Acidic pH environments increase the expression of cathepsin B in osteoblasts: the significance of ER stress in bone physiology.
Hypoxia, inflammation, and acidity occur after bone fracture. To simplify the fracture model, we tested the effects of acidity in osteoblasts. We tested three osteoblast cell lines, MG63, MC3T3E1, and HOS cells, with MG63 cells showing much higher sensitivity to acidic pH. In physiologically acidic surroundings, pH 7.2, the endoplasmic reticulum stress response was measured through the expression of unfolded protein response proteins. Acidic surroundings time-dependently increased IL-6 secretion. Cathepsin B, a marker of the inflammation and angiogenic processes that occur after bone fracture, also increased. Thus, acidity can cause ER stress, increase IL-6, and increases cathepsin B expression in osteoblasts.
Han
Song-Hee
SH
Department of Pharmacology and Cardiovascular Research Center, School of Medicine, Chonbuk National University, Jeonju, Republic of Korea.
Chae
Soo-Wan
SW
Choi
Je-Yong
JY
Kim
Eun-Cheol
EC
Chae
Han-Jung
HJ
Kim
Hyung-Ryong
HR
D000818:Animals; D002401:Cathepsin B / Q000096:biosynthesis*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D050723:Fractures, Bone / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006863:Hydrogen-Ion Concentration; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis; D008954:Models, Biological; D018919:Neovascularization, Physiologic; D010006:Osteoblasts / Q000201:enzymology*; D017510:Protein Folding; D013312:Stress, Physiological
D018836:Inflammation Mediators; D015850:Interleukin-6; D002401:Cathepsin B