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LKB1 regulates pancreatic beta cell size, polarity, and function
Zvi Granot1, Avital Swisa, Judith Magenheim
1Department of Developmental Biology and Cancer Research and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
Cell Metabolism
|October 8, 2009
Summary
Liver kinase B1 (LKB1) regulates pancreatic beta cell function. LKB1 deficiency dramatically increases insulin secretion and beta cell size by affecting distinct molecular targets.
Area of Science:
- Cell Biology
- Endocrinology
- Metabolism
Background:
- Pancreatic beta cells regulate blood glucose by sensing glucose and secreting insulin.
- Liver kinase B1 (LKB1) is a key kinase involved in cell polarity and energy metabolism.
- The role of LKB1 in adult beta cell function remains largely uncharacterized.
Purpose of the Study:
- To investigate the function of LKB1 in adult pancreatic beta cells.
- To elucidate the molecular mechanisms by which LKB1 controls beta cell size, polarity, and insulin secretion.
Main Methods:
- Generation of LKB1-deficient beta cells in vivo.
- Histological analysis of beta cell morphology and localization.
- Assessment of insulin secretion and content.
- Investigation of LKB1 signaling pathways, including mTOR, Par1b, and AMPK.
Main Results:
- LKB1-deficient beta cells exhibit a significant increase in insulin secretion and a 65% increase in cell volume.
- Loss of LKB1 leads to altered localization of the nucleus and cilia, indicating a shift in cell polarity.
- LKB1 controls beta cell size via the mTOR pathway and nuclear position via Par1b.
- Insulin secretion and content are regulated by LKB1, partly through AMPK.
Conclusions:
- LKB1 plays a crucial role in maintaining the coordinated regulation of beta cell size, form, and function.
- Distinct LKB1 targets mediate its effects on beta cell size, polarity, and insulin secretion.
- These findings reveal a molecular framework orchestrated by LKB1 for beta cell homeostasis.
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