Carbonic anhydrase-III immunohistochemical localization in human skeletal muscle

Deletion of metal transporter Zip14 (Slc39a14) produces skeletal muscle wasting, endotoxemia, Mef2c activation and induction of miR-675 and Hspb7

Skeletal muscle represents the largest pool of body zinc, however, little is known about muscle zinc homeostasis or muscle-specific zinc functions. Zip14 (Slc39a14) was the most highly expressed zinc transporter in skeletal muscle of mice in response to LPS-induced inflammation. We compared metabolic parameters of skeletal muscle from global Zip14 knockout (KO) and wild-type mice (WT). At basal steady state Zip14 KO mice exhibited a phenotype that included muscle wasting and metabolic endotoxemia. Microarray and qPCR analysis of gastrocnemius muscle RNA revealed that ablation of Zip14 produced increased muscle p-Mef2c, Hspb7 and miR-675-5p expression and increased p38 activation. ChIP assays showed enhanced binding of NF-[Formula: see text] to the Mef2c promoter. In contrast, LPS-induced systemic inflammation enhanced Zip14-dependent zinc uptake by muscle, increased expression of Atrogin1 and MuRF1 and markedly reduced MyoD. These signatures of muscle atrophy and cachexia were not influenced by Zip14 ablation, however. LPS-induced miR-675-3p and -5p expression was Zip14-dependent. Collectively, these results with an integrative model are consistent with a Zip14 function in skeletal muscle at steady state that supports myogenesis through suppression of metabolic endotoxemia and that Zip14 ablation coincides with sustained activity of phosphorylated components of signaling pathways including p-Mef2c, which causes Hspb7-dependent muscle wasting.

Proteomic analysis of the skeletal muscles from dysferlinopathy patients

Dysferlinopathy is an autosomal recessive disease caused by pathogenic variants in DYSF gene. We compared muscle protein extracts from dysferlinopathy patients and control subjects to identify new biomarkers of this myopathy. We reviewed the medical records from January 2002 to October 2016. Eight vastus lateralis muscle samples from five dysferlinopathy patients and three control subjects were selected. We separated proteins/peptides from all eight muscle protein extracts using two-dimensional electrophoresis (2DE). Data were acquired from liquid chromatography-mass spectrometry protein fragmentation patterns after comparing the spot volumes. Western blotting revealed total dysferlin loss in the dysferlinopathy patients but normal expression in the control subjects. 2DE indicated somewhat diverse protein constellations between the dysferlinopathy and control groups. Image analysis showed that 80 spots were differently expressed between two dysferlinopathy and one control samples. We selected 44 spots with consistently different volume between dysferlinopathy and control groups. Liquid chromatography-mass spectrometry indicated 26 differently expressed proteins. Western blotting revealed that creatine kinase M-type, carbonic anhydrase III (muscle specific) and desmin were significantly elevated in dysferlinopathy muscle. Additionally, four proteins (myosin light chain 1/3, skeletal muscle isoform; lamin A/C; ankyrin repeat domain 2; and eukaryotic translation initiation factor 5A-1) were inconsistently elevated in the dysferlinopathy samples. We confirmed the usefulness of the classic biomarker and have newly identified the altered expression of proteins in the skeletal muscles of dysferlinopathy patients.

Quantitative analysis of proteins of metabolism by reverse phase protein microarrays identifies potential biomarkers of rare neuromuscular diseases

Background

Muscle diseases have been associated with changes in the expression of proteins involved in energy metabolism. To this aim we have developed a number of monoclonal antibodies against proteins of energy metabolism.

Methods

Herein, we have used Reverse Phase Protein Microarrays (RPMA), a high throughput technique, to investigate quantitative changes in protein expression with the aim of identifying potential biomarkers in rare neuromuscular diseases. A cohort of 73 muscle biopsies that included samples from patients diagnosed of Duchenne (DMD), Becker (BMD), symptomatic forms of DMD and BMD in female carriers (Xp21 Carriers), Limb Girdle Muscular Dystrophy Type 2C (LGMD2C), neuronal ceroid lipofuscinosis (NCL), glycogenosis type V (Mc Ardle disease), isolated mitochondrial complex I deficiency, intensive care unit myopathy and control donors were investigated. The nineteen proteins of energy metabolism studied included members of the mitochondrial oxidation of pyruvate, the tricarboxylic acid cycle, β-oxidation of fatty acids, electron transport and oxidative phosphorylation, glycogen metabolism, glycolysis and oxidative stress using highly specific antibodies.

Results

The results indicate that the phenotype of energy metabolism offers potential biomarkers that could be implemented to refine the understanding of the biological principles of rare diseases and, eventually, the management of these patients.

Conclusions

We suggest that some biomarkers of energy metabolism could be translated into the clinics to contribute to the improvement of the clinical handling of patients affected by rare diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0424-1) contains supplementary material, which is available to authorized users.

