PT  - JOURNAL ARTICLE
AU  - Robert W. Robey
AU  - Andrea N. Robinson
AU  - Fatima Ali-Rahmani
AU  - Lyn M. Huff
AU  - Sabrina Lusvarghi
AU  - Shahrooz Vahedi
AU  - Jordan Hotz
AU  - Andrew C. Warner
AU  - Donna Butcher
AU  - Jennifer Matta
AU  - Elijah F. Edmondson
AU  - Tobie D. Lee
AU  - Jacob S. Roth
AU  - Olivia W. Lee
AU  - Min Shen
AU  - Kandice Tanner
AU  - Matthew D. Hall
AU  - Suresh V. Ambudkar
AU  - Michael M. Gottesman
TI  - Characterization and tissue localization of zebrafish homologs of the human <em>ABCB1</em> multidrug transporter
AID  - 10.1101/2021.02.18.431829
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.02.18.431829
4099  - http://biorxiv.org/content/early/2021/02/18/2021.02.18.431829.short
4100  - http://biorxiv.org/content/early/2021/02/18/2021.02.18.431829.full
AB  - Given its similarities with mammalian systems, the zebrafish has emerged as a potential model to study the blood-brain barrier (BBB). Capillary endothelial cells at the human BBB express high levels of P-glycoprotein (P-gp, encoded by the ABCB1 gene) and ABCG2 (encoded by the ABCG2 gene). However, little information has been available about ATP-binding cassette transporters expressed at the zebrafish BBB. In this study, we focus on the characterization and tissue localization of two genes that are similar to human ABCB1, zebrafish abcb4 and abcb5. Cytotoxicity assays with stably-transfected cell lines revealed that zebrafish Abcb5 cannot efficiently transport the substrates doxorubicin and mitoxantrone compared to human P-gp and zebrafish Abcb4. Additionally, zebrafish Abcb5 did not transport the fluorescent probes BODIPY-ethylenediamine or LDS 751, while they were readily transported by Abcb4 and P-gp. A high-throughput screen conducted with 90 human P-gp substrates confirmed that zebrafish Abcb4 has overlapping substrate specificity with P-gp. Basal ATPase activity of zebrafish Abcb4 and Abcb5 was comparable to that of human P-gp. In the brain vasculature, RNAscope probes to detect abcb4 colocalized with staining by the P-gp antibody C219, while abcb5 was not detected. Zebrafish abcb4 also colocalized with claudin-5 expression in brain endothelial cells. Abcb4 and Abcb5 had different tissue localizations in multiple zebrafish tissues, consistent with different functions. The data suggest that zebrafish Abcb4 most closely phenocopies P-gp and that the zebrafish may be a viable model to study the role of the multidrug transporter P-gp at the BBB.Competing Interest StatementThe authors have declared no competing interest.