Assessing type I collagen expression and quality in cellular models of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a group of genetic disorders of bone formation characterized by soft and shorter brittle bones in affected individuals. OI is generally considered a collagenopathy resulting from abnormal expression of type I collagen. As assay system to detect the cellular level and quality of type I collagen would help in rapid and correct detection of OI from the diagnostic perspectives. Here, we report an immunofluorescence assay for detection of type I collagen in fibroblast models of OI and represented them into two broad categories based on the expression level and aggregation characteristics of pro‐α1(I). Cell phenotypic assays of pro‐α1(I) in OI‐related gene knocked down fibroblasts revealed aggregates of pro‐α1(I) in conditions with knockdown of SERPINF1, CRTAP, P3H1, PPIB, SERPINH1, FKBP10, TMEM38B, MESD, and KDELR2, whereas pro‐α1(I) expression was very low in fibroblasts which had knockdown of IFITM5, SP7, BMP1, WNT1, CREB3L1, MBTPS2, and CCDC134. The expression of pro‐α1(I) showed abundant and non‐aggregated distribution in the fibroblasts with knockdown of non‐OI skeletal disorder‐related genes (RAB33B and IFT52). The in vitro assay accurately detected abnormally expressed pro‐α1(I) levels in cellular models of various types of OI. Thus, this procedure represents a promising point‐of‐detection assay for potential diagnosis and therapeutic decisions in OI. [ABSTRACT FROM AUTHOR]