Affinity proteomics within rare diseases: a BIO-NMD study for blood biomarkers of muscular dystrophies

Despite the recent progress in the broad-scaled analysis of proteins in body fluids, there is still a lack in protein profiling approaches for biomarkers of rare diseases. Scarcity of samples is the main obstacle hindering attempts to apply discovery driven protein profiling in rare diseases. We addressed this challenge by combining samples collected within the BIO-NMD consortium from four geographically dispersed clinical sites to identify protein markers associated with muscular dystrophy using an antibody bead array platform with 384 antibodies. Based on concordance in statistical significance and confirmatory results obtained from analysis of both serum and plasma, we identified eleven proteins associated with muscular dystrophy, among which four proteins were elevated in blood from muscular dystrophy patients: carbonic anhydrase III (CA3) and myosin light chain 3 (MYL3), both specifically expressed in slow-twitch muscle fibers and mitochondrial malate dehydrogenase 2 (MDH2) and electron transfer flavoprotein A (ETFA). Using age-matched sub-cohorts, 9 protein profiles correlating with disease progression and severity were identified, which hold promise for the development of new clinical tools for management of dystrophinopathies.

Purification of chicken carbonic anhydrase isozyme-III (CA-III) and its measurement in White Leghorn chickens

Background

The developmental profile of chicken carbonic anhydrase-III (CA-III) blood levels has not been previously determined or reported. We isolated CA-III from chicken muscle and investigated age-related changes in the levels of CA-III in blood.

Methods

CA-III was purified from chicken muscle. The levels of CA-III in plasma and erythrocytes from 278 female chickens (aged 1-93 weeks) and 68 male chickens (aged 3-59 weeks) were determined by ELISA.

Results

The mean level of CA-III in female chicken erythrocytes (1 week old) was 4.6 μg/g of Hb, and the CA-III level did not change until 16 weeks of age. The level then increased until 63 weeks of age (11.8 μg/g of Hb), decreased to 4.7 μg/g of Hb at 73 weeks of age, and increased again until 93 weeks of age (8.6 μg/g of Hb). The mean level of CA-III in erythrocytes from male chickens (3 weeks old) was 2.4 μg/g of Hb, and this level remained steady until 59 weeks of age. The mean plasma level of CA-III in 1-week-old female chickens was 60 ng/mL, and this level was increased at 3 weeks of age (141 ng/mL) and then remained steady until 80 weeks of age (122 ng/mL). The mean plasma level of CA-III in 3-week-old male chickens was 58 ng/mL, and this level remained steady until 59 weeks of age.

Conclusion

We observed both developmental changes and sex differences in CA-III concentrations in White Leghorn (WL) chicken erythrocytes and plasma. Simple linear regression analysis showed a significant association between the erythrocyte CA-III level and egg-laying rate in WL-chickens 16-63 weeks of age (p < 0.01).

Isolation and measurement of carbonic anhydrase isoenzyme III in plasma, sera, and tissues of dogs

OBJECTIVE

To purify canine carbonic anhydrase isoenzyme III (CA-III) and determine plasma, serum, and tissue concentrations of CA-III in healthy dogs and dogs with experimentally induced muscle damage.

ANIMALS

121 healthy Beagles.

PROCEDURE

Muscle was obtained from 2 Beagles after euthanasia, and CA-III was purified and characterized by use of column chromatography and electrophoresis, respectively. A CA-III-specific ELISA was developed to determine concentrations of CA-III in plasma of 116 dogs and tissues of 1 dog. Serum creatine kinase (CK) activity and CA-III concentration were also determined before and after induction of muscle damage by IM injection of 2 ml of 10% lidocaine to 2 dogs.

RESULTS

Canine CA-III had a molecular weight of 28 kd and an isoelectric point of 8.2. Mean (+/- SD) concentration of CA-III in plasma of healthy dogs was 16.91 +/- 9.55 ng/ml. The highest tissue concentration of CA-III was detected in skeletal muscle. Serum concentration of CA-III increased and peaked within the first 2 to 3 hours after induction of muscle damage. The increase in CA-III concentration was more rapid than that of CK activity, and concentration reached its maximum and returned to baseline sooner than did CK activity.

CONCLUSIONS AND CLINICAL RELEVANCE

The CA-III ELISA we developed was a sensitive method for determining CA-III concentrations in plasma, serum samples, and tissue specimens of dogs. Use of this ELISA requires only a small volume of serum and may enable the study of changes in CA isoenzyme concentrations associated with muscle disorders in dogs.

Carbonic anhydrase III content in various equine muscles

1. In this study, carbonic anhydrase III (CA-III) content in 18 equine muscles was determined by enzyme immunoassay. 2. It was found to differ in several muscles. 3. That in external intercostal muscle, rectus abdominis muscle and splenius muscle from four horses was very high. 4. Although the masseter muscle had only type I fibers, CA-III content was similar to that in mixed-fiber type muscles such as the biceps femoris muscle. 5. It thus appear that equine type I fibers can be further subgrouped.

