ABSTRACT
Two different isoforms of the adenine nucleotide translocase (ANT1 and ANT2) have been identified in the rat. In order to obtain enhanced knowledge of the ANT isoform expression, we analyzed the transcription pattern of both isoforms and their mRNA levels in various tissues of the rat using the PCR technique. A predominant ANT1 mRNA percentage was recorded in the skeletal muscle, heart and brain, ranging from 81 to 58%. In contrast to these tissues, the percentages of ANT2 were dominant with a range from 59 to 75% in the kidney, lung, spleen and liver. The level of total ANT mRNA varied markedly in the various organs. Tissues with a dominant ANT1 percentage simultaneously showed a high level of total ANT transcription (24-41 attomol/ng total RNA). In comparison to the latter, tissues with a prevalent ANT2 transcription were shown to have an even lower ANT transcription level (2-5 attomol/ng total RNA). The predominance of the ANT1 expression appeared to be restricted to tissues with an inability to regenerate by means of mitotic division, whereas a prevalent ANT2 transcription is found in cell types able to proliferate. The level of total ANT transcription but not the individual ANT isoform expression depends to a great extent on the energy requirements of the tissue.
Subject(s)
Mitochondrial ADP, ATP Translocases/genetics , Animals , Brain/metabolism , DNA, Complementary/analysis , Kidney/metabolism , Liver/metabolism , Lung/metabolism , Male , Muscle, Skeletal/metabolism , Myocardium/metabolism , Polymerase Chain Reaction , Protein Isoforms/genetics , RNA, Messenger/analysis , Rats , Rats, Inbred WKY , Spleen/metabolism , Transcription, GeneticABSTRACT
Three adenine nucleotide translocase isoforms (ANT1, ANT2 and ANT3) are coded by different genes. The relative amounts of the three ANT isoform mRNAs were determined in detail in various human tissues. ANT isoforms were co-expressed in all tested tissues revealing tissue-specific transcription patterns. The highest ANT1 mRNA proportions were found in terminally differentiated tissues like skeletal muscle, heart and brain, whereas ANT2 was mainly expressed in tissues capable of proliferation and regeneration as in the kidneys, spleen, liver, fibroblasts and lymphocytes. The ANT3 mRNA proportion was not prominently expressed in any of the tissues tested. In conclusion, tissue-specific expression of ANT isoforms is strongly related to the state of cellular differentiation.
