Transcriptomic Differences Underlying the Activin-A Induced Large Osteoclast Formation in Both Healthy Control and Fibrodysplasia Ossificans Progressiva Osteoclasts

• Published in: International journal of molecular sciences 2023-04, Vol.24 (7), p.6822
• Main Authors: Schoenmaker, Ton, Zwaak, Joy, Loos, Bruno G, Volckmann, Richard, Koster, Jan, Eekhoff, E Marelise W, de Vries, Teun J
• Format: Article
• Language: English
• Subjects: Activin; Activin Receptors, Type I - genetics; Activin Receptors, Type I - metabolism; Activin-A; Activins - metabolism; Analysis; Bones; CD14 antigen; Cell adhesion & migration; Cell culture; Cell differentiation; Cell fusion; cell size; fibrodysplasia ossificans progressiva; Gene expression; Genes; Genetic disorders; Growth factors; Humans; Kinases; Ligands; Monocytes; Mutation; Myositis ossificans; Myositis Ossificans - genetics; Myositis Ossificans - metabolism; Ossification (ectopic); Ossification, Heterotopic - genetics; osteoclast; Osteoclastogenesis; Osteoclasts; Osteoclasts - metabolism; Principal components analysis; RNA sequencing; RNAseq; Sequence analysis; Soft tissues; Stem cells; Transcriptome; Transcriptomics; Variability
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24076822

Fibrodysplasia Ossificans Progressiva (FOP) is a very rare genetic disease characterized by progressive heterotopic ossification (HO) of soft tissues, leading to immobility and premature death. FOP is caused by a mutation in the Activin receptor Type 1 (ACVR1) gene, resulting in altered responsiveness to Activin-A. We recently revealed that Activin-A induces fewer, but larger and more active, osteoclasts regardless of the presence of the mutated ACVR1 receptor. The underlying mechanism of Activin-A-induced changes in osteoclastogenesis at the gene expression level remains unknown. Transcriptomic changes induced by Activin-A during osteoclast formation from healthy controls and patient-derived CD14-positive monocytes were studied using RNA sequencing. CD14-positive monocytes from six FOP patients and six age- and sex-matched healthy controls were differentiated into osteoclasts in the absence or presence of Activin-A. RNA samples were isolated after 14 days of culturing and analyzed by RNA sequencing. Non-supervised principal component analysis (PCA) showed that samples from the same culture conditions (e.g., without or with Activin-A) tended to cluster, indicating that the variability induced by Activin-A treatment was larger than the variability between the control and FOP samples. RNA sequencing analysis revealed 1480 differentially expressed genes induced by Activin-A in healthy control and FOP osteoclasts with (adj) < 0.01 and a Log2 fold change of ≥±2. Pathway and gene ontology enrichment analysis revealed several significantly enriched pathways for genes upregulated by Activin-A that could be linked to the differentiation or function of osteoclasts, cell fusion or inflammation. Our data showed that Activin-A has a substantial effect on gene expression during osteoclast formation and that this effect occurred regardless of the presence of the mutated ACVR1 receptor causing FOP.