The FMR1 disorders (Fragile X syndrome, etc)

1. The FMR1 disorders(Fragile X syndrome, etc)

2. Mary Beth Busby • founding board member of the Fragile X Research Foundation (FRAXA) • Walter Kaufmann • Director, Center for Genetic Disorders of Cognition and Behavior, Kennedy Krieger Institute, The Johns Hopkins University • Karen Usdin • Chief, Gene Structure and Disease Section • LMCB, NIDDK

3. Understanding the molecular basis of the FMR1 gene disorders promoter exon 1 intron 1 5’ UTR X chromosome (CGG)n Karen Usdin

4. FXPOI FXPOI

5. Huntington disease SCA 1, 2, 6, 7 Haw River Syndrome (DRPLA) FRAXE MR Progressive myoclonus epilepsy FMR1 disorders Friedreich ataxia SCA10 Myotonic dystrophy type 2 Kennedy Disease (SBMA) Myotonic dystrophy type 1 Also: SCA 8, SCA12, and HDL2 The Repeat Expansion Diseases (C4GC4GCG)n (CGG)n (GAA)n (ATTCT)n (CCTG)n (CAG)n (CTG)n Intron ORF 3’ UTR Promoter 5’ UTR O R

7. gametogenesis

8. Premutation symptoms result from RNA “toxicity” • The RNA is somehow deleterious • the CGG-repeats may • trigger deleterious processes • sequester proteins that are important for normal neuronal and ovarian function

11. RNA “toxicity” hypothesis • The RNA is somehow deleterious • the CGG-repeats may initiate or trigger deleterious processes • the CGG-repeats may sequester proteins that are important for normal neuronal and ovarian function

13. RNA interference Hannon (2002)

14. SK cells SK cells+CGG88 DAPI lamin merge

15. Is FXTAS a laminopathy? • mutations in Lamin A/C are associated with one form of Charcot-Marie-Tooth disease, a neurological disorder • other mutations in Lamin A/C result in premature aging

18. DNA methylation Histone modifications Gene silencing in mammals

19. Science, 1991

20. 5-azadeoxycytidine

22. What does FMRP do?

23. learning difficulties • macroorchidism • altered circadian rhythms • rapid early growth rate • audiogenic seizures • anxiety

24. WT KO Qin and Beebe-Smith (NIMH)

25. NDF FMRP structure

26. RNAs bound by FMRP • FMR1 • Glucocorticoid receptor • GABAA receptor subunits • CAMKIIα • MAP1B • Rac1 • Calbindin • Vimentin • etc, etc

27. FMRPI304N FMRP - protein product Protein gel

28. Increased rates of cerebral glucose metabolism in a mouse model of fragile X mental retardation Nissl staining [14C] DG WT KO Qin, Kang, and Beebe Smith(2002) (NIMH)

29. Results of “fishing” for FMRP interacting proteins • FXR1P • FXR2P • CYFIP1 and CYFIP2 • Poly(A)-binding protein • eIF2C2/AGO1 • Dicer • kinesin heavy chain

31. RNA interference Hannon (2002)

32. axon synapse dendrite

33. Grazyna Gorny

34. Synaptic transmission

35. Dendritic Spine Structural Anomalies in Fragile-X Mental Retardation Syndrome Irwin, Galvez and William T. Greenough Cerebral Cortex (2000) FXS Un

36. Results of “fishing” for FMRP interacting proteins • FXR1P • FXR2P • CYFIP1 and CYFIP2 • Poly(A)-binding protein • eIF2C2/AGO1 • Dicer • kinesin heavy chain

37. RISC FMRP

38. mGluR5 receptor

41. WT FX MG+/- FX/MG+/-

47. Minocycline

48. Metalloproteinase-9 (MMP-9)

50. Take home messages • FXTAS and FXPOI result from repeat-induced hyperexpression of the FMR1 gene and the deleterious effects of high levels of CGG-repeat containing mRNA. • FXS results from repeat-induced gene silencing. • silencing leads to a deficiency of FMRP, a protein important for the regulation of translation in the synapses of neurons • the resultant abnormal expression of proteins like mGluR5, GSK-3, GABAA and MMP-9 results in the symptoms of FXS • normalizing expression of these proteins may provide targeted approaches to the treatment of FXS.