Differentially expressed genes in autosomal dominant osteopetrosis type II osteoclasts reveal known and novel pathways for osteoclast biology

Abstract

Autosomal dominant osteopetrosis type II (ADO II) is a rare, heritable bone disorder characterized by a high bone mass and insufficient osteoclast activity. Mutations in the CLCN7 gene have been reported to cause ADO II. To gain novel insights into the pathways dysregulated in ADOII osteoclasts, we identified changes in gene expression in osteoclasts from patients with a heterozygous mutation of CLCN7. To do this, we carried out a transcriptomic study comparing gene expression in the osteoclasts of patients with ADO II and healthy donors. Our data show that, according to our selection criteria, 182 genes were differentially expressed in osteoclasts from patients and controls. From the 18 displaying the highest change in microarray, we confirmed differential expression for seven by qPCR. Although two of them have previously been found to be expressed in osteoclasts (ITGB5 and SERPINE2), the other five (CES1 (carboxyl esterase 1), UCHL1 (ubiquitin carboxy-terminal esterase L1, also known as ubiquitin thiolesterase), WARS (tryptophanyl-tRNA synthetase), GBP4 (guanylate-binding protein 4), and PRF1) are not yet known to have a role in this cell type. At the protein level, we confirmed elevated expression of ITGB5 and reduced expression of WARS, PRF1, and SERPINE2. Transfection of ClC-7 harboring the G215R mutation into osteoclasts resulted in an increased ITGB5 and reduced PRF1 expression of borderline significance. Finally, we observed that the ADO II patients presented a normal or increased serum level of bone formation markers, demonstrating a coupling between dysfunctional osteoclasts and osteoblasts. Sphingosine kinase 1 mRNA was expressed at the same level in ADO II and control osteoclasts. In conclusion, these data suggest that in addition to an acidification dysfunction caused by the CLCN7 mutation, a change in ITGB5, PRF1, WARS, and SERPINE2 expression could be part of the osteoclastic phenotype of ADO II.

Is there a relationship between solubility and resorbability of different calcium phosphate phases in vitro ?

“…For that reason, our choice has settled on polymerase (RNA) II polypeptide A (PolR2a), the second closest gene to C t = 25, having C t = 24.485, and the one with the highest uniformity of expression among all the eight genes falling within 23 < C t < 27, having the SD of 0.046. To determine that RAW 264.7 cells did indeed differentiate into an osteoclastic cell type, real-time qPCR was used to measure the expression levels of two different markers of osteoclast differentiation, cathepsin K (CTSK) and Acp5 (TRAP) [55]. Analysis of CTSK and TRAP, Fig.…”

Effects of Negative Pressure Wound Therapy on Mesenchymal Stem Cells Proliferation and Osteogenic Differentiation in a Fibrin Matrix

“…It has been proven that osteoclast maturation is accelerated in mice that lack integrin β5 subunit [36]. And, the expression level of integrin β5 in osteoclast from autosomal dominant osteopetrosis type II (ADO II) patients is higher than normal donors [37]. These results indicate that integrin β5 could inhibit osteoclast formation and may participate in NPWT driven oseogenesis through enhance osteoblastic differentiation and decrease osteoclast formation.…”

Enhanced but hypofunctional osteoclastogenesis in an autosomal dominant osteopetrosis type II case carrying a c.1856C>T mutation in CLCN7

“…These inconsistent gene profiles may be due to the differences in OC formation and functions. 33 A previous study suggested that the polymorphisms on the non-disease allele of CLCN7 and a modifier gene(s) located in chromosome 9q21–22 may affect ADO2 disease status and severity. 34 The variability in osteoclast functions and clinical phenotypes of ADO2 deserves further investigation.…”