SOX2 suppresses osteoblast differentiation of MC3T3-E1 cells through activating the transcription of LGR4.

Osteogenic differentiation is a crucial process of new bone formation. This study aimed to explore the roles and mechanism of SRY-Box Transcription Factor 2 (SOX2) on proliferation and osteogenic differentiation of MC3T3-E1 cells. Bone morphogenetic protein 2 (BMP2) was used to induce the osteogenic differentiation of MC3T3-E1 cells. The expression of SOX2 was determined by quantitative real-time PCR (RT-PCR) at different time points after induction. The SOX2 overexpression plasmids were constructed and transfected into MC3T3-E1 cells. Osteogenic differentiation was evaluated by Alizarin Red S staining and alkaline phosphatase (ALP) assay. The expressions of osteogenic differentiation markers including runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN) were detected by western blot assay. Luciferase reporter and CHIP assays were used to confirm that SOX2 regulated the transcriptional activation of leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4). We found that SOX2 was down-regulated upon BMP2-induced osteogenic differentiation in MC3T3-E1 cells. Overexpression of SOX2 effectively inhibited osteogenic differentiation with decreased ALP activity, calcification, and osteogenic differentiation markers' expression including Runx2, OPN, and OCN. LGR4 was identified as a target of SOX2, and the inhibitory effect of SOX2 on osteogenic differentiation was reversed by knockdown of LGR4. The present study confirmed that SOX2 suppressed osteogenic differentiation of MC3T3-E1 cells through targeting LGR4, which possesses a therapeutic strategy for bone formation and generation.

Efficacy of threading lasso fixation in repairing partial articular supraspinatus tendon avulsion lesions: a retrospective study.

BACKGROUND: The partial articular supraspinatus tendon avulsion (PASTA) lesion repair remains a topic of debate. We have performed in situ repair of PASTA lesions using a potentially viable threading lasso fixation technique. This retrospective case series aimed to evaluate the clinical outcomes of PASTA lesion repair using threading lasso fixation. To the best of our knowledge, this is the first study to review this technique and its outcomes in terms of pain and upper extremity function. METHODS: Twenty-five patients with PASTA lesions who were treated with threading lasso fixation were reviewed. All patients were followed up for at least 1 year. Preoperative and follow-up data were retrospectively collected and reviewed. Clinical outcomes were assessed to evaluate the efficacy of the surgery. RESULTS: There were no postoperative complications. The average follow-up period was 25.7 (22-27) months. At the last follow-up, all patients underwent follow-up magnetic resonance imaging; only two cases showed a partially healed tendon and no case converted to full-thickness tear. Furthermore, shoulder pain decreased and mobility was recovered, with statistically significant differences in all scoring measures. Specifically, the mean visual analog scale score decreased from 5.4 ± 1.2 before surgery to 1.1 ± 0.8 at the last follow-up (t = 14.908, P < 0.01), and the mean American Shoulder and Elbow Surgeons Shoulder Assessment Form score improved significantly from 51.6 ± 6.4 to 89.3 ± 5.2 (t = 22.859, P < 0.01). Additionally, the mean University of California Los Angeles score improved from 17.8 ± 3.5 preoperatively to 32.3 ± 1.4 (t = 19.233, P < 0.01). CONCLUSIONS: Arthroscopic repair using threading lasso fixation is a novel transtendinous technique for patients with partial articular supraspinatus tendon avulsion. Tendon integrity is preserved with this method, which may result in improved function. Overall, threading lasso fixation technique is an effective treatment.

Autophagy promotion enhances the protective effect of Morroniside on human OA chondrocyte.

Morroniside plays a therapeutic role in knee osteoarthritis (OA) by protecting chondrocytes. PI3K/AKT signaling is involved in the regulation of chondrocytes by Morroniside. PI3K/AKT suppresses autophagy through downstream signaling. However, the regulation of chondrocyte autophagy by Morroniside and the significance of the above effect on protecting chondrocytes aren't clear. The results showed that Morroniside inhibited the autophagiy of human OA chondrocytes. Besides, both PI3K inhibitors and mTOR inhibitors significantly reversed the autophagy reduced by Morroniside, but had no effect on the protective effect of Morroniside on chondrocytes. However, the enhanced autophagy caused by overexpression of autophagic genes enhanced the protective effect of Morroniside on chondrocytes. In conclusion, Morroniside represses the autophagy of human OA chondrocyte, which is related to PI3K/mTOR pathway. Moreover, the upregulation of autophagy further promoted the role of Morroniside in treating chondrocytes. Our data present a potential clue for the therapeutic strategies of Morroniside in treating OA.