Leakage of carbonic anhydrase III from normal and denervated rat skeletal muscle following contractile activity

Skeletal muscle extracellular carbonic anhydrase III was investigated in anesthetized rats by a microdialysis technique. A small dialysis probe was inserted into the tibialis anterior (TA) muscle and perfused continuously. Perfusates were collected before and during muscle contraction, induced by electrical stimulation of the muscle or of the sciatic nerve. In the perfusate of resting normal and denervated muscle, the concentration of CA III was 10 to 12 ng/mL, as measured by a radioimmunosorbent technique. During contractile activity, the concentrations of CA III increased markedly in the normal and denervated muscle. A TA muscle suspended in physiological saline behaved similarly, even though the leakage before and during contraction was higher than in vivo. The results show that skeletal muscle leaks CA III both in vivo and in vitro, a leakage which was markedly increased by contractile activity. The microdialysis technique should also be useful in humans to study the efflux of various proteins from different kinds of diseased or fatigued muscles.

Carbonic anhydrase in skeletal and cardiac muscle from rabbit and rat

We have studied the distribution of carbonic anhydrases (CA) in several skeletal muscles of the hindlimb of rabbits and rats and in cardiac muscle of the rabbit. To remove erythrocyte CA, hindlimbs and hearts were thoroughly perfused with dextran solution, and the effectiveness of the perfusion was in most cases assessed by determining the contamination of the muscles with radioisotopes that had been used to label the erythrocytes before the perfusion was started. We observed three forms of CA: (1) cytosolic (sulphonamide-resistant) CA III; (2) a cytosolic sulphonamide-sensitive CA, probably isoenzyme II; (3) a membrane-bound form that was extracted from the particulate fraction using Triton X-100. These CA isoforms were distributed as follows. (1) CA III is located in the cytoplasm of slow, oxidative skeletal muscles and is absent from or low in fast skeletal and cardiac muscle; this holds for rabbits and rats and is identical with the pattern previously described for several other species. (2) The cytosolic sulphonamide-sensitive CA is present in fast rabbit muscles and absent from slow muscles of this species. In contrast, all skeletal muscles of the rat studied here lack, or possess only very low, activity of this isoenzyme. (3) The membrane-bound form of CA is present in all rabbit muscles studied; its activity appears somewhat higher in fast than in slow skeletal muscles. (4) Cardiac muscle constitutes an exception among all striated muscles of the rabbit as it possesses no form of cytosolic CA but a high activity of the membrane-bound form.

Quantification of carbonic anhydrase III and myoglobin in different fiber types of human psoas muscle

Carbonic anhydrase (CA III) and myoglobin contents from isolated human muscle fibers were quantified using a sensitive time-resolved fluoroimmunoassay. Human psoas muscle specimens were freeze-dried, and single fibers were dissected out and classified into type I, IIA and IIB by myosin ATPase staining. Fiber typing was further confirmed by SDS-PAGE. CA III and myoglobin were found in all fiber types. Type I fibers contained higher concentrations of CA III and myoglobin than type IIA and IIB fibers. The relative concentrations of CA III in type IIA and IIB fibers were respectively 24% and 10% of that in type I fibers. The relative concentrations of myoglobin in type IIA and IIB fibers were 60% and 28% of that in type I fibers. Anti-CA III immunoblotting results from fiber-specific pooled samples agreed well with quantitative measurements. The results indicate that CA III is a more specific marker than myoglobin for type I fibers.

Determination and developmental changes in carbonic anhydrase III in swine liver

1. CA-III was measured by enzyme-immunoassay in the livers of male and female swine aged from the fetus to 5 years old. 2. No sexual dimorphism in porcine liver could be detected at 6 months, but stag showed twice as much as swine of the same age. 3. The concentration of CA-III in the liver increased during development up to 6 months of age, followed by decline due to senescence.

Effect of immobilization on carbonic anhydrase III and myoglobin content in human leg muscle

Carbonic anhydrase III and myoglobin concentrations were measured from vastus medialis muscle samples before and 6 weeks after postoperative leg immobilization following knee ligament reconstruction. Seven patients were immobilized with conventional cast so that the knee joint was fixed at 20 degrees flexion. Seven other patients used braces allowing a motion of 30-70 degrees. The atrophy of the medial part of musculus quadriceps was estimated by computer tomography. No difference in carbonic anhydrase III and myoglobin concentrations or muscle atrophy between the cast and brace groups was observed. The cross-sectional area of the medial part of musculus quadriceps decreased 38% during immobilization. The specific concentrations of carbonic anhydrase III and myoglobin remained unaltered. Due to the remarkable postoperative atrophy of the muscle the total carbonic anhydrase III and myoglobin contents, however, decreased significantly (37% and 31%, respectively). The results suggest that the net breakdown of carbonic anhydrase III and myoglobin during disuse atrophy occur at the same rate as the average net degradation of mixed muscle proteins and that the process is independent of the immobilization procedure.

