Creatine Kinase Isoenzymes in Chicken Cerebellum: Specific Localization of Brain-type Creatine Kinase in Bergmann Glial Cells and Muscle-type Creatine Kinase in Purkinje Neurons (original) (raw)
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Mitochondrial creatine kinase (EC 2.7.3.2) in the brain
Clinica Chimica Acta, 1982
No CK MM was found in human brain tissue. Both human and rat brain tissue, however, contain a non MM, non BB CK isozyme. The protein is membrane bound. Evidence is presented that it is a rnitochondrial variant of the enzyme. This mitochondrial brain CK occurs in two forms. Both a low molecular mass form (M, = 65000) and a high molecular mass form are detectable. The isoelectric point of the low molecular mass form, Br-Ck,,, is similar to the isoelectric point of CK MM. Complications may arise when techniques are used that try to separate the mitochondrial CK forms from CK MM on basis of differences in net charge. The two mitochondrial brain CK forms are called Br-CK,, and Br-CK,,. Whether these two enzymes are identical to the mitochondrial heart CK forms remains unclear. Induction A previous study [I] was indicative of "non MM, non BB" CK activity in human brain extracts. Wood and Swanson [2] had already noticed CK activity in a mitochondrial fraction from guinea pig brain. Their finding was corroborated in the marker enzyme study by Swanson [3] and in the work of Jacobs et al [4]. However, marker enzyme studies by Kleine [5] and Dawson et al [6] did not confirm the existence of mitochondrial brain CK. Since 1977 three studies have been publish~ which are important for the localization and the identity of a second, non BB isozyme of creatine kinase in the brain. Friedhoff and Lerner [7] use a centrifugation scheme developed by Whittaker [13]. The mitochondrial pellet also contains synaptosomes and synaptic vesicles.
Structural and behavioural consequences of double deficiency for creatine kinases BCK and UbCKmit
Behavioural Brain Research, 2005
The cytosolic brain-type creatine kinase (BCK) isoform and the mitochondrial ubiquitous creatine kinase (UbCKmit) isoform are both important for the maintenance and distribution of cellular energy in neurons and astrocytes. Previously, we reported that mice deficient for BCK or UbCKmit each showed a surprisingly mild phenotype, probably due to reciprocal functional compensation by the remaining creatine kinase. This study shows that adult male mice lacking both creatine kinase isoforms (CK--/--double knockout mice) have a reduced body weight, and demonstrate a severely impaired spatial learning in both a dry and a wet maze, lower nestbuilding activity and diminished acoustic startle reflex responses when compared to age-matched male wildtype mice with the same genetic background. In contrast, their visual and motor functions, exploration behaviour, prepulse inhibition and anxiety-related responses were not changed, suggesting no global deficit in sensorimotor function, hearing or motivation. Morphological analysis of CK--/--double knockout brains revealed a reduction of ∼7% in wet brain weight and hippocampal size, a ∼15% smaller regio-inferior and relatively larger supra-pyramidal, and intra-infra-pyramidal mossy fiber areas.
