Chemoproteomic strategy identified p120-catenin glutathionylation regulates E-cadherin degradation and cell migration.

Identification of cysteines with high oxidation susceptibility is important for understanding redox-mediated biological processes. In this report, we report a chemical proteomic strategy that finds cysteines with high susceptibility to S-glutathionylation. Our proteomic strategy, named clickable glutathione-based isotope-coded affinity tag (G-ICAT), identified 1,518 glutathionylated cysteines while determining their relative levels of glutathionylated and reduced forms upon adding hydrogen peroxide. Among identified cysteines, we demonstrated that CTNND1 (p120) C692 has high susceptibility to glutathionylation. Also, p120 wild type (WT), compared to C692S, induces its dissociation from E-cadherin under oxidative stress, such as glucose depletion. p120 and E-cadherin dissociation correlated with E-cadherin destabilization via its proteasomal degradation. Lastly, we showed that p120 WT, compared to C692S, increases migration and invasion of MCF7 cells under glucose depletion, supporting a model that p120 C692 glutathionylation increases cell migration and invasion by destabilization of E-cadherin, a core player in cell-cell adhesion.

Photoactive electron donor-acceptor complex platform for Ni-mediated C(sp3)-C(sp2) bond formation.

A dual photochemical/nickel-mediated decarboxylative strategy for the assembly of C(sp3)-C(sp2) linkages is disclosed. Under light irradiation at 390 nm, commercially available and inexpensive Hantzsch ester (HE) functions as a potent organic photoreductant to deliver catalytically active Ni(0) species through single-electron transfer (SET) manifolds. As part of its dual role, the Hantzsch ester effects a decarboxylative-based radical generation through electron donor-acceptor (EDA) complex activation. This homogeneous, net-reductive platform bypasses the need for exogenous photocatalysts, stoichiometric metal reductants, and additives. Under this cross-electrophile paradigm, the coupling of diverse C(sp3)-centered radical architectures (including primary, secondary, stabilized benzylic, α-oxy, and α-amino systems) with (hetero)aryl bromides has been accomplished. The protocol proceeds under mild reaction conditions in the presence of sensitive functional groups and pharmaceutically relevant cores.

Iron-Catalyzed Direct Oxidative Alkylation and Hydroxylation of Indolin-2-ones with Alkyl-Substituted N-Heteroarenes.

Presented herein is the first direct alkylation and hydroxylation reaction between two different C(sp3 )-H bonds, indolin-2-ones and alkyl-substituted N-heteroarenes, through an oxidative cross-coupling reaction. The reaction is catalyzed by a simple iron salt under mild ligand-free and base-free conditions. The reaction is environmentally benign, employs air (molecular oxygen) as the terminal oxidant and oxygen source for the synthesis of O-containing compounds, and produces only water as the byproduct.

TCF7L2 regulates pancreatic ß-cell function through PI3K/AKT signal pathway.

BACKGROUND: Transcription factor 7-like 2 (TCF7L2), which previously known as TCF-4, is a major form of transcription factor involved in the downstream WNT signaling and exhibits the strongest association to diabetes susceptibility. Although we still do not know mechanistically how TCF7L2 exerts its physiological functions on pancreatic endocrine cells, it had been suggested that TCF7L2 may directly affect ß-cell function by regulating the activation of PI3K/AKT signaling pathway. METHODS: MIN6 cells were transfected with TCF7L2 knockdown virus or lenti-TCF7L2 virus for 48 h to evaluate the contribution of TCF7L2 to the PI3K/AKT signaling pathway and pancreatic ß-cell function. This was confirmed by measuring the expression of PI3K p85 and p-Akt by western blotting and insulin secretion by enzyme-linked immunosorbent assay (ELISA), respectively. Chromatin immunoprecipitation (ChIP) and polymerase chain reaction (PCR) experiments were performed to explore the genomic distribution of TCF7L2-binding sites in the promoter of PIK3R1, the affinity between which was analyzed by the luciferase reporter assay. RESULTS: In the present study, we strikingly identified that TCF7L2 could profoundly inhibit the expression of PIK3R1 gene and its encoding protein PI3K p85, which then could lead to the activation of PI3K/AKT signaling and stimulate insulin secretion in pancreatic ß-cells. However, the integrity and stability of evolutionarily conserved TCF7L2-binding motif plays a very crucial role in the binding events between transcription factor TCF7L2 and its candidate target genes. We also found that the affinity of TCF7L2 to the promoter region of PIK3R1 alters upon the specific binding sites, which further provides statistical validation to the necessity of TCF7L2-binding motif. CONCLUSIONS: This study demonstrated that TCF7L2 is closely bound to the specific binding regions of PIK3R1 promoter and prominently controls the transcription of its encoding protein p85, which further affects the activation of PI3K/AKT signaling pathway and insulin secretion.

