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Updated: Aug 16, 2026
08:46
Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium
Published on: September 1, 2015
PKD2 functions as an epidermal growth factor-activated plasma membrane channel
Rong Ma1, Wei-Ping Li, Dana Rundle
1Department of Cell Biology, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Boulevard, Oklahoma City, OK 73104, USA.
Molecular and Cellular Biology
|September 2, 2005
Summary
Polycystin 2 (PKD2) channel activation by epidermal growth factor (EGF) is negatively regulated by phosphatidylinositol-4,5-bisphosphate (PIP2). EGF signaling releases PKD2 from PIP2 inhibition, impacting kidney epithelial cell function.
Area of Science:
- Molecular Biology
- Cell Physiology
- Renal Pathophysiology
Background:
- Polycystin 2 (PKD2) is a cation channel linked to autosomal dominant polycystic kidney disease.
- The precise mechanism regulating PKD2 channel activation remains largely unknown.
- PKD2 functions as a nonselective cation channel in the plasma membrane.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying PKD2 activation.
- To investigate the role of epidermal growth factor (EGF) in PKD2 channel regulation.
- To identify key signaling pathways and lipids involved in PKD2 activation.
Main Methods:
- Overexpression and knockdown (RNA interference) of PKD2 in LLC-PK(1) kidney epithelial cells.
- Electrophysiological recordings to measure EGF-induced currents.
- Pharmacological inhibition of phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K).
- Lipid manipulation via pipette infusion of phosphatidylinositol-4,5-bisphosphate (PIP2) and phosphatidylinositol-3,4,5-trisphosphate (PIP3).
- Biochemical assays (co-immunoprecipitation) to assess protein interactions.
- Confocal microscopy to determine subcellular localization.
Main Results:
- EGF stimulation significantly increased PKD2-mediated inward currents in kidney epithelial cells.
- PKD2 knockdown or expression of a pathogenic variant (PKD2-D511V) abolished EGF-induced currents.
- EGF-induced PKD2 activation required PLC and PI3K activity but was independent of store depletion.
- PIP2 infusion suppressed PKD2 activity, while PIP3 had no effect, suggesting negative regulation by PIP2.
- PKD2 was found to interact with PLC-gamma2 and the EGF receptor (EGFR) and colocalize with EGFR and PIP2 in primary cilia.
Conclusions:
- Plasma membrane PKD2 activity is negatively regulated by PIP2.
- EGF signaling likely reduces the threshold for PKD2 activation by releasing it from PIP2-mediated inhibition.
- These findings provide novel insights into PKD2 channel regulation and its potential role in polycystic kidney disease pathogenesis.
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