FEBS Letters, 1990
In addition to the two monomer subunits of chicken brain-type creatine kinase EC, 2.7.3.2), temd Bb basic) and Ba (acidic), another subspecies called Bb* was identified by chromatofocussing in the presence of 8 M urea (Quest et al., [201). The latter low abundance protein species, isolated from tissue extracts, comigrated on 2Dgels with three minor species (Bbl-3), initially identified in immunoprecipitated, p?Jhnethionine labeled in vitro translation products of cDNA coding for the basic monomer Bb. During in vitro translation experiments in the presence of p2P]-y -ATP, Bbl-3 were labeled while phosphatase treatment eliminated these minor species. It is concluded that Bb* is identical to Bbl-3 and represents phosphorylated derivatives of Bb. BCK dimer populations from different tissues were separated by ion-exchange chromatography and the X, values of the resulting fractions were determined under phosphocreatine (CP)-limiting conditions. In fractions containing only Bb and Bb* two kinetically different enzyme species were detected (J& values for CP = 1.6 mM and 0.8 mM), while fractions containing B-CK dimers composed of the major Ba and Bb monomers, but no Bb*, were homogeneous in this respect (& for CP = 1.6 mM). Phosphorylation of Bb to yield Bb* is concluded to reduce the K, of B-CK dimers for CP by about 50%~ This K, shift is within the range of CP concentrations found in tissues expressing the B-CK isoform and may therefore be of physiological relevance. Phosphorylation of creatine kinase; Regulation of creatine kinase. activity; Intracellular ATP level; Energetica
Brain creatine phosphate and creatine kinase in mice fed an analogue of creatine
Brain Research, 1989
Brain phosphocreatine (PCr) concentration and creatine kinase (CK) activity have been studied by 31p nuclear magnetic resonance (NMR) spectroscopy in mice fed an analogue of creatine, fl-guanidinopropionic acid (GPA). The phosphorylated analogue (GPAP), which almost completely replaces PCr in skeletal muscle, is a poor substrate for CK. Mice, which received GPA in food (2%) and water (0.5%) for up to 9 months beginning at 35 days of age, were normal in appearance and activity. Maximal brain GPAP concentration, reached after two weeks of feedings, was approximately equal to the concentration of PCr. The concentration of PCr decreased at least 20% relative to that of the nucleoside triphosphates. When GPA feedings were stopped, GPAP disappeared in about 20 days from skeletal muscle, but only after 40-50 days from brain. Steady-state NMR saturation transfer studies showed a markedly reduced chemical exchange rate from PCr to ATP in brains of GPA-fed mice. These results suggest a compartmentation of brain PCr. The GPA-accessible PCr compartment has a slow rate of PCr turnover compared to skeletal muscle. The slow reaction rate of the GPA-inaccessible PCr as a CK substrate is consistent with the hypothesis that this residual PCr is the same compartment which is stable in hypoxic or seizing animals. * Part of these results have already been published (ref. 17).
Neuroprotective mechanisms of creatine occur in the absence of mitochondrial creatine kinase
Neurobiology of Disease, 2004
There is substantial evidence that creatine administration exerts neuroprotective effects both in vitro and in vivo. The precise mechanisms for these neuroprotective effects however are as yet unclear. We investigated whether creatine administration could exert neuroprotective effects in mice deficient in ubiquitous mitochondrial creatine kinase (UbMi-CK). UbMi-CK-deficient mice showed increased sensitivity to 1-methyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced dopamine depletion and loss of tyrosine hydroxylase (TH) stained neurons. Isolated mitochondria from these mice showed no alterations in calcium retention, oxygen utilization, membrane potential, or swelling in response to a calcium challenge. Creatine administration significantly increased brain concentrations of both creatine and PCr in the UbMi-CK knockout mice. Creatine administration to the UbMi-CK-deficient mice exerted significant neuroprotective effects against MPTP toxicity that were comparable in magnitude to those seen in wild-type mice. These results suggest that the neuroprotective effects of creatine are not mediated by an effect on UbMi-CK to inhibit the mitochondrial permeability transition, and are more likely to be mediated by maintenance of appropriate ATP/ADP and PCr/Cr levels. D
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2014
AMP-activated protein kinase (AMPK) and cytosolic brain-type creatine kinase (BCK) cooperate under energy stress to compensate for loss of adenosine triphosphate (ATP) by either stimulating ATP-generating and inhibiting ATP-consuming pathways, or by direct ATP regeneration from phosphocreatine, respectively. Here we report on AMPK-dependent phosphorylation of BCK from different species identified by in vitro screening for AMPK substrates in mouse brain. Mass spectrometry, protein sequencing, and site-directed mutagenesis identified Ser6 as a relevant residue with one site phosphorylated per BCK dimer. Yeast two-hybrid analysis revealed interaction of active AMPK specifically with non-phosphorylated BCK. Pharmacological activation of AMPK mimicking energy stress led to BCK phosphorylation in astrocytes and fibroblasts, as evidenced with a highly specific phospho-Ser6 antibody. BCK phosphorylation at Ser6 did not affect its enzymatic activity, but led to the appearance of the phosphorylated enzyme at the endoplasmic reticulum (ER), close to the ER calcium pump, a location known for muscle-type cytosolic creatine kinase (CK) to support Ca 2+ -pumping.