Protein tyrosine phosphatase non-receptor type 11 modulates osteoclast secretion and bone resorption through hypoxia-inducible factor-1α

Abstract

Objective To investigate the expression and function of protein tyrosine phosphatase non-receptor type 11 (PTPN11) in human osteoclast. Methods Peripheral mononuclear cells were collected from healthy volunteers of different ages (youth group, 28 people, 20-45 years old; middle-aged group, 33 people, 46-60 years old; old group, 31 people, 61-80 years old). Osteoclasts were induced and then divided into control, blank and Adv-PTPN11 infection group. Recombinant adenovirus Adv-PTPN11 was constructed and transfected into osteoclasts of transfection group. Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to evaluate mRNA expression of PTPN11, hypoxia-inducible factor-1α (HIF-1α). Western blotting was used to analyze PTPN11 and HIF-1α protein expression. Methyl thiazol tetrazolium (MTT) was employed to determine cell survival. enzyme linked immunosorbent assay (ELISA) was used to measure the secretion of stromal cell-derived factor-1 (SDF-1), interleukin (IL)-6, macrophage inflammatory protein (MIP)-1α, B cell activating factor belonging to the tumor necrosis factor (TNF) family (BAFF). Bone resorption was analyzed. Results Compared with youth (mRNA: 4.468±1.441, protein: 1.000±0.055) and middle-aged group (mRNA: 4.673±1.469, protein: 1.021±0.076), the expression of PTPN11 mRNA (7.510±1.941) and protein (1.556±0.123) was significantly enhanced. Adv-PTPN11 did not influence cell survival at 24, 48 and 72 h following the infection. Further, the expression of HIF-1α mRNA and protein in Adv-PTPN11 infection group was higher than that in control and blank group. In addition, the expression of SDF-1 [(94.2±10.3) ng/ml], IL-6 [(25.1±3.2) ng/ml], MIP-1α [(31.2±3.9) ng/ml], BAFF [(39.8±3.7) ng/ml] was augmented in Adv-PTPN11 infection group, with increased number and area of bone resorption pits. Treating with HIF-1α inhibitor YC-1 dampened SDF-1 [(73.8±7.5) ng/ml], IL-6 [(17.9±2.5) ng/ml], MIP-1α [(19.8±1.6) ng/ml], BAFF [(23.5±2.7) ng/ml] expression and bone resorption. Conclusion PTPN11 affects cytokine expression and bone resorption function in osteoclast via modulating HIF-1α. Key words: Protein tyrosine phosphatase non-receptor type 11; Osteoclast; Hypoxia-inducible factor-1α; Cytokine; Bone resorption