The structure of mouse RIPK1 RHIM-containing domain as a homo-amyloid and in RIPK1/RIPK3 complex.

Receptor-interacting protein kinase 1 (RIPK1) is a therapeutic target in treating neurodegenerative diseases and cancers. RIPK1 has three distinct functional domains, with the center domain containing a receptor-interacting protein homotypic interaction motif (RHIM), which mediates amyloid formation. The functional amyloid formed by RIPK1 and/or RIPK3 is a crucial intermediate in regulating cell necroptosis. In this study, the amyloid structure of mouse RIPK1, formed by an 82-residue sequence centered at RHIM, is presented. It reveals the "N"-shaped folding of the protein subunit in the fibril with four ß-strands. The folding pattern is shared by several amyloid structures formed by proteins with RHIM, with the central ß-strand formed by the most conserved tetrad sequence I/VQI/VG. However, the solid-state NMR results indicate a structural difference between mouse RIPK1 and mouse RIPK3. A change in the structural rigidity is also suggested by the observation of weakened signals for mouse RIPK3 upon mixing with RIPK1 to form the RIPK1/RIPK3 complex fibrils. Our results provide vital information to understand the interactions between different proteins with RHIM, which will help us further comprehend the regulation mechanism in cell necroptosis.

Recent advances in lipid nanovesicles for targeted treatment of spinal cord injury.

The effective regeneration and functional restoration of damaged spinal cord tissue have been a long-standing concern in regenerative medicine. Treatment of spinal cord injury (SCI) is challenging due to the obstruction of the blood-spinal cord barrier (BSCB), the lack of targeting of drugs, and the complex pathophysiology of injury sites. Lipid nanovesicles, including cell-derived nanovesicles and synthetic lipid nanovesicles, are highly biocompatible and can penetrate BSCB, and are therefore effective delivery systems for targeted treatment of SCI. We summarize the progress of lipid nanovesicles for the targeted treatment of SCI, discuss their advantages and challenges, and provide a perspective on the application of lipid nanovesicles for SCI treatment. Although most of the lipid nanovesicle-based therapy of SCI is still in preclinical studies, this low immunogenicity, low toxicity, and highly engineerable nanovesicles will hold great promise for future spinal cord injury treatments.

Medium-Term Clinical Results of High-Flexion Knee Prostheses in Patients with Rheumatoid Arthritis.

OBJECTIVE: This study was performed to evaluate the function and satisfaction outcome of patients with rheumatoid arthritis (RA) who underwent total knee arthroplasty (TKA) with high-flexion prostheses. MATERIALS AND METHODS: Twenty-two patients (35 knees) using high-flexion prostheses (Zimmer, Warsaw, IN) were followed up for a period of 7-11 years from February 2007 to December 2009. Clinical and radiographic follow-up was performed using Hospital for Special Surgery (HSS), Short-Form 36 scores (SF-36), American Knee Society score (KSS), and Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Patient satisfaction assessments took place at the final follow-up sessions using the Marsh Satisfaction Questionnaire. RESULTS: The average ROM improved from preoperative 68.43° ± 33.78° to 95.54° ± 7.03° at the final follow-up. The HSS score and KSS score for pain improved from (46.49 ± 12.73) points to (85.46 ± 3.90) points and from 20.57 ± 5.91 points to 47.43 ± 3.51 points at the follow-up evaluation, respectively. Physical Component Summary(PCS) and Physical Component Summary (MCS) scores were 45.38 and 52.56, respectively by the end of follow-up. Deep venous thrombosis developed in one patient and one patient required surgical revision due to infection. There were no instances of prosthetic loosening. The satisfaction rate of patients was 95.5%. CONCLUSION: Although this particular model of TKA did not yield high-flexion angles (ie, 140°) required for kneeling, squatting, or rising from the floor, significant clinical and radiographic gains were evident in these patients with RA.

The amyloid structure of mouse RIPK3 (receptor interacting protein kinase 3) in cell necroptosis.

RIPK3 amyloid complex plays crucial roles during TNF-induced necroptosis and in response to immune defense in both human and mouse. Here, we have structurally characterized mouse RIPK3 homogeneous self-assembly using solid-state NMR, revealing a well-ordered N-shaped amyloid core structure featured with 3 parallel in-register ß-sheets. This structure differs from previously published human RIPK1/RIPK3 hetero-amyloid complex structure, which adopted a serpentine fold. Functional studies indicate both RIPK1-RIPK3 binding and RIPK3 amyloid formation are essential but not sufficient for TNF-induced necroptosis. The structural integrity of RIPK3 fibril with three ß-strands is necessary for signaling. Molecular dynamics simulations with a mouse RIPK1/RIPK3 model indicate that the hetero-amyloid is less stable when adopting the RIPK3 fibril conformation, suggesting a structural transformation of RIPK3 from RIPK1-RIPK3 binding to RIPK3 amyloid formation. This structural transformation would provide the missing link connecting RIPK1-RIPK3 binding to RIPK3 homo-oligomer formation in the signal transduction.

Reduced expression of autophagy markers correlates with high-risk human papillomavirus infection in human cervical squamous cell carcinoma.