Carbonic anhydrase inhibition and calcium transients in soleus fibers

We simultaneously measured cytoplasmic Ca2+ transients using Fura-2 and isometric force in rat soleus fiber bundles. In the presence of the carbonic anhydrase inhibitor, chlorzolamide, we observed a decreased amplitude and retarded decay of the Ca2+ signal. This corresponded with a decreased isometric force and a retarded muscle relaxation. We conclude that muscle carbonic anhydrase participates in excitation-contraction coupling, possibly by rapidly providing protons that are exchanged for Ca2+ across the sarcoplasmic reticulum membrane.

Immunohistochemical studies of the carbonic anhydrase isozymes in the bovine placenta

Placentae from 11 cows, ranging from about 80 to 270 days gestation, were studied for immunohistochemical localization of carbonic anhydrase isozymes. CA isozymes were localized using the avidin-biotin-peroxidase complex (ABC) method in the bovine placenta. CA-II was found in the fetal trophoblastic cells with single nuclei as well as in erythrocytes of maternal and fetal blood. The percentage of positive cells for anti-CA-II in the trophoblastic cells did not change during development of gestation in the fetal bovine. CA-I and CA-III were not detected in the bovine placenta.

Carbonic anhydrase III in equine tissues and sera determined by a highly sensitive enzyme-immunoassay

A sensitive sandwich enzyme immunoassay (EIA) for measuring equine carbonic anhydrase III (CA-III) was established using a microplate as a solid-phase and peroxidase as a labelling enzyme. The assay can detect concentrations as low as 5 ng/ml using 20 microliters of sample sera. Within-run coefficients of variation obtained using standard equine CA-III were less than 5 per cent. CA-III levels in equine serum ranged from 5 to 50 ng/ml (n = 370), and apparently abnormal levels of CA-III from 100 to 1900 ng/ml (n = 27) were observed. The concentrations of immunoreactive CA-III in the extracts of various equine tissues were also determined; it was present at high concentrations in skeletal muscle and liver and to a much lesser extent in the thymus. Other tissues contained much smaller amounts.

Serum carbonic anhydrase III, an enzyme of type I muscle fibres, and the intensity of physical exercise

The effects of 30 min running with stepwise increasing intensity (exhaustive, energy demand approx. 50----100% of VO2max), 60 s supramaximal running (anaerobic, greater than or equal to 125% of VO2max) and 40-60 min low-intensity running (aerobic, 40-60% of VO2max) on serum concentration of muscle-derived proteins were studied in 5 male and 5 female elite orienteerers. S-Carbonic anhydrase III (S-CA III) was used as a marker of protein leakage from type I (slow oxidative) muscle fibres and S-myoglobin (S-Mb) as a non-selective (type I + II) muscular marker. The fractional increase in S-CA III (delta S-Ca III) was 0.37 +/- 0.09 (mean +/- SEM, p less than 0.001), 0.10 +/- 0.05 (N. S.) and 0.46 +/- 0.09 (p less than 0.001) 1 h after exhaustive, anaerobic and aerobic exercise, respectively. The corresponding values for delta S-Mb were 1.45 +/- 0.36 (p less than 0.001), 0.39 +/- 0.13 (p less than 0.01) and 0.67 +/- 0.18 (p less than 0.001). The value for the delta S-CA III/delta S-Mb ratio was 0.68 +/- 0.03 after the aerobic exercise, but only 0.25-0.26 (p vs. aerobic exercise less than 0.001) after the two high-intensity forms of exercise. Since type I fibres of skeletal muscle are known to be responsible for power production during low-intensity exercise, whereas fibres of both type I and type II are active at higher intensities, the delta S-CA III/delta S-Mb ratio may depend on the recruitment profile of type I vs. type I + II fibres.

Acetazolamide-sensitive and resistant carbonic anhydrase activity in rat and rabbit skeletal muscles of different fiber type composition

1. Acetazolamide (ACET)-resistant and -sensitive carbonic anhydrase (CA) activity was measured in post-mitochondrial supernatants from the soleus (SOL), deep vastus lateralis (DVL) and superficial vastus lateralis (SVL) muscles of rats and rabbits. 2. The relative total CA activity in the three muscles of both species can be summarized as SOL greater than DVL greater than SVL. 3. ACET-resistant CA activity was found in the SOL and DVL muscles of both species whereas a low level of ACET-sensitive CA activity was detected in the SVL muscle. 4. ACET-sensitive CA activity was also found in sarcoplasmic reticulum preparations from rat and rabbit SOL muscles.

