Mechanism of Actin Polymerization in Cellular ATP Depletion

Simon J. Atkinson, Melanie A. Hosford, Bruce Molitoris

Research output: Contribution to journalArticle

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Abstract

Cellular ATP depletion in diverse cell types results in the net conversion of monomeric G-actin to polymeric F-actin and is an important aspect of cellular injury in tissue ischemia. We propose that this conversion results from altering the ratio of ATP-G-actin and ADP-G-actin, causing a net decrease in the concentration of thymosinactin complexes as a consequence of the differential affinity of thymosin β4 for ATP- and ADP-G-actin. To test this hypothesis we examined the effect of ATP depletion induced by antimycin A and substrate depletion on actin polymerization, the nucleotide state of the monomer pool, and the association of actin monomers with thymosin and profilin in the kidney epithelial cell line LLC-PK1. ATP depletion for 30 min increased F-actin content to 145% of the levels under physiological conditions, accompanied by a corresponding decrease in G-actin content. Cytochalasin D treatment did not reduce F-actin formation during ATP depletion, indicating that it was predominantly not because of barbed end monomer addition. ATP-G-actin levels decreased rapidly during depletion, but there was no change in the concentration of ADP-G-actin monomers. The decrease in ATP-G-actin levels could be accounted for by dissociation of the thymosin-G-actin binary complex, resulting in a rise in the concentration of free thymosin β4 from 4 to 11 μM. Increased detection of profilin-actin complexes during depletion indicated that profilin may participate in catalyzing nucleotide exchange during depletion. This mechanism provides a biochemical basis for the accumulation of F-actin aggregates in ischemic cells.

Original languageEnglish
Pages (from-to)5194-5199
Number of pages6
JournalJournal of Biological Chemistry
Volume279
Issue number7
DOIs
StatePublished - Feb 13 2004

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Polymerization
Actins
Adenosine Triphosphate
Thymosin
Profilins
Monomers
Nucleotides
Antimycin A
Cytochalasin D
Ischemia
Epithelial Cells
Association reactions
Tissue
Kidney
Cell Line
ATP-G-actin
Wounds and Injuries
Substrates

ASJC Scopus subject areas

  • Biochemistry

Cite this

Mechanism of Actin Polymerization in Cellular ATP Depletion. / Atkinson, Simon J.; Hosford, Melanie A.; Molitoris, Bruce.

In: Journal of Biological Chemistry, Vol. 279, No. 7, 13.02.2004, p. 5194-5199.

Research output: Contribution to journalArticle

Atkinson, Simon J. ; Hosford, Melanie A. ; Molitoris, Bruce. / Mechanism of Actin Polymerization in Cellular ATP Depletion. In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 7. pp. 5194-5199.
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