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Kelly Gu & Jackie Tsao

Amyloid precursor protein regulates neurogenesis by antagonizing miR-574-5p in the developing cerebral cortex . Kelly Gu & Jackie Tsao. Outline. Defining APP Defining miRNA Purpose Setup: Why miR-574- 5p? Connection b/w APP and miRNA miRnA-574- 5p in depth

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Kelly Gu & Jackie Tsao

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  1. Amyloid precursor protein regulates neurogenesis by antagonizing miR-574-5p in the developing cerebral cortex Kelly Gu & Jackie Tsao

  2. Outline • Defining APP • Defining miRNA • Purpose • Setup: Why miR-574-5p? • Connection b/w APP and miRNA • miRnA-574-5p in depth • Results: Proliferation, Migration, Differentiation • Implications

  3. Amyloid precursor protein (APP) • Transmembrane glycoprotein • Developing and mature brain • Cleaved by enzymes to release amyloid beta • This study: APP and microRNA

  4. micro rna (miRNA) • Define microRNA  Regulates genes to promote neurogenesis • Regulates: • migration of neurons • Neurogenesis/differentiation from a neural progenitor cell (NPC) Defining NPC: biological cell that tends to differentiate into a specific type of cell

  5. Purpose • How APP regulates microRNA • How microRNA regulates proliferation, migration,and differentiation • APP deficiency enhances neurogenesis… “but the mechanisms underlying this process are not known.” (citation)  Proves relationship, not mechanism • Absence or presence of APP

  6. why miR-574-5p? • Microarray: looks for what APP is regulating • Found that several different microRNAs are regulated • The miRNA that was the most upregulated miR-574-5p

  7. Upregulation of mir-574-5p in the cortex of APP KO mice

  8. Expression of miR-574-5p in the developing cortex Wild Type (WT) Knockout (KO)

  9. APP and mirna • APP negatively regulates miRNA in the cortex and the neural progenitors • APP to 0 miRNA-574-5p • Abnormal clumping of APP product in the brain *Increase in APP≠AD

  10. APP and mirna A. APP KO = 574 upregulated B. Overexpression of APP = reduced 574 expression C. Overexpression of APP in APP-KO NPCs decreases the upregulated 574 transcripts D. Expression of 574 or anti-574 DID NOT affect the APP protein level (downstream target)

  11. The specifics of miRnA-574-5p • Function via base pairing with complementary sequences of mRNA molecules • gene silencing via translational repression or targeted degradation • Essential for brain morphogenesis and neurogenesis

  12. Breakdown • Proliferation • Migration • Differentiation All three have to be tightly coordinated • essential for the proper development of the nervous system

  13. A step further

  14. miRnA-574-5p *Differentiation is involved in neurogenesis

  15. Results • Pathogenesis of AD • Developing and adult brain • Ablation of APP in mice enhance neural progenitor cells differentiation during embryonic development Discovery: APP controls growth and maturation of brain cells • APP may control the balance between proliferation and differentiation of NPCs through the regulation of specific miRNAs

  16. Proving the effects of microrna

  17. Proliferation • microRNA • APP increases proliferation • When DNA synthesizes  creates nucleotides • When neural progenitor cells are transfected with the miR-574-5p, there is 40% reduction in BrdU incorporation

  18. migration • Migration of the NPCs • Subventricularzone (start) = where neurons develop • Cortical cortex (finish) =where neurons end up

  19. Migration miR-574-4p expression was knocked down in SVZ progenitor cells through electroporation. Traced the migration process. One day after: 62% of the transfected cells present in the SVZ Normal migration: cells primarily distributed throughout CP, with limited number left in SVZ miR-574-4p knockdown cells display a defect in ability to migrate into the CP

  20. Differentiation • APP  miRNA differentiation  • Neurogenesis and Differentiation • NPCs from APP-knockout mice: 40-50% increase in neurogenesis compared with wild type • NPCs from miRNA-574-5p knockdown: 59% reduction in cells entering the CP

  21. Conclusion • miR-574-5p • maintains the balance between NPCs proliferation and differentiation in vitro • regulates neuronal cell migration during cortical development

  22. neurogenesis

  23. proliferation

  24. Implications (LAST SLIDE) • New therapeutic drugs • New biomarkers • Potentially use the 574 as a biomarker • miR-574-5p = important molecule that regulates multiple phases of neurogenesis in embryonic cortex and • APP-mediated effects on neural stem cell fate

  25. Citations Zhang, W., Thevapriya, S., Kim, P.J., Yu, W.P., Je, H.S., Tan, E.K., Zeng, L.. (2014). Amyloid precursor protein regulates neurogenesis by antagonizing miR-574-5p in the developing cerebral cortex. Nature Communications, 5 3330. Retrieved from http://www.nature.com/ncomms/2014/140303/ncomms4330/full/ncomms4330.html#/discussion “APP is your friend and your enemy.” “It’s like wheat in the winter. You want a good amount.”

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