Abstract 13222: Hax1 Overexpression Promotes Sca1+ Cardiac Stem Cell Proliferation and Protects Against Hypoxia-induced Apoptosis
Background: HCLS-associated protein X-1 (HAX1) has been reported to regulate cell proliferation and improve cell survival. Here, we investigate whether HAX1 overexpression can promote the capacity for self-renewal and elicit anti-apoptotic effects on sca1+ cardiac stem cells (CSCssca1+).
Methods and Results: CSCssca1+ were isolated from mouse hearts and sorted by flow cytometry. The murine HAX1-encoding gene was constructed into a lentivirus (Lenti-HAX1), and then transduced into CSCssca1+. Lentivirus containing non-encoding DNA sequence (Lenti-Null) served as the control. HAX1 expression level increased by 2.3-fold in the Lenti-HAX1 group, without changing CSCssca1+ characteristics (Fig.1A). Flow cytometry cell cycle analysis revealed that the proportion of cells in S-phase was increased by nearly 6 fold in Lenti-HAX1 CSCssca1+ (46%) than in the Lenti-Null group (8%) (Fig. 1B), which was attributed to retinoblastoma protein hyperphosphorylation (Fig. 1C). The number of 5-bromo-2-deoxyuridine (BrdU)-labeled nuclei was also augmented in Lenti-HAX1 CSCssca1+, supporting the hypothesis that HAX1 overexpression can promote CSCssca1+ proliferation (Fig. 1C). In response to a 72-hour hypoxia challenge, more HAX1 overexpressing CSCssca1+ survived as confirmed by the decreased number of apoptotic cells as compared to Lenti-Null group (Fig. 1D). Importantly, following hypoxia, HAX1 overexpression promoted the expression of HIF-1α by 1.22 fold at 24 hour (Fig. 1E).
Conclusion: HAX1 overexpression can improve CSCssca1+ proliferation by promoting entry into synthetic phase and enhance HIF-1α expression level to protect cells against hypoxia-induced apoptosis.
Author Disclosures: W. Cai: None. W. Huang: None. S. Kim: None. J. Liang: None. R. Ma: None. H. Kondo: None. H. Kim: None. M. Xu: None. R.W. Millard: None. Y. Wang: None.
- © 2014 by American Heart Association, Inc.