Generation and Release of Neurogranin, Vimentin, and MBP Proteolytic Peptides, Following Traumatic Brain Injury

Abstract

Traumatic brain injury (TBI) is a major neurological disorder without FDA-approved therapies. In this study, we have examined the concept that TBI might trigger global brain proteolysis in the acute post-injury phase. Thus, we conducted a systemic proteolytic peptidomics analysis using acute cerebrospinal fluid (CSF) samples from TBI patients and normal control samples. We employed ultrafiltration-based low molecular weight (LMW; < 10 kDa) peptide enrichment, coupled with nano-reversed-phase liquid chromatography/tandem mass spectrometry analysis, followed with orthogonal quantitative immunoblotting-based protein degradation analysis. We indeed identified novel patterns of injury-dependent proteolytic peptides derived from neuronal components (pre-and post-synaptic terminal, dendrites, axons), extracellular matrix, oligodendrocytes, microglial cells, and astrocytes. Among these, post-synaptic protein neurogranin was identified for the first time converted to neurogranin peptides including neurogranin peptide (aa 16-64) that is phosphorylated at Ser-36/48 (P-NG-fragment) in acute human TBI CSF samples vs. normal control with a receiver operating characteristic area under the curve of 0.957. We also identified detailed processing of astroglia protein (vimentin) and oligodendrocyte protein (MBP and Golli-MBP) to protein breakdown products (BDPs) and/or LMW proteolytic peptides after TBI. In addition, using MS/ MS selected reaction monitoring method, two C-terminally released MBP peptides TQDENPVVHFF and TQDENPVVHF were found to be elevated in acute and subacute TBI CSF samples as compared to their normal control counterparts. These findings imply that future therapeutic strategies might be placed on the suppression of brain proteolysis as a target. The endogenous proteolytic peptides discovered in human TBI biofluid could represent useful diagnostic and monitoring tools for TBI.

Comparative analysis of hippocampal extracellular space uncovers widely altered peptidome upon epileptic seizure in urethane-anaesthetized rats

“…Nrgn was suggested as a biomarker for synapse degeneration [ 39 ], and its CSF level correlated with cognitive decline in Alzheimer’s disease [ 35 ]. Nrgn level was elevated in the serum of epileptic seizure patients [ 32 ] and traumatic brain injury [ 59 ], we also detected an increased level of one of its peptides and its C-terminal peptide ([54–78] was detected mostly in 4-AP treated samples, suggesting its elevation upon seizures.…”

“…In our study, most of the peptides from synapse-related proteins increased upon seizure induction in urethane-anaesthetized rats. Proteins and proteolytic peptides of synaptic and astroglial markers increased in the CSF, serum, and plasma of patients with acute neurological diseases [ 59 , 61 , 78 ]. It confirms that brain ECF can be a reliable source of disease-related markers.…”

Neuroprotective Peptides and New Strategies for Ischemic Stroke Drug Discoveries

“…Omics technologies make it possible to obtain multiple genome-wide data arrays at a time and carry out multiple results comparisons in the conditions of one experiment. Studies based on transcriptomic and proteomic approaches can reveal the expression profiles of RNAs (RNA-Seq, single-cell RNA-Seq), proteins, and peptides to assess how much neuropathology has distorted biomolecule levels [122,124,[127][128][129][130][131]. At the same time, the normalization (compensation) of the disturbed profiles of the analyzed molecules after exposure to the peptide is evidence of the potential drug (peptide)'s neuroprotective properties under neuropathological conditions.…”

Functional recovery following traumatic brain injury in rats is enhanced by oral supplementation with bovine thymus extract

“…3 TBI is known to induce the production of IgG-class autoantibodies against neuronal and glial antigens, presumably driven by the breakdown of the BBB and release of brain-specific proteins and their byproducts into the bloodstream and the cerebrospinal fluid (CSF). 9,[21][22][23][24][25][26][27] Some of these peptides found in blood and CSF, including neuron-specific enolase (NSE), S100 calciumbinding protein B (S100B), glial fibrillary acidic protein (GFAP), and myelin basic protein (MBP), also serve as promising biomarkers of TBI. Circulating IgG antibodies against neuronal and glial antigens may also indicate neurodegenerative disease, nervous system injury, and inflammatory response, where the damage to the BBB, combined with the breakdown of cells and tissues containing neuronal and glial peptides, contributes to poor recovery from the injury and exacerbates neurological sequelae.…”

“…TBI is known to induce the production of IgG‐class autoantibodies against neuronal and glial antigens, presumably driven by the breakdown of the BBB and release of brain‐specific proteins and their byproducts into the bloodstream and the cerebrospinal fluid (CSF) 9,21–27 . Some of these peptides found in blood and CSF, including neuron‐specific enolase (NSE), S100 calcium‐binding protein B (S100B), glial fibrillary acidic protein (GFAP), and myelin basic protein (MBP), also serve as promising biomarkers of TBI.…”