Tendon-Specific Dicer Deficient Mice Exhibit Hypoplastic Tendon Through the Downregulation of Tendon-Related Genes and MicroRNAs

Takenori Omoto; Dilimulati Yimiti; Yohei Sanada; Minoru Toriyama; Chenyang Ding; Yuta Hayashi; Yasunari Ikuta; Tomoyuki Nakasa; Masakazu Ishikawa; Masayuki Sano; Minjung Lee; Takayuki Akimoto; Chisa Shukunami; Shigeru Miyaki; Nobuo Adachi

doi:10.3389/fcell.2022.898428

Tendon-Specific Dicer Deficient Mice Exhibit Hypoplastic Tendon Through the Downregulation of Tendon-Related Genes and MicroRNAs

Front Cell Dev Biol. 2022 Jun 14:10:898428. doi: 10.3389/fcell.2022.898428. eCollection 2022.

Authors

Takenori Omoto¹, Dilimulati Yimiti¹, Yohei Sanada^{1

2}, Minoru Toriyama¹, Chenyang Ding¹, Yuta Hayashi^{1

3}, Yasunari Ikuta¹, Tomoyuki Nakasa^{1

2}, Masakazu Ishikawa^{1

4}, Masayuki Sano⁵, Minjung Lee⁶, Takayuki Akimoto⁶, Chisa Shukunami⁷, Shigeru Miyaki^{1

2}, Nobuo Adachi¹

Affiliations

¹ Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
² Medical Center for Translational and Clinical Research, Hiroshima University Hospital, Hiroshima, Japan.
³ Department of Musculoskeletal Traumatology and Reconstructive Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
⁴ Department of Artificial Joints and Biomaterials, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
⁵ Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
⁶ Faculty of Sport Sciences, Waseda University, Saitama, Japan.
⁷ Department of Molecular Biology and Biochemistry, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.

Abstract

Tendon is a fibrous connective tissue, that is, transmitting the forces that permit body movement. However, tendon/ligament biology is still not fully understood and especially, the role of miRNAs in tendon/ligament is sparse and uncharacterized in in vivo models. The objectives of this study were to address the function of DICER using mice with tendon/ligament-specific deletion of Dicer (Dicer conditional knockout; cKO), and to identify key miRNAs in tendon/ligament. Dicer cKO mice exhibited hypoplastic tendons through structurally abnormal collagen fibrils with downregulation of tendon-related genes. The fragility of tendon did not significantly affect the tensile strength of tendon in Dicer cKO mice, but they showed larger dorsiflexion angle in gait compared with Control mice. We identified two miRNAs, miR-135a and miR-1247, which were highly expressed in the Achilles tendon of Control mice and were downregulated in the Achilles tendon of Dicer cKO mice compared with Control mice. miR-135a mimic increased the expression of tendon-related genes in injured Achilles tendon-derived fibroblasts. In this study, Dicer cKO mice exhibited immature tendons in which collagen fibrils have small diameter with the downregulation of tendon-related genes such as transcriptional factor, extracellular matrix, and miRNAs. Thus, DICER plays an important role in tendon maturation, and miR-135a may have the potential to become key miRNA for tendon maturation and healing.

Keywords: collagen fibrils; dicer; extracellular matrix; knockout mice; microRNA; tendon; tendon abnormality.