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Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
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WNK1 and OSR1 regulate the Na+, K+, 2Cl- cotransporter in HeLa cells

Anthony N Anselmo1, Svetlana Earnest, Wei Chen

  • 1Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

Proceedings of the National Academy of Sciences of the United States of America
|July 13, 2006
PubMed

Insights

Protein kinase WNK1 regulates oxidative stress-responsive kinase (OSR1) and sterile20-related, proline-, alanine-rich kinase (SPAK) activity. Both WNK1 and OSR1 are essential for sodium, potassium, two chloride cotransporter (NKCC) function, impacting cell volume and blood pressure.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Physiology

Background:

  • Oxidative stress-responsive kinase (OSR) 1 and sterile20-related, proline-, alanine-rich kinase (SPAK) are protein kinases that interact with the sodium, potassium, two chloride cotransporter (NKCC).
  • The upstream regulators of OSR1, SPAK, and NKCC remain incompletely understood, particularly in the context of cellular homeostasis.

Purpose of the Study:

  • To investigate the role of the serine/threonine kinase WNK1 (with no lysine [K]) in regulating OSR1, SPAK, and NKCC.
  • To elucidate the pathway connecting WNK1, OSR1, and NKCC in cellular processes.

Main Methods:

  • Cellular co-immunoprecipitation to assess protein complex formation between WNK1 and OSR1.
  • In vitro kinase assays using recombinant WNK1 to determine its effect on OSR1 activity.
  • Small interfering RNA (siRNA) mediated depletion of WNK1 and OSR1 in HeLa cells.
  • Measurement of NKCC activity following WNK1 or OSR1 depletion.

Main Results:

  • WNK1 forms a complex with OSR1 in cells and activates OSR1 kinase activity in vitro.
  • WNK1-dependent phosphorylation of OSR1 was observed in cellular systems.
  • Depletion of WNK1 led to reduced OSR1 kinase activity.
  • Depletion of either WNK1 or OSR1 significantly reduced NKCC activity.

Conclusions:

  • WNK1 is a key regulator of OSR1, SPAK, and NKCC.
  • OSR1 acts as a crucial intermediary linking WNK1 to NKCC function.
  • The WNK1-OSR1-SPAK-NKCC pathway is vital for mammalian volume regulation and blood pressure homeostasis.

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