Emerging Roles of Meis1 in Cardiac Regeneration, Stem Cells, and Cancer.

Background: Meis1 is a member of three-amino-acid loop extension (TALE) homeodomain transcription factors. Studies in the last decade have shown that Meis1 has crucial roles in cardiac regeneration, stem cell function, and tumorigenesis. Objective: We have recently demonstrated that knocking out of Meis1 in adult cardiomyocytes resulted in the induction of cardiomyocyte proliferation. This suggests that targeting of Meis1 might be utilized in the manipulation of cardiomyocyte cell cycle post cardiac injuries. In addition, hematopoietic stem cell (HSC) specific deletion of Meis1 leads to in vivo expansion of HSCs pool. Thus, targeting Meis1 may lead to not only cell cycle entry but also ex vivo and in vivo expansion of HSCs. On the other hand, Meis1 transcriptionally regulates the expression of hypoxic tumor markers, namely Hif-1 alpha and Hif-2 alpha. Hif-1 alpha and Hif-2 alpha are involved in the induction of cytoplasmic glycolysis and scavenging of reactive oxygen species (ROS), respectively. Conclusion: Studies highlight emerging roles of Meis1 towards development of new therapeutic approaches in the treatment of myocardial injuries, bone failure, and cancer.