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.

FLT3 tyrosine kinase inhibitors synergize with BCL-2 inhibition to eliminate FLT3/ITD acute leukemia cells through BIM activation.

Tyrosine kinase inhibitors (TKIs) targeting FLT3 have shown activity but when used alone have achieved limited success in clinical trials, suggesting the need for combination with other drugs. We investigated the combination of FLT3 TKIs (Gilteritinib or Sorafenib), with Venetoclax, a BCL-2 selective inhibitor (BCL-2i), on FLT3/ITD leukemia cells. The combination of a FLT3 TKI and a BCL-2i synergistically reduced cell proliferation and enhanced apoptosis/cell death in FLT3/ITD cell lines and primary AML samples. Venetoclax also re-sensitized FLT3 TKI-resistant cells to Gilteritinib or Sorafenib treatment, mediated through MAPK pathway inhibition. Gilteritinib treatment alone dissociated BIM from MCL-1 but increased the binding of BIM to BCL-2. Venetoclax treatment enhanced the binding of BIM to MCL-1 but dissociated BIM from BCL-2. Treatment with the drugs together resulted in dissociation of BIM from both BCL-2 and MCL-1, with an increased binding of BIM to the cell death mediator BAX, leading to increased apoptosis. These findings suggest that Venetoclax mitigates the unintended pro-survival effects of FLT3 TKI mainly through the dissociation of BIM and BCL-2 and also decreased BIM expression. This study provides evidence that the addition of BCL-2i enhances the effect of FLT3 TKI therapy in FLT3/ITD AML treatment.

Deletions in FLT-3 juxtamembrane domain define a new class of pathogenic mutations: case report and systematic analysis.

The FMS-like tyrosine kinase 3 (FLT-3) is the most frequently mutated gene in acute myeloid leukemia (AML), a high-risk feature, and now the target of tyrosine kinase inhibitors (TKIs), which are approved and in development. The most common mutation is the internal tandem duplication (ITD). We present a novel mutation, FLT-3/Q575Δ, identified in a patient with AML through next-generation sequencing (NGS). This mutation is activating, drives downstream signaling comparable to FLT-3/ITD, and can be targeted using available FLT-3 TKIs. We present the results of a systematic analysis that identified Y572Δ, E573Δ, and S574Δ as similarly activating and targetable deletions located in the FLT-3 juxtamembrane domain (JMD). These mutations target key residues in the JMD involved in the interactions within FLT-3 that regulate its activation. Our results suggest a new class of FLT-3 mutations that may have an impact on patient care and highlight the increasing importance of a systematic understanding of FLT-3 mutations other than ITD. It is likely that, as NGS becomes more commonly used in the diagnosis of patients with AML, these and other activating mutations will be discovered with increasing frequency.

Glycoprotein Targeted CAR-NK Cells for the Treatment of SARS-CoV-2 Infection.

H84T-Banana Lectin (BanLec) CAR-NK cells bind high mannose glycosites that decorate the SARS-CoV-2 envelope, thereby decreasing cellular infection in a model of SARS-CoV-2. H84T-BanLec CAR-NK cells are innate effector cells, activated by virus. This novel cellular agent is a promising therapeutic, capable of clearing circulating SARS-CoV-2 virus and infected cells. Banana Lectin (BanLec) binds high mannose glycans on viral envelopes, exerting an anti-viral effect. A point mutation (H84T) divorces BanLec mitogenicity from antiviral activity. SARS-CoV-2 contains high mannose glycosites in proximity to the receptor binding domain of the envelope Spike (S) protein. We designed a chimeric antigen receptor (CAR) that incorporates H84T-BanLec as the extracellular moiety. Our H84T-BanLec CAR was devised to specifically direct NK cell binding of SARS-CoV-2 envelope glycosites to promote viral clearance. The H84T-BanLec CAR was stably expressed at high density on primary human NK cells during two weeks of ex vivo expansion. H84T-BanLec CAR-NK cells reduced S-protein pseudotyped lentiviral infection of 293T cells expressing ACE2, the receptor for SARS-CoV-2. NK cells were activated to secrete inflammatory cytokines when in culture with virally infected cells. H84T-BanLec CAR-NK cells are a promising cell therapy for further testing against wild-type SARS-CoV-2 virus in models of SARS-CoV-2 infection. They may represent a viable off-the-shelf immunotherapy for patients suffering from COVID-19.

