Michael Lovett Ph.D.

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Epigenetics of the Mouse Inner Ear

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Epigenetics of the mouse inner ear
Michael Lovett, Ph.D., Imperial College London
David Raible, Ph.D., University of Washington
Neil Segil, Ph.D., University of Southern California
Jennifer Stone, Ph.D., University of Washington

Inner ear supporting cells from newborn mice harbor a latent capacity for some regenerative responses, but these disappear within the first few weeks of life. This observation provides an experimental window this proposal will exploit to address fundamental questions about the failure of hair cell regeneration in mammals. Specifically, we propose experiments to identify those changes in the genetic material, the chromatin, that are responsible for orchestrating the differentiation of new hair cells within the perinatal organ of Corti; and investigating the changes in the chromatin, the epigenome, that lead to the failure of regeneration in the adult inner ear.

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Establishing the Human Utricle from Surgical Patients as a Translational in Vitro Model for Hair Cell Regeneration

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Establishing the human utricle from surgical patients as a translational in vitro model for hair cell regeneration
Alain Dabdoub, Ph.D. University of Toronto
Stefan Heller, Ph.D. Stanford University
Michael Lovett, Ph.D. Imperial College London

These investigators will work with human utricles harvested during surgery to examine whether the response of human inner ear tissue to damage is similar to that of our mammalian model, the mouse. They will culture human utricles for extended lengths of time following damage with aminoglycoside drugs and determine whether the utricles show any proliferation of their supporting cells (making new supporting cells) or regeneration of their hair cells (making new hair cells). Mouse utricles have a limited ability to show proliferation and regeneration, and it is important to determine whether they are a good model for humans. The investigators also intend to examine gene expression in these human utricles to determine the molecular similarity of the cells of interest to their human counterpart cells.

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Epigenetics of Mouse Inner Ear Maturation and Transdifferentiation

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Epigenetics of mouse inner ear maturation and transdifferentiation
Neil Segil, Ph.D. University of Southern California
Jennifer Stone, Ph.D. University of Washington
Michael Lovett, Ph.D. Imperial College London
David Raible, Ph.D. University of Washington

Many genes are turned off by chemical modifications (epigenetic marks) that prevent activation of the gene. One hypothesis is that mammals cannot activate a hair cell regeneration program after the first few postnatal days because the responsible genes have been epigenetically silenced. This second-year project looks at these epigenetic marks in the ear for every gene, during both early and late development. The investigators will use this analysis to find candidate promoter regions, which control gene activity. Preliminary data support the idea that supporting cells turn off expression of key hair cell genes (e.g., Atoh1), and so a plausible approach to triggering regeneration in the mammalian ear is to reverse such changes.

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Transcriptomics-based Analysis of Hair Cell Regeneration in Non-Mammals

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Transcriptomics-based analysis of hair cell regeneration in non-mammals
Stefan Heller, Ph.D. Stanford University
Tatjana Piotrowski, Ph.D. Stowers Institute for Medical Research
Jennifer Stone, Ph.D. University of Washington
Mark Warchol, Ph.D. Washington University in St. Louis
Michael Lovett, Ph.D. Imperial College London

In this third-year project, we will disrupt hair cells, then analyze how gene expression changes in single cells from species that show robust hair cell regeneration. Heller’s lab will examine the consequences of aminoglycoside damage at the single-cell level in the chick utricle, while the Piotrowski lab will examine fish lateral-line cells. In another component, the project will add two time points to the chick cochlea and utricle bulk RNA-seq datasets that were generated by Lovett and Warchol and which are extremely valuable datasets for the HRP consortium.

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Single-cell transcriptional profiling of chicken utricle and Basilar Papilla Sensory Epithelium Cells After Aminoglycoside-induced Hair Cell loss

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Single-cell transcriptional profiling of chicken utricle and basilar papilla sensory epithelium cells after aminoglycoside-induced hair cell loss
Stefan Heller, Ph.D. Stanford University School of Medicine
Jennifer S. Stone, Ph.D. University of Washington
Michael Lovett, Ph.D. Imperial College London
Mark Warchol, Ph.D. Washington University School of Medicine

The broad premise of the HRP is to identify molecules that could control hair cell regeneration. To do this, we are studying cell types and regenerative processes in multiple contexts and species, then integrating these data together to identify mechanisms that could potentially be turned on in the mouse cochlea to drive transdifferentiation (activating the correct set of hair cell–promoting genes in supporting cells). The role of this systems biology project is to provide the necessary data integration “glue,” binding together the results from the data generation projects. We will combine much of the data that is being generated by the HRP to advance our knowledge of hair cells, supporting cells, conversion of one cell type to another, and the potential for regeneration. By modeling all of the available HRP data, we will identify regulatory molecules that may contribute to regeneration.

Bioinformatic Analysis and Integration of Existing and Pending RNA-seq and ChiP-seq Datasets

Bioinformatic analysis and integration of existing and pending RNA-seq and ChiP-seq datasets
Michael Lovett, Ph.D. Imperial College London

As with the Segil bioinformatics proposal, the Lovett group has an acute need for a bioinformaticist to analyze the data generated by the group and integrate with the other HRP genomic data. The bioinformaticist supported by this project will analyze the group’s data in more detail and determine how the mouse differs from the two regenerating species (chick and zebrafish).

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Comparative MiRNA Profiling of the Postnatal Mouse Cochlea and Regenerating Avian Basal Papilla

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Comparative miRNA profiling of the postnatal mouse cochlea and regenerating avian basal papilla
Michael Lovett, Ph.D. Imperial College London
Neil Segil, Ph.D. University of Southern California
Mark Warchol, Ph.D. Washington University School of Medicine

Micro RNAs (miRNAs) are small molecules that are transcribed from genomic DNA but not translated into protein. They provide regulation to many processes, uniquely affecting many genes simultaneously. This feature makes miRNA regulation of hair-cell regeneration a particularly interesting target for pharmacological intervention. This project will examine miRNA expression in the inner ears of mice and chicks, and determine the differences in response to hair-cell damage between organs that regenerate their hair cells (chick basilar papilla) and those that do not (mouse cochlea).

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Single Cell Transcriptional Profiling of Chicken Utricle and Basilar Papilla Sensory Epithelium Cells After Aminoglycoside-Induced Hair Cell Loss

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Single cell transcriptional profiling of chicken utricle and basilar papilla sensory epithelium cells after aminoglycoside-induced hair cell loss
Stefan Heller, Ph.D. Stanford University School of Medicine
Mark Warchol, Ph.D. Washington University School of Medicine
Jennifer S. Stone, Ph.D. University of Washington
Michael Lovett, Ph.D. Imperial College London

While the HRP has excellent datasets showing the response of chicken auditory and vestibular cells to damage, the experiments examine all cells (including both hair cells and supporting cells) and are not temporally precise. In these experiments, the investigators will damage hair cells, then examine the molecular responses of hundreds of individual cells. Bioinformatics techniques will allow them to order those cells along a timeline that will reveal the molecular changes that unfold during hair cell regeneration.

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