Differential Gene Expression Pattern in Osteoclast Precursor Cells of Indian Postmenopausal Women with and Without Osteoporosis: A Microarray Based Study Mehrunnisa M Raje 1 , Suhas T Mhaske 2 , Payel Ghosh 3 , Mohan R Wani 2 and Richa Ashma 1* 1 Center for advanced studies, Department of Zoology, Savitribai Phule Pune University, Pune, India 2 National Centre for Cell Science, India 3 Bioinformatics Centre, Savitribai Phule Pune University, Pune, India * Corresponding author: Richa Ashma, Center for advanced studies, Department of Zoology, Savitribai Phule Pune University, Pune – 411007, India, Tel: 91-02025601436 Ext. 41; Fax 91-20-25690617; E-mail : richaashma@unipune.ac.in Received Date: October 27, 2017; Accepted Date: November 29, 2017; Published Date: December 07, 2017 Copyright: © 2017 Mehrunnisa RJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Background: Osteoporosis is a multifactorial disease with strong genetic and epigenetic component. In spite of enormous candidate gene association studies, the etiology and molecular mechanism of disease is not fully known. For identification of new markers of osteoporosis which could be vital in diagnosis and prognosis of disease, genome-wide microarray expression approach was employed. Methods: Osteoclast precursor cells were sorted from circulating monocytes of osteoporotic and non- osteoporotic post menopausal females with similar life-style and year after menopause. Following microarray experimentation, gene enrichment analysis was performed on significant DEGs using Database for Annotation, Visualization and Integrated Discovery (DAVID) tool. Top 10 novel genes were further used for construction of protein-protein interaction network using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. To validate microarray gene expression pattern, Real time-PCR was performed. Results: A total of 269 genes were found to be differentially expressed between disease and normal groups, of which 138 were observed to be up regulated and 131 down regulated. Furthermore, novel LHX1 gene was observed to be up regulated and its interaction with BMP4 protein was observed. Three known genes for osteoclastogenesis (viz., CX3CL1, ACP5 and CSF1) were found to be up- regulated. Similar pattern of gene expression have been obtained using RT-PCR. Conclusion: Significant enrichment of PI3K-Akt and TGF-ß signaling pathways involving DEGs was found in postmenopausal Asian Indian women. Moreover, up regulated LHX1 gene was discovered as novel gene which may have a role in pathogenesis of osteoporosis and can be used for diagnosis and prognosis along with known osteoporotic markers. Keywords: Osteoporosis; Monocytes; Osteoclast precursors; Microarray; Diferential gene expression; LHX1 gene Introduction Osteoclasts play a pivotal role in the bone resorption. Generally, the formation and resorption of the bone is tightly regulated by nutrition and intrinsic factors. However, when the resorption of the bone prevails over its formation, it leads to a skeletal disorder, osteoporosis. Osteoclast precursors are hematopoietic in origin and diferentiate into osteoclasts to resorb bone [1]. Osteoclasts are derived from macrophage colony-stimulating factor (M-CSF)-dependent blood precursors, including monocytes present in the peripheral blood mononuclear cell (PBMC) population. Osteoclast precursors circulate in the blood stream to fnd the correct site (bone surface) for osteoclastogenesis [2]. If the bone surface is not available, diferentiation of these precursors into osteoclasts may become insensitive and regain osteoclastogenesis when bound to bone. So adhesion of osteoclast precursors to bone dictates their fate [3]. However, the most likely candidate for the osteoclast precursor in PBMC population is the CD14 marker, which is strongly expressed on monocytes. CD14+ cells are putative osteoclast precursors in the peripheral blood [4,5]. Like osteoclasts, immune cells also originate from hematopoietic stem cells and a link between immune cells and bone cells has revealed that along with RANK/RANKL/OPG system, activated T cells may both positively and negatively regulate bone resorption [6]. Apart from these, hormones, interleukins, growth factors, nutrition, physical activity and lifestyle play a major role in the development, diferentiation and maturation of osteoblasts and osteoclast precursor cells, suggesting that bone resorption is being infuenced by both local and systemic factors [7]. Tus, osteoporosis is a multifactorial disease in which genetic and epigenetic factors along with lifestyle play an important role [8]. For primary osteoporosis along with these factors, menopause status is the most vulnerable factor in women. Defciency of estrogen with simultaneous increase in the FSH level accelerates bone loss inducing osteoporosis [9]. Estrogen depletion recruits large number of osteoclast precursors to activate osteoclastogenesis [10,11]. Reduced J o u r n a l o f B o n e R e s e a r c h ISSN: 2572-4916 Journal of Bone Research Raje et al., J Bone Res 2017, 5:3 DOI: 10.4172/2572-4916.1000185 Research Article Open Access J Bone Res, an open access journal ISSN:2572-4916 Volume 5 • Issue 3 • 1000185