Enhanced p53 Levels Are Involved in the Reduced Mineralization Capacity of Osteoblasts Derived from Shwachman–Diamond Syndrome Subjects

• Published in: International journal of molecular sciences Vol. 22; no. 24; p. 13331
• Main Authors: Frattini, Annalisa, Bolamperti, Simona, Valli, Roberto, Cipolli, Marco, Pinto, Rita Maria, Bergami, Elena, Frau, Maria Rita, Cesaro, Simone, Signo, Michela, Bezzerri, Valentino, Porta, Giovanni, Khan, Abdul Waheed, Rubinacci, Alessandro, Villa, Isabella
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11.12.2021; MDPI
• Subjects: Biopsy; Calcification, Physiologic; Cells, Cultured; Chromosomes; Female; Gene expression; Humans; Male; Mineralization; Morphology; Mutation; Osteoblasts - metabolism; Osteoblasts - pathology; Patients; Proteins; Proteins - genetics; Proteins - metabolism; Shwachman-Diamond Syndrome - genetics; Shwachman-Diamond Syndrome - metabolism; Shwachman-Diamond Syndrome - pathology; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism; bone cells; ribosomopathies; mineralization; transcriptome; p53
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms222413331

Shwachman–Diamond syndrome (SDS) is a rare autosomal recessive disorder characterized by bone marrow failure, exocrine pancreatic insufficiency, and skeletal abnormalities, caused by loss-of-function mutations in the SBDS gene, a factor involved in ribosome biogenesis. By analyzing osteoblasts from SDS patients (SDS-OBs), we show that SDS-OBs displayed reduced SBDS gene expression and reduced/undetectable SBDS protein compared to osteoblasts from healthy subjects (H-OBs). SDS-OBs cultured in an osteogenic medium displayed a lower mineralization capacity compared to H-OBs. Whole transcriptome analysis showed significant differences in the gene expression of SDS-OBs vs. H-OBs, particularly in the ossification pathway. SDS-OBs expressed lower levels of the main genes responsible for osteoblastogenesis. Of all downregulated genes, Western blot analyses confirmed lower levels of alkaline phosphatase and collagen type I in SDS-OBs than in H-OBs. Interestingly, SDS-OBs showed higher protein levels of p53, an inhibitor of osteogenesis, compared to H-OBs. Silencing of Tp53 was associated with higher collagen type I and alkaline phosphatase protein levels and an increase in SDS-OB mineralization capacity. In conclusion, our results show that the reduced capacity of SDS-OBs to mineralize is mediated, at least in part, by the high levels of p53 and highlight an important role of SBDS in osteoblast functions.