Induction of apoptosis in the synovium of mice with autoantibody-mediated arthritis by the intraarticular injection of double-stranded MicroRNA-15a.
OBJECTIVE
MicroRNA is a family of noncoding RNAs that exhibit tissue-specific or developmental stage-specific expression patterns and are associated with human diseases. MicroRNA-15a (miR-15a) is reported to induce cell apoptosis by negatively regulating the expression of Bcl-2, which suppresses the apoptotic processes. The purpose of this study was to investigate whether double-stranded miR-15a administered by intraarticular injection could be taken up by cells and could induce Bcl-2 dysfunction and cell apoptosis in the synovium of arthritic mice in vivo.


METHODS
Autoantibody-mediated arthritis was induced in male DBA/1J mice. In the experimental group, double-stranded miR-15a labeled with FAM-atelocollagen complex was injected into the knee joint. In the control group, control small interfering RNA-atelocollagen complex was injected into the knee joint. Synovial expression of miR-15a was analyzed by quantitative polymerase chain reaction, FAM by fluorescence microscopy, Bcl-2 by Western blotting, and Bcl-2 and caspase 3 by immunohistochemistry.


RESULTS
The expression of miR-15a in the synovium of the experimental group was significantly higher than that in the control group. Green fluorescence emission of FAM was observed in the synovium of the experimental group. Bcl-2 protein was down-regulated and the expression of caspase 3 was increased as compared with that in the control group.


CONCLUSIONS
These results indicate that the induction of cell apoptosis after intraarticular injection of double-stranded miR-15a occurs through inhibition of the translation of Bcl-2 protein in arthritic synovium.
Nagata
Yoshihiko
Y
Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan.
Nakasa
Tomoyuki
T
Mochizuki
Yu
Y
Ishikawa
Masakazu
M
Miyaki
Shigeru
S
Shibuya
Hayatoshi
H
Yamasaki
Keiichiro
K
Adachi
Nobuo
N
Asahara
Hiroshi
H
Ochi
Mitsuo
M
D000276:Adjuvants, Immunologic / Q000009:adverse effects; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001169:Arthritis, Experimental / Q000378:metabolism* / Q000473:pathology; D001323:Autoantibodies / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D004195:Disease Models, Animal; D007270:Injections, Intra-Articular; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D035683:MicroRNAs / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology
D000276:Adjuvants, Immunologic; D001323:Autoantibodies; D035683:MicroRNAs; C544301:Mirn15a microRNA, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D012330:RNA, Double-Stranded; D053148:Caspase 3