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Steven Steinberg, Ph.D., F.A.C.M.G. Hugo W. Moser Research Institute at KKI & Johns Hopkins University School of Medicine.

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Presentation on theme: "Steven Steinberg, Ph.D., F.A.C.M.G. Hugo W. Moser Research Institute at KKI & Johns Hopkins University School of Medicine."— Presentation transcript:

1 Steven Steinberg, Ph.D., F.A.C.M.G. Hugo W. Moser Research Institute at KKI & Johns Hopkins University School of Medicine

2 Zellweger Spectrum Disorders MostSevereLeastSevere ZellwegerSyndromeNeonatalAdreno-leukodystrophyInfantileRefsumDisease

3 Peroxisome Assembly: Matrix Protein Receptor Recycling

4 PEX1 Common Mutations Severity ZellwegerSyndrome NeonatalAdreno-leukodystrophyInfantileRefsumDisease I700fs & I700fs I700fs & G843D G843D & G843D LeastSevere MostSevere

5 Biochemical: Summary

6 Why Create a Pex1-G844D Mouse Model? -A model for testing possible therapeutic interventions. e.g.PEX1-G843D is temperature sensitive, indicating it may be responsive to a chaperone-like molecule M wild type PEX1- thiolase P P, thiolase precursor, 44 kD M, mature thiolase, 42 kD Pex5 -A means of exploring aspects of pathogenesis not readily explored in humans e.g. RNA expression profiling of multiple tissues

7 Construct Design: Pex1-G844D Construct generated → ES cells electroporation and selection → Blastocyst injection, implantation & chimera birth → Chimera breeding → Germline G844D Transmission

8 Matings of Pex1-G844D Heterozygotes MaleFemaleTotal Wt / Wt91423(25.3%) G844D / Wt192544(48.4%) G844D / G844D131124(26.4%) TOTAL:41 (45%)50 (55%)91 No evidence of neonatal lethality.

9 3 Week Old Littermates Pex1-G844D / WT Pex1-G844D / Pex1G844D

10 Growth Curve (n = 14) (n = 13) (n = 26) (n = 22) (n = 17) (n = 10)

11 Survival Homozygotes as of June 2013 DIED OF NATURAL CAUSES SexNumberRange (in days)Median Male Female LIVING COMFORTABLY SexNumberRange (in days)Median Male Female

12 Fertility Male homozygotes can be fertile 4 Male Homozygote x Female Heterozygote Matings yielded litters Male homozygote age range at litter birth: days Female heterozygote age range at litter birth: days Number of days pair were together at litter birth:25-67 days No evidence that female homozygotes are fertile 5 Male Homozygote x Female Homozygote Matings Male homozygote age range at end of time together: days Female heterozygote age range at end of time together: days Number of days pair were together:52-92 days

13 Cultured Fibroblasts Very Long Chain Fatty Acid Content Pex1-G844D AllelesC26:0 µg/mgC26:0/C22:0 Wildtype Carrier Homozygote

14 Cultured Fibroblasts Plasmalogen Synthesis Pex1-G844D Alleles 3 H / 14 CC16DMAC18DMA Wildtype Carrier Homozygote

15 Cultured Fibroblasts Branched Chain Fatty Acid Metabolism pmol / 48 hours / mg protein Pex1-G844D AllelesPhytanic AcidPristanic Acid Wildtype Carrier406 (70%)509 (105%) Homozygote119 (20%)300 (62%)

16 Cultured Fibroblasts Catalase Solubility Pex1-G844D Alleles% Soluble Wildtype11.6% Carrier11.8% Homozygote83.3%

17 Immunocytochemistry WildtypePex1-G844D / Pex1G844D

18 Chaperone Treatment of Fibroblasts

19

20 Whole Blood Lipids C26:0-Lysophosphorylcholine Pex1-G844D Alleles% C26:0-LPC Wildtype (n=42)0.052 ± Carrier (n=67)0.052 ± Homozygote (n=17)0.558 ± 0.363

21 Whole Blood Lipids Phosphatidylethanolamine Plasmalogens Pex1-G844D AllelesSum of Four (pmoles) Wildtype (n=42)5.97 ± 2.34 Carrier (n=67)5.96 ± 2.83 Homozygote (n=17)2.82 ± 2.22

22 Bile Acid Intermediate DHCA Pex1-G844D AllelesPlasma*Feces** Wildtype (n=3,4)0.063 ± ±0.378 Carrier (n=5,4)0.073 ± ±0.406 Homozygote (n=1,3) ± *pmol per 10µl plasma; **pmol per mg feces

23 Liver Histology Wildtype Pex1-G844D / G844D

24 Tissue Lipids p = 0.007

25 ERG Wave Forms Visual Testing Electroretinograms b-wave a-wave

26 Visual Testing Electroretinograms Series 1 = Wildtype and Heterozygous Mice, n=4 Series 2 = Pex1-G844D Homozygous Mice, n=4

27 Visual Testing Retinal Histology: Cone Photoreceptor Staining Homozygote, 28 days Heterozygote, 28 days Homozygote, 147 daysWildtype, 149 days inl = inner nuclear layer onl = outer nuclear layer is = inner segment of photoreceptor layer os = outer segment of photoreceptor layer

28 Pex1-G844D Mouse Model Summary -Growth stunted - -Males can be fertile, but not female -Biochemical profile is comparable to human patients homozygous for PEX1-G843D -Compelling evidence of retinal pathology and dysfunction comparable to human patients -Preliminary evidence of liver dysfunction that is likely comparable to human patients

29 Pex1-G844D Mouse Future Plans -Treatment with compounds identified by drug screening using a cell model system to test for in vivo efficacy -Behavioral studies -Generate Pex1 knock out and generate Pex1-KO / Pex1-G844D compound heterozygotes and tissue specific knock outs

30 Collaborators -Amanda Lauer -Tomohiro Masuda -Don Zack -Shandi Hiebler -Ann Moser -Anita Liu -Paul Watkins -Dominik Reisinger -Outside KKI / JHU -Jean Bennett -Nancy Braverman -Gerald Raymond -Joseph Hacia -Michael Paine -Phyllis Faust Sponsored by the Park-Hopkins and Woodbury research funds donations at Kennedy Krieger Institute


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