Infection by an oncogenic human papillomavirus (HPV), in particular HPV16 and 18, is a high risk factor for developing cervical cancer; however, viral infection alone is not sufficient for cancer progression. Autophagy is hypothesized to be an important process during carcinogenesis. The aim of the present study was to investigate the association between autophagy and high-risk HPV (hrHPV) infection in human cervical squamous cell carcinomas (SCCs), and to analyze the clinical significance of this association. Quantum dot (QD)-based immunofluorescence histochemistry was used to detect the expression of autophagy markers, Beclin-1 and microtubule-associated proteins 1A/1B light chain 3B (LC3B) proteins, in 104 cases of cervical cancer (including 80 SCCs and 24 adenocarcinomas) and 20 normal cervical tissues. hrHPV (HPV16/18) infection was detected by QDs based fluorescence in situ hybridization in cervical cancers. The results revealed that the expression levels of Beclin-1 and LC3B were significantly lower in cervical cancer cells when compared with those of normal cervical squamous epithelial cells, and were found to negatively correlate with hrHPV infection. The expression levels of Beclin-1 and LC3B were not associated with age, tumor grade, tumor stage, tumor node metastasis stage or lymph node metastasis. However, a positive correlation was identified between Beclin-1 and LC3B protein expression. In addition, the absence of autophagy in combination with hrHPV infection may accelerate the progression of cervical SCC. In conclusion, decreased expression of Beclin-1 and LC3B may be important in cervical carcinogenesis. The hrHPV-host cell interaction may inhibit autophagy, which may aid virus duplication and infection, as well as cervical cancer development.

Prognostic significance of α5ß1-integrin expression in cervical cancer.

The purpose of this study was to evaluate the association of expression of α5ß1-integrin with clinicopathologic features and prognosis in cervical cancer. Levels of α5ß1-integrin in normal cervical mucosa and cervical cancer tissue were detected with immunohistochemistry. Survival analysis by the Kaplan-Meier method was performed to assess prognostic significance. α5ß1-integrin expression was detected in 84.6% (143/169) cervical cancer samples, significantly different from that in normal cervical mucosa (P < 0.05). Positive expression rates of α5ß1-integrin in patients with poor histologic differentiation, lymph node metastasis, and recurrence were elevated. Using Kaplan-Meier analysis, a comparison of survival curves of low versus high expression of α5ß1-integrin revealed a highly significant difference in human cervical cancer cases (P < 0.05), suggesting that overexpression of α5ß1-integrin is associated with a worse prognosis.The α5ß1-integrin promotes angiogenesis and associates with lymph node metastasis, vascular invasion and poor prognosis of cervical cancer. The current study indicated that α5ß1-integrin may be an independent prognostic factor for cervical cancer patients.

[Study of correlationship between congenital heart disease and 5, 10-methylenetetra hydrofolate reductase gene's polymorphism or folacin intakes].

OBJECTIVE: To investigate the correlationship between congenital heart disease and 5, 10-methylenetetra hydrofolate reductase (MTHFR)'s C677T or folacin intakes, and to study the interaction of them in the occurring of congenital heart disease. METHODS: We used case-control study (case = 104, control = 208) method. Cases and controls were chosen by age, sex and other conditions. The MTHFR C677T genotype distribution was analyzed by using polymerase chain reaction restricted fragment length polymorphism (PCR-RFLP), and non-conditional and multi-conditional logistic regression analysis were also used to analyze the correlationship and interaction of the factors. RESULTS: In case group, the number of people in low folacin intake level was 38 (36.54%), which in control group was 21(10.10%). The intake level of folacin during pregnancy was related to congenital heart disease (chi(2) = 31.614, nu = 1, P < 0.0001). The value of OR was 1.417 with 95%CI 1.216 - 1.651, indicating that the low level of folacin intakes was a risk factor to the congenital heart disease. In case group, the number of TT genotype was 46 (44.24%), the number of CT genotype was 42 (40.38%), the number of CC genotype was 16 (15.38%). In control group, the number of TT genotype was 39 (18.75%), the number of CT genotype was 114 (54.81%), the number of CC genotype was 55 (26.44%). A significant genotype distribution difference was identified between case and control group (chi(2) = 23.13, nu = 2, P < 0.0001). Genotype MTHFR 677TT was a risk factor of congenital heart disease and the OR value was 3.437 (95%CI: 2.042 - 5.784). The interaction analysis suggested that the low level of folacin intakes and the MTHFR 677TT genotype had a positive adding effect in the occurring of congenital heart disease. After adjusted some factors such as the ages of parents, fetus age and sex, the effect values of interaction were 13.343 and 15.911 respectively, and the percentages of attributable interaction effects were 0.619 and 0.612. The percentages of effect values of interaction between pure factors were 0.649 and 0.637 and the population attributable risks were 25.26% and 27.82% according to the estimated exposure rate of population risk factors. CONCLUSION: The low level of folacin intakes during pregancy should be a risk factor to congenital heart disease and the MTHFR 677TT genotype be correlated to congenital heart disease. There is interaction between folacin intakes and the MTHFR 677TT genotype. Increasing the intakes of folacin among MTHFR 677TT genotype people might decrease the incidence rate of congenital heart disease.

[Functions of spleen tyrosine kinase (Syk) gene and its correlation to neoplasms].

Spleen tyrosine kinase (Syk) was thought to be a hematopoietic cell-specific signaling molecule and plays an essential role in maturation of lymphocytes and activation of immune cells. Recent evidences show that it is also expressed by many non-hematopoietic cell types. Down-regulation of Syk expression was first observed during breast cancer progression, now its abnormal expression has also been detected in many other types of tumors. Syk could suppress tumorigenesis and metastasis, but the molecular mechanism remains unknown. Promoter hypermethylation is one of the mechanisms that lead to silencing of Syk gene. Increasing clinical evidences reveal a positive correlation of reduced Syk expression to increased risk for metastasis, and indicate that Syk may be a potential new tumor suppressor.