Immunocytochemical localization of carbonic anhydrase isozyme III in equine thymus

Sections of equine thymus were examined for the presence of carbonic anhydrase (CA) isozymes by an immunohistochemical method. Carbonic anhydrase III, a major enzyme of skeletal muscle, was localized in some of the epithelial-reticular cells of the equine thymus. This finding suggests the presence of a new type of cell in the thymic cortex. The concentration of CA-III in the thymus was 17 micrograms/g wet tissue. CA-I and CA-II were not found in equine thymus.

The immunohistolocalization of carbonic anhydrase III in the submandibular gland of rats and hamsters

Carbonic anhydrase III has been localized using the avidin-biotin-glucose oxidase complex (ABC) method in the submandibular gland of the rat and hamster. This isozyme, which is predominant in skeletal muscle, was observed in intercalated duct, striated duct and excretory duct cells in the rat submandibular glands. In contrast, only some striated duct cells in hamster submandibular glands were stained.

Differential effects of distal and proximal nerve lesions on carbonic anhydrase activity in rat primary sensory neurons, ventral and dorsal root axons

The effect of proximal and distal peripheral nerve injuries on the histochemistry of carbonic anhydrase (CA) in rat dorsal root ganglion (DRG) neurons, and myelinated (MyF) dorsal and ventral root fibers was studied. Sciatic neurectomy induced no change. Contrariwise, 7 days after lumbar spinal nerve section the numbers of CA-stained ventral root MyF and DRG cells at the L4 and L5 levels decreased to 73.2% and 51.9% of their original values respectively, although the numbers returned to normal by the 90th postoperative day. Dorsal root MyF followed a similar trend, albeit with some delay. Major morphological changes comprised atrophy of dorsal root sensory neurons and axons, particularly in long term experiments, as well as nuclear eccentricity in DRG neurons. These results suggest that, depending on the site of lesion, the rat peripheral nervous system (PNS) either maintains or quickly restores its capacity to synthesize CA. They stand in contrast to the long-lasting metabolic dysfunctions reported to occur when primary neurons are disconnected from the periphery. It is uncertain whether this difference is due to the critical role of CA in neuronal metabolism.

Histochemical localization of carbonic anhydrase in normal and diseased human muscle

A method is described for histological localization of carbonic anhydrase (CA) in sections of frozen human muscle using the rapid and inexpensive histochemical technique of Hansson. Results obtained in normal subjects indicate clearly that CA reactive fibers are of type 1. Similarly, abnormalities seen with CA in the muscle biopsy of a patient presenting with type 1 fiber hypotrophy and preponderance duplicated almost exactly those observed with the actinomyosine adenosine triphosphatase and the reduced nicotinamide adenine dinucleotide dehydrogenase reactions. Observations of grouped CA-positive muscle fibers in a case of chronic neurogenic atrophy suggest that, like other enzymes, CA expression in muscle is under neurogenic control.

Carbonic anhydrase inhibition affects contraction of directly stimulated rat soleus

We have studied the contractile parameters of directly stimulated isolated rat soleus muscles incubated in media containing the carbonic anhydrase inhibitors chlorzolamide (5.10(-4)M) or cyanate (10(-2)M). Both inhibitors caused a decrease in isometric twitch and tetanic (5s) tensions and an increase in muscle relaxation time. It is speculated that among the three types of skeletal muscle carbonic anhydrase it may be the enzyme associated with the sarcoplasmatic reticulum whose inhibition caused the observed changes in contractile parameters.

Immunocytochemical localisation of carbonic anhydrase isozyme III in equine skeletal muscle

The location of carbonic anhydrase III (CA-III) in frozen sections of biopsies of Thoroughbred horse skeletal muscle was studied. Fibre types were determined by ATP-ase and succinate dehydrogenase staining. CA-III isozyme was detected using a peroxidase conjugated anti-CA-III antibody. CA-III was found to be localised in slow twitch oxidative fibres (ST), but was also present in fast twitch oxidative (FTH) fibres in small amounts. Fast twitch glycolytic (FT) fibres were stained lightly compared with control sections. The concentrations of CA-III in muscle and liver were 70 micrograms/mg protein and 4 micrograms/mg protein, respectively. CA-I and CA-II were not found in muscle extracts by the double immunodiffusion method.

The multiplicity of combinations of myosin light chains and heavy chains in histochemically typed single fibres. Rabbit tibialis anterior muscle

1. Combined histochemical and biochemical single-fibre analyses [Staron & Pette (1987) Biochem. J. 243, 687-693], were used to investigate the rabbit tibialis-anterior fibre population. 2. This muscle is composed of four histochemically defined fibre types (I, IIC, IIA and IIB). 3. Type I fibres contain slow myosin light chains LC1s and LC2 and the slow myosin heavy chain HCI, and types IIA and IIB contain the fast myosin light chains LC1f, LC2f and LC3f and the fast heavy chains HCIIa and HCIIb respectively. 4. A small fraction of fibres (IIAB), histochemically intermediate between types IIA and IIB, contain the fast light myosin chains but display a coexistence of HCIIa and HCIIb. 5. Similarly to the soleus muscle, C fibres in the tibialis anterior muscle contain both fast and slow myosin light chains and heavy chains. The IIC fibres show a predominance of the fast forms and the IC fibres (histochemically intermediate between types I and IIC) a predominance of the slow forms. 6. A total of 60 theoretical isomyosins can be derived from these findings on the distribution of fast and slow myosin light and heavy chains in the fibres of rabbit tibialis anterior muscle.