The association analysis polymorphism of CDKAL1 and diabetic retinopathy in Chinese Han population.

AIM: To identify the contribution of CDKAL1 to the development of diabetic retinopathy (DR) in Chinese population. METHODS: A case-control study was performed to investigate the genetic association between DR and polymorphic variants of CDKAL1 in Chinese Han population with type 2 diabetes mellitus (T2DM). A well-defined population with T2DM, consisting of 475 controls and 105 DR patients, was recruited. All subjects were genotyped for the genetic variant (rs10946398) of CDKAL1. Genotyping was performed by iPLEX technology. The association between rs10946398 and T2DM was assessed by univariate and multivariate logistic regression (MLR) analysis. RESULTS: There were significant differences in C allele frequencies of rs10946398 (CDKAL1) between control and DR groups (45.06% versus 55.00%, P<0.05). The rs10946398 of CDKAL1 was found to be associated with the increased risk of DR among patients with diabetes. CONCLUSION: Our findings suggest that rs10946398 of CDKAL1 is independently associated with DR in a Chinese Han population.

High-normal urinary albumin-to-creatinine ratio is independently associated with metabolic syndrome in Chinese patients with type 2 diabetes mellitus: A cross-sectional community-based study.

AIMS/INTRODUCTION: Microalbuminuria is positively related to metabolic syndrome (MetS). Our aim was to investigate whether urinary albumin-to-creatinine ratio (UACR) within the normal range is independently associated with MetS in Chinese community-based patients with type 2 diabetes. MATERIALS AND METHODS: A total of 514 participants (206 males and 308 females; mean age 66 years) with UACR less than 3.5 mg/mmol were enrolled from two downtown areas of Shanghai. The participants were stratified into quartiles according to UACR levels. The prevalence of MetS was assessed and compared among the four groups by binary logistic regression. RESULTS: Compared with participants with UACRs in the first quartile, the other quartiles had a higher prevalence of MetS (65.9%, 74.4% and 81.3%, respectively, P = 0.001) after adjustment for sex and age. After adjusting for potential confounders, participants in the second to the fourth quartile group had a 1.36-, 1.84- and 2.73-fold risk of MetS, respectively, relative to those in the lowest quartile. Furthermore, UACR, whether as quartile groups or as a continuous variable, is an independent predictor of MetS after fully adjusting for other variables. CONCLUSIONS: These results suggest that UACR even within the normal range is independently associated with MetS in Chinese community-based patients with type 2 diabetes mellitus.

An analysis of the association between a polymorphism of KCNJ11 and diabetic retinopathy in a Chinese Han population.

