Glycomic and Proteomic Changes in Aging Brain Nigrostriatal Pathway

Abstract

Parkinson's disease (PD) is a neurological disorder characterized by the progressive loss of functional dopaminergic neurons in the nigrostriatal pathway in the brain. Although current treatments provide only symptomatic relief, gene therapy has the potential to slow or halt the degeneration of nigrostriatal dopamine neurons in PD patients. Adeno-associated viruses (AAV) are vectors of choice in gene therapy because of their well-characterized safety and efficacy profiles; however, although gene therapy has been successful in preclinical models of the disease, clinical trials in humans have failed to demonstrate efficacy. Significantly, all primary AAV receptors of the virus are glycans. We thus hypothesize that age related changes in glycan receptors of heparan sulfate (HS) proteoglycans (receptor for rAAV2), and/or -glycans with terminal galactose (receptor for rAAV9) results in poor adeno-associated virus binding in either the striatum or substantia nigra, or both, affecting transduction and gene delivery. To test our hypothesis we analyzed the striatum and substantia nigra for changes in HS,-glycans and proteomic signatures in young aged rat brain striatum and substantia nigra. We observed different brain region-specific HS disaccharide profiles in aged compared with young adult rats for brain region-specific profiles in striatum substantia nigra. We observed brain region- and age-specific -glycan compositional profiles with respect to the terminal galactose units that serve as receptors for AAV9. We also observed brain region-specific changes in protein expression in the aging nigrostriatal pathway. These studies provide insight into age- and brain region-specific changes in glycan receptors and proteome that will inform design of improved viral vectors for Parkinson Disease (PD) gene therapy.

A glycomics and proteomics study of aging and Parkinson’s disease in human brain

“…Label free proteomics data were acquired as described previously 24,26 . Briefly, a Q-Exactive HF mass spectrometer interfaced with a 150 µm C18 column was used with a 120 min gradient.…”

“…White matter is composed primarily of myelinated axon tracts. We used our technique whereby glycans and proteins are released by serial digestion with small droplets of enzyme solution, corresponding to a spot of about 5 mm, from the surface of a tissue slide 24,27,28 . This allowed us to select grey matter areas accurately.…”

“…Briefly, all samples were blinded and processed in random order. Tissue slides were immersed in a series of ethanol washes (100%, 90%, 70%, 50%, 30%, water) and then digested using a series of glycosidase enzymes followed by trypsin as described 24,26 . The slides were digested first using five cycles of hyaluronidase and the digestion products were extracted using a dilute ammonium hydroxide solution.…”

Replicative senescense as a consequence of stochastic processes

“…In the present work, we will show, if sporadic cell alterations occur in a homogenous set of stem cells, they lengthen the cell cycle and these are fixed with greater probability than non-altered stem cells.This effect is due to the inherent characteristics of the renewal dynamics and as time goes by it leads to a quiescence state for stem cells due to the recurrent fixation of such altered cell. 7 genomic [6-8], epigenomic [9, 10] and proteomic [11][12][13], although the scope and 8 consequences of these changes have not been well established. Consider a tissue or 9 part of it, whose cell renewal processes is due to small set of SC, (as in the intestinal 10 crypts).…”

Age-related changes in bioelectric activity of the ergotropic zone of hypothalamus in female rats

“…Найнижчий рівень цього показника відповідає частоті дельта-подібного ритму. З віком синтетична активність пресинаптичних нейронів поступово зростає, що призводить до відповідного зросту абсолютної потужності відповідного ритму в тварин досліджених вікових групи [17,18]. Спектральна потужність цього ритму з віком навпаки знижується, що обумовлено поступовим зростанням представленості більш високочастотних десинхроних ритмів.…”