Intron retention as a new pre-symptomatic marker of aging and its recovery to the normal state by a traditional Japanese multi-herbal medicine.

Intron retention (IR) is an important regulatory mechanism that affects gene expression and protein functions. Using klotho mice at the pre-symptomatic state, we discovered that retained-introns accumulated in several organs including the liver and that among these retained introns in the liver a subset was recovered to the normal state by a Japanese traditional herbal medicine. This is the first report of IR recovery by a medicine. IR-recovered genes fell into two categories: those involved in liver-specific metabolism and in splicing. Metabolome analysis of the liver showed that the klotho mice were under starvation stress. In addition, our differentially expressed gene analysis showed that liver metabolism was actually recovered by the herbal medicine at the transcriptional level. By analogy with the widespread accumulation of intron-retained pre-mRNAs induced by heat shock stress, we propose a model in which retained-introns in klotho mice were induced by an aging stress and in which this medicine-related IR recovery is indicative of the actual recovery of liver-specific metabolic function to the healthy state. Accumulation of retained-introns was also observed at the pre-symptomatic state of aging in wild-type mice and may be an excellent marker for this state in general.