BACKGROUND: Genome-wide association studies (GWAS) have reported that the polymorphism rs5219 of the potassium inwardly rectifying channel, subfamily J, member 11 (KCNJ11) is associated with type 2 diabetes mellitus (T2DM). Given that diabetic retinopathy (DR) is one of the most common microvascular complications of T2DM, GWAS have identified a number of potential susceptibility genes for DR. However, only a fraction of them have been replicated in different studies and show consistent genetic associations with the occurrence of DR. The aim of the present study was to investigate whether common variants of KCNJ11 confer DR in a cohort of the Chinese Han population. METHODS: A case-control study of 580 T2DM patients, including 105 T2DM with DR and 475 T2DM without DR was performed. A single nucleotide polymorphism (SNP) of KCNJ11 (rs5219) was genotyped, and its association with DR was explored using a dominant genetic model. Genotyping was performed by iPLEX technology. Univariate and multivariate logistic regression (MLR) analysis controlling for confounders was conducted to evaluate the association between rs5219 and DR. RESULTS: The A allele frequency of rs5219 was significantly higher in DR patients than that in the patients without DR (49.01% versus 38.68%, P <0.05). We found the minor A allele could increase the risk to develop DR (ORint = 1.58, 95% CI: 1.139 to 2.192 for allele and P = 0.006, ORint =1.607, 95% CI: 1.267 to 2.038 for genotype and P <0.001) in the Chinese Han population. CONCLUSIONS: Our findings provided evidence that KCNJ11 was associated with DR in Chinese Han patients with T2DM.

Association and interaction analysis of PPARGC1A and serum uric acid on type 2 diabetes mellitus in Chinese Han population.

BACKGROUND: Peroxisome proliferator-activated receptor gamma coactivator-1α (PPARGC1A/ PGC-1α) is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily. The activity of PGC-1α or genetic variations in the gene encoding the enzyme may contribute to individual variations in mitochondrial function and insulin resistance or diabetes. The objective of this study was to assess the extent to which PPARGC1A (rs8192678) and serum uric acid (UA) and its interaction impact on T2DM susceptibility in Chinese Han population. METHOD: We conducted a study in a cohort that included 1166 T2DM patients and 1135 controls, and was genotyped for the presence of the PPARGC1A rs8192678 polymorphisms. Genotyping was performed by iPLEX technology. The association between rs8192678 or UA and T2DM was assessed by univariate and multivariate logistic regression (MLR) analysis controlling for confounders. The interaction between rs8192678 and UA for T2DM susceptibility was also assessed by MLR analysis. RESULTS: The generalized linear regression analysis failed to show an association between the PPARGC1A rs8192678 polymorphisms and T2DM. Interestingly, the present study provided data suggesting that the minor A-allele of PPARGC1A (rs8192678) had a protective effect against T2DM in subjects with higher level of UA (ORint =1.50 95% CI: 1.06-2.12 for allele and P = 0.02, ORint =1.63 95% CI: 1.17-2.26 for genotype and P = 0.004). CONCLUSION: The combination of higher level of UA and PPARGC1A (rs8192678) was an independent predictor for T2DM.

IGF2BP2 and obesity interaction analysis for type 2 diabetes mellitus in Chinese Han population.

BACKGROUND: The objective of this study was to systematically evaluate the contribution of the insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) to type 2 diabetes mellitus (T2DM) and its interaction with obesity to T2DM susceptibility. METHODS: To clarify whether IGF2BP2 is an independent risk factor for T2DM in Chinese population, we conducted a study with a total of 2,301 Chinese Han subjects, including 1,166 T2DM patients and 1,135 controls, for the genotype of a most common and widely studied polymorphism-rs4402960 of IGF2BP2. Genotyping was performed by iPLEX technology. Gene and environment interaction analysis was performed by using multiple logistic regression models. RESULTS: The repeatedly confirmed association between IGF2BP2 (rs4402960) and T2DM had not been replicated in this cohort (P = 0.182). Interestingly, we found that obese subjects (body mass index (BMI) ≥ 28.0 kg/m2) bearing the minor A allele had an increased risk to develop T2DM (P = 0.008 for allele analysis and P < 0.001 for genotype analysis). CONCLUSIONS: The present study provided data suggesting that the wild C allele of IGF2BP2 (rs4402960) had a protective effect against T2DM in obese subjects of Chinese Han population.

Low-grade albuminuria is associated with early but not late carotid atherosclerotic lesions in community-based patients with type 2 diabetes.

