Overnutrition induces β-cell differentiation through prolonged activation of β-cells in zebrafish larvae.
- Authors
- Li, M., Maddison, L.A., Page-McCaw, P., and Chen, W.
- ID
- ZDB-PUB-140402-15
- Date
- 2014
- Source
- American journal of physiology. Endocrinology and metabolism 306(7): E799-807 (Journal)
- Registered Authors
- Chen, Wenbiao, Li, Mingyu, Page-McCaw, Patrick
- Keywords
- none
- MeSH Terms
-
- Animals
- Animals, Genetically Modified
- Calcium Channels, L-Type/physiology
- Cell Count
- Cell Differentiation*
- Disease Models, Animal*
- Embryo, Nonmammalian
- Glucokinase/genetics
- Insulin-Secreting Cells/cytology
- Insulin-Secreting Cells/physiology*
- KATP Channels/physiology
- Larva
- Membrane Potentials/physiology
- Overnutrition/metabolism
- Overnutrition/physiopathology*
- Potassium Channels, Inwardly Rectifying/genetics
- Zebrafish*
- PubMed
- 24473439 Full text @ Am. J. Physiol. Endocrinol. Metab.
Insulin from islet β cells maintains glucose homeostasis by stimulating peripheral tissues to remove glucose from circulation. Persistent elevation of insulin demand increases β-cell number through self-replication or neogenesis (differentiation) as part of a compensatory response. However, it is not well understood how a persistent increase of insulin demand is detected. We have previously demonstrated that a persistent increase of insulin demand by overnutrition induces compensatory β-cell differentiation in zebrafish. Here, we use a series of pharmacological and genetic analyses to show that prolonged stimulation of existing β cells is necessary and sufficient for the compensatory response. In the absence of feeding, tonic, but not intermittent, pharmacological activation of β-cell secretion was sufficient to induce β-cell differentiation. Conversely, drugs that block β-cell secretion, including a KATP channel agonist and an L-type Ca2+ channel blocker, suppressed the overnutrition response. Genetic experiments specifically targeting β cells confirm existing β cells as the overnutrition sensor. First, inducible expression of a constitutively active KATP channel in β cells suppressed the overnutrition effect. Second, inducible expression of a dominant-negative KATP mutant induced β-cell differentiation independent of nutrients. Third, sensitizing β-cell metabolism by transgenic expression of a hyperactive GCK potentiated differentiation. Finally, ablation of the existing β cells abolished the differentiation response. Taken together, these data establish that overnutrition induces β-cell differentiation in larval zebrafish through prolonged activation of β cells. These findings demonstrate an essential role for existing β cells in sensing overnutrition and compensating for their own insufficiency by recruiting additional β cells.