Kelch-like Protein 21 (KLHL21) Targets IκB Kinase-ß to Regulate Nuclear Factor κ-Light Chain Enhancer of Activated B Cells (NF-κB) Signaling Negatively.

Activation of IKKß is the key step in canonical activation of NF-κB signaling. Extensive work has provided insight into the mechanisms underlying IKKß activation through the identification of context-specific regulators. However, the molecular processes responsible for its negative regulation are not completely understood. Here, we identified KLHL21, a member of the Kelch-like gene family, as a novel negative regulator of IKKß. The expression of KLHL21 was rapidly down-regulated in macrophages upon treatment with proinflammatory stimuli. Overexpression of KLHL21 inhibited the activation of IKKß and degradation of IκBα, whereas KLHL21 depletion via siRNA showed the opposite results. Coimmunoprecipitation assays revealed that KLHL21 specifically bound to the kinase domain of IKKß via its Kelch domains and that this interaction was gradually attenuated upon TNFα treatment. Furthermore, KLHL21 did not disrupt the interaction between IKKß and TAK1, TRAF2, or IκBα. Also, KLHL21 did not require its E3 ubiquitin ligase activity for IKKß inhibition. Our findings suggest that KLHL21 may exert its inhibitory function by binding to the kinase domain and sequestering the region from potential IKKß inducers. Taken together, our data clearly demonstrate that KLHL21 negatively regulates TNFα-activated NF-κB signaling via targeting IKKß, providing new insight into the mechanisms underlying NF-κB regulation in cells.

Potential urine biomarkers for gestational hypertension and preeclampsia.

Differential proteomic technology was used to identify urine proteomic profile of gestational hypertension and preeclampsia. Urine samples were collected from 10 patients with gestational hypertension, 10 patients with mild preeclampsia, 10 patients with severe preeclampsia and 10 normal pregnancies and analyzed by 2­D difference gel electrophoresis, then matrix assisted laser desorption ionization mass spectrometry was used to identify differential proteins. Subsequently, ELISA was used to verify the content variation of the identified proteins in 200 urine samples. In total, 30 differential proteins were identified. For prostaglandin­H2 D­isomerase (L­PGDS), perlecan and other 15 proteins, the contents in patients with gestational hypertension were higher than that of normal pregnancies, but lower in mild and severe preeclampsia. By contrast, serum albumin and α­1­antitrypsin was lower in samples from patients with gestational hypertension and higher in patients with mild and severe preeclampsia compared with normal pregnancies. ELISA verified that the urinary concentration of L­PGDS and perlecan were significantly lower in patients with preeclampsia than in normal pregnancies (P<0.05). Urine proteomics is a useful tool to identify potential biomarkers to distinguish between different types of hypertensive disorders in pregnancy. L­PGDS and perlecan could potentially be used as markers to reflect the state of renal function, and may participate in the genesis and development of renal injury during preeclampsia.

[Screening and verification of plasma biomarkers for stable angina pectoris: a differential proteomic analysis].

OBJECTIVE: To compare and analyze the differentially expressed plasma proteome between patients with stable angina pectoris (SAP) and healthy donors to identify the biomarkers for early diagnosis of SAP. METHODS: Plasma samples from 60 patients with SAP and 60 healthy controls were collected. Twenty samples (100 mL each) randomly selected from each group were pooled and after removing high-abundance proteins from the pooled plasma, two-dimensional gel electrophoresis (2DE) was performed to isolate the total proteins. The protein spots with more than 2 fold changes were selected after 2D analysis using software, and the differentially expressed proteins were identified by MALDI TOF/TOF mass spectrometer. ELISA was performed to detect hemoglobin subunit delta (HBD) levels in 40 randomly selected samples from each group for verification of the results of 2DE. RESULTS: A total of 7 differentially expressed proteins were found in plasma samples from patients with SAP, including 3 up regulated proteins (serum albumin, hemoglobin subunit alpha and hemoglobin subunit delta,) and 4 down?regulated ones (apolipoprotein L1, apolipoprotein C3, apolipoprotein E and complement C4B). ELISA results showed that HBD level was increased in SAP plasma, which was consistent with the results of 2DE. CONCLUSION: Patients with SAP have different plasma protein profiles from those of healthy controls, and HBD may serve as a potential specific biomarker for early diagnosis of SAP.