BACKGROUND: Low-grade albuminuria is associated with cardiovascular risk factors and mortality. Our aim was to investigate the association between low-grade albuminuria and carotid atherosclerotic lesions in community-based patients with type 2 diabetes. METHODS: A cross-sectional study was performed in 475 community-based patients with type 2 diabetes (190 males and 285 females) with normal urinary albumin-to-creatinine ratios (UACR) (< 3.5 mg/mmol) from Shanghai, China. The subjects were stratified into tertiles based on UACR levels (the lowest tertile was UACR ≤ 1.19 mg/mmol, and the highest tertile was UACR ≥ 2 mg/mmol). Carotid intima-media thickness (CIMT), carotid atherosclerotic plaque formation and stenosis were assessed and compared among the three groups based on ultrasonography. The urinary albumin excretion rate was determined as the mean of the values obtained from three separate early morning urine samples. RESULTS: Compared with the subjects with UACR in the lowest tertile, the subjects with UACR in the middle and highest tertiles had greater CIMT values (0.88 ± 0.35 mm, 0.99 ± 0.43 mm and 1.04 ± 0.35 mm, respectively; all p < 0.05) and a higher prevalence of carotid atherosclerotic plaques (25.3%, 39.0% and 46.2%, respectively; all p < 0.05) after adjusting for sex and age. Fully adjusted multiple linear regression and logistic regression analyses revealed that UACR tertiles were significantly associated with elevated CIMT (p = 0.007) and that, compared with the subjects in the first tertile of UACR, those in the second and third tertiles had 1.878- and 2.028-fold risk of carotid plaques, respectively. However, there was no statistical association between UACR tertile and the prevalence of carotid stenosis. CONCLUSIONS: Higher UACR within the normal range was independently associated with early but not late carotid atherosclerotic lesions in community-based patients with type 2 diabetes. Low-grade albuminuria contributes to the risk of carotid atherosclerosis and may be used as an early marker for the detection of atherosclerosis in patients with type 2 diabetes.

Deficiency of IRTKS as an adaptor of insulin receptor leads to insulin resistance.

IRTKS encodes a member of the IRSp53/MIM homology domain family, which has been shown to play an important role in the formation of plasma membrane protrusions. Although the phosphorylation of IRTKS occurs in response to insulin stimulation, the role of this protein in insulin signaling remains unknown. Here we show that IRTKS-deficient mice exhibit insulin resistance, including hyperglycemia, hyperinsulinemia, glucose intolerance, decreased insulin sensitivity, and increased hepatic glucose production. The administration of ectopic IRTKS can ameliorate the insulin resistance of IRTKS-deficient and diabetic mice. In parallel, the expression level of IRTKS was significantly decreased in diabetic mouse model. Furthermore, DNA hypermethylation of the IRTKS promoter was also observed in these subjects. We also show that IRTKS, as an adaptor of the insulin receptor (IR), modulates IR-IRS1-PI3K-AKT signaling via regulating the phosphorylation of IR. These findings add new insights into our understanding of insulin signaling and resistance.

Glycemic control among patients in China with type 2 diabetes mellitus receiving oral drugs or injectables.

BACKGROUND: The prevalence of type 2 diabetes mellitus (T2DM) is increasing rapidly among Chinese adults, and limited data are available on T2DM management and the status of glycemic control in China. We assessed the efficacy of oral antidiabetes drugs (OADs), glucagon-like peptide-1 (GLP-1) receptor agonists, and insulin for treatment of T2DM across multiple regions in China. METHODS: This was a multicenter, cross-sectional survey of outpatients conducted in 606 hospitals across China. Data from all the patients were collected between April and June, 2011. RESULTS: A total of 238,639 patients were included in the survey. Eligible patients were treated with either OADs alone (n=157,212 [65.88%]), OADs plus insulin (n=80,973 [33.93%]), or OADs plus GLP-1 receptor agonists (n=454 [0.19%]). The OAD monotherapy, OAD + insulin, and OAD + GLP-1 receptor agonist groups had mean glycosylated hemoglobin (HbA1c) levels (±SD) of 7.67% (±1.58%), 8.21% (±1.91%), and 7.80% (±1.76%), respectively. Among those three groups, 34.63%, 26.21%, and 36.12% met the goal of HbA1c <7.0%, respectively. Mean HbA1c and achievement of A1c <7.0% was related to the duration of T2DM. CONCLUSIONS: Less than one third of the patients had achieved the goal of HbA1c <7.0%. Glycemic control decreased and insulin use increased with the duration of diabetes.

