Bone Abstracts

OPTN seems to have an important role in bone metabolism by being part of NfkB pathway. CCDC3 is highly expressed in adipocytes and it seems to be negatively regulated by TNFa, however the mechanisms are not very clear. These genes have a ‘head-to-head’ orientation in the genome, which suggests that they might be regulated by a bidirectional promoter that coordinates the expression of both genes in different tissues. Using bioinformatic tools we analyzed the shared region between OPTN and CCDC3 to look for NFkB putative binding sites and performed several deletion constructs to identify the most important region within the bidirectional promoter and by transfection and co-transfection assays we analyzed the activity of each construct. Our results showed that the region shared by OPTN and CCDC3 can act as a bidirectional regulatory region and that NFkB can regulate both genes. We also analyzed OPTN and CCDC3 expression in several mice and zebrafish tissues by qPCR and our results showed that OPTN and CCDC3 seem to have differential gene expression with OPTN being more expressed in calcified tissues and soft tissues such as heart, eye and muscle and CCDC3 being low expressed in these tissues and highly expressed in fat and brain. The analysis of this bidirectional promoter allows us to clarify a new level of regulation of these genes and clarify the regions that are important for the activation of each gene. Also with this work we were able to define the regions important for the NFkB regulatory effect and hypothesize a new role of OPTN and CCDC3 in bone metabolism. All of these data could be relevant to develop new therapies to control the expression levels of these genes in diseases in which there is an imbalance of OPTN or CCDC3 expression.