S100a0 (alpha alpha) protein, a calcium-binding protein, is localized in the slow-twitch muscle fiber

We previously showed that, in contrast to the distribution of S100b (beta beta), S100a0 (alpha alpha) is mainly present in human skeletal and heart muscles at the level of 1-2 micrograms/mg of soluble protein and is universally distributed at high levels in skeletal and heart muscles of various mammals. To elucidate cellular and ultrastructural localizations of the alpha subunit of S100 protein (S100-alpha) in skeletal muscle, we used immunohistochemical and enzyme immunoassay methods. The immunohistochemical study revealed that S100-alpha is mainly localized in slow-twitch muscle fibers, whereas the beta subunit of S100 protein (S100-beta) was not detected in both types of muscle fibers, an observation indicating that the predominant form of S100 protein in the slow-twitch muscle fiber is not S100a or S100b, but S100a0. The quantitative analysis using enzyme immunoassay corroborates the immunohistochemical finding: The S100-alpha concentration of mouse soleus muscle (mainly composed of slow-twitch muscle fibers) is about threefold higher than that of mouse rectus femoris muscle (mainly composed of fast-twitch muscle fibers). At the ultrastructural level, S100-alpha is associated with polysomes, sarcoplasmic reticulum, the plasma membrane, the pellicle around lipid droplets, the outer membrane of mitochondria, and thin and thick filaments, by immunoelectron microscopy.

Carbonic anhydrases

Some of the current studies of carbonic anhydrases are directed to the genetic mechanisms underlying their synthesis. Determination of the structure of their genes will probably most readily resolve the question of whether the membrane bound forms of the enzyme represent products of additional loci other than those of the three well-known soluble forms. Extensions of our knowledge of the sequences of these isozymes as well as those from lower animals and from plants will make possible a more precise evaluation of the extent of the multigene aspects of these proteins and their evolutionary backgrounds. Studies of the interrelationships of the regulation of the transcriptional and translational processes of the well-known isozymes and in particular the effects of hormones will be of interest. Insights into modifications of the isozymes' synthetic processes occurring in various diseases should also be forth-coming from these studies. In addition to the above the applications of what are perhaps today somewhat classical methods of protein chemistry will be needed to explore the reasons for the changes in activity accompanying the sequence variations of the different isozymes, the decreases or increases in activity accompanying derivatizations of specific residues and the reasons for the differences in the activity of different inhibitors on the various isozymes. The broad specificity of these enzymes for different substrates and the ability of CA-III to hydrolyze various phenyl esters and in some cases to become derivatized also present problems in protein structural chemistry. In terms of the latter reactions, the meaning of the relationships of these activities to those of the protein ubiquitin, which is homologous to CA-III, needs clarification. It would appear that various of the protein structural studies will be aided by crystallographic investigations of not only CA-III but of various of its derivatives which undergo either increases or decreases in activity. The above areas of studies present a wide variety of problems for workers in various disciplines and backgrounds who are interested in the carbonic anhydrases.

Serum carbonic anhydrase III in myotonic dystrophy

Serum carbonic anhydrase III (CAIII) levels were determined by means of an enzyme immunoassay method and were compared with serum creatine kinase (CK) and muscle-specific enolase (MSE) levels in 33 patients with myotonic dystrophy. Serum CAIII levels were elevated in all 33 patients, whereas serum CK and MSE levels were elevated in 12 and 10 patients, respectively. Serum CAIII levels showed a good correlation with CK levels, but a poor one with MSE levels. There was no obvious correlation between the serum CAIII level and the duration of illness or the age of the patient. These results suggest that serum CAIII is probably a more sensitive marker than CK and MSE in myotonic dystrophy and may also reflect the type 1 fiber abnormality more predominantly observed in myotonic dystrophy.