Proteomic identification of alpha-2-HS-glycoprotein as a plasma biomarker of hypopharyngeal squamous cell carcinoma.

Hypopharyngeal squamous cell carcinoma (HSCC) has very poor prognosis compared with other head and neck squamous cell carcinomas. Late-stage diagnosis of HSCC increases mortality. Therefore, more effective biomarkers for early diagnosis of HSCC are necessary. Unfortunately, appropriate biomarkers for clinical diagnosis and prognosis have not been identified yet. However, recent progresses in quantitative proteomics have offered opportunities to identify plasma proteins as biomarkers for HSCC. In the present study, plasma samples were analyzed by two-dimensional differential gel electrophoresis (2D-DIGE), and differentially expressed proteins were identified by matrix assisted laser desorption ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS). A total of 26 proteins representing 12 unique gene products were identified. The up-regulation proteins were alpha-2-HS-glycoprotein (AHSG), complement C4-B, haptoglobin, C-reactive protein, and ceruloplasmin, whereas the down-regulation proteins were serum albumin, angiotensinogen, alpha-1-antichymotrypsin, Ig gamma-3 chain C region, fibrinogen gamma chain, apolipoprotein A-I, and Ig kappa chain C region. Among all the differentially expressed proteins, AHSG was validated by western blot and ELISA. The results were consistent with the data from 2D-DIGE, further suggesting that AHSG may be employed as a potential biomarker for the early diagnosis of HSCC. In summary, this study was the first to use 2D-DIGE and MALDI-TOF/TOF platform to identify the potential plasma biomarkers for HSCC. The plasma AHSG showed great potential for HSCC screening.

3, 4-dihydroxyl-phenyl lactic acid restores NADH dehydrogenase 1 α subunit 10 to ameliorate cardiac reperfusion injury.

The present study aimed to detect the role of 3, 4-dihydroxyl-phenyl lactic acid (DLA) during ischemia/reperfusion (I/R) induced myocardial injury with emphasis on the underlying mechanism of DLA antioxidant. Male Spragu-Dawley (SD) rats were subjected to left descending artery occlusion followed by reperfusion. Treatment with DLA ameliorated myocardial structure and function disorder, blunted the impairment of Complex I activity and mitochondrial function after I/R. The results of 2-D fluorescence difference gel electrophoresis revealed that DLA prevented the decrease in NDUFA10 expression, one of the subunits of Complex I. To find the target of DLA, the binding affinity of Sirtuin 1 (SIRT1) to DLA and DLA derivatives with replaced two phenolic hydroxyls was detected using surface plasmon resonance and bilayer interferometry. The results showed that DLA could activate SIRT1 after I/R probably by binding to this protein, depending on phenolic hydroxyl. Moreover, the importance of SIRT1 to DLA effectiveness was confirmed through siRNA transfection in vitro. These results demonstrated that DLA was able to prevent I/R induced decrease in NDUFA10 expression, improve Complex I activity and mitochondrial function, eventually attenuate cardiac structure and function injury after I/R, which was possibly related to its ability of binding to and activating SIRT1.

Acute coronary syndrome remodels the protein cargo and functions of high-density lipoprotein subfractions.

