EN
au is a microtubule-associated protein important for the assembly and stabilization of microtubules. Six tau isoforms are produced in the central nervous system from one single gene as a result of the alternative splicing of exons 2, 3 (N-terminal part) and exon 10 (C-terminal part). The shortest isoform (2-3-10-, 0N 3R) is characteristic for fetal brains, whereas the remaining (2+3-10-, 1N 3R; 2+3+10-, 2N 3R; 2-3-10+, 0N 4R; 2+3-10+, 1N 4R; 2+3+10+, 2N 4R) for adult brains. The aim of the study was to establish a profile of tau protein variants in the C57BL/6J mouse frontal cortex during the aging process. The total RNA was isolated from tissues, followed by reverse transcription and PCR reaction. It was found that the sequence encoded by exon 10 was absent in the youngest 5-day old newborns (isoform 3R), while it was present in 21, 70 and 140-day old animals (isoform 4R). The most abundant isoform in 5-day old mice was 1N and accounted for 66% of the total tau protein. The percentage of 1N isoforms lowered with age and was 31% in 140-day old animals. The total percentage of 0N isoforms was 11% in 5-day old mice and was approximately threefold lower than in each of the older groups. It may be concluded that alternative splicing of the tau protein undergoes age-dependent regulation in the mouse brain cortex.