DNAJB1 negatively regulates MIG6 to promote epidermal growth factor receptor signaling.

Mitogen-inducible gene 6 (MIG6) is a tumor suppressor implicated in the development of human cancers; however, the regulatory mechanisms of MIG6 remain unknown. Here, using a yeast two-hybrid screen, we identified DnaJ homolog subfamily B member I (DNAJB1) as a novel MIG6-interacting protein. We found that DNAJB1 binds to and decreases MIG6 protein, but not mRNA, levels. DNAJB1 overexpression dosage-dependently decreased MIG6 protein levels. Conversely, DNAJB1 knockdown increased MIG6 protein levels. DNAJB1 destabilizes MIG6 by enhancing K48-linked ubiquitination of MIG6. However, knocking-down of DNAJB1 reduced the ubiquitination of MIG6. DNAJB1 positively regulates the epidermal growth factor receptors (EGFR) signaling pathway via destabilization of MIG6; however, DNAJB1 knockdown diminishes activation of EGFR signaling as well as elevation of MIG6. Importantly, the increased levels of MIG6 by DNAJB1 knockdown greatly enhanced the gefitinib sensitivity in A549 cells. Thus, our study provides a new molecular mechanism to regulate EGFR signaling through modulation of MIG6 by DNAJB1 as a negative regulator.

TLR2 deficiency attenuates skeletal muscle atrophy in mice.

Oxidative stress and inflammation are associated with skeletal muscle atrophy. Because the activation of toll-like receptor (TLR) 2 induces oxidative stress and inflammation, TLR2 may be directly linked to skeletal muscle atrophy. This study examined the role of TLR2 in skeletal muscle atrophy in wild-type (WT) and TLR2 knockout (KO) mice. Immobilization for 2 weeks increased the expression of cytokine genes and the levels of carbonylated proteins and nitrotyrosine in the skeletal muscle, but these increases were lower in the TLR2 KO mice. Muscle weight loss and a reduction in treadmill running times induced by immobilization were also attenuated in TLR2 KO mice. Furthermore, immobilization increased the protein levels of forkhead box O 1/3, atrogin-1 and muscle ring finger 1 in the WT mice, which was attenuated in TLR2 KO mice. In addition, immobilization-associated increases in ubiquitinated protein levels were lower in the TLR2 KO mice. Immobilization increased the phosphorylation of Akt and p70S6K similarly in WT and KO mice. Furthermore, cardiotoxin injection into the skeletal muscle increased the protein levels of atrogin-1, interleukin-6, and nitrotyrosine and increased the levels of ubiquitinated proteins, although these levels were increased to a lesser extent in TLR2 KO mice. These results suggest that TLR2 is involved in skeletal muscle atrophy, and the inhibition of TLR2 offers a potential target for preventing skeletal muscle atrophy.

Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA).

Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis.

Reliability of the classification and treatment of dislocations of the acromioclavicular joint.

BACKGROUND: We evaluated interobserver and intraobserver reliability of the classification and treatment of acromioclavicular (AC) joint dislocations and assessed the impact of adding 3-dimensional computed tomography (3D CT) on the reliability of classification and treatment choice. METHODS: Ten surgeons independently reviewed plain radiographs and 3D CT in 28 cases with AC joint dislocation. Images from each case were randomly presented to the observers, with plain radiographs alone being presented first, followed by plain radiographs plus 3D CT 2 weeks later. Four weeks later, they repeated the same survey to evaluate intraobserver reliability. Reliability was assessed on the basis of Fleiss κ values. RESULTS: On the basis of plain radiographs alone, interobserver and intraobserver reliability of the Rockwood classification were fair (κ = .214) and moderate (κ = .474), respectively. Interobserver and intraobserver reliability of treatment were both fair (κ = .213 and .399, respectively). On the basis of a combination of plain radiographs and 3D CT, interobserver and intraobserver reliability of the Rockwood classification were slight (κ = .177) and moderate (κ = .565), respectively. Interobserver and intraobserver reliability of treatment were fair (κ = .253) and moderate (κ = .554), respectively. There were no significant differences in reliability between the two groups in terms of any κ values. CONCLUSION: This study suggests an overall lack of reliability of the Rockwood classification of AC joint dislocations and of decisions regarding their treatment. There is especially poor agreement between experienced shoulder surgeons. The addition of 3D CT did not improve reliability of classification and treatment of AC joint dislocations.