OBJECTIVES: This study examined alterations in the functions and proteome of high-density lipoprotein (HDL) subfractions (HDL2 and HDL3) isolated from patients with acute coronary syndrome (ACS) compared with control subjects. METHODS: We measured HDL subfraction cholesterol efflux capacity, inflammatory index (HII), paraoxonase-1 (PON1) activity, and lipid hydroperoxide (LOOH) levels in both male age-matched controls and the ACS group (n = 40/group). Additionally, proteomic analysis was used to monitor changes in the HDL subfraction proteome between controls and ACS subjects. RESULTS: Both HDL2 and HDL3 from ACS patients had greater HII and LOOH levels compared with controls (P<0.001); PON1 activity and cholesterol efflux capacity in both HDL2 and HDL3 from the ACS group were significantly less than those of controls (P<0.001). Using proteomic analysis, we demonstrated that, compared with the control group, nine proteins were selectively enriched in HDL3 from subjects with ACS, and ras-related protein Rab-7b was decreased in HDL3. Additionally, in the ACS subjects, 12 proteins were decreased in HDL2 and 4 proteins were increased in HDL2. CONCLUSIONS: Functional HDL subfractions shifted to dysfunctional HDL subfractions during ACS, and the functional impairment was linked to remodeled protein cargo in HDL subfractions from ACS patients.

[Identification of protein markers for gestational diabetes mellitus complicated by pregnancy-induced hypertensive syndrome].

OBJECTIVE: To identify the serum protein markers for the gestational diabetes mellitus (GDM) complicated by pregnancy-induced hypertensive (PIH) syndrome to provide a molecular biological basis for the screening, prevention and therapy of the related diseases. METHODS: Serum samples were collected from the patients with GDM, PIH syndrome, and GDM complicated by PIH syndrome. IgG and albumins were removed from the samples before SDS -PAGE. The protein bands showing significant differences among the 3 samples were collected, digested and identified with mass spectrometry, and the function of the identified proteins was analyzed. RESULTS: Three SDS-PAGE were performed in parallel to confirm the differentially expressed proteins. Mass spectrometry indicated that the proteins showing obvious differences among the 3 samples were haptoglobin, protein SMG8 and apoptosis-inducing factor-1. CONCLUSIONS: The protein markers identified in GDM complicated by PIH syndrome may be integrated into the proteomic database of gestational metabolic diseases. Identification of the associated protein markers may provide significant experimental data for the prevention, diagnosis and therapy of the related diseases.

Proteomic analysis of human serum from diabetic retinopathy.

AIM: To establish and compare serum proteomic of diabetic retinopathy (DR) patients in various phases and discuss pathogenesis of DR so as to find out possible serum specific molecular markers for early diagnosis of DR. METHODS: Thirty-two subjects were divided into four groups: one group of eight type 2 diabetes mellitus (T2DM) patients without apparent DR (No-DR, NDR), one group of eight T2DM patients with non-proliferative diabetic retinopathy (NPDR), one group of eight T2DM patients with proliferative diabetic retinopathy (PDR) and one group of eight healthy volunteer participants. Two dimensional fluorescence difference gel electrophoresis (2D-DIGE) was applied to establish differential protein expression profiles in four groups. Matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry (MALDI-TOF-TOF MS) was applied to identify mass spectrometry of differential proteins and analyze follow-up bioinformatics. RESULTS: 2D-DIGE maps of serum protein were satisfactory obtained from NDR, NPDR, PDR and normal control groups. Twenty-six different proteins spots were screened (the volume ratio was >1.5 based on DeCyder software analysis). Twenty-four of them were verified and two of them were not. Fifteen proteins were verified. Most of them were high-abundant proteins in serum. The four relatively low-abundant ones were beta 2-glycoprotein I (ß(2)-GPI), alpha2-HS-glycoprotein(AHSG), alpha1-acid glycoprotein(α(1)-AGP) and apolipoprotein A-1(apo A-1). ß(2)-GPI expression was gradually increased in the development of DR but unrelated to the severity of DR. The volume ratio of ß(2)-GPI is 1.54, 2.43, and 2.84 in NDR, NPDR and PDR group respectively compared with normal control group. CONCLUSION: Serum proteomic analysis of 2D-DIGE combined with MALDI-TOF-TOF MS is feasible to be applied in the study of DR. ß(2)-GPI probably takes part in the process of DR occurrence and development and it could be a candidate biomarker on DR diagnosis in early phase.

