Proliferative Regeneration of Zebrafish Lateral Line Hair Cells after Different Ototoxic Insults

Abstract

Sensory hair cells in the zebrafish lateral line regenerate rapidly and completely after damage. Previous studies have used a variety of ototoxins to kill lateral line hair cells to study different phenomena including mechanisms of hair cell death and regeneration. We sought to directly compare these ototoxins to determine if they differentially affected the rate and amount of hair cell replacement. In addition, previous studies have found evidence of proliferative hair cell regeneration in zebrafish, but both proliferation and non-mitotic direct transdifferentiation have been observed during hair cell regeneration in the sensory epithelia of birds and amphibians. We sought to test whether a similar combination of regenerative mechanisms exist in the fish. We analyzed the time course of regeneration after treatment with different ototoxic compounds and also labeled dividing hair cell progenitors. Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days. However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla. The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases. Inhibiting proliferation with flubendazole blocked the production of new hair cells and prevented the accumulation of additional precursors, indicating that proliferation has a dominant role during regeneration of lateral line hair cells.

Robust regeneration of adult zebrafish lateral line hair cells reflects continued precursor pool maintenance

“…1B). This rate of recovery is similar to previous reports examining hair cell regeneration and maturation in larval zebrafish (Ma et al, 2008; Mackenzie and Raible, 2012). These results indicate that lateral line hair cell regeneration is not developmentally limited, and that it is maintained in neuromasts of adult zebrafish.…”

Enhanced Cell-Specific Ablation in Zebrafish Using a Triple Mutant of Escherichia Coli Nitroreductase

“…1,2 This approach provides a novel means to investigate the mechanisms shaping how individual stem cell niches detect and respond to selective cell loss. Targeted cell ablation can be accomplished using other methodologies as well, but it typically has been limited to select contexts (e.g., hair cell regeneration 3 ). A key advantage of the NTR system is the ability to target any cell type of interest that can be labeled with standard transgenic techniques.…”

Retinoic Acid Signaling Mediates Hair Cell Regeneration by Repressingp27kip andsox2in Supporting Cells

“…In addition, RA pathway is required in both systems, albeit they show some differences on the activated genes of the RA pathway and the kinetics of hair cell regeneration. In the lateral line, several works indicate that transdifferentiation is negligible (Ló pez-Schier and Hudspeth, 2006;Ma et al, 2008;Mackenzie and Raible, 2012;Romero-Carvajal et al, 2015), but time-lapse imaging of regeneration in the inner ear is needed to elucidate the exact contribution of transdifferentiation events in zebrafish (as it happens in chick) (Adler and Raphael, 1996). Together, our results on RA signaling during regeneration might be useful to further understand the molecular mechanisms underlying nonmammalian vertebrate hair cell regeneration and at longer term could be a potential therapeutic agent for treating hearing loss.…”