Contribution of genetic and epigenetic mechanisms to Wnt pathway activity in prevalent skeletal disorders

We reported previously that the expression of Wnt-related genes is lower in osteoporotic hip fractures than in osteoarthritis. We aimed to confirm those results by analyzing β-catenin levels and explored potential genetic and epigenetic mechanisms involved.     

Role of osteoblast suppression in multiple myeloma

Multiple myeloma is the most common form of plasma cell dyscrasia and virtually all cases of myeloma exhibit osteolytic lesions, which result in bone pain, pathological fractures, spinal cord compression, and hypercalcaemia. Malignant plasma cells disrupt the delicate balance between bone formation and bone resorption, which ultimately leads to the debilitating osteolytic lesions. This review focuses principally on mechanisms of osteoblast inhibition by malignant plasma cells with emphasis placed on our experimental findings, which support a model for abnormal Wnt signaling in osteoblast suppression. We describe how excessive amounts of soluble Wnt inhibitors secreted by malignant plasma cells in multiple myeloma could promote osteolytic lesions, tumor growth, suppress hematopoiesis, prevent proper engraftment, and expansion of transplanted stem cells. Finally, we detail current therapies shown to disrupt the interaction between the myeloma cell and the microenvironment, leading to activation of osteoblasts.     

Characterization of Frzb-Cre transgenic mouse

The Wnt family of glycoproteins is involved in numerous developmental and disease processes in higher eukaryotes, exerting their action by binding to cell-surface receptors. In the extracellular space, Wnts are negatively regulated by secreted antagonists that either bind to the receptors directly (Dkk1) or to Wnt molecules themselves (Sfrp-FRZB family), preventing its subsequent binding to the receptor. Here we report on a transgenic mouse expressing Cre under the control of the mouse Frzb promoter element. Analysis of the Cre expression was carried out at 10.5 and 14.5 dpc using the ROSA26R mouse line. Expression of the transgenic construct was detected in the limbs, the heart, the nasal epithelium, bone, whiskers, and around the orbita of the eye. The mouse could be used for conditional gene modification in those tissues.     

FRZB as a key molecule in abdominal aortic aneurysm progression affecting vascular integrity

Abdominal aortic aneurysm (AAA), when ruptured, results in high mortality. The identification of molecular pathways involved in AAA progression is required to improve AAA prognosis. The aim of the present study was to assess the key genes for the progression of AAA and their functional role. Genomic and clinical data of three independent cohorts were downloaded from the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) ({"type":"entrez-geo","attrs":{"text":"GSE57691","term_id":"57691"}}GSE57691, {"type":"entrez-geo","attrs":{"text":"GSE7084","term_id":"7084"}}GSE7084, and {"type":"entrez-geo","attrs":{"text":"GSE98278","term_id":"98278"}}GSE98278). To develop AAA diagnosis and progression-related differentially expressed genes (DEGs), we used a significance analysis of microarray (SAM). Spearman correlation test and gene set analysis were performed to identify potential enriched pathways for DEGs. Only the Frizzled-related protein (FRZB) gene and chromosome 1 open reading frame 24 (C1orf24) exhibited significant down-regulation in all analyses. With FRZB, the pathways were associated with RHO GTPase and elastin fiber formation. With C1orf24, the pathways were elastic fiber formation, extracellular matrix organization, and cell–cell communication. Since only FRZB was evolutionally conserved in the vertebrates, function of FRZB was validated using zebrafish embryos. Knockdown of frzb remarkably reduced vascular integrity in zebrafish embryos. We believe that FRZB is a key gene involved in AAA initiation and progression affecting vascular integrity.