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Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
09:17

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions

Published on: August 2, 2018

Characterization of carbonic anhydrase IX interactome reveals proteins assisting its nuclear localization in hypoxic

Pasquale Buanne1, Giovanni Renzone, Francesca Monteleone

  • 1CEINGE Biotecnologie Avanzate SCaRL, Naples, Italy.

Journal of Proteome Research
|November 28, 2012
PubMed

Insights

This study reveals that carbonic anhydrase IX (CA IX), a protein crucial for tumor survival, interacts with nuclear transport machinery. These interactions suggest novel intracellular roles for CA IX beyond its cell surface functions.

Area of Science:

  • Molecular and Cellular Biology
  • Oncology
  • Biochemistry

Background:

  • Carbonic anhydrase IX (CA IX) is a transmembrane protein involved in pH regulation, cell migration, invasion, and survival, particularly in hypoxic tumors.
  • The molecular mechanisms and protein interactions governing CA IX functions are not fully understood, especially regarding its potential intracellular roles.

Purpose of the Study:

  • To characterize the protein interactome of carbonic anhydrase IX (CA IX) in hypoxic conditions.
  • To identify novel molecular partners of CA IX and elucidate their functional implications.

Main Methods:

  • Proteomic analysis of CA IX interactome in hypoxic HEK-293 cells.
  • Co-immunoprecipitation assays to confirm interactions with specific proteins (XPO1, TNPO1, CAND1).
  • Assessment of CA IX localization in cells and tissues using immunofluorescence and tissue analysis.

Main Results:

  • Identified numerous CA IX-binding partners, predominantly involved in nuclear transport and containing HEAT/ARM repeat domains.
  • Confirmed interactions of CA IX with XPO1 exportin and TNPO1 importin via its C-terminal region, enhanced by phosphorylation.
  • Demonstrated nuclear localization of CA IX in hypoxic cells and renal cell carcinoma tissues, and its interaction with CAND1, affecting CA IX protein stability.

Conclusions:

  • CA IX interacts with proteins involved in nuclear transport, gene transcription, and protein stability, suggesting novel intracellular functions.
  • Nuclear CA IX subpopulations may play roles distinct from its established cell-surface functions in cancer.
  • These findings expand our understanding of CA IX signaling pathways and its multifaceted roles in tumor biology.

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