Speaker: Lauren Walker, PhD. Assistant Professor Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College

91福利 the speaker:聽Lauren has always been fascinated with how we build, maintain, and regenerate complex structures like the nervous system. She studied degeneration as a PhD student at Washington University in St. Louis with Aaron DiAntonio and then switched to regeneration during her postdoc with Michael Granato at the University of Pennsylvania. She established her lab in 2024 at Dartmouth, where they use a zebrafish model to study how motor neurons find their correct muscle targets to enable coordinated movement. More recently, they have expanded their focus to tissue regeneration. They use a combination of genetics, molecular biology, live imaging, and transcriptomics to understand how the cells and signals that drive functional regeneration.

91福利 the Seminar: Humans are poor regenerators: injured nerves frequently reconnect to incorrect targets, and limb regeneration is limited to the fingertip. Achieving accurate, faithful regrowth of complex tissue remains a central unsolved problem in regenerative biology. We address this using the larval zebrafish pectoral fin, a transparent, regenerating vertebrate appendage developmentally homologous to the tetrapod forelimb. We employ two complementary injury paradigms: laser-mediated transection of only motor axons and full amputation of the fin. In both cases, functional regeneration is complete within days, giving us a window into nerve and tissue regrowth. This system allows us a unified set of questions: how does the nervous system regenerate, how does a tissue regenerate, and how does the nervous system regenerate within a tissue that is itself still regenerating? Using transgenic labeling of individual cell types, we employ longitudinal live imaging to observe cell interactions and compare motor axon targeting over time, across development, isolated nerve injury, and whole-appendage regeneration. Across these contexts we find that axons are strongly biased toward reinnervating their correct original targets, but that the degree to which they make, and ultimately correct, errors differs between contexts. By comparing development, injury, and regeneration within a single model, we are working to identify the injury conditions and molecular mechanisms that determine accurate versus aberrant innervation as tissue and nerve regenerate together.

Please join us for this in person event in 107 Norman Smith Hall.

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Speaker: Iain Drummond PhD, Professor and Scientific Director, MDIBL

91福利 the speaker:聽 Iain Drummond received his PhD from UC Berkeley and went on to postdoc at Northwestern University Medical School and University of Chicago working on cell signaling and gene expression. As faculty at Massachusetts General Hospital/Harvard Medical School in the 1990鈥檚, Dr. Drummond initiated genetic studies of the zebrafish kidney as part of the large scale zebrafish mutagenesis screen. Over two decades at MGH, his lab established the zebrafish kidney as a model of organ development, disease, and regeneration. His lab identified genes that play key roles in epithelial patterning, ciliogenesis, developmental cell signaling, and kidney morphogenesis. Moving to MDIBL, his lab works on adult kidney stem cells and immune regulation of kidney regeneration in zebrafish.

91福利 the seminar: Zebrafish regenerate their kidneys after damage by activating quiescent kidney stem cells, however the injury signals that activate kidney stem cells are not known. We find that cytokine responses are required and sufficient to induce full kidney regeneration. Acute injury induces cxcl11 expression which is sufficient to induce stem cell aggregation via Fgf expression. A second stage of Wnt-signaling completes kidney stem cell differentiation into functional nephrons. These findings shift our focus on inflammation away from fibrosis and scarring to an examination of the positive, regenerative effects of immune responses to cell and tissue damage.

Please join us for this in person event in 107 Norman Smith Hall.

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Speaker: Basile Tarchini, Ph.D. Professor, The Jackson Laboratory

Biography: Basile Tarchini is a Professor at The Jackson Laboratory in Bar Harbor, Maine, and an affiliated research faculty at Tufts University School of Medicine. He grew up in Switzerland and earned his Ph.D. at the University of Geneva with Denis Duboule, using mouse genetics to decipher how Hox gene transcription encodes position and timing along the developing limb and spinal cord. During postdoctoral work with Michel Cayouette at the Montreal Clinical Research Institute (IRCM), he became interested in the mechanisms of cell polarization, and diverged from the laboratory’s model system, the mouse retina, to explore the inner ear. He continued this work after establishing his laboratory at The Jackson Laboratory in 2015, building numerous collaborations across the auditory and vestibular research communities in the United States and abroad. Dr. Tarchini’s research combines mouse genetics, imaging, and hearing and balance tests to discover the genes and mechanisms that build and maintain sensory hair cells, the cells that convert sound and head movement into electrical signals sent to the brain. His laboratory investigates how hair cells assemble and preserve their mechanically sensitive compartment, the stereociliary bundle, with particular attention to the contributions of G proteins to cytoskeleton polarization.

91福利 the seminar: Our work over the past decade shows that inhibitory G proteins (GNAI/Gai) are essential for hearing and balance, and perform distinct polarization tasks within the same sensory hair cell, each entrusted to a different regulator. We found that the orphan receptor GPR156 signals through GNAI to regulate hair cell orientation, producing for example the mirror-image arrangements that give some vestibular organs and fish neuromasts bidirectional sensitivity. Separately, the scaffold GPSM2 binds GNAI to distinguish the first stereocilia row and confer its tallest identity, building the graded height architecture that makes individual stereociliary bundles directionally sensitive. I will close with our more recent findings that the same GPSM2-GNAI complex persists in adult hair cells to hold stereocilia at precise, stable heights. Because mammalian hair cells are terminally differentiated, this fundamental work also supports emerging repair or regeneration therapies.

Please join us for this in-person event in 107 Norman Smith Hall.

The post COBRE Seminar: Dual Roles for G Proteins in the Cellular Geometry of Hearing and Balance appeared first on Center for Biomedical Research Excellence (COBRE).