Nucleotide sequence and structure of the mouse carbonic anhydrase III gene

Sexual dimorphism in LEC rat liver: suppression of carbonic anhydrase III by copper accumulation during hepatocarcinogenesis

We examined age-related changes in the protein expression of carbonic anhydrase III (CAIII) in livers of Long-Evans with a cinnamon-like color (LEC) rats using an agouti color (LEA) rats as controls. The levels of the protein of CAIII in the liver of LEC male rats increased before 20 weeks of age, at the stage of acute hepatitis, and were decreased at 54 weeks of age, while those of CAIII in the liver of LEA male rats were highly expressed at all ages. In the normal LEA rats, CAIII showed sexual dimorphism. The level of CAIII in LEA male rat liver relative to female was four times higher. On the other hand, young LEC rat (at 4-12 weeks) showed a higher protein level of CAIII than LEA rats, and then decreased during development of hepatitis. CAIII mRNA also decreased in the LEC rat liver during hepatocarcinogenesis. The level of CAIII in the tumor region was lower than that in the tumor-free region. Immunohistochemical analysis showed that glutathione S-transferase P (GST-P) was positive and CAIII was negative in the precancerous region. The expression of CAIII was suppressed in cancerous lesions in hepatoma-bearing LEC rat liver compared to uninvolved surrounding tissues. These results indicated that suppression of CAIII accompanied hepatocarcinogenesis and it is a secondary consequence of the high copper levels in the liver.

EST-based identification of genes expressed in brain and spinal cord of Gekko japonicus, a species demonstrating intrinsic capacity of spinal cord regeneration

In the present study, a brain and spinal cord cDNA library of Gekko japonicus was constructed, and 2349 unique expressed sequence tags (ESTs), composed of 494 clusters and 1855 singletons, were determined from 4108 randomly selected clones. Of these sequences, 54.8% (1287/2349) ESTs are identified as known genes and 45.2% (1062/2349), as unknown genes. The identified ESTs were classified with respect to their functional categorization; both the housekeeping genes and the nervous system-related genes were well represented in the library. The complete open reading frame (ORF)-containing clones derived from the library were identified as well; 303 clones were obtained to date. Finally, two clones with sequence homology to endothelial differentiation-related factor 1 (EDF-1) and to myelin-associated glycoprotein (MAG) precursor were selected, and their expression patterns in normal and regenerating spinal cord were analyzed by RT-PCR. Both of them were expressed in the spinal cord, and the expression level decreased significantly after tail amputation. This study provides a preliminary view of the gene expression profiles of the central nervous system in gecko, and it might accelerate the process of gene discovery and function analysis in this organism, which demonstrates an intrinsic capacity of spinal cord regeneration.

A quantitative study of bioenergetics in skeletal muscle lacking carbonic anhydrase III using 31P magnetic resonance spectroscopy

Oxidative slow skeletal muscle contains carbonic anhydrase III in high concentration, but its primary function remains unknown. To determine whether its lack handicaps energy metabolism and/or acid elimination, we measured the intracellular pH and energy phosphates by (31)P magnetic resonance spectroscopy in hind limb muscles of wild-type and CA III knockout mice during and after ischemia and intense exercise (electrical stimulation). Thirty minutes of ischemia caused phosphocreatine (PCr) to fall and P(i) to rise while pH and ATP remained constant in both strains of mice. PCr and P(i) kinetics during ischemia and recovery were not significantly different between the two genotypes. From this we conclude that under neutral pH conditions resting muscle anaerobic metabolism, the rate of the creatine kinase reaction, intracellular buffering of protons, and phosphorylation of creatine by mitochondrial oxygen metabolism are not influenced by the lack of CA III. Two minutes of intense stimulation of the mouse gastrocnemius caused PCr, ATP, and pH to fall and ADP and P(i) to rise, and these changes, with the exception of ATP, were all significantly larger in the CA III knockouts. The rate of return of pH and ADP to control values was the same in wild-type and mutant mice, but in the mutants PCr and P(i) recovery were delayed in the first minute after stimulation. Because the tension decrease during fatigue is known to be the same in the two genotypes, we conclude that a lack of CA III impairs mitochondrial ATP synthesis.

Phenotypic responses to mechanical stress in fibroblasts from tendon, cornea and skin

Primary fibroblasts isolated from foetal mouse cornea, skin and tendon were subjected to linear shear stress and analysed for morphological parameters and by microarray, as compared with unstimulated controls. Approx. 350 genes were either up- or down-regulated by a significant amount, with 51 of these being common to all three cell types. Approx. 50% of altered genes in tendon and cornea fibroblasts were changed in common with one of the other cell types, with the remaining approx. 50% being specific to tendon or cornea. In skin fibroblasts, however, less than 25% of genes whose transcription was altered were specific only to skin. The functional spectrum of genes that were up- or down-regulated was diverse, with apparent house-keeping genes forming the major category of up-regulated genes. However, a significant number of genes associated with cell adhesion, extracellular matrix and matrix remodelling, as well as cytokines and other signalling factors, were also affected. Somewhat surprisingly, in these latter categories the trend was towards a reduction in mRNA levels. Verification of the mRNA quantity of a subset of these genes was performed by reverse transcriptase PCR and was found to be in agreement with the microarray analysis. These findings provide the first in-depth analysis of phenotypic differences between fibroblast cells from different tissue sources and reveal the responses of these cells to mechanical stress.

Carbonic anhydrase III is not required in the mouse for normal growth, development, and life span

Carbonic anhydrase III is a cytosolic protein which is particularly abundant in skeletal muscle, adipocytes, and liver. The specific activity of this isozyme is quite low, suggesting that its physiological function is not that of hydrating carbon dioxide. To understand the cellular roles of carbonic anhydrase III, we inactivated the Car3 gene. Mice lacking carbonic anhydrase III were viable and fertile and had normal life spans. Carbonic anhydrase III has also been implicated in the response to oxidative stress. We found that mice lacking the protein had the same response to a hyperoxic challenge as did their wild-type siblings. No anatomic alterations were noted in the mice lacking carbonic anhydrase III. They had normal amounts and distribution of fat, despite the fact that carbonic anhydrase III constitutes about 30% of the soluble protein in adipocytes. We conclude that carbonic anhydrase III is dispensable for mice living under standard laboratory husbandry conditions.