title: Cytoskeleton of cortical astrocytes as a target to proline through oxidative stress mechanisms.
abstract: Hyperprolinemia is an inherited disorder of proline (Pro) metabolism and patients affected by this disease may present neurological manifestations. However, the mechanisms of neural excitotoxicity elicited by hyperprolinemia are far from being understood. Considering the pivotal role of cytoskeletal remodeling in several neurodegenerative pathologies and the potential links between cytoskeleton, reactive oxygen species production and cell death, the aim of the present work was to study the effects of Pro on astrocyte and neuron cytoskeletal remodeling and the possible oxidative stress involvement. Pro induced a shift of actin cytoskeleton in stress fibers together with increased RhoA immunocontent and ERK1/2 phosphorylation/activation in cortical astrocytes. Unlike astrocytes, results evidenced little susceptibility of neuron cytoskeleton remodeling, since Pro-treated neurons presented unaltered neuritogenesis. We observed increased hydrogen peroxide production characterizing oxidative stress together with decreased superoxide dismutase (SOD) and catalase (CAT) activities in cortical astrocytes after Pro treatment, while glutathione peroxidase (GSHPx) activity remained unaltered. However, coincubation with Pro and Trolox/melatonin prevented decreased SOD and CAT activities in Pro-treated astrocytes. Accordingly, these antioxidants were able to prevent the remodeling of the actin cytoskeleton, RhoA increased levels and ERK1/2 phosphorylation in response to high Pro exposure. Taken together, these findings indicated that the cytoskeleton of cortical astrocytes, but not of neurons in culture, is a target to Pro and such effects could be mediated, at least in part, by redox imbalance, RhoA and ERK1/2 signaling pathways. The vulnerability of astrocyte cytoskeleton may have important implications for understanding the effects of Pro in the neurotoxicity linked to inborn errors of Pro metabolism.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul UFRGS, Porto Alegre, RS, Brazil. emaildasamanta@yahoo.com.br
authors.forename: Samanta Oliveira
authors.initials: SO
authors.lastname: Loureiro
authors.forename: Luana
authors.initials: L
authors.lastname: Heimfarth
authors.forename: Emilene B S
authors.initials: EB
authors.lastname: Scherer
authors.forename: Maira J
authors.initials: MJ
authors.lastname: da Cunha
authors.forename: Bárbara Ortiz
authors.initials: BO
authors.lastname: de Lima
authors.forename: Helena
authors.initials: H
authors.lastname: Biasibetti
authors.forename: Regina
authors.initials: R
authors.lastname: Pessoa-Pureur
authors.forename: Angela T S
authors.initials: AT
authors.lastname: Wyse
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000378:metabolism; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D003599:Cytoskeleton / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004622:Embryo, Mammalian; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D011392:Proline / Q000009:adverse effects / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D011392:Proline