Advanced glycation end products biphasically modulate bone resorption in osteoclast-like cells

Abstract

Advanced glycation end products (AGEs) disturb bone remodeling during aging, and this process is accelerated in diabetes. However, their role in modulation of osteoclast-induced bone resorption is controversial, with some studies indicating that AGEs enhance bone resorption and others showing the opposite effect. We determined whether AGEs present at different stages of osteoclast differentiation affect bone resorption differently. Based on increased levels of tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK), we identified day 4 of induction as the dividing time of cell fusion stage and mature stage in RAW264.7 cell-derived osteoclast-like cells (OCLs). AGE-modified BSA (50-400 μg/ml) or control BSA (100 μg/ml) was then added at the beginning of each stage. Results showed that the presence of AGEs at the cell fusion stage reduced pit numbers, resorption area, and CTSK expression. Moreover, expression of receptor activator of nuclear factor-κB (RANK) as well as the number of TRAP-positive cells, nuclei per OCL, actin rings, and podosomes also decreased. However, the presence of AGEs at the mature stage enlarged the resorption area markedly and increased pit numbers slightly. Intriguingly, only the number of nuclei per OCL and podosomes increased. These data indicate that AGEs biphasically modulate bone resorption activity of OCLs in a differentiation stage-dependent manner. AGEs at the cell fusion stage reduce bone resorption dramatically, mainly via suppression of RANK expression in osteoclast precursors, whereas AGEs at the mature stage enhance bone resorption slightly, most likely by increasing the number of podosomes in mature OCLs.

Regulator of G Protein Signaling Protein 12 (Rgs12) Controls Mouse Osteoblast Differentiation via Calcium Channel/Oscillation and Gαi-ERK Signaling

“…Quantitative real‐time PCR (qPCR) was carried out as described, with slight modifications . In brief, total RNA was extracted using Trizol and quantified by NanoDrop™ 2000 (Thermo Fisher Scientific).…”

“…(32) Quantitative real-time PCR Quantitative real-time PCR (qPCR) was carried out as described, with slight modifications. (27,33) In brief, total RNA was extracted using Trizol and quantified by NanoDrop TM 2000 (Thermo Fisher Scientific). cDNA was synthesized from 2 mg of total RNA, and PCR amplifications were performed in triplicate with SYBR Green qPCR Master Mix (Bimake.com, Houston, TX, USA) on CFX96 realtime PCR machine (Bio-Rad Laboratories, Hercules, CA, USA) using the following steps: 95°C for 5 min, 40 cycles of 95°C for 15 s, and 60°C for 30 s. Gene expression were calculated using the delta-delta comparative threshold cycle algorithm (2 -DDCT ) method and normalized to housekeeping gene GAPDH.…”

Synergistic alveolar bone resorption by diabetic advanced glycation end products and mechanical forces

“…Although the relationship between DM and bone diseases is widely acknowledged, mechanistic pathways underlying the enhancement of AB resorption remain unresolved at present. As well, therapeutic modalities for DM‐associated AB destruction have not been determined yet . Increased severity of periodontitis in individuals with diabetes has been attributed to multiple biological factors such as microbial effects, hyperglycemia (HG), and immune cytokines.…”

“…Bone mineral density in patients with type 2 diabetes is similar to, or higher than, that in non‐diabetes subjects . Moreover, AGEs at the cell fusion stage reduces bone resorption, mainly via the suppression of RANK expression in osteoclast precursors …”

Parathyroid hormone attenuates radiation-induced increases in collagen crosslink ratio at periosteal surfaces of mouse tibia

“…We have previously established that the early post-RTx increase in osteoclastic bone resorption is followed by long-term depletion of local osteoclasts (weeks 4–26) [27]. Additionally, accumulation of AGEs has been known to inhibit osteoclast multinucleation and resorption activity [35, 36] and render the collagen less susceptible to cathepsin K-mediated degradation [37]. This decrease in osteoclastic activity via loss of osteoclasts or substrate-mediated inhibition of cellular function, allows bone tissue to persist for longer than normal without remodeling, permitting collagen hyper-mineralization and hyper-orientation.…”