Glutathione prevents free fatty acids-induced oxidative stress and apoptosis in human brain vascular endothelial cells through Akt pathway.

AIMS: The damage of human brain vascular endothelial cells (HBVECs) is the key pathogenesis of diabetes-associated cerebral vascular complications. The aim of this study was to elucidate the effects of glutathione (GSH) on free fatty acids (FFAs)-induced HBVECs apoptosis, oxidative stress, and the involved possible signaling pathway. METHODS: After culturing HBVECs for 72 h with GSH and FFAs, we determined cell proliferation by CCK8, detected apoptosis by caspase-3 and Annexin V-FITC/PI staining, and judged oxygen stress by determining the reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP). We investigated whether the Akt pathway was involved in FFAs-induced signaling pathway alteration and whether GSH influenced the above effects. RESULTS: After being cultured in 200 µM FFAs for 72 h, the HBVECs proliferation significantly decreased; HBVECs apoptosis increased; the ROS levels increased; and the HBVECs MMP subsequently decreased. FFAs induced a significant decrease in phosphorylated active Akt. These alterations were obviously prevented when 1 mM GSH was added to culture medium containing FFAs, and the above effects of GSH were blocked by Akt inhibitor. CONCLUSION: GSH may prevent FFAs-induced HBVECs damage, oxidative stress, and apoptosis through activating the Akt pathway.

Mutation of 3ß-hydroxysteroid dehydrogenase (3ß-HSD) at the 3'-untranslated region is associated with adrenocortical insufficiency.

In the present study, we report the mutation of the 3ß-hydroxysteroid dehydrogenase (3ß-HSD) gene in a family suffering from adrenocortical insufficiency. The index patient was clinically diagnosed with adrenocortical insufficiency. Peripheral venous blood (5 ml) was collected from the proband and 5 members of his family, and genomic DNA was extracted. Exons 1, 2, 3 and 4 of the 3ß-HSD gene and their flanking sequences were amplified by polymerase chain reaction (PCR). Some of the family members were examined by amplifying only exon 4. The PCR products were then purified and sequenced. The C to T homozygous mutation at nucleotide 1088 and C to G homozygous mutation at nucleotide 1132 within exon 4 of the 3ß-HSD gene were found in the family members with abnormal phenotype. In the family members with normal phenotype, heterozygous mutations at the sites mentioned above were identified in the parents and Aunt 1, but not in Aunt 2 of the proband. In conclusion, a family with 3ß-HSD deficiency was identified in the present study. The cause of the disease in the studied family appears to be two novel homozygous mutations in the 3ß-HSD gene.

Calorie restriction from a young age preserves the functions of pancreatic ß cells in aging rats.

Calorie restriction (CR) is a simple method for delaying aging process, extending lifespan, and preventing the onset of aging-related diseases, such as diabetes. However, the mechanism, by which CR influences ß-cell functions during the aging process, still remains unclear. In this study, sixteen 8-week-old male Sprague-Dawley rats were randomized to control group with food intake ad libitum and CR group fed with 70% of food intake of the control group. Twenty-four weeks later, the body weights of the rats with CR were significantly lower with the smaller amounts of perirenal and epididymal fats, compared to those of control rats. The ß-cell activity, as judged by the early insulin secretion in the intraperitoneal glucose tolerance test, was significantly higher in the CR group than that in control animals. Moreover, CR animals showed the increased ß-cell mass and proliferation of ß-cells in pancreas. The plasma level of malondialdehyde was lower in CR rats than that in control rats, while the activities of superoxide dismutase, catalase and glutathione peroxidase in plasma were higher in CR rats than control rats. These results indicate that aging is associated with the increases in oxidative stress, which was, however, alleviated by CR. In conclusion, CR from a young age preserves the principal ß-cell function of early insulin secretion in rats probably by stimulating the ß-cell proliferation. Our observations provide the evidence for clinical significance of CR in preventing ß-cell dysfunction during the aging process, which may delay the onset of aging-related disease, including diabetes in humans.