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.

EGFR-c-Src-Mediated HDAC3 Phosphorylation Exacerbates Invasion of Breast Cancer Cells.

Breast cancer is one of the leading causes of morbidity and mortality among women. Epidermal growth factor receptor (EGFR) and proto-oncogene tyrosine-protein kinase Src (c-Src) are critical components of the signaling pathways that are associated with breast cancer. However, the regulatory mechanism of histone deacetylase 3 (HDAC3) in these pathways remains unclear. Using the Net Phos 3.1 program for the analysis of kinase consensus motifs, we found two c-Src-mediated putative phosphorylation sites, tyrosine (Tyr, Y)-328 and Y331 on HDAC3, and generated a phospho-specific HDAC3 antibody against these sites. c-Src-mediated phosphorylation was observed in the cells expressing wild-type HDAC3 (HDAC3WT), but not in cells overexpressing phosphorylation-defective HDAC3 (HDAC3Y328/331A). Phosphorylated HDAC3 showed relatively higher deacetylase activity, and PP2, which is a c-Src inhibitor, blocked HDAC3 phosphorylation and reduced its enzymatic activity. EGF treatment resulted in HDAC3 phosphorylation in both MDA-MB-231 and EGFR-overexpressing MCF7 (MCF7-EGFR) cells, but not in MCF7 cells. Total internal reflection fluorescence analysis showed that HDAC3 was recruited to the plasma membrane following EGF stimulation. HDAC3 inhibition with either c-Src knockdown or PP2 treatment significantly ameliorated the invasiveness of breast cancer cells. Altogether, our findings reveal an EGF signaling cascade involving EGFR, c-Src, and HDAC3 in breast cancer cells.

EPB41L5 Mediates TGFß-Induced Metastasis of Gastric Cancer.

PURPOSE: Because of disease heterogeneity, limited studies on effective chemotherapies and therapeutic agents for advanced gastric cancer are available. Erythrocyte membrane protein band 4.1-like 5 (EPB41L5) has critical roles in renal and breast cancer metastasis. However, its role in metastatic gastric cancer remains unknown. EXPERIMENTAL DESIGN: The specimens of 78 gastric cancer patients were analyzed by oligonucleotide microarray and survival analysis. In vitro experiments and metastatic mice models were used to assess the effects of EPB41L5 on gastric cancer metastasis. RESULTS: Gastric cancer patients with high EPB41L5 levels had poor prognosis and low survival rate. Further, TGFß1-induced EPB41L5 expression promoted gastric cancer cell migration and invasion by Smad-dependent TGFß signaling. Phospho-Smad3 recruitment to the EPB41L5 promoter was significantly inhibited by a TGFß inhibitor. EPB41L5 overexpression increased lung metastasis of gastric cancer cells in nude mice, which was completely reversed by anti-EPB41L5 monoclonal antibody treatment. Importantly, p120-catenin knockdown abolished EPB41L5-enhanced gastric cancer cell metastasis. Anti-EPB41L5 monoclonal antibody treatment blocked the association of EPB41L5 with p120-catenin. CONCLUSIONS: TGFß/EPB41L5/p120-catenin axis regulates gastric cancer cell metastasis, and EPB41L5 is a promising therapeutic target for advanced gastric cancer.

GPR177 promotes gastric cancer proliferation by suppressing endoplasmic reticulum stress-induced cell death.