Does COVID-19 Infection within 1 Week after Total Knee Arthroplasty Affect Patients' Early Clinical Outcomes? A Matched Case-Control Study.

Recent studies have reported the impact of previous COVID-19 infection on the early clinical outcome after total knee arthroplasty (TKA). However, the timing of infection before the surgery was not constant and a study on patients with COVID-19 infection within 1 week after TKA is lacking. This study aimed to determine the effect of COVID-19 infection within one week after TKA on the postoperative outcomes and to compare the early clinical outcomes to those who were not infected with COVID-19 before and after surgery. No significant differences were observed between the two groups in terms of clinical outcomes or complications. The length of the hospital stay (LOS) was significantly longer for the COVID-19 group than for the non-COVID-19 group (p < 0.05). The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were higher for the study group on postoperative days 9 and 12 than for those in the control group (p < 0.05). However, D-dimer levels were not significantly different between the two groups. We should cautiously consider that COVID-19 infection within 1 week after TKA may be associated with increased ESR, CRP levels, and length of hospital stay, but they are not associated with the worsening of early clinical outcomes or the occurrence of complications.

A Comparison of U-blade Gamma3 and Gamma3 Nails Used for the Treatment of Intertrochanteric Fractures.

PURPOSE: To compare outcomes (i.e., clinical and radiological findings, postoperative complication) in the fixation of intertrochanteric fractures with U-blade Gamma3 and Gamma3 nails. MATERIALS AND METHODS: A review of 162 patients (both male and female) treated for intertrochanteric fractures between December 2012 and December 2018 was conducted. All patients were older than 65 years of age and treated with U-blade Gamma3 (n=90) or Gamma3 (n=72) nails. Evaluations included: (i) screw-head position, (ii) fracture-reduction status, (iii) time to union, (iv) cases of cut-out, (v) tip-apex distance, and (vi) lag screw sliding distance. Differences in pre- and postoperative ambulatory ability was also investigated. RESULTS: There were no significant differences in baseline demographics between the two groups. While the lag-screw sliding distance was significantly shorter in U-blade Gamma3 nail group (4.7 mm vs. 3.6 mm; P=0.025), the mean time to union was similar between the groups (P=0.053). Three and six cases of cut-out were noted in the U-blade Gamma3 and Gamma3 nail groups, respectively (P=0.18), however no other postoperative complications were noted in either group. Lastly, there was no difference between the change from pre- to postoperative activity level between the groups (P=0.753). CONCLUSION: Of all the clinical and radiological outcomes assessed, the only significant improvement between those treated with U-Blade Gamma and Gamma3 nails was a shorter lag-screw sliding distance. These findings should benefit clinicians when deciding between the use of U-Blade Gamma or Gamma3 nails.

Treatment of Modified Mason Type III or IV Radial Head Fracture: Open Reduction and Internal Fixation versus Arthroplasty.

