Head-down tilt increases rat cardiac muscle eIF-2α phosphorylation

V. Menon, Donald Thomason

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We previously demonstrated that head-down tilt in rats decreases heart polypeptide initiation rate and proposed a mechanism whereby redistribution of the chaperone heat-shock cognate/heat-shock protein-70 (HSC/HSP-70) facilitates the phosphorylation of eukaryotic initiation factor-2α (eIF- 2α). In this study, two-dimensional gel electrophoretic analysis of eIF-2α showed no phosphorylation in control hearts. At 8 h of head-down tilt, there was a 45% increase in total eIF-2α, and 79% was phosphorylated. At 18 h, eIF-2α increased to 142% of control, of which 4% was phosphorylated. This is consistent with the previous study where, at 8 h, there was a 78% increase in polysomal HSC/HSP-70 and a shift in the polysome center-of-mass to lighter polysomes (indicating decreased initiation). After 18 h of suspension, polysomal HSC/HSP-70 levels were 24% relative to control, and the center-of- mass returned toward control. We conclude that the decrease in polypeptide initiation during head-down tilt is mediated by HSC/HSP-70 via phosphorylation eIF-2α.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume269
Issue number3 38-3
StatePublished - 1995

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HSC70 Heat-Shock Proteins
Head-Down Tilt
Phosphorylation
Muscle
Rats
Shock
Myocardium
Hot Temperature
Polyribosomes
Eukaryotic Initiation Factor-2
Peptides
Suspensions
Gels

All Science Journal Classification (ASJC) codes

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

Head-down tilt increases rat cardiac muscle eIF-2α phosphorylation. / Menon, V.; Thomason, Donald.

In: American Journal of Physiology - Cell Physiology, Vol. 269, No. 3 38-3, 1995.

Research output: Contribution to journalArticle

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AB - We previously demonstrated that head-down tilt in rats decreases heart polypeptide initiation rate and proposed a mechanism whereby redistribution of the chaperone heat-shock cognate/heat-shock protein-70 (HSC/HSP-70) facilitates the phosphorylation of eukaryotic initiation factor-2α (eIF- 2α). In this study, two-dimensional gel electrophoretic analysis of eIF-2α showed no phosphorylation in control hearts. At 8 h of head-down tilt, there was a 45% increase in total eIF-2α, and 79% was phosphorylated. At 18 h, eIF-2α increased to 142% of control, of which 4% was phosphorylated. This is consistent with the previous study where, at 8 h, there was a 78% increase in polysomal HSC/HSP-70 and a shift in the polysome center-of-mass to lighter polysomes (indicating decreased initiation). After 18 h of suspension, polysomal HSC/HSP-70 levels were 24% relative to control, and the center-of- mass returned toward control. We conclude that the decrease in polypeptide initiation during head-down tilt is mediated by HSC/HSP-70 via phosphorylation eIF-2α.

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