Gastric cancer is the fourth most common cancer worldwide. Despite the high incidence of gastric cancer, efficient chemotherapy treatments still need to be developed. In this study, we examined the anticancer effects of endoplasmic reticulum (ER) stress inducer tunicamycin in gastric cancer. Previously, we found that overexpression of WLS1/GPR177 correlated with poor prognosis in patients with gastric cancer. Furthermore, tunicamycin treatment downregulated GPR177 expression in a dose-dependent manner. GPR177 transports WNT ligand from ER to the plasma membrane, mediating its secretion to the extracellular matrix. In gastric cancer cells, GPR177 preferentially localizes to the ER. Small interfering RNA-mediated knockdown of GPR177 leads to sensitization to ER stress and induces apoptosis of cancer cells along with tunicamycin treatment. GPR177 suppression promoted the ER stress-mediated proapoptotic pathway, such as PERK-CHOP cascade. Furthermore, fluorouracil treatment combined with tunicamycin dramatically reduced cancer cell proliferation. Efficacy of tunicamycin chemotherapy treatments depended on GPR177 expression in gastric cancer cell lines. Together, our results indicate that ER stress can potentiate anticancer effects and suggest GPR177 as a potential gastric cancer therapeutic target.

Tyrosine phosphorylation of HDAC3 by Src kinase mediates proliferation of HER2-positive breast cancer cells.

The role of histone deacetylase 3 (HDAC3) is to repress the expression of various genes by eliminating acetyl group from histone. Thus, the regulation of HDAC3 activity is essential to maintain cellular homeostasis. In this study, we found that HDAC3 interacts with c-Src kinase. However, the interaction between HDAC3 and c-Src was previously reported, it has still been ambiguous whether c-Src phosphorylates HDAC3 and affects the function of HDAC3. First, we confirmed that HDAC3 directly binds to c-Src, and c-Src identified to interact with C-terminal domain (277-428 a.a.) of HDAC3. c-Src also phosphorylated three tyrosine sites of HDAC3 at tyrosine 325, 328, and 331. Importantly, wild-type c-Src increases HDAC3 activity, but not mutant c-SrcK298M (kinase inactive form). When these tyrosine residues are all substituted for alanine residues, the deacetylase activity of mutant HDAC3 was abolished. In addition, a proliferation of HER2-positive breast cancer cells expressing phosphorylation deficient mutant HDAC3 is decreased in comparison with control cells. Thus, our findings suggested that phosphorylation of HDAC3 by c-Src kinase regulates the HDAC3 activity and the proliferation of breast cancer cells.

Serine/threonine kinase 31 promotes PDCD5-mediated apoptosis in p53-dependent human colon cancer cells.

Although programed cell death 5 (PDCD5) is an important protein in p53-mediated proapoptotic signaling, very little is known about PDCD5-related cell death. In this study, we report that serine/threonine kinase 31 (STK31) interacts with PDCD5, which maintains the stability of PDCD5. STK31 overexpression significantly activated PDCD5 stabilization and p53-mediated apoptosis in response to etoposide (ET). However, STK31 knockdown did not enhance apoptosis by ET treatment. Moreover, when STK31 was depleted, PDCD5 inhibited the activation of the p53 signaling pathway with ET, indicating that the PDCD5-STK31 network has an essential role in p53 activation. Importantly, STK31 activated the p53 signaling pathway by genotoxic stress through positive regulation of PDCD5-mediated apoptosis. We thus demonstrated that overexpression of STK31 greatly inhibited tumorigenic growth and increased the chemosensitivity of HCT116 human colorectal carcinoma cells. Taken together, these findings demonstrate that the STK31-PDCD5 complex network regulates apoptosis of cancer cells, and STK31 is a positive apoptosis regulator that inhibits tumorigenesis of colon cancer cells by inducing PDCD5-mediated apoptosis in response to genotoxic stress.

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.

Inhibition of Wntless/GPR177 suppresses gastric tumorigenesis.

