Article

Characterization of CA XIII, a Novel Member of the Carbonic Anhydrase Isozyme Family

University of Florence, Florens, Tuscany, Italy
Journal of Biological Chemistry (Impact Factor: 4.57). 02/2004; 279(4):2719-27. DOI: 10.1074/jbc.M308984200
Source: PubMed

ABSTRACT

The carbonic anhydrase (CA) gene family has been reported to consist of at least 11 enzymatically active members and a few
inactive homologous proteins. Recent analyses of human and mouse databases provided evidence that human and mouse genomes
contain genes for still another novel CA isozyme hereby named CA XIII. In the present study, we modeled the structure of human
CA XIII. This model revealed a globular molecule with high structural similarity to cytosolic isozymes, CA I, II, and III.
Recombinant mouse CA XIII showed catalytic activity similar to those of mitochondrial CA V and cytosolic CA I, with kcat/Km of 4.3 × 107 m–1 s–1, and kcat of 8.3 × 104 s–1. It is very susceptible to inhibition by sulfonamide and anionic inhibitors, with inhibition constants of 17 nm for acetazolamide, a clinically used sulfonamide, and of 0.25 μm, for cyanate, respectively. Using panels of cDNAs we evaluated human and mouse CA13 gene expression in a number of different tissues. In human tissues, positive signals were identified in the thymus, small
intestine, spleen, prostate, ovary, colon, and testis. In mouse, positive tissues included the spleen, lung, kidney, heart,
brain, skeletal muscle, and testis. We also investigated the cellular and subcellular localization of CA XIII in human and
mouse tissues using an antibody raised against a polypeptide of 14 amino acids common for both human and mouse orthologues.
Immunohistochemical staining showed a unique and widespread distribution pattern for CA XIII compared with the other cytosolic
CA isozymes. In conclusion, the predicted amino acid sequence, structural model, distribution, and activity data suggest that
CA XIII represents a novel enzyme, which may play important physiological roles in several organs.

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    • "However, CA III deficiency in mice results only in a mild muscle defect [16], pointing at some compensatory events by other isoenzymes. CA XIII shows a widespread distribution in adult human and murine tissues [17]. "
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    ABSTRACT: Carbonic anhydrases (CAs) play fundamental roles in several physiological events, and emerging evidence points at their involvement in an array of disorders, including cancer. The expression of CAs in the different cells of teeth is unknown, let alone their expression patterns during odontogenesis. As a first step towards understanding the role of CAs during odontogenesis, we used immunohistochemistry, histochemistry and in situ hybridization to reveal hitherto unknown dynamic distribution patterns of eight CAs in mice. The most salient findings include expression of CAII/Car2 not only in maturation-stage ameloblasts (MA) but also in the papillary layer, dental papilla mesenchyme, odontoblasts and the epithelial rests of Malassez. We uncovered that the latter form lace-like networks around incisors; hitherto these have been known to occur only in molars. All CAs studied were produced by MA, however CAIV, CAIX and CARPXI proteins were distinctly enriched in the ruffled membrane of the ruffled MA but exhibited a homogeneous distribution in smooth-ended MA. While CAIV, CAVI/Car6, CAIX, CARPXI and CAXIV were produced by all odontoblasts, CAIII distribution displayed a striking asymmetry, in that it was virtually confined to odontoblasts in the root of molars and root analog of incisors. Remarkably, from initiation until near completion of odontogenesis and in several other tissues, CAXIII localized mainly in intracellular punctae/vesicles that we show to overlap with LAMP-1- and LAMP-2-positive vesicles, suggesting that CAXIII localizes within lysosomes. We showed that expression of CAs in developing teeth is not confined to cells involved in biomineralization, pointing at their participation in other biological events. Finally, we uncovered novel sites of CA expression, including the developing brain and eye, the olfactory epithelium, melanoblasts, tongue, notochord, nucleus pulposus and sebaceous glands. Our study provides important information for future single or multiple gene targeting strategies aiming at deciphering the function of CAs during odontogenesis.
    Full-text · Article · May 2014 · PLoS ONE
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    • "The mammalian α-CA gene family includes at least 15 enzymatically active isoforms with different structural and catalytic properties. Six of the active CA isozymes are cytosolic (CA-I, -II, -III, -VII, -VIII, and -XIII), 4 are membrane-associated (CA-IV, -IX, -XII, and -XIV), 2 are mitochondrial (CA-VA and CA-VB), and 1 is secretory form (CA-VI), while 2 CA-related proteins (CA-X and XI) are inactive variants [1-3]. The physiological function of carbonic anhydrase is to maintain the acid–base balance in various tissues and biological fluids [4]. "
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    Full-text · Article · Feb 2014 · BMC Research Notes
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    • "The CA reaction is involved in many physiological and pathological processes, including: respiration and transport of CO 2 and bicarbonate between metabolizing tissues and lungs; pH and CO 2 homeostasis; electrolyte secretion in various tissues and organs; biosynthetic reactions such as gluconeogenesis, lipogenesis and ureagenesis; bone resorption; calcification ; and tumourigenicity [24] [25] [26] [27] [28] [29] [30]. Many of the CA isoenzymes involved in these processes are important therapeutic targets with the potential to be inhibited and to treat a range of disorders, including oedema, glaucoma, obesity, cancer, epilepsy and osteoporosis [31] [32] [33] [34] [35]. "
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    Full-text · Article · Jan 2014 · Macedonian Journal of Chemistry and Chemical Engineering
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