The Department of Molecular and Cellular Biochemistry
Jill A. Rafael-FortneyAssociate Professor |
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Ph.D. - University of Michigan |
Post Doctoral - University of Oxford |
The long-term goals of my laboratory are to delineate the pathogenic mechanisms of neuromuscular diseases in order to design rational approaches for treatments. Our lab focuses on two different basic science projects: 1) The roles of the PDZ domain proteins Dlg and CASK at the mammalian neuromuscular junction and in neuromuscular disease. 2) Delineation of the pathways leading to cardiomyopathy and skeletal muscle fiber-type abnormalities in a mouse model of Duchenne muscular dystrophy (DMD). CASK and Dlg Membrane-associated guanylate kinases (MAGUKs) serve as scaffold proteins at cell junctions and synapses. We have shown that CASK localizes to both the pre- and post-synaptic membranes of the neuromuscular junction, where it forms a complex with another MAGUK, Dlg. We have gone on to show that CASK undergoes relocalization from the nucleus to the cytoplasm during development in a myogenic cell line and that both CASK and Dlg localize to nuclei in a motor neuron cell line. CASK and Dlg are also recruited to the neuromuscular junction independent of acetylcholine receptor complexes. These studies delineate important developmental characteristics of CASK and Dlg and suggest dual roles for these proteins in both the skeletal muscle and motor neuron components of the neuromuscular junction. We are currently analyzing transgenic mice expressing deleted versions of Dlg and CASK in order to gain insight into the role of this PDZ protein family in the organization and function of the mammalian neuromuscular junction. Cardiomyopathy We have shown that the cardiomyopathic features of the utrophin/dystrophin-deficient mouse can be prevented by the presence of dystrophin in cardiomyocytes but not in cardiovasculature. These data provide the first evidence that dystrophin plays a mechanical role in cardiomyocytes similar to its role in skeletal muscle. These results indicate that treatment of cardiomyocytes but not cardiovasculature is essential in dystrophinopathies. We have gone on to show that the cell junction protein claudin-5 localizes to the lateral membranes of normal cardiomyocytes, but is decreased in utrophin/dystrophin-deficient hearts. Intercalated disc cell junction proteins that are remodeled in other models of cardiomyopathy are not altered in these hearts. These data provide the first example of an alteration of a cell junction protein at the lateral membrane of cardiomyocytes in cardiomyopathy. |
Relevant Publications: |
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Acharyya S, Villalta SA, Bakkar N, Bupha-Intr T, Janssen PM, Carathers M, Li ZW, Beg AA, Ghosh S,
Sahenk Z, Weinstein M, Gardner KL, Rafael-Fortney JA, Karin M, Tidball JG, Baldwin AS and Guttridge
DC (2007) "Interplay of IKK/NF-kappaB signaling in macrophages and myofibers promotes muscle
degeneration in Duchenne muscular dystrophy" J Clin Invest 117(4):889-901.
Zhou L, Porter JD, Cheng G, Gong B, Hatala D, Merriam A, Zhou X, Rafael JA and Kaminski HJ (2006) "Temporal and Spatial mRNA Expression Patterns of TGF-B1, 2, 3 and TGFBRI, II, III in Skeletal Muscles of Mdx Mice" Neuromuscul Disord 16:32-8. Baker PE, Kearney JA, Gong B, Merriam AP, Kuhn DE, Porter JD and Rafael-Fortney JA (2006) "Analysis of Gene Expression Differences Between Utrophin/ dystrophin-deficient Versus mdx Skeletal Muscles Reveals a Specific Upregulation of Slow Muscle Genes in Limb Muscles" Neurogenetics 7(2):81-91. Hanft LM, Rybakova IN, Patel JR, Rafael-Fortney JA and Ervasti JM (2006) "Cytoplasmic Gamma-actin Contributes to a Compensatory Remodeling Response in Dystrophin-deficient Muscle" Proc Natl Acad Sci U S A 103:5385-90. Gardner KL, Kearney JA, Edwards and Rafael-Fortney JA (2006) "Restoration of all dystrophin protein interactions by functional domains in trans does not rescue dystrophy" Gene Ther 13(9):744-51. Acharyya S, Butchbach ME Sahenk Z, Wang H, Saji M, Carathers M, Ringel MD, Skipworth RJ, Fearon KC, Hollingsworth MA, Muscarella P, Burghes AH, Rafael-Fortney JA and Guttridge DC (2005) "Dystrophin glycoprotein complex dysfunction: a regulatory link between muscular dystrophy and cancer cachexia" Canc Cell 8(5):421-32. Janssen PML, Hiranandani N, Mays TA and Rafael-Fortney JA (2005) "Utrophin deficiency worsens cardiac contractile dysfunction present in dystrophin-deficient mdx mice" Am J Physiol-Heart C 289(6):H2373-8. Gardner KL, Sanford JL, Mays TA and Rafael-Fortney JA (2005) "CASK localizes to nuclei in developing skeletal muscle and motor neuron culture models and is agrin-independent" J Cell Physiol 206(1):196-202. Sanford JL, Edwards JD, Mays TA, Gong B, Merriam AP and Rafael-Fortney JA (2005) "Claudin-5 localizes to the lateral side of cardiomyocytes and is altered in utrophin/ dystrophin-deficient cardiomyopathic mice" J Mol Cell Cardiol 38(2):323-332. Sanford JL, Mays TA and Rafael-Fortney JA (2004) "CASK and Dlg form a PDZ protein complex at the mammalian neuromuscular junction" Muscle and Nerve 30(2):164-71. Hainsey TA, Senapati S, Kuhn DE and Rafael JA (2003) "Cardiomyopathic features associated with muscular dystrophy are independent of dystrophin absence in cardiovasculature" Neuromusc. Disord. 13(4):294-302. Rafael JA, Townsend ER, Squire SE, Potter AC, Chamberlain JS and Davies KE (2000) "Dystrophin and utrophin influence fiber-type composition and post-synaptic membrane structure" Hum Mol Gen 9(9):1357-1367. Rafael JA and Brown SC (2000) "Dystrophin and utrophin: genetic analysis of their role in skeletal muscle" (Invited Review) Microscopy Research and Techniques 48(3-4):155-66. Rafael JA*, Tinsley JM*, Potter AC, Deconinck AE and Davies KE (1998) "Skeletal muscle- specific expression of a utrophin transgene rescues utrophin-dystrophin deficient mice" Nat Gen 19(1):79-82. Deconinck AE*, Rafael JA*, Skinner JA, Brown SC, Potter AC, Metzinger L, Watt DJ, Dickson JG, Tinsley JM and Davies KE (1997) "Utrophin-dystrophin deficient mice as a model for Duchenne muscular dystrophy" Cell 90(4):717-27. (*The first two authors contributed equally to this work.) |