Wntless/GPR177 functions as WNT ligand carrier protein and activator of WNT/ß-catenin signaling, however, its molecular role in gastric cancer (GC) has remained elusive. We investigated the role of GPR177 in gastric tumorigenesis and provided the therapeutic potential of a clinical development of anti-GPR177 monoclonal antibodies. GPR177 mRNA expression was assessed in GC transcriptome data sets (GSE15459, n = 184; GSE66229, n = 300); protein expression was assessed in independent patient tumor tissues (Yonsei TMA, n = 909). GPR177 expression were associated with unfavorable prognosis [log-rank test, GSE15459 (P = 0.00736), GSE66229 (P = 0.0142), and Yonsei TMA (P = 0.0334)] and identified as an independent risk predictor of clinical outcomes: GSE15459 [hazard ratio (HR) 1.731 (95% confidence interval; CI; 1.103- 2.715), P = 0.017], GSE66229 [HR 1.54 (95% CI, 1.10-2.151), P = 0.011], and Yonsei TMA [HR 1.254 (95% CI, 1.049- 1.500), P = 0.013]. Either antibody treatment or GPR177 knockdown suppressed proliferation of GC cells and sensitized cells to apoptosis. And also inhibition of GPR177 suppresses in vitro and in vivo tumorogenesis in GC cells and inhibits WNT/ß-catenin signaling. Finally, targeting and inhibition of GPR177 with antibody suppressed tumorigenesis in PDX model. Together, these results suggest GPR177 as a novel candidate for prognostic marker as well as a promising target for treatment of GC patients. [BMB Reports 2018; 51(5): 255-260].

Programmed cell death 5 suppresses AKT-mediated cytoprotection of endothelium.

Programmed cell death 5 (PDCD5) has been associated with human cancers as a regulator of cell death; however, the role of PDCD5 in the endothelium has not been revealed. Thus, we investigated whether PDCD5 regulates protein kinase B (PKB/AKT)-endothelial nitric oxide synthase (eNOS)-dependent signal transduction in the endothelium and affects atherosclerosis. Endothelial-specific PDCD5 knockout mice showed significantly reduced vascular remodeling compared with wild-type (WT) mice after partial carotid ligation. WT PDCD5 competitively inhibited interaction between histone deacetylase 3 (HDAC3) and AKT, but PDCD5L6R, an HDAC3-binding-deficient mutant, did not. Knockdown of PDCD5 accelerated HDAC3-AKT interaction, AKT and eNOS phosphorylation, and nitric oxide (NO) production in human umbilical vein endothelial cells. Moreover, we found that serum PDCD5 levels reflect endothelial NO production and are correlated with diabetes mellitus, high-density lipoprotein cholesterol, and coronary calcium in human samples obtained from the cardiovascular high-risk cohort. Therefore, we conclude that PDCD5 is associated with endothelial dysfunction and may be a novel therapeutic target in atherosclerosis.

Protein serine/threonine phosphatase PPEF-1 suppresses genotoxic stress response via dephosphorylation of PDCD5.

Programmed cell death 5 (PDCD5) is believed to play a crucial role in p53 activation; however, the underlying mechanism of how PDCD5 function is regulated during apoptosis remains obscure. Here, we report that the serine/threonine phosphatase PPEF-1 interacts with and dephosphorylates PDCD5 at Ser-119, which leads to PDCD5 destabilization. Overexpression of wild-type PPEF-1, but not inactive PPEF-1D172N, efficiently suppressed CK2α-mediated stabilization of PDCD5 and p53-mediated apoptosis in response to etoposide (ET). Conversely, PPEF-1 knockdown further enhanced genotoxic stress responses. Notably, PPEF-1 suppressed p53-mediated genotoxic stress response via negative regulation of PDCD5. We also determined that overexpression of wild-type PPEF-1, but not inactive PPEF-1D172N, significantly increased tumorigenic growth and chemoresistance of A549 human lung carcinoma cells. Collectively, these data demonstrate that PPEF-1 plays a pivotal role in tumorigenesis of lung cancer cells by reducing PDCD5-mediated genotoxic stress responses.

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.

The use of Subject Matter Experts in Validating an Oral Health-Related Quality of Life measure in Korean.

