Characterization of interneuromast cell regrowth in the zebrafish lateral line system
Hearing loss is a potentially debilitating condition that afflicts tens of millions of Americans. The principal cause of hearing loss is the deterioration or destruction of hair cells in the inner ear. Although these delicate cells do not naturally regenerate in the human ear, non-mammalian vertebrates can replace hair cells rapidly and robustly. Despite extensive study the molecular events driving regrowth in such animals—and its absence in mammals—remain poorly understood. We study the process of hair-cell regeneration in a non-mammalian model system, the lateral line of the zebrafish, with the goal of identifying cellular and molecular mechanisms governing hair-cell recovery.
The zebrafish lateral line consists of small hair cell-containing sensory organs known as neuromasts that are connected by a string of elongated interneuromast cells. Although interneuromast cells are capable of producing entirely new neuromasts—complete with hair cells—during development and after partial amputation of the animal’s tail, relatively little is known about the biology of these cells themselves. In previous experiments we have destroyed individual transgenically-labeled interneuromast cells using a laser, creating a gap in the string of interneuromast cells, and have observed that neighboring cells rapidly extend new processes to connect with each other across the gap. We are employing laser ablation and timelapse confocal microscopy to characterize the extension of these new processes. We are also interested in molecular cues that mediate interneuromast cell process extension and reconnection. These studies promise to further our understanding of an important progenitor cell type, and may one day contribute to therapies for hearing loss.
A 3-day-old zebrafish larva carrying the ET20sg transgene expresses green-fluorescent protein in mantle cells and in the interneuromast cells connecting the neuromasts.
ET20sg transgenic interneuromast cell recovery
Molecular regulators of hair-cell regeneration in the zebrafish
In our group's previous research we discovered a number of genes that are likely regulators of hair-cell regeneration in zebrafish, due to their expression within hair-cell progenitors or differential expression during regeneration. We are using morpholino oligonucleotides, genome editing techniques, and transgenesis to knock down or overexpress select genes' expression to test their involvement in regeneration. Students in our laboratory have the opportunity to claim ownership of and examine a gene or group of genes. The purpose of these studies is to identify and characterize novel regulators of the hair-cell regeneration process. The end goal of our research is to single out molecular targets that may be manipulated in the human ear to stimulate hair-cell regeneration and restore hearing to individuals with hearing loss.
Hierarchical clustering analysis reveals the expression patterns of genes that are differentially regulated following CuSO4-mediated hair cell ablation.