Effect of leukotrienes on osteoblasts proliferation

Abstract

Bone metabolism is regulated by several factors and different signaling pathways and transcriptional regulators triggered by the interaction between local and systemic molecules, such as hormones, cytokines and lipid mediators in which act in an autocrine, paracrine and endocrine manner. It is known that inflammatory processes controlled by specific mediators on bone microenvironment are able to modulate the osteoclastogenesis and therefore, bone metabolism. Leukotrienes (LTs) are inflammatory mediators synthesized by osteoblasts and osteoclasts and signaling by transmembrane type receptors coupled to protein G. They are derived from arachidonic acid, through 5-lipoxygenase (5-LO) pathway, the enzyme responsible for the LTs synthesis. The literature shows that LTs induce bone resorption and osteoclastogenesis, but there are few studies showing its effects on osteogenesis. In addition, the mitogen-activated protein kinase pathway (MAPK - ERK) is one of the major intracellular signaling pathways involved in various cellular functions, modulating cell proliferation and differentiation. Therefore, there are few studies highlighting the LTs role on osteoblast proliferation. Thus, in 129/Sv wild type (WT) and 5-LO Knockout (5-LO KO) mice osteoblasts, we intend to evaluate the cell proliferation through flow cytometry and MTT assay, in addition to evaluating the gene expression of bone proliferation markers by qPCR in the presence or absence of the inhibitor of LTs synthesis (MK 886 compound), or the BLT1/2 and cisLT1/2 receptor antagonists. In addition, we will investigate the involvement of the ERK1,2 signaling pathway, in those responses, using its specific inhibitor and/or evaluating its activation during the proliferation, by western blot. (AU)