Maturational Changes in Gene Expression for Adenine Nucleotide Translocator Isoforms and βF1-ATPase in Rabbit Heart

Abstract

Maturational changes in myocardial respiratory control have been related to postnatal accumulation of adenine nucleotide translocator (ANT) in the inner mitochondrial membrane. Alternatively alterations in relative isoform distribution for this nuclear-encoded gene during myocardial maturation might be responsible for changing the kinetics of respiratory control. Rabbit hearts were analyzed for adenine nucleotide translocator isoform (ANT1, ANT2, ANT3) gene expression and distribution at four ages (fetal, 29/31 days of gestation; 1 h postnatal; 9 days postnatal; and 3–4 months postnatal). Transcript levels for the coordinately expressed βF1-ATPase were also examined in these hearts. These studies demonstrated that mRNA expression for ANT1 in coordination with βF1-ATPase increased substantially after 9 days of age in rabbit hearts. Expression of the minor isoform ANT3 parallels ANT1, though no change in expression of the kidney-specific isoform ANT2 occurs in heart during this developmental period. Previous work has demonstrated that ANT protein accumulation is closely coordinated with mRNA expression for ANT1. These results support previous studies, which indicate that the operational mode of myocardial respiratory control depends on adenine nucleotide mRNA expression. Changes in relative adenine nucleotide translocator isoform distribution do occur during fetal to mature transition and may contribute to observed changes in the mode of respiratory control.