title: Up-regulation of soluble Axl and Mer receptor tyrosine kinases negatively correlates with Gas6 in established multiple sclerosis lesions.
abstract: Multiple sclerosis is a disease that is characterized by inflammation, demyelination, and axonal damage; it ultimately forms gliotic scars and lesions that severely compromise the function of the central nervous system. Evidence has shown previously that altered growth factor receptor signaling contributes to lesion formation, impedes recovery, and plays a role in disease progression. Growth arrest-specific protein 6 (Gas6), the ligand for the TAM receptor tyrosine kinase family, consisting of Tyro3, Axl, and Mer, is important for cell growth, survival, and clearance of debris. In this study, we show that levels of membrane-bound Mer (205 kd), soluble Mer ( approximately 150 kd), and soluble Axl (80 kd) were all significantly elevated in homogenates from established multiple sclerosis lesions comprised of both chronic active and chronic silent lesions. Whereas in normal tissue Gas6 positively correlated with soluble Axl and Mer, there was a negative correlation between Gas6 and soluble Axl and Mer in established multiple sclerosis lesions. In addition, increased levels of soluble Axl and Mer were associated with increased levels of mature ADAM17, mature ADAM10, and Furin, proteins that are associated with Axl and Mer solubilization. Soluble Axl and Mer are both known to act as decoy receptors and block Gas6 binding to membrane-bound receptors. These data suggest that in multiple sclerosis lesions, dysregulation of protective Gas6 receptor signaling may prolong lesion activity.
authors: Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461, USA. zagardo@aecom.yu.edu
authors: Jason G
authors: JG
authors: Weinger
authors: Kakuri M
authors: KM
authors: Omari
authors: Kurt
authors: K
authors: Marsden
authors: Cedric S
authors: CS
authors: Raine
authors: Bridget
authors: B
authors: Shafit-Zagardo
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000072197:ADAM10 Protein; D000072198:ADAM17 Protein; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D005260:Female; D045683:Furin / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000235:genetics / Q000378:metabolism*; D009457:Neuroglia / Q000378:metabolism; D015513:Oncogene Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D015854:Up-Regulation; D000076202:c-Mer Tyrosine Kinase; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6
chemical_list: D051722:ADAM Proteins; D000072197:ADAM10 Protein; D000072198:ADAM17 Protein; D053829:Amyloid Precursor Protein Secretases; D045683:Furin; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D000076202:c-Mer Tyrosine Kinase; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6; C097072:MERTK protein, human; C468731:FURIN protein, human; C491236:ADAM10 protein, human; C000606462:ADAM17 protein, human; C000722289:AXL protein, human