Carbonic anhydrase III protects osteocytes from oxidative stress

Abstract

Osteocytes are master orchestrators of bone remodeling; they control osteoblast and osteoclast activities both directly cell-to-cell communication and indirectly secreted factors, and they are the main postnatal source of sclerostin and RANKL (receptor activator of NF-kB ligand), two regulators of osteoblast and osteoclast function. Despite progress in understanding osteocyte biology and function, much remains to be elucidated. Recently developed osteocytic cell lines-together with new genome editing tools-has allowed a closer look at the biology and molecular makeup of these cells. By using single-cell cloning, we identified genes that are associated with high Sost/sclerostin expression and analyzed their regulation and function. Unbiased transcriptome analysis of high- low-Sost/sclerostin-expressing cells identified known and novel genes. Dmp1 (dentin matrix protein 1), Dkk1 (Dickkopf WNT signaling pathway inhibitor 1), and Phex were among the most up-regulated known genes, whereas Srpx2, Cd200, and carbonic anhydrase III (CAIII) were identified as novel markers of differentiated osteocytes. Aspn, Enpp2, Robo2, Nov, and Serpina3g were among the transcripts that were most significantly suppressed in high-Sost cells. Considering that CAII was recently identified as being regulated by Sost/sclerostin and capable of controlling mineral homeostasis, we focused our attention on CAIII. Here, we report that CAIII is highly expressed in osteocytes, is regulated by parathyroid hormone both and , and protects osteocytes from oxidative stress.-Shi, C., Uda, Y., Dedic, C., Azab, E., Sun, N., Hussein, A. I., Petty, C. A., Fulzele, K., Mitterberger-Vogt, M. C., Zwerschke, W., Pereira, R., Wang, K., Divieti Pajevic, P. Carbonic anhydrase III protects osteocytes from oxidative stress.

Overexpression of transcription factor Foxa1 and target genes remediate therapeutic protein production bottlenecks in Chinese hamster ovary cells

“…Ca3 upregulation was also observed in the easy‐ and difficult‐to‐express protein high producer clones as well as in Foxa1‐overexpressing cells and to a lesser extent in Tagap‐overexpressing cells. Notably, Ca3 was shown to inhibit H 2 O 2 ‐induced apoptosis and to reduce H 2 O 2 ‐induced ROS activity (Raisanen et al, 1999; Shi et al, 2018). It was also shown to protect cells against hypoxic stress (reviewed in Di Fiore et al, 2018).…”

Gene expression profiling in the hippocampus of adolescent rats after chronic alcohol administration

“…Some studies have reported that an increase in CA3 inhibited death of osteocytes and nucleus pulposus cells of rats due to hydrogen peroxide, showing that CA3 is an important factor in protecting cell viability against oxidative stress. 62,63 Another study demonstrated that CA3 was decreased in the damaged hepatocytes of adult rats exposed to alcohol, suggesting that CA3 could be a biomarker of hepatocyte injury by alcohol. 64 We also found that chronic treatment of alcohol induced down-regulation of Car3 mRNA in the hippocampus of adolescent rats.…”

Ex Vivo Organ Cultures as Models to Study Bone Biology

“…Ex vivo bone organ cultures have been used extensively to better understand the functions of osteocytes in bone. Using this approach, it was demonstrated that direct effects on osteocytes mediate some of the actions of Parathyroid hormone (PTH) on the skeleton . For instance, the pro‐resorptive actions of PTH are associated with upregulation of the pro‐osteoclastogenic cytokine Rankl .…”

“…More recently, ex vivo osteocyte‐enriched organ cultures were used to study the expression and regulation of carbonic anhydrase III in osteocytes. It was found that carbonic anhydrase III is highly expressed in osteocytes; it is regulated by PTH, and protects osteocytes from oxidative stress …”

“…Using this approach, it was demonstrated that direct effects on osteocytes mediate some of the actions of Parathyroid hormone (PTH) on the skeleton. (21)(22)(23)(24)(25)(26) For instance, the pro-resorptive actions of PTH are associated with upregulation of the pro-osteoclastogenic cytokine Rankl. (27)(28)(29) Using genetic approaches, our group found in vivo that PTH signaling in osteocytes increases Rankl expression in bone through the distal control region (DCR) of the Rankl promoter.…”