Work

Osteoblasts and osteoclasts generation from iPSCs to study CFTR role in cystic fibrosis-related bone disease

Year: 2022

Type: article

Abstract: Introduction: Osteogenesis Imperfecta (OI) is a rare inherited connective tissue diseases family sharing bone deformities and fragility.Mutations in the TMEM38B cause the autosomal recessive OI type XIV.This gene encodes a trimeric intracellular cation channel B (TRIC-B) present in the rER membrane where it acts as monovalent K + channel necessary to regulate intracellular Ca 2+ flux.The molecular basis of the OI type XIV phenotype is still puzzling the field.Purpose: The aim of the project was to evaluate the TRIC-B function in vivo, specifically in the bone tissue.To this purpose, we generated and characterized a Tmem38b osteoblast specific conditional knock-out mouse (Runx2Cre;Tmem38b fl/fl ).Methods: The Cre/loxP system was used to remove the exon 3 from the Tmem38b gene specifically in osteoblasts using mice expressing Cre recombinase under the Runx2 promoter (Ethical approval N 8/2019-PR).The genomic targeting was confirmed by sequencing and the lack of TRIC-B by western blot.The mouse model was characterized by x-ray, micro computed tomography (microCT) and skeletal staining.The impact of loss of TRIC-B function on osteoblasts activity was then investigated in vitro using primary osteoblasts.Results: Long bone deformity and fractures and vertebral mineralization delay were detected in the Runx2Cre;Tmem38b fl/fl skeleton.The mutant mice were also significantly smaller than WT littermates (pb0.05).microCT analysis revealed a severe osteoporotic phenotype affecting both the cortical (bone volume/ total volume, BV/TV 41.17% in mutant versus 48.75% in WT, pb0.05) and the trabecular (BV/TV 1.43% versus 3.43%, pb0.05) compartments.Mineralization (3.2% versus 5.4%) and alkaline phosphatase activity (3.9 U/mg versus 10.1 U/mg, pb0.05) were decreased in vitro in mutant osteoblasts and the analyses of osteoblastogenic genes expression revealed a delay in differentiation. Conclusion:The presence of an osteoporotic phenotype in the Runx2Cre;Tmem38b fl/fl mouse demonstrated the primary function of TRIC-B expressed in osteoblasts for bone development.

Source: Bone Reports

DOI: 10.1016/j.bonr.2022.101286

Authors: Claire Dumortier, Frédéric Velard, Andrew Frauenpreis, Soula Danopoulos, Denise Al Alam

Institutions: Biomatériaux et Inflammation en Site Osseux, Université de Reims Champagne-Ardenne, The Lundquist Institute, Harbor–UCLA Medical Center

Language: English

Topic: Bone Metabolism and Diseases

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,060