Cytosolic proteome profiling of monocytes for male osteoporosis

Abstract

Summary In male Caucasians with discordant hip bone mineral density (BMD), we applied the subcellular separation and proteome profiling to investigate the monocytic cytosol. Three BMD-associated proteins (ALDOA, MYH14, and Rap1B) were identified based on multiple omics evidence, and they may influence the pathogenic mechanisms of osteoporosis by regulating the activities of monocytes. Introduction Osteoporosis is a serious public health problem, leading to significant mortality not only in aging females but also in males. Peripheral blood monocytes (PBMs) play important roles in bone metabolism by acting as precursors of osteoclasts and producing cytokines important for osteoclast development. The first cytosolic sub-proteome profiling analysis was performed in male PBMs to identify differentially expressed proteins (DEPs) that are associated with BMDs and risk of osteoporosis. Methods Here, we conducted a comparative proteomics analysis in PBMs from Caucasian male subjects with discordant hip BMD (29 low BMD vs. 30 high BMD). To decrease the proteome complexity and expand the coverage range of the cellular proteome, we separated the PBM proteome into several subcellular compartments and focused on the cytosolic fractions, which are involved in a wide range of fundamental biochemical processes. Results Of the total of 3796 detected cytosolic proteins, we identified 16 significant (P < 0.05) and an additional 22 suggestive (P < 0.1) DEPs between samples with low vs. high hip BMDs. Some of the genes for DEPs, including ALDOA, MYH14, and Rap1B, showed an association with BMD in multiple omics studies (proteomic, transcriptomic, and genomic). Further bioinformatics analysis revealed the enrichment of DEPs in functional terms for monocyte proliferation, differentiation, and migration. Conclusions The combination strategy of subcellular separation and proteome profiling allows an in-depth and refined investigation into the composition and functions of cytosolic proteome, which may shed light on the monocyte-mediated pathogenic mechanisms of osteoporosis.

Rap1b Is an Effector of Axin2 Regulating Crosstalk of Signaling Pathways During Skeletal Development

“…In humans, multiple omics studies have recently identified Rap1b as one of the genes associated with bone mineral density and male osteoporosis. (54) It has also shown to be important for osteoclast function and bone remodeling in mice. (55) Most recently, we have demonstrated that Axin2expressing cells are bona fide stem cells residing in the suture mesenchyme essential for development, homeostasis, and injury repair of the calvarial bone.…”

“…Although Rap1b has been implicated in angiogenesis, lens epithelial maintenance, and immune cell functions, its role in skeletogenesis has yet to be reported. In humans, multiple omics studies have recently identified Rap1b as one of the genes associated with bone mineral density and male osteoporosis . It has also shown to be important for osteoclast function and bone remodeling in mice .…”

Myosins in Osteoclast Formation and Function

“…Similarly, Myo2c’s potential functions in osteoclast biology are not yet characterized. However, a recent study performed cytosolic proteomic profiling of monocytes from male osteoporosis patients, and revealed that MYH14 , the Myo2c heavy chain gene, was one of sixteen genes to show significantly upregulated expression in patients with low bone mineral density [65]. Analyses of other datasets revealed that MYH14 showed association with low bone mineral density at the proteomic, transcriptomic, and genomic levels [65].…”

Identification of osteoporosis markers through bioinformatic functional analysis of serum proteome

“…Many studies have investigated the processes of bone metabolisms and the molecular features of osteoporosis. Zhu et al [ 4 ] performed a profiling of cytosolic proteome with multiomics techniques in Caucasian male osteoporotic patients and identified BMD-associated genes for the monocyte-mediated osteoporosis. Despite that osteoporosis has been increasingly studied, the mechanisms underlying low BMD and osteoporosis have not been fully understood.…”

“…[ 10 , 11 ] Several studies using omics technologies identified differential expression of extracellular proteins in various levels, from mRNA, protein expression, to posttranslational modifications, indicating a vital role of circulating proteins in the regulation of BMD and osteoporosis. [ 4 , 12 , 13 ]…”