Carbonic anhydrase in the sarcoplasmic reticulum of rabbit skeletal muscle

Sarcoplasmic reticulum vesicles and mitochondria were prepared from red and white skeletal muscles of the rabbit. The preparations were characterized in terms of their specific activities of citrate synthase, basal (Mg2+-dependent) and Ca2+-dependent ATPase (the latter two in the presence of NaN3 and ouabain), and their specific carbonic anhydrase activities were determined. Skeletal muscle mitochondria had high specific activities of citrate synthase (700-1200 mu. mg protein-1) and low carbonic anhydrase activities (0.1-0.4 u. ml mg protein-1). The latter are likely to be due to a contamination of the preparations with sarcoplasmic reticulum (s.r.) Preparations of s.r. vesicles showed negligible activities of citrate synthase and the expected differing patterns of basal and Ca2+-dependent ATPase in red and white muscles. Specific carbonic anhydrase activities in s.r. from both muscle types were high (2-4 u. ml mg protein-1). The highest carbonic anhydrase activity, 11 u. ml mg protein-1, was found in s.r. from rabbit m. masseter. The inhibition constant of s.r. carbonic anhydrase towards acetazolamide was 4-6 X 10(-8) M and similar but not identical to that of cytosolic carbonic anhydrase II. It appears possible that the carbonic anhydrase II-like enzyme previously found by us in muscle homogenates (Siffert & Gros, 1982) originates from the s.r. Histochemical studies using the dansylsuphonamide method described previously (Dermietzel, Leibstein, Siffert, Zamboglou & Gros, 1985) showed an intracellular pattern of carbonic anhydrase staining compatible with the presence of the enzyme in s.r.: spots homogeneously distributed across the fibre cross-sections in transversely sectioned fibres and thin, longitudinally oriented, bands in longitudinally sectioned fibres. It is estimated that s.r. carbonic anhydrase accelerates CO2 hydration within the s.r. approximately 1000-fold. Thus, CO2 and HCO3- react fast enough to provide a rapid source and sink for protons leaving and entering the s.r. in exchange for Ca2+.

Immunoelectron microscopic localization of carbonic anhydrase III in rat skeletal muscle

The subcellular distribution of carbonic anhydrase III in rat soleus and vastus lateralis muscles was studied using an immunogold technique. The enzyme protein was found to be distributed diffusely in the cytoplasm of skeletal muscle cells. Red skeletal muscle (mainly type I fibers) revealed very strong immunogold staining whereas in white muscle (mainly type II fibers) gold particles were almost completely absent. No immunoreaction was observed in mitochondria or in other intracellular organelles.

Serum carbonic anhydrase III in neuromuscular disorders and in healthy persons after a long-distance run

A radioimmunosorbent technique was used for the assay of the skeletal muscle specific enzyme, carbonic anhydrase III (CA III). The usefulness of serum CA III determinations for detecting skeletal muscle damage was evaluated by comparing the serum levels of this enzyme and of myoglobin and creatine kinase in 64 patients with neuromuscular disorders and in 13 healthy volunteers before and after a long-distance run. Increased serum CA III levels were found in all patients with muscular dystrophy, chronic polymyositis and amyotrophic lateral sclerosis and in many with myasthenia gravis. In patients with polymyositis who were followed up with repeated blood sampling, the time courses of serum CA III levels, myoglobin levels and clinical symptoms were closely related. In all the runners the serum CA III level immediately after the run was increased. In the present study serum CA III and myoglobin seemed to be equally sensitive as biochemical markers of muscular damage and more sensitive than creatine kinase.

Purification and localization of human carbonic anhydrase. III. Typing of skeletal muscle fibers in paraffin embedded sections

Three different isoenzymes of human carbonic anhydrase are now well characterized. Carbonic anhydrase I and II have been known for several years and are located in high amounts in red blood cells as well as in many other tissues. Carbonic anhydrase III, a protein showing CO2 hydratase and p-nitrophenylphosphatase activity was isolated from skeletal muscle some years ago. Earlier observations based on enzyme activity and radioimmunoassay studies have suggested that this protein is present in greater quantities in red skeletal muscles than in white ones. We have purified CA III from human soleus muscle and using obtained monospecific polyclonal antibody localized this protein in the same muscle fibers which show acid resistant ATPase activity. Using this protein as a marker for type I muscle fibers, fiber classification into type I and II could now be done also from paraffin embedded sections.

Evaluation of carrier detection of Duchenne muscular dystrophy using carbonic anhydrase III and creatine kinase

Carbonic anhydrase III (CAIII) and creatine kinase (CK) were measured in plasma samples from a series of females at-risk as carriers of Duchenne muscular dystrophy and compared with control groups. Both plasma CAIII and CK levels were raised in a proportion of carriers. Although measurement of CAIII and CK was no more successful in identifying carriers than CK alone, CAIII could fulfill a useful confirmatory role, particularly for cases with a marginally elevated CK or where the sample is poorly preserved. The difference between the CK and CAIII results could indicate biochemical heterogeneity in the expression of Duchenne muscular dystrophy.

Immunohistochemical demonstration of carbonic anhydrase III and muscle-specific enolase in paraffin-embedded human skeletal muscle sections

We have demonstrated the histochemical fiber types of human skeletal muscle in paraffin sections by the immunohistochemical method, together with compatible observations previously made in frozen sections that carbonic anhydrase III is mainly localized in type 1 fibers (Shima et al. 1983), and muscle-specific enolase in type 2 fibers (Ibi et al. 1983). This method is useful to analyze the fiber types when frozen muscle samples at biopsy or autopsy cannot be obtained.

