta cells.
Recombinant DNA Technology: Bacterial Production of Insulin
Human insulin can also be produced using recombinant DNA technology. This method involves constructing bacterial strains that carry synthetic genes for the A and B chains of human insulin. These chains are produced as part of a larger precursor protein within the bacterial cells and are later separated and purified to form active insulin. This technique has been successfully used to produce large quantities of human insulin for clinical use.
Insulin Production in Stem Cells
Research has also explored the potential of producing insulin from stem cells. For instance, canine bone marrow-derived mesenchymal stem cells (BMSCs) have been genetically modified to express key transcription factors such as Pdx1, Beta2, and Mafa, which induce the production of insulin. This approach holds promise for developing beta-cell replacement therapies for diabetes.
Conclusion
Insulin is primarily produced by pancreatic beta cells, but recent studies have shown that it is also synthesized in the brain by the choroid plexus and certain neurons. Additionally, recombinant DNA technology and stem cell research offer alternative methods for insulin production, which could have significant implications for diabetes treatment. Understanding these diverse sources and mechanisms of insulin production is crucial for advancing therapeutic strategies for diabetes and other metabolic disorders.
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