Activity of cyclic AMP-dependent microsomal protein kinase and phosphorylation of ribosomal protein in rat brain during postnatal development

Developmental changes of protein substrates of Ca2+/calmodulin-dependent protein kinase II in the rat forebrain

We previously reported that the level of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) alpha and beta proteins increases with postnatal age. In the present study, we investigated the developmental changes in whole protein substrates of CaM kinase II as compared with those of cAMP-dependent protein kinase (A-kinase) in the rat forebrain. Protein substrates were phosphorylated with [gamma-33P]ATP, and analysed by two-dimensional gel electrophoresis. More than 50 substrates for CaM kinase II were found in the soluble and particulate fractions. The phosphorylation level of more than 15 substrates increased in the particulate fraction during development. Similarly, that of more than 3 substrates increased in the soluble fraction. Some substrates for A-kinase also increased during development, although some decreased. These findings suggest that the expression of some substrates is regulated during development and that the phosphorylation reaction involves the regulation of neuronal development.

Phosphorylation of synaptic proteins in chick forebrain: changes with development and passive avoidance training

We have used synaptic plasma membranes (SPMs) and postsynaptic densities (PSDs) to study protein phosphorylation at the synapse in the developing chick forebrain and in 1-day-old chick forebrain following training on a passive avoidance task. Endogenous phosphorylation patterns in SPMs and PSDs prepared by extraction with n-octylglucoside isolated from chick forebrain were investigated by labelling with [32P]ATP. The phosphoprotein components of the SPM and PSD fractions were separated using sodium dodecyl sulphate gradient polyacrylamide gel electrophoresis. Autoradiography and densitometry of the Coomassie Blue protein staining pattern revealed phosphate incorporation into several SPM components including those of molecular mass 52, 37, and 29 kilodaltons (kDa). Bands of similar molecular mass were not phosphorylated in PSD fractions. This difference in phosphorylation between SPMs and PSDs was not due to the detergent n-octylglucoside. In a developmental study in which SPM and PSD fractions were prepared from 1-day-old, 14-day-old, and 21-day-old chickens, the phosphorylation patterns of SPMs were similar throughout, but striking differences occurred in PSDs, both in the level of phosphorylation and in the components phosphorylated. A time-course study was carried out in which phosphorylation of SPMs and PSDs from 1-day-old chicks trained on a passive avoidance task was compared with patterns from control chicks trained on a water-coated bead and untrained chicks. In SPMs prepared from forebrains removed 10 mins following training, a consistent but nonsignificant decrease (-21%) in phosphorylation of a 52 kDa band occurred in chicks with passive avoidance training compared with water-trained and untrained chicks.(ABSTRACT TRUNCATED AT 250 WORDS)

Subcellular distribution of a calmodulin-dependent protein kinase activity in rat cerebral cortex during development

The postnatal development of calmodulin-stimulated phosphorylation of endogenous proteins, in particular the autophosphorylated subunits of the calmodulin-stimulated protein kinase II, were investigated in subcellular fractions of rat cerebral cortex. The major subunit had a mol. wt. of 53,000 Da (designated 50 kDa) and the minor one a mol. wt. of 63,000 Da (designated 60 kDa). The 50-kDa subunit was found to be the only significant phosphoprotein in each fraction and throughout development at its molecular weight. However, the 60-kDa subunit was found to comigrate with other phosphoproteins that accounted for up to 15% of the radioactivity at this molecular weight and which differed between the fractions. 50-kDa autophosphorylation was found to be 3-fold greater in cytoplasmic fractions at day 10 and by adults was evenly distributed between membrane and cytoplasmic fractions. A similar pattern was also found for the total calmodulin-stimulated phosphorylation. Changes in autophosphorylation activity of the 50-kDa subunit were found to represent changes in kinase activity rather than alterations in phosphatase activity. In the membrane, this change was shown to be due to changes in the amount of enzyme. Although in the adult autophosphorylation activity is evenly distributed between membrane and soluble fractions, when differences in phosphatase activity and lack of autophosphorylation activity of the majority of post-synaptic density-associated kinase is taken into account, it is clear that the vast majority of the enzyme is membrane-bound. Phosphorylation of endogenous substrates paralleled the development of 50-kDa subunit autophosphorylation, most of which occurred between day 14 and day 30, a period which follows the most rapid phase of synaptogenesis. This pattern was different from that of the phosphorylation of myelin basic protein and two substrates of the calcium-phospholipid-dependent protein kinase. There was also a change in the ratio of autophosphorylation activity of the 50-kDa and 60-kDa subunits during development which appears to be due to a change in the amount of the subunits themselves. This ratio was the same in all fractions at any one age. We suggest that this change is due to the existence of at least two developmentally regulated isoenzymes in the cortex.

Protein phosphorylation in isolated synaptic junctional structures: changes during development

Endogenous phosphorylation in subcellular fractions enriched in synaptic plasma membranes (SPM) and purified synaptic junctions (SJ) has been examined in vitro at various stages of postnatal development. Protein kinase activity was measured using both endogenous and exogenous (histones) proteins as substrates. Protein phosphorylation that is regulated by cyclic AMP also was investigated. SPM and SJ fractions displayed large increments in kinase activities and cyclic AMP-stimulated protein phosphorylation between postnatal days 5 and 15. SJ fractions exhibited a dramatic age-dependent change in the cyclic AMP-stimulated phosphorylation of endogenous proteins of molecular weights 73,000 (1a), 68,000 (1b), 65,000 (1c) and 55,000. Experiments in which isolated SJs were phosphorylated with soluble cyclic AMP-dependent kinase showed that the phosphorylation of proteins 1a, 1b and 1c resulted from their de novo appearance in newborn SJ fractions and not from a maturation-dependent coupling of kinases and substrates that were already present in newborn SJ fractions. The levels of regulatory (R) subunits of cyclic AMP-dependent kinases in synaptic fractions were measured by [3H]cyclic AMP binding and photoaffinity labeling with [32P]8-N3-cyclic AMP and were observed to change little during postnatal development. These findings show that there is a strong correlation between the in situ appearance of synapses and the enzymatic maturation of endogenous, cyclic AMP-stimulated protein phosphorylation in SJ fractions isolated at different stages of development.