BACKGROUND: The treatment of modified Mason Type III or IV fractures is controversial. Many authors report open reduction and internal fixation (ORIF) with reconstruction of the radial head, but others advocate radial head arthroplasty (RHA). This study compares the clinical and radiological outcomes of ORIF and RHA in modified Mason Type III or IV radial head fracture and evaluates correlations between prognostic factors and postoperative clinical outcomes. MATERIALS AND METHODS: 42 patients with modified Mason Type III or IV radial head fractures who were surgically treated between January 2010 and January 2014 were retrospectively analyzed (20 patients with RHA and 22 patients with ORIF group were selected). Clinically, the patient rated elbow evaluation (PREE), the disabilities of the arm, shoulder and hand (DASH), and the range of motion (ROM) were measured. Radiologically, plain radiographs and computed tomography scans were taken. RESULTS: The mean PREE scores were 13.9 for the RHA group and 13.0 for the ORIF group, and mean DASH scores were 9.5 and 10.7, respectively. The differences were not statistically significant. When comparing ROM, the patients in the RHA group showed greater movement at all measured angles. In multiple regression analysis, age was the only variable significantly associated with both PREE and DASH. CONCLUSION: Overall, there were no significant differences in clinical outcomes of modified Mason Type III or IV radial head fractures treated with ORIF or RHA. However, a subgroup of younger patients had better clinical outcomes with ORIF treatment. Therefore, ORIF should be the First line of treatment, particularly if the reduction is possible.

Arthroscopic management of septic arthritis of the shoulder joint.

BACKGROUND: Nineteen patients with septic arthritis of the glenohumeral joint were treated with a combination of arthroscopic irrigation and débridement and systemic antibiotics according to bacterial sensitivity. We retrospectively reviewed the series to determine the efficacy and safety of this treatment. METHODS: There were seventeen men and two women, with a mean age of fifty-nine years. Underlying medical disease was present in thirteen patients, with six of them having diabetes. The average duration of symptoms prior to the arthroscopic lavage was three weeks. Fifteen patients had had local injections into the shoulder joint. The arthroscopic staging of the infection was based on the modified criteria of Gächter. The functional outcome was evaluated with use of the UCLA scoring system. RESULTS: As determined at arthroscopy, one infection was classified as stage I; seven, as stage II; nine, as stage III; and two, as stage IV. Staphylococcus was the most common organism identified. The infection was eradicated completely with a single arthroscopic procedure in fourteen patients. The mean UCLA score at the time of the last follow-up was 26 points, with a mean score of 23.7 points for the eleven patients with a rotator cuff tear and 29 points for the eight with an intact rotator cuff. Patients who had had symptoms for no more than two weeks prior to the arthroscopic lavage had better results than those who had had symptoms for longer than two weeks. CONCLUSIONS: Arthroscopic débridement for the treatment of septic arthritis of the shoulder is safe and efficient, particularly in the early stages of the disease. Underlying medical diseases such as diabetes, prior injections, or a preexisting rotator cuff tear were seen in a high proportion of these patients.

SUMOylation of TBL1 and TBLR1 promotes androgen-independent prostate cancer cell growth.

Chronic inflammation is strongly associated with prostate cancer pathogenesis. Transducin ß-like protein (TBL1) and Transducin ß-like 1X-linked receptor 1 (TBLR1) have been identified recently as a coactivator for NF-κB-mediated transcription; however, the underlying mechanism by which TBL1 and TBLR1 activate NF-κB function during inflammation remains unknown. Here, we demonstrate that cytokine production is significantly elevated in androgen-independent PC-3 prostate cancer cells compared with androgen-dependent LNCaP prostate cancer cells. Elevated cytokine production positively correlates with the TBL1 and TBLR1 SUMOylation level in PC-3 cells. We show that both TBL1 and TBLR1 are SUMOylated in response to TNF-α treatment, and this increases formation of the TBL1-TBLR1-NF-κB complex, which leads to NF-κB-mediated transcriptional activation of cytokine gene expression. Conversely, SENP1-mediated deSUMOylation of TBL1 and TBLR1 inhibits NF-κB-target gene expression by dissociating TBL1 and TBLR1 from the nuclear hormone receptor corepressor (NCoR) complex. TBL1 knockdown substantially suppresses inflammatory signaling and PC-3 cell proliferation. Collectively, these results suggest that targeted SUMOylation of TBL1 and TBLR1 may be a useful strategy for therapeutic treatment of androgen-independent prostate cancer.

Frequent CpG island methylation in precursor lesions and early gastric adenocarcinomas.

