Carbonic anhydrases IV and IX: subcellular localization and functional role in mouse skeletal muscle

Abstract

The subcellular localization of carbonic anhydrase (CA) IV and CA IX in mouse skeletal muscle fibers has been studied immunohistochemically by confocal laser scanning microscopy. CA IV has been found to be located on the plasma membrane as well as on the sarcoplasmic reticulum (SR) membrane. CA IX is not localized in the plasma membrane but in the region of the t-tubular (TT)/terminal SR membrane. CA IV contributes 20% and CA IX 60% to the total CA activity of SR membrane vesicles isolated from mouse skeletal muscles. Our aim was to examine whether SR CA IV and TT/SR CA IX affect muscle contraction. Isolated fiber bundles of fast-twitch extensor digitorum longus and slow-twitch soleus muscle from mouse were investigated for isometric twitch and tetanic contractions and by a fatigue test. The muscle functions of CA IV knockout (KO) fibers and of CA IX KO fibers do not differ from the function of wild-type (WT) fibers. Muscle function of CA IV/XIV double KO mice unexpectedly shows a decrease in rise and relaxation time and in force of single twitches. In contrast, the CA inhibitor dorzolamide, whether applied to WT or to double KO muscle fibers, leads to a significant increase in rise time and force of twitches. It is concluded that the function of mouse skeletal muscle fibers expressing three membrane-associated CAs, IV, IX, and XIV, is not affected by the lack of one isoform but is possibly affected by the lack of all three CAs, as indicated by the inhibition studies.

Carbonic anhydrase in minor salivary glands of quail: histochemistry versus immunohistochemistry

“…Rather, using antisera to human CAIV, a specific immunostaining, fully coincident with the histochemical staining, was found in the villus cavity cells of the chick chorioallantoic membrane 20 . Although a conclusive characterization of such a membrane-associated CA remains to be achieved, its functional meaning might be consistent with that attributed to mammalian CAIV at the different sites where it proved to be expressed [22][23][24][25] . In the quail lingual glands, a putative membrane-associated CA isoform at the basolateral borders of the secretory cells might serve, analogously to CAIV isoenzyme, to regulate the extracellular pH and, thereby, contribute to maintaining the balance of the oral environment.…”

Expression of carbonic anhydrase in the fetal eye and extra-ocular tissues

“…However, we did not ensure it due to unknown reasons. CA9 is known to express in the fetal musculoskeletal system to maintain pH against hypoxia (Schultz et al, 2011;Liao et al, 2009;Scheibe et al, 2008). Strong CA9 expression in the cartilaginous pulley and the tendon of the superior obliquus muscle seemed to correspond to a fact that the adjacent fetal joint surfaces are positive for CA9 (Schultz et al, 2011) and suggested a mechanical stress between the developing pulley and tendon.…”

“…Notably, in contrast to other CAs isoenzymes, CA9 expression was reported in fetal joint cartilages, tendons and ligaments those receive mechanical stress due to increased size of the adjacent structures (Schultz et al, 2011;Liao et al, 2009;Scheibe et al, 2008). Therefore, we attempted to clarify spatial expression of CAs, especially CA9, in human fetus extra-occular tissues.…”

Caveolin 3, Flotillin 1 and Influenza Virus Hemagglutinin Reside in Distinct Domains on the Sarcolemma of Skeletal Myofibers

“…Flotillin 2 is not expressed in skeletal muscle cells [32]; however, there may still be an unknown partner for flotillin 1 to form flask structures. It is notable that the glycophosphatidylinositol-anchored carbonic anhydrase IV was recently localized to transverse tubule openings in mouse skeletal myofibers [33], and it is possible that this protein and flotillin 1 reside in the same lipid rafts.…”