[Effect of adipose differentiation-related protein on the apoptosis of H9c2 cells by palmitic acid].

AIM: To construct a eukaryotic expression vector for expressing adipose differentiation-related protein(ADRP) protein and obtain a stable transfected H9c2 cell line. METHODS: (1)The full length DNA fragment of ADRP gene was amplified by PCR from the myocardium of adult SD rats and was inserted into pEGFP-C1 with T4 ligase. After the identification of digestion and sequencing on the recombinant pEGFP-C1-ADRP, the recombinant was transformed into E.coli strain DH5α.and the positive recombinant plasmid was selected. (2)The selected positive recombinant clones were amplified and transfected into H9c2 cells by lipofectamine(TM);2000. Cells containing stable transformants were selected by the ability of resistance to G418. The stable transfected cell line expressing high level of ADRP were obtained. Expression of green fluorescent protein gene was observed under fluorescence microscope and the expression of ADRP was identified by RT-qPCR and Western blot analysis. (3)The apoptotic percentage of H9c2 cells caused by PA was determined by flow cytometry. RESULTS: (1)Restriction map analysis and DNA sequencing analysis revealed that our target gene fragment was inserted into the expressing vector pEGFP-C1 successfully. (2)Green fluorescent was observed by fluorescence microscope on the cells which were transfected with pEGFP-C1 and pEGFP-C1-ADRP and did not disappear even at the twentieth passage of H9c2 cells. RT-qPCR and Western blot analysis showed that recombinant cells exhibit higher levers of mRNA and protein. (3)After treatment with different levels of PA, the apoptosis percentage of recombinant cells was lower than those of the other two cells. CONCLUSION: (1)The eukaryotic expression vector pEGFP-C1-ADRP and stable transfected H9c2 cells were established successfully. (2)The overexpression of ADRP gene could prevent apoptosis of cells caused by PA, which indicated that ADRP might play a protective role in H9c2 cells.

[Effect of FAM172A protein on apoptosis and proliferation in HEK293 cells].

OBJECTIVE: To study the effect of FAM172A protein related to diabetic macroangiopathy on apoptosis and proliferation in HEK293 cells. METHODS: The pDrive-FAM172A plasmid constructed in our previous study was used as a template to amplify human FAM172A open reading frame by a polymerase chain reaction. The resulting PCR products were subcloned into the eukaryotic expression vector PDC315 to construct recombinant PDC315-FAM172A plasmid. PDC315-FAM172A plasmid was identified by enzyme cleavage and sequencing analysis. HEK293 cells were transiently transfected respectively with appropriate PDC315 or PDC315-FAM172A plasmid by Lipofectamine 2000 according to the manufacturer's instruction. XTT assay and growth curve were used to observe the effect of over-expression of FAM172A gene on HEK293 cell proliferation. PI and Annexin V/PI staining method were used to assess the effect of FAM172A gene on apoptosis and cell cycle of HEK293 cell. RESULTS: Eukaryotic expression vector PDC315-FAM172A was successfully constructed and identified by enzyme cleavage and sequencing analysis. Compared with PDC315 plasmid transfection, the XTT assay showed that optical density (A) value increased by 52% when transfected with PDC315-FAM172A plasmid (0.21±0.07 vs 0.32±0.06, P<0.01). Growth curve revealed that HEK293 cells transfected with PDC315-FAM172A plasmid proliferated faster than those transfected with PDC315 plasmid. PI staining showed that, as compared with PDC315 plasmid transfection, the apoptotic rate of HEK293 cells transfected with PDC315-FAM172A plasmid decreased by 38.5% (23.79±1.36 vs 14.64±0.95, P<0.01), cell percentage of G0-G1 phases significantly decreased (66.79±1.73 vs 58.16±0.75, P<0.01) and cell percentage of S phases significantly increased (22.62±1.16 vs 33.56±0.94, P<0.01). Annexin V/PI staining revealed that, as compared with PDC315 plasmid transfection, the percentage of early and advanced apoptotic cells decreased by 28% (13.63±0.56 vs 9.79±0.39, P<0.01) and 29% (7.70±0.29 vs 5.43±0.29, P<0.01) respectively. CONCLUSION: FAM172A protein promotes cell proliferation, inhibits cell apoptosis and facilitates S-phases entry. It indicates that FAM172A protein is involved in cell growth regulation. Our findings provide a clue for further study on its physiological functions and roles in diabetic macroangiopathy.