Gastric carcinogenesis involves multiple genetic and epigenetic alterations. Epigenetic silencing of tumor-related genes due to CpG island methylation (CIM) has been recently reported in gastric cancer, but the role in precursor lesions is not well understood. We analysed the methylation status of the tumor suppressor gene p16, the DNA mismatch repair gene hMLH1, and four CpG islands (MINT1, MINT2, MINT25, and MINT31) using methylation-specific polymerase chain reaction in 35 polypoid adenomas and 46 flat dysplasias unassociated with carcinoma, 34 early adenocarcinomas (T1N0M0) and associated adenomas/dysplasias, and corresponding adjacent non-neoplastic mucosa. The extent of CIM was defined by the fraction of methylated loci (methylation index), and compared with previously characterized genetic alterations (microsatellite instability (MSI) and APC gene mutation). We found that methylation of p16 was more frequent in adenocarcinoma-associated dysplasias/adenomas (29%) and adenocarcinomas (44%) as compared to flat dysplasias (4%) and adenomas (18%) unassociated with adenocarcinoma (P=0.001). The mean methylation index increased from normal/chronic gastritis (CG) mucosa (0.09) to intestinal metaplasia (IM) (0.16), flat dysplasias (0.40) or polypoid adenomas (0.41) unassociated with carcinoma, dysplasias/adenomas associated with carcinoma (0.44), and adenocarcinomas (0.44). There was no difference in frequencies of high-level CpG island methylation (CIM-H, methylation index > or =0.5) among flat dysplasias (50%) and polypoid adenomas (51%) unassociated with carcinoma, dysplasias/adenomas associated with adenocarcinoma (47%), and adenocarcinoma (47%). CIM-H was present in 15% of IM, but not in normal/CG mucosa. There was a significant correlation between methylation of hMLH1 and high-level of microsatellite instability (MSI-H): methylation of hMLH1 was present in 71% of MSI-H tumors, but only 8% of MSI-low tumors and 13% of microsatellite-stable tumors (P=0.0001). There was no statistical difference between methylation index and APC mutation. Our results indicate that concurrent promoter methylation is an early and frequent event in gastric tumorigenesis, including both MSI-H and microsatellite-stable neoplasms. Methylation of the p16 gene may contribute to the malignant transformation of gastric precursor lesions.

Hemin, heme oxygenase-1 inducer, attenuates immobilization-induced skeletal muscle atrophy in mice.

AIMS: The present study examined the effect of the heme oxygenase (HO)-1 inducer hemin on skeletal muscle atrophy induced by single limb immobilization in mice. MAIN METHODS: Immobilization was conducted in the left hindlimb of C57BL/6 mice for 1 week and the right hindlimb was used as a control. Hemin (30 mg/kg) was administered intraperitoneally once a day during the immobilization period. Gastrocnemius muscles were used for analysis. Muscle weight was measured to quantify degree of atrophy, and exhaustion treadmill test was performed to assess muscle function. KEY FINDINGS: Immobilization increased HO-1 protein levels in skeletal muscle, which was further increased by hemin treatment. Immobilization induced weight loss and a functional reduction in skeletal muscle, which were attenuated by hemin treatment. Gene expression and protein levels of MuRF1 and atrogin-1 were increased by immobilization and hemin treatment attenuated the increment. The phosphorylation of mTOR and p70S6k was decreased by immobilization in skeletal muscle and hemin had no effect on mTOR and p70S6k phosphorylation. Gene expression of the antioxidants superoxide dismutase and glutathione peroxidase 1 in skeletal muscle was reduced by immobilization and hemin treatment recovered the reduction. Immobilization increased levels of carbonylated protein and nitrotyrosine in skeletal muscle, which was reversed by hemin treatment. Gene expression of inflammatory cytokines was increased by immobilization and was normalized as a result of hemin treatment. SIGNIFICANCE: These results suggest that hemin attenuates immobilization-induced skeletal muscle atrophy through the suppression of protein degradation via its anti-oxidant and anti-inflammatory properties.