Opposite transitions of chick brain catalytically active cytosolic creatine kinase isoenzymes during development

Citation
O. Ramirez et E. Jimenez, Opposite transitions of chick brain catalytically active cytosolic creatine kinase isoenzymes during development, INT J DEV N, 18(8), 2000, pp. 815-823
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
INTERNATIONAL JOURNAL OF DEVELOPMENTAL NEUROSCIENCE
ISSN journal
0736-5748 → ACNP
Volume
18
Issue
8
Year of publication
2000
Pages
815 - 823
Database
ISI
SICI code
0736-5748(200012)18:8<815:OTOCBC>2.0.ZU;2-F
Abstract
Postnatally the rat brain synthesizes catalytic forms of muscle type (MM) a nd heart type (MB) creatine kinase (CK), besides the supposedly sole type v ertebrate brain-specific (BB) CK. We intended to demonstrate that in Rhode :Island chicken brain, cytosolic (c) CK isoenzymatic transitions, (for ex:a mple BB-CK is followed by the appearance of MB-CK and MM-CK during muscle d ifferentiation), can also occur during development and aging. Cytosolic pos t 125 000 x g, mitochondrial CK-free, brain samples were obtained for zone electrophoresis separation and identification of catalytically active cCK i soforms. BB-CK was never found during chicken brain ontogeny. Against the a ccepted view, an opposite isoenzyme transition pattern from MM through BB-C K was found in the chicken embryonic brain from the very early stages of de velopment up to day 2 post-hatching. At very early stages of chicken brain ontogeny constitutive MM- and MB-CK isoenzymes were present before the adve nt of creatine. It seems to be that typical and atypical brain MM- and MB-C K could be working as ATPases in the absence of creatine before embryonic s tage 28 (day 5.5) and/or such CK isoforms may begin to form part of the slo w component b in developing early neurons and later in the nuclei of glial cells to be used by the CK/phosphocreatine (PC) system as the neural tissue s mature. The post-hatching transition pattern showed simultaneous expressi on of more than one CK isoenzyme within the same neural sample as in post-n atal rat brain, presumably due to regional differential transphosphorylatio n requirements. Strain-dependent enzymatic specific activities have been re ported in several species. Since equivalent values of brain CK specific act ivity were obtained previously from the embryonic plateau phase of CK activ ity during White Leghorn development, and those from Rhode Island brain neu rons cultured 11 days, we compared if, in vivo, a similar brain CK specific activity pattern was physiologically equivalent during Rhode Island and Wh ite Leghorn chicken ontogeny. We found quantitatively different strain-spec ific CK specific activity patterns during this period. Rhode Island brain C K activity values were approximately 4.5-fold those of White Leghorn ones. This indicates that production of energy from anaerobic metabolism and tran sphosphorylation by the CK/PC system to synthesize ATP more efficiently is strain-specific. Tn Rhode Islands, there was an age-dependent increase of C K specific activity, mostly in older animals (440% above the value found du ring the embryonic plateau), when the Krebs cycle and glycolysis lose capac ity. During adult life and aging, under physiological conditions, the three CK isoenzymes may participate in diverse functions hf the different cell c ompartments of brain glia and neurons with regard to their high and fluctua ting energy demands that are not completely covered by anaerobic and aerobi c glycolisis. (C) 2000 ISDN. Published by Elsevier Science Ltd. All rights reserved.