Effect of the branched-chain alpha-ketoacids accumulating in maple syrup urine disease on the high molecular weight neurofilament subunit (NF-H) in rat cerebral cortex.
In this study we investigated the effects of the branched chain alpha-ketoacids accumulating in maple syrup urine disease (MSUD) on the concentrations of the high molecular weight neurofilament subunit (NF-H) associated with the cytoskeletal fraction of the cerebral cortex of 12-day-old rats. Cortical slices were incubated with alpha-ketoisocaproic acid (KIC), alpha-keto beta-methylvaleric acid (KMV) and alpha-ketoisovaleric acid (KIV) at concentrations ranging from 0.5 to 1.0 mM. The cytoskeletal fraction was extracted and the immunoreactivity for phosphorylated and total NF-H was analyzed by immunoblotting. The in vitro 32P incorporation into NF-H was also determined. Results showed that treatment of tissue slices induced with KMV increased Triton-insoluble phosphorylated NF-H immunoreactivity, with no alteration in total NF-H immunoreactivity. Furthermore, KIC treatment drastically increased the total amount of NF-H, whereas KIV did not change either phosphorylated or total NF-H immunoreactivity. KMV also increased the in vitro 32P incorporation into NF-H, confirming the highly phosphorylated NF-H levels detected in the immunoblot. These findings demonstrate that KIC and KMV alter the dynamic regulation of NF-H assembly in the cytoskeletal fraction. Therefore we may suggest that cytoskeletal disorganization may be one of the factors associated with the neurodegeneration characteristic of MSUD disease.
Pessoa-Pureur
R
R
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil. rpureur@vortex.ufrgs.br
Funchal
C
C
de Lima Pelaez
P
P
Vivian
L
L
Oliveira Loureiro
S
S
de Freitas Miranda
R
R
Wajner
M
M
D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D045782:Hemiterpenes; D007150:Immunohistochemistry; D007651:Keto Acids / Q000378:metabolism* / Q000494:pharmacology; D008375:Maple Syrup Urine Disease / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D009410:Nerve Degeneration / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D016900:Neurofilament Proteins / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013347:Subcellular Fractions
D045782:Hemiterpenes; D007651:Keto Acids; D016900:Neurofilament Proteins; C016211:alpha-keto-beta-methylvaleric acid; C001505:alpha-ketoisovalerate; C013082:alpha-ketoisocaproic acid