Improvement of multiple pathophysiological phenotypes of klotho (kl/kl) mice by adenovirus-mediated expression of the klotho gene

Background: We have established a novel mouse mutant, klotho (kl), by insertional mutation of a transgene and identified the structural gene. The mouse homozygous for the mutation exhibits multiple pathological conditions resembling age-related disorders in humans and can be regarded as a model of human premature aging syndromes. However, the pathophysiological role of Klotho protein has not been clarified. Methods: A replication-deficient adenoviral vector expressing the membrane form of the mouse klotho gene was constructed and we examined Klotho expression in vitro. The recombinant adenoviral vector was then administered intravenously into klotho mice at 4-5 weeks of age and its therapeutic potential was examined. Results: Expression of Klotho protein was observed in the adenoviral vector-infected CHO cells. The klotho mice infused with the recombinant adenovirus showed a significant extension of life span and gain in body weight at 1 week after treatment. Macroscopic and histological analyses demonstrated the improvement of multiple pathological findings such as restoration from atrophy and cell formation and differentiation in the gonadal cells, immune tissues and subcutaneous fat. Conclusion: We showed that local expression of the klotho gene retards or partially improves pathological abnormalities in several organs of klotho mice after onset of the phenotypes. Therefore, the recombinant adenovirus vector will provide an important tool for investigating the molecular mechanism of the Klotho protein and give clues to understanding the individual disease mechanisms.