Altered proteolytic events in experimental autoimmune encephalomyelitis discovered by iTRAQ shotgun proteomics analysis of spinal cord.
BACKGROUND
Abnormal activation of protease activities during experimental autoimmune encephalomyelitis (EAE) in rats, a rodent model of multiple sclerosis, have been implicated in either the direct destruction of myelin components or the intracellular signal transduction pathways that lead to lymphocyte infiltration, oligodendrocyte destruction, neuronal dysfunctions and axonal degeneration. The identification of changes in regulated proteolytic events during EAE is crucial for uncovering activated proteases that may underline the pathological features such as inflammation and demyelination. We searched for either non-tryptic or semi-tryptic peptides from a previous shotgun proteomics study using isobaric tags for relative and absolute quantification (iTRAQ) to compare the proteomes of normal and EAE rat lumbar spinal cords.


RESULTS
We discovered that several proteins, such as alpha1-macroglobulin, a protease inhibitor, alpha1B-glycoprotein, beta2-microglobulin, neurofilament light polypeptide and sulfated glycoprotein 1 had non-tryptic peptide iTRAQ ratios that were substantially different from the overall protein iTRAQ ratios, suggesting that such peptides may be markers for the proteolytic products generated by the protease(s) altered during EAE. Indeed, subsequent Western blotting confirmed the dysregulation of specific protein cleavages in EAE tissues. Additional proteolytic changes in alpha2-macroglobulin, another protease inhibitor similar to alpha1-macroglobulin was also observed.


CONCLUSIONS
The results from this study revealed changes among both neuronal protein processing and endogenous proteolysis modulators in EAE animals. This information may provide a rationale for protease inhibitor-based therapeutic interventions for multiple sclerosis.
Jain
Mohit Raja
MR
Center for Advanced Proteomics Research and Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School Cancer Research Center, Newark, NJ 07103, USA.
Bian
Shengjie
S
Center for Advanced Proteomics Research and Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School Cancer Research Center, Newark, NJ 07103, USA.
Liu
Tong
T
Center for Advanced Proteomics Research and Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School Cancer Research Center, Newark, NJ 07103, USA.
Hu
Jun
J
Center for Advanced Proteomics Research and Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School Cancer Research Center, Newark, NJ 07103, USA.
Elkabes
Stella
S
Department of Neurology and Neuroscience, UMDNJ-New Jersey Medical School, Newark, NJ 07103, USA.
Li
Hong
H
Center for Advanced Proteomics Research and Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School Cancer Research Center, Newark, NJ 07103, USA.