Multiple localizations of adenylate cyclase in rat hippocampus. A histochemical study

A new method for the histochemical demonstration of adenylate cyclase activity, introduced and biochemically tested by Poeggel et al. (1981 a), was employed in nervous tissue. Using this method a multiple pattern of activity was detectable. Activity occurs in nervous as well as glial elements. Biochemical results and physiological conclusions could be confirmed by ultrahistochemical visualization of adenylate cyclase activity in nervous tissue. The specificity of the reaction is controlled by a number of variations of the incubation methods.

Specific regulation by steroid hormones of protein kinases in the endometrium. 1. Alteration by estrogen and progesterone in levels of protein kinases in rabbit endometrium

The alteration in activities of multiple protein kinases has been studied in the endometrium of a rabbit treated with estrogen and progesterone. The administration of estrogen or progesterone to the castrated rabbit resulted in a remarkable increase of total activity in the cytosol fraction of the endometrium. The administration of estrogen caused an increase of type I adenosine-3',5'-monophosphate-dependent (cAMP-dependent) protein kinase and a slight decrease of type II cAMP-dependent protein kinase. In contrast, the treatment with progesterone after priming administration of estrogen brought about an increase of type II cAMP-dependent protein kinase and a decrease of type I cAMP-dependent protein kinase. Therefore, the activity ratio of type II to type I decreased by estrogen and increased by progesterone. The simultaneous administration of cycloheximide abolished the stimulatory effect of respective hormones on the level of each protein kinase. The activity profile of protein kinases on DEAE-cellulose column after ovulation caused by the administration of human chorionic gonadotropin to a non-castrated rabbit was similar to that of the rabbit treated with progesterone. The results presented demonstrate the specific regulation by the steroid hormones of de novo synthesis of protein kinases in the target organ.

Characterization of two adenosine 3':5'-phosphate-dependent protein kinase species from Chinese hamster ovary cells

Chinese hamster ovary cells exhibit several characteristic morphological and physiological responses upon treatment with agents which increase the intracellular level of adenosine 3':5'-phosphate (cyclic AMP). To better understand the mechanism of these cyclic AMP-mediated responses, we separated two cyclic AMP-dependent protein kinases (ATP:protein phosphotransferase, EC 2.7.1.37) (protein kinase I and protein kinase II) from the cytosol of Chinese hamster ovary cells by DEAE-cellulose chromatography and studied their properties. Protein kinase I is eluted at a lower salt concentration than protein kinase II and is stimulable to 10 times its basal catalytic activity, while protein kinase II is stimulable only 2-fold. Both kinases are completely dissociated by cyclic AMP and inhibited by specific cyclic AMP-dependent protein kinase inhibitor. They have similar Km values for magnesium (approximately 1 mM), cyclic AMP (approximately 60 nM), and ATP (approximately 0.1 mM), and the dissociation constant (Kdis) for cyclic AMP (approximately 13 nM) is the same for both enzymes. However, they appear to have different substrate preferences and cyclic AMP-binding properties in that cyclic AMP bound to protein kinase II exchanges readily with free cyclic AMP, while that bound to protein kinase I is not exchangeable. The native enzymes have different sedimentation coefficients (6.4 S for protein kinase I and 4.8 S for protein kinase II), whereas those of the activated enzymes are the same (2.9--3.0 S). It appears that the two cyclic AMP-dependent protein kinases which differ from each other in their regulatory subunits may play different roles in the mediation of cyclic AMP action in Chinese hamster ovary cells.

Cyclic nucleotides in nervous tissue

A review of the literature emphasizes that cyclic nucleotides play a key role in regulation of cell growth, differentiation and metabolism in diverse tissues and, in addition, are closely involved in neural tissue function. The role of cAMP as a second messenger is discussed.

The role of cyclic nucleotides in the CNS

On the basis of the information presented in this review, it is difficult to reach any firm decision regarding the role of cyclic AMP (or cyclic GMP) in synaptic transmission in the brain. While it is clear that cyclic nucleotide levels can be altered by the exposure of neural tissues to various neurotransmitters, it would be premature to claim that these nucleotides are, or are not, essential to the transmission process in the pre-or post-synaptic components of the synapse. In future experiments with cyclic AMP it will be necessary to consider more critically whether the extracellularly applied nucleotide merely provides a source of adenosine and is thus activating an extracellularly located adenosine receptor, or whether it is actually reaching the hypothetical sites at which it might act as a second messenger. The application of cyclic AMP by intrcellular injection techniques should minimize this particular problem, although possibly at the expense of new diffulties. Prio blockade of the adenosine receptor with agents such as theophylline or adenine xylofuranoside may also assist in the categorization of responses to extracellularly applied cyclic AMP as being a result either of activation of the adenosine receptor or of some other mechanism. Utimately, the developement of highly specific inhibitor for adenylate cyclase should provide a firm basis from which to draw conclusions about the role of cyclic AMP in synaptic transmission. Similar considerations apply to the action of cyclic GMP and the role of its synthesizing enzyme, guanylate cyclase. The use of phosphodiesterase inhibitors in studies on cyclic nucleotides must also be approached with caution. The diverse actions of many of these compounds, which include calcium mobilization and block of adenosine uptake, could account for many of the results that have been reported in the literature.