A novel nested gene Aff3ir participates in vascular remodelling by enhancing endothelial cell differentiation in mice

Zhao, Y.; Ehteramyan, M.; Li, Y.; Bai, X.; Huang, L.; Gao, Y.; Angbohang, A.; Yang, X.; Lynham, S.; Margariti, A.; Shah, A.; Tao, Y.; Cai, T.; Li, T.; Zhang, M.; Zeng, L.

doi:10.1101/2023.12.09.570916

bioRxiv · 10.1101/2023.12.09.570916

A novel nested gene Aff3ir participates in vascular remodelling by enhancing endothelial cell differentiation in mice

Zhao, Y.·Ehteramyan, M.·Li, Y.·Bai, X.·Huang, L.·Gao, Y.·Angbohang, A.·Yang, X.·Lynham, S.·Margariti, A.·Shah, A.·Tao, Y.·Cai, T.·Li, T.·Zhang, M.·Zeng, L.

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Abstract

Endothelial integrity in the vasculature is critically maintained by vascular stem/progenitor cells (SPCs) giving rise to endothelial cells (ECs). However, the genes significantly activated during differentiation remain incompletely understood. Based on mouse aorta and vein cDNA library, we unearthed a hitherto unidentified gene nested residing within intron 6 of Aff3, christened as Aff3 intron resident (Aff3ir), upregulated during laminar shear stress-induced ECs differentiation in mouse. Proteomic analysis substantiated the presence of a 45-amino acid(aa) peptide (AFF3IR-ORF1) and 109-aa or 151-aa protein (AFF3IR-ORF2) encoded from two transcript variants. During embryonic development, AFF3IR-ORF1 peaked at E14.5, while AFF3IR-ORF2 displayed a continuous increase until E19.5. In adult mice, AFF3IR-ORF1 was detected in the lung, liver, spleen, and kidney, while AFF3IR-ORF2 was most abundant in the aorta. Furthermore, Western blot and immunofluorescence analyses revealed a specific upregulation of AFF3IR-ORF2, but not AFF3IR-ORF1, three days after femoral artery injury or hindlimb ischemia in vivo. Overexpression of AFF3IR-ORF2 enhanced, while its knockdown attenuated, SPCs differentiation into ECs induced by shear stress or vascular endothelial growth factor in vitro. Notably, the upregulated AFF3IR-ORF2 hindered SPCs proliferation by sequestering minichromosome maintenance complex component 3 in the cytoplasm, thereby shifting the status of SPCs from a pro-proliferation to a pro-differentiation state. In conclusion, our discoveries unveil the novel protein-coding gene Aff3ir as a participant in ECs differentiation, providing fresh insights into the regulation of vascular endothelial integrity.

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Zhao, Y., Ehteramyan, M., Li, Y., Bai, X., Huang, L., Gao, Y., Angbohang, A., Yang, X., Lynham, S., Margariti, A., Shah, A., Tao, Y., Cai, T., Li, T., Zhang, M., Zeng, L.. 2023-12-10. A novel nested gene Aff3ir participates in vascular remodelling by enhancing endothelial cell differentiation in mice. https://doi.org/10.1101/2023.12.09.570916

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