Molecular and Genetic Dissection of Arginine Methylation Regulation of Bone Mass.

• Applicant: Dr. Virginia Piombo
• Subject Area: Developmental Biology ; Evolutionary Cell and Developmental Biology (Zoology) ; Public Health, Healthcare Research, Social and Occupational Medicine
• Term: from 2013 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 241860841

Osteoporosis is a systemic disorder, which affects millions of people and is characterized by dysregulation of bone remodeling. Understanding the pathogenic mechanisms leading to the disruption of bone mass is of paramount importance to the development of effective pharmacological treatments for osteoporosis. Recent studies in human and animal models have demonstrated that many endocrine stimuli impinge on the posttranslational modifications of intracellular proteins to regulate deposition of new bone matrix by osteoblasts. During post-translational modification of many proteins, nitrogen atoms of arginine residues are covalently methylated by the action of protein arginine methyltransferases (PRMT). Arginine methylation plays important roles in multiple cellular processes, including inter cell communications using nitric oxide, RNA processing, transcriptional regulation, signal transduction, and protein-protein interactions. The functional consequences of alterations by arginine methylation in bone remodeling and in osteoporosis remain to be elucidated. I hypothesize that arginine methylation regulates critical intracellular pathways in the osteoblasts that regulate bone (patho)physiology. The main experimental evidences supporting this claim are: 1) Prmt genes are expressed in the osteoblasts and bone; and 2) preliminary study that Prmt expression is altered during osteoblasts proliferation and differentiation. The specific aims of this application are: Aim 1: Analysis of expression and regulation of Prmt genes in skeletal cells in vitro and in vivo. Aim 2: To define, using mouse models, the involvement of PRMT1 in the regulation of bone mass. Aim 3: To determine, using a combination of biochemical and pharmacological and genetic epistasis approaches in vitro and in vivo, the pathways in which PRMT1 functions. To achieve these aims we will use in vitro cultures and animal models for understanding the role of Prmts in osteoblasts. Dr. Yadav s laboratory has already generated conditional (for tissue specific deletion) knockout mice for Prmt 1. We will conditionally inactivate the selected Prmt in osteoblasts (Col1a1-Cre) to understand the role of these proteins in the regulation of bone mass. These mutant mice along with their wild-type (WT) littermates will be analyzed for: Skeletogenesis: Whole mount skeletal preparations and in situ hybridization of bone markers (Col1a1, Ocn, Osx, etc.) will be performed. We will analyze 4, 12 and 24 week old WT and mutant mice for changes in bone mass through microCT and histology and histomorphometry analysis. We will also use pharmacological modulators of arginine methylation in ovariectomy induced osteoporosis models to investigate their therapeutic relevance.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Vijay Yadav, Ph.D.