Fetal plasma carbonic anhydrase III in prenatal diagnosis of Duchenne muscular dystrophy

Carbonic anhydrase III (CAIII), a skeletal-muscle-specific enzyme which is elevated in the plasma of Duchenne muscular dystrophy (DMD) patients, was measured by radioimmunoassay in fetal plasma in order to evaluate its application to prenatal diagnosis of DMD. Using fetoscopy, pure fetal blood samples were taken at 17-24 weeks gestation from 25 fetuses at risk for DMD and from 78 control fetuses. Care was taken in the handling and storage of all samples. Normal sons were born in eight cases at risk for DMD. The CAIII levels in the infants were not significantly different from those of the control infants. Pregnancies were terminated in the remaining 17 at-risk cases. The CAIII levels in the fetuses were significantly different (p = 0.0034) from those of the control fetuses, although the distributions overlapped. Based on prior maternal risk, seven affected fetuses were expected in the terminated group; five had CAIII levels at or above the 95th centile of the control range. It is suggested that measurement of CAIII achieves partial discrimination between affected fetuses and their normal at-risk brethren.

Development of a highly sensitive enzyme-immunoassay for serum carbonic anhydrase-III

A highly sensitive sandwich enzyme-immunoassay (EIA) for human muscle carbonic anhydrase isozyme III (CA-III) has been developed using microplate as a solid-phase and peroxidase as a labelled enzyme. The assay can detect levels as low as 2 ng/ml when 20 microliter of sample sera were used. Sera from patients with various neurological diseases were studied using this method, and elevated serum CA-III levels were found in patients with Duchenne muscular dystrophy, limb-girdle dystrophy, fascioscapulohumeral dystrophy, polymyositis and amyotrophic lateral sclerosis. The values correlated well with the results of radioimmunoassay (RIA), with a correlation coefficient of 0.92 (P less than 0.001). We feel EIA is preferable to RIA for its simple methodology.

Distribution of immunoreactive carbonic anhydrase III in various human tissues determined by a sensitive enzyme immunoassay method

A sensitive sandwich enzyme immunoassay method for measurement of carbonic anhydrase III (CA-III) was established by use of purified antibodies to CA-III. The assay system consisted of polystyrene balls with immobilized antibody F(ab')2 fragments and the same antibody Fab' fragments labeled with beta-D-galactosidase from E. coli. The assay was highly sensitive and pg levels of CA-III were measureable. Coefficients of variation in within-run and between-run precision studies for serum CA-III were less than 10%. Serum CA-III levels in healthy subjects of various ages ranged from 0.8 to 24 ng/ml. Concentrations of immunoreactive CA-III in the extracts of various human tissues were also determined. Tissues composed of striated muscle contained more than 10 micrograms/mg protein of CA-III, whereas other tissues, including heart muscle, contained less than 0.5 microgram/mg protein. These results were consistent with other data showing that serum CA-III levels were raised in patients with progressive muscular dystrophy but not in those with acute myocardial infarction.

Inhibition properties and inhibition kinetics of an extracellular carbonic anhydrase in perfused skeletal muscle

We have investigated the properties of the carbonic anhydrase which is functionally available to CO2 and HCO3- in the capillary bed of skeletal muscle. We used essentially the indicator-dilution technique of Effros and Weissman (J. Appl. Physiol. 47, 1090-1098, 1979). Into hindlimbs of rabbits perfused with dextran solution we injected boli containing H14CO3- or 36Cl-, and 3H-dextran (MW 80 000) as an intravasal indicator, and observed the washout of these indicators by fractionated collection and analysis of the venous effluent. In agreement with previous studies we found that addition of 10(-4) M of the carbonic anhydrase inhibitor acetazolamide to the perfusate considerably speeds up the washout of 14C, reducing the extraction of 14C from 0.72 to 0.45. A half-maximal effect on 14C extraction was achieved with 1 x 10(-6) M acetazolamide (IC50). The carbonic anhydrase inhibitors methazolamide and benzolamide both yielded IC50 values of 10(-5) M. This pattern of inhibitory potency of the three sulfonamides is incompatible with their inhibitory effects on the two known cytosolic isoenzymes of skeletal muscle, CAII and CAIII. While cells take up acetazolamide and benzolamide extremely slowly, with half-times of several minutes to hours, the effect of both sulfonamides on 14C washout occurred very rapidly: less than 1 min, probably not more than a few seconds, were necessary to achieve inhibitory effects. We conclude that (1) a tissue carbonic anhydrase converts the injected H14CO3- quickly into 14CO2 which then diffuses into the intracellular space thus causing a washout of 14C that is much slower than that of the intravasal indicator or that of 36Cl-, (2) this carbonic anhydrase is not intra- but extracellular and presumably membrane-bound, and (3) its properties suggest that it is distinct from the well-known cytosolic carbonic anhydrases and represents a different isoenzyme.