Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download ttk69 - University of Oregon (SPUR)
Document related concepts
Transcript
How do neurons intrinsically regulate axon growth? Alex Whitebirch Herman Lab University of Oregon How is the the circuitry of the nervous system formed? axon nucleus cell body dendrites synapse Neurons establish connections through the activity of the growth cone Neuron with projecting axon Neurons establish connections through the activity of the growth cone Neuron with projecting axon Neurons establish connections through the activity of the growth cone Neuron with projecting axon Neurons establish connections through the activity of the growth cone Neuron with projecting axon Growth Cone Lowery and Vactor. Nat Rev MCB 10 (2009) Neurons establish connections through the activity of the growth cone Neuron with projecting axon Growth Cone Lowery and Vactor. Nat Rev MCB 10 (2009) How is the propulsive motion of growth cones regulated to allow new axons to establish a highly organized set of connections? Growth cones are guided by external signals Attractive signal e.g. Netrins Repulsive signal e.g. Ephrins Cellular responses to axotomy demonstrate intrinsic regulation of axon growth Cell body axon synapse Liu K. et al. Annu. Rev. Neurosci. 34: 131-52 (2011) Cellular responses to axotomy demonstrate intrinsic regulation of axon growth Cell body Retraction bulb axon synapse Growth cone Liu K. et al. Annu. Rev. Neurosci. 34: 131-52 (2011) The Drosophila visual system provides a model of axon growth Ttk69 Prospero Phalloidin R3 R2 R1 R4 R8 R5 R6 R7 MARCM enables precise genetic manipulation of R7 cells MARCM: mosaic analysis with a repressible cell marker MARCM enables precise genetic manipulation of R7 cells MARCM: mosaic analysis with a repressible cell marker MARCM enables precise genetic manipulation of R7 cells MARCM: mosaic analysis with a repressible cell marker Tramtrack69 is necessary to restrict axon growth Misexpression of Tramtrack69 is sufficient to terminate axon growth 48 hr APF 48 hr APF UAS-ttk69 WT 24B10 CD8-GFP Misexpression of Tramtrack69 is sufficient to terminate axon growth 48 hr APF 48 hr APF UAS-ttk69 WT 24B10 CD8-GFP What does Tramtrack69 do on a molecular level to restrict axon growth? Tramtrack69 is a transcription factor Ttk69 Ttk69 is a transcriptional repressor Transcription RNA product No transcription Tramtrack69 is a transcription factor Ttk69 Ttk69 is a transcriptional repressor Transcription RNA product What genes is Ttk69 regulating in order to inhibit axon growth? No transcription TGF-β/Activin signaling pathway is necessary to inhibit axon growth Activin Baboon dSmad2 Ting C et al. Neuron 56 (2007) Axon growth Tramtrack69 acts upstream of Baboon to restrict axon growth Wild type Axon growth ttk69 dSmad2 Axon growth dSmad2 Baboon Baboon Activin Activin Nuclear FLAG-dSmad2 (fold enriched) 2 n = 10 n = 10 1.5 1 Hypothesis: Tramtrack69 restricts axon growth by repressing an antagonist of Activin signaling Wild type Axon growth Antagonist dSmad2 Baboon Activin Hypothesis: Tramtrack69 restricts axon growth by repressing an antagonist of Activin signaling ttk69 Wild type Axon growth Axon growth Antagonist Antagonist dSmad2 dSmad2 Baboon Baboon Activin Activin Hypothesis: Tramtrack69 restricts axon growth by repressing an antagonist of Activin signaling ttk69 Wild type ttk69, Antagonist-RNAi Axon growth Axon growth Axon growth Antagonist Antagonist Antagonist RNAi dSmad2 dSmad2 dSmad2 Baboon Baboon Baboon Activin Activin Activin Double mutants showed no overgrowth phenotype 24B10 SytGFP WT ttk69 ttk69, Follistatin-RNAi ttk69, Cripto-RNAi Double mutants showed no overgrowth phenotype 24B10 SytGFP WT ttk69 ttk69, Follistatin-RNAi A perfect rescue?... ttk69, Cripto-RNAi My “ttk69” chromosome lacked the ttk69 mutation ttk69 24B10 SytGFP ttk69 Ttk69 Prospero Phalloidin My “ttk69” My “ttk69,” Follistatin-RNAi Ttk69 Future Directions 1. Rebuilding ttk1e11 stock and repeating the experiment 1. Exploring the potential role of other activin antagonists in the tramtrack69 pathway 3. If there is a rescue…. Recombineering with BACs: bacterial artificial chromosomes Follistatin – GFP Acknowledgments The Herman Lab University of Oregon Institute of Molecular Biology Tory Sasha Eric Jen Jon Sarah Dave Erika Mike Summer Program for Undergraduate Research Peter O’Day Adam Unger NICHD R25 Summer Research Program Acknowledgments The Herman Lab University of Oregon Institute of Molecular Biology Tory Sasha Eric Jen Jon Sarah Dave Erika Mike Summer Program for Undergraduate Research Peter O’Day Adam Unger NICHD R25 Summer Research Program Questions?
![Neuron [or Nerve Cell]](http://s1.studyres.com/store/data/000229750_1-5b124d2a0cf6014a7e82bd7195acd798-150x150.png)