[Construction of a eukaryotic expression vector for alpha-1-antitrypsin and the localization of the expression product in NIH 3T3 cells].

OBJECTIVE: To construct a eukaryotic expression vector for alpha-1-antitrypsin (AAT) and detect its expression and localization in NIH 3T3 cells. METHODS: The total RNA was extracted from the liver tissue of BALB/c mice, and the corresponding coding sequences for mouse AAT (GenBank accession No. NM_009243) were amplified by RT-PCR and cloned into hemagglutinin (HA)-tagged vector pcDNA3-HA. The construct was then transfected into NIH 3T3 cells, which were observed under fluorescence microscope. RESULTS: The recombinant plasmid was verified by PCR, enzyme digestion and sequence analysis, and the fusion protein was highly expressed in NIH 3T3 cells. Under fluorescence microscope, the fusion protein was found to distribute mainly in the cytoplasm. CONCLUSION: The expression vector for AAT-HA fusion protein has been successfully constructed and effectively expressed in mammalian cells to allow future functional study of AAT in mammalian cells.

[Extraction and two-dimensional liquid chromatographic fractionation of plasma membrane proteome of mouse liver cells].

OBJECTIVE: To extract the plasma membrane proteins from mouse liver cells and investigate the approach for fractionating the protein mixtures by two-dimensional liquid chromatography. METHODS: The plasma membrane of the liver cells from 10 mice was extracted by differential centrifugation and sucrose density-gradient centrifugation. The plasma membrane proteins were exchanged with the start buffer and separated by chromatofocusing in the first-dimensional fractionation. The final results were transformed into UV/pI maps using ProteoVue software. RESULTS: We successfully extracted the plasma membrane proteins from mouse liver cells. Sixteen fractions between pH 8.5-4.0 were recovered in the first-dimensional chromatofocusing followed by 2D- chromatographic fractionation, and the results were displayed as UV/pI maps. CONCLUSION: This approach for fractionating the mouse liver cell plasma membrane protein study provides the foundation for further studies on the functions of plasma membrane proteins and differential proteome of diseases.

[Expression and localization of endogenous C-reactive protein in THP-1 monocytes and LO2 hepatocytes].

OBJECTIVE: To observe the expression and localization of endogenous C-reactive protein (CRP) in cells from different tissues under different conditions. METHODS: Macrophages differentiated from THP-1 monocytes with phorbol ester (PMA) induction and human LO2 hepatocytes were stimulated with lipopolysaccharide (LPS). The culture supernatant of the LPS-stimulated THP-1 cells was collected and added into LO2 cell culture, and after incubation, the cells were lysed to extract the proteins for SDS-PAGE and Western blotting. The stimulated cells were also examined immunocytochemically for CRP expression. RESULTS: Western blotting detected CRP in both of the unstimulated cell lysates, but in neither of the two cell supernatants. After LPS stimulation, CRP expression was significantly increased in the cell lysate of THP-1 cells with also a small amount present in the supernatant, but CRP expression and release in the LO2 cells showed no significant variation. Treatment of the LO2 cells with the culture supernatant of LPS-stimulated THP-1 cells resulted in positivity of CRP in the cell lysate and the culture supernatant. Immunocytochemistry identified CRP expression throughout the THP-1 cell body (most obvious in the nuclei), which increased after LPS stimulation. In LO2 hepatocytes, CRP expression was found only outside the nuclei and increased after stimulation with the culture supernatant of LPS-treated THP-1 cells, especially obvious around the membrane. CONCLUSION: CRP can not be up-regulated directly by LPS treatment in LO2 cells, but can be induced by certain cytokines (IL-6) secreted from LPS-stimulated THP-1 cells. The localization of CRP represents the characteristics of secreted protein in LO2 cells, but in THP-1 cells, CRP is found mainly in the cell nuclei.