Do connexin 43 gap-junctional hemichannels activate and cause cell damage during ATP depletion of renal-tubule cells?

L. Vergara, Xiaoyong Bao, E. Bello-Reuss, Luis Reuss

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We review our evidence in favour of the hypothesis that gap-junctional hemichannels (GJH) are activated by depletion of adenosine triphosphate (ATP) in human renal proximal tubule cells in primary culture (hPT cells). Undocked GJH permit fluxes of ions and hydrophilic molecules up to 1 kDa, and thus their opening can cause alterations of cell composition conducive to cell damage. We show that hPT cells express connexin 43 (Cx43) (at the mRNA and protein levels) and that the protein is expressed on the plasma membrane. Moderate levels of pharmacological depletion of ATP increased plasma-membrane permeability, as shown by loading with the hydrophilic dye 5/6 carboxyfluorescein (CF, 376 Da) and other low-molecular weight dyes, but not with fluorescein-labelled dextran (>1500 Da). Roles for endocytosis and activation of purinergic-receptor channels were experimentally ruled out. Moderate ATP depletion also caused necrosis, assessed by cell permeabilization to propidium iodide. Prolonged exposure to gadolinium reduced both the dye loading and the necrosis induced by ATP depletion, i.e. it protected the cells. Cx43 overexpressed in insect cells, purified to homogeneity and reconstituted in proteoliposomes formed hemichannels that are activated by dephosphorylation of Ser368, a residue in a protein-kinase-C consensus phosphorylation sequence near the end of the C-terminal domain. Conclusions: (1) ATP depletion of hPT cells induces a Gd 3+-sensitive permeability of the plasma membrane to hydrophilic dyes with a cut-off size consistent with Cx43 GJH. (2) ATP depletion also increases the percentage of necrotic cells, an effect also reduced by Gd3+. (3) The experiments with purified Cx43 reconstituted in liposomes suggest that dephosphorylation of Ser368 is sufficient to activate GJH, although other mechanisms may be involved in some cells.

Original languageEnglish (US)
Pages (from-to)33-38
Number of pages6
JournalActa Physiologica Scandinavica
Volume179
Issue number1
DOIs
StatePublished - Sep 1 2003

Fingerprint

Connexin 43
Adenosine Triphosphate
Kidney
Proximal Kidney Tubule
Primary Cell Culture
Coloring Agents
Cell Membrane
Permeability
Necrosis
Purinergic Receptors
Propidium
Consensus Sequence
Gadolinium
Endocytosis
Liposomes
Protein Kinase C
Insects
Proteins
Molecular Weight
Phosphorylation

Keywords

  • Cell injury
  • Connexin 43
  • Human
  • Hypoxia
  • Ischaemia
  • Kidney

ASJC Scopus subject areas

  • Physiology

Cite this

Do connexin 43 gap-junctional hemichannels activate and cause cell damage during ATP depletion of renal-tubule cells? / Vergara, L.; Bao, Xiaoyong; Bello-Reuss, E.; Reuss, Luis.

In: Acta Physiologica Scandinavica, Vol. 179, No. 1, 01.09.2003, p. 33-38.

Research output: Contribution to journalArticle

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