OBJECTIVES: This paper aimed to employ subject matter experts (SMEs) to assess the extent to which the Korean version of the short-form of the OHIP (OHIP-14 K) is culturally valid and equivalent in Korean. METHODS: We approached 17 bilingual Korean SMEs from which 10 independently rated the clarity, relevance, and cultural equivalence of the OHIP-14 K. SME's varied between 10 and 41 years of clinical experience and were mostly males (# 7). We used Item-level Content Validity Index (I-CVI) to gauge the proportion of SMEs who considered the content of OHIP items (e.g., instruction, response format, etc.) to be culturally valid. We also performed additional analysis to determine the level of agreement between the SMEs. RESULTS: The experts rated most of the items to be clear (S-CVI = 0.93) while having difficulties in assigning relevance of the questions to the expected domains (S-CVI = 0.42). Moreover, considerable disagreement existed among the experts in regard to the relevance (Kfree = 0.19 to 1.00) and the cultural equivalence indexes (ADM = 0.36 to 0.96). The content of the OHIP-14 K for the most part clearly reproduced the language of the original OHIP-14. However, experts disagreed on the relevance and conceptual equivalence of the OHIP-14 K for a Korean population. CONCLUSIONS: Patient-oriented outcome measures such as the OHIP can be used across cultures once there are indeed assessing the same domains and constructs of interest. The CVI technique seems to be an alternative tool for evaluating content validity and equivalency of an OHQoL measure. A more refined, culturally relevant version of OHIP-14 K was proposed although there is no available data yet to support a better score validity, reliability and responsiveness of this proposed version.

Programmed cell death 5 mediates HDAC3 decay to promote genotoxic stress response.

The inhibition of p53 activity by histone deacetylase 3 (HDAC3) has been reported, but the precise molecular mechanism is unknown. Here we show that programmed cell death 5 (PDCD5) selectively mediates HDAC3 dissociation from p53, which induces HDAC3 cleavage and ubiquitin-dependent proteasomal degradation. Casein kinase 2 alpha phosphorylates PDCD5 at Ser-119 to enhance its stability and importin 13-mediated nuclear translocation of PDCD5. Genetic deletion of PDCD5 abrogates etoposide (ET)-induced p53 stabilization and HDAC3 cleavage, indicating an essential role of PDCD5 in p53 activation. Restoration of PDCD5(WT) in PDCD5(-/-) MEFs restores ET-induced HDAC3 cleavage. Reduction of both PDCD5 and p53, but not reduction of either protein alone, significantly enhances in vivo tumorigenicity of AGS gastric cancer cells and correlates with poor prognosis in gastric cancer patients. Our results define a mechanism for p53 activation via PDCD5-dependent HDAC3 decay under genotoxic stress conditions.

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.

YAF2 promotes TP53-mediated genotoxic stress response via stabilization of PDCD5.

Programmed cell death 5 (PDCD5) plays a crucial role in TP53-mediated apoptosis, but the regulatory mechanism of PDCD5 itself during apoptosis remains obscure. We identified YY1-associated factor 2 (YAF2) as a novel PDCD5-interacting protein in a yeast two-hybrid screen for PDCD5-interacting proteins. We found that YY1-associated factor 2 (YAF2) binds to and increases PDCD5 stability by inhibiting the ubiquitin-dependent proteosomal degradation pathway. However, knocking-down of YAF2 diminishes the levels of PDCD5 protein but not the levels of PDCD5 mRNA. Upon genotoxic stress response, YAF2 promotes TP53 activation via association with PDCD5. Strikingly, YAF2 failed to promote TP53 activation in the deletion of PDCD5, whereas restoration of wild-type PDCD5WT efficiently reversed the ineffectiveness of YAF2 on TP53 activation. Conversely, PDCD5 efficiently overcame the knockdown effect of YAF2 on ET-induced TP53 activation. Finally, impaired apoptosis upon PDCD5 ablation was substantially rescued by restoration of PDCD5WT but not YAF2-interacting defective PDCD5E4D nor TP53-interacting defective PDCD5E16D mutant. Our findings uncovered an apoptotic signaling cascade linking YAF2, PDCD5, and TP53 during genotoxic stress responses.