Retinol increases catalase activity and protein content by a reactive species-dependent mechanism in Sertoli cells.
Vitamin A (retinol) is widely used as an antioxidant in therapeutic interventions and dietary supplementations. However, the redox properties of retinoids have been the subject of intense debate in the last few years, as recent works observed deleterious effects caused by retinol supplementation in clinical trials. In the present work, we show that retinol treatment (7 microM, 24 h) led to catalase (EC 1.11.1.6; CAT) activation in cultured Sertoli cells by increasing its protein content in a reactive species-dependent manner. Retinol treatment also increased cell lipoperoxidation, assessed by determination of thiobarbituric acid-reactive substances (TBARS), and intracellular reactive species production, determined by the real-time dihydrochlorofluorescein (DCFH-DA) assay. However, no alterations on CAT mRNA expression (assessed by RT-PCR) were observed, indicating an effect independent of CAT gene-transcription regulation. Importantly, all the effects induced by retinol were inhibited by the antioxidant Trolox, a hydrophilic analogue of alpha-tocopherol. These results show for the first time that retinol increases CAT activity by a redox-dependent modulation of its protein content in a cell culture model. CAT activity or expression are widely used as indexes of oxidative stress in biological systems; since no changes in CAT mRNA expression were detected in these conditions, the use of CAT gene-transcription activation when assessing oxidative stress should be re-evaluated.
Gelain
Daniel Pens
DP
Centro de Estudos em Estresse Oxidativo, Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. dgelain@yahoo.com.br
de Bittencourt Pasquali
Matheus Augusto
MA
Zanotto-Filho
Alfeu
A
de Souza
Luiz Fernando
LF
de Oliveira
Ramatis Birnfeld
RB
Klamt
Fábio
F
Moreira
José Cláudio Fonseca
JC
D000818:Animals; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D014801:Vitamin A / Q000494:pharmacology*
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014801:Vitamin A; D002374:Catalase