Brap2 facilitates HsCdc14A Lys-63 linked ubiquitin modification.

Protein phosphotase Cdc14 (Cell division cycle gene 14) is a key regulator of late mitotic events in Saccharomyces cerevisiae. However the function of human Cdc14 (HsCdc14A & B) and its regulatory network are still elusive. In this study, we identified a new partner of HsCdc14A named Brap2 (BRCA1 associated protein 2) using yeast two-hybrid screening assay. The interaction between these two proteins is confirmed by co-immunoprecipitation in human HEK 293T cells. Brap2 co-localizes with HsCdc14A on mitotic spindle poles and over-expression of Brap2 causes multiple spindle poles. Furthermore, we found that Brap2, which has intrinsic RING domain dependent E3 ligase activity, facilitates HsCdc14A Lys-63 linked ubiquitin modification, indicating that Brap2 may be the ubiquitin E3 Ligase of HsCdc14A. Our findings imply that Brap2 plays a significant role in cell cycle regulation besides its facilitation of HsCdc14A ubiquitination.

[Molecular cloning of a novel gene, C5orf21 gene and its roles in diabetic macroangiopathy].

OBJECTIVE: To clone a novel diabetic angiopathy related protein gene-C5orf21 and study its roles in diabetic macroangiopathy. METHODS: The open reading frame (ORF) of C5orf21 gene was cloned into vector from human aortic tissues by a RT-PCR-based approach and identified by enzyme-cutting and sequencing. The structure and function of C5orf21 gene and protein were further analyzed by bioinformatics technology. The mRNA expression of C5orf21 gene in human tissues and in vascular cells was analyzed by RT-PCR. RT-PCR was used to observe the effect of high glucose, low-density lipoprotein (LDL) and free fatty acid (FFA) upon the expression of C5orf21 gene in macrophages. RESULTS: C5orf21 gene was successfully inserted into pDrive vector and identified for the first time at the level of mRNA. There are five C5orf21 gene splice variants in human aortic tissue and their length of ORF are 1251, 1113, 894, 810 and 810 bp respectively. Two kinds of splice variants have yet to be included in GenBank database. Two kinds of splice variants have the same ORF and their differences are mainly in the bases in the 5' untranslated region. Bioinformatics analysis found that C5orf21 gene was located in chromosome 5q15 and C5orf21 protein contained Arb2 domain associated with histone H3 lysine 9 methylation. C5orf21 gene was normally expressed in many tissues. Fat and aortic tissues had the highest expression. The expression of C5orf21 gene could be detected in human aortic endothelial cell, aortic smooth muscle cell and macrophages. High glucose, LDL and FFA (esp.high glucose) up-regulated the expression of C5orf21 gene in macrophage. CONCLUSION: C5orf21 gene contains five splice variants and it is identified for the first time at the level of mRNA. The changes of C5orf21 gene expression are correlated with diabetic macroangiopathy.