Control of poly(A)-tail length and translation in vertebrate oocytes and early embryos

During oocyte maturation and early embryogenesis, changes in mRNA poly(A)-tail lengths strongly influence translation, but how these tail-length changes are orchestrated has been unclear. Here, we performed tail-length and translational profiling of mRNA reporter libraries (each with millions of 3' UTR sequence variants) in frog oocytes and embryos and in fish embryos. Contrasting to previously proposed cytoplasmic polyadenylation elements (CPEs), we found that a shorter element, UUUUA, together with the polyadenylation signal (PAS), specify cytoplasmic polyadenylation, and we identified contextual features that modulate the activity of both elements. In maturing oocytes, this tail lengthening occurs against a backdrop of global deadenylation and the action of C-rich elements that specify tail-length-independent translational repression. In embryos, cytoplasmic polyadenylation becomes more permissive, and additional elements specify waves of stage-specific deadenylation. Together, these findings largely explain the complex tapestry of tail-length changes observed in early frog and fish development, with strong evidence of conservation in both mice and humans.

Nuclear release of eIF1 globally increases stringency of start-codon selection to preserve mitotic arrest physiology

Regulated start-codon selection has the potential to reshape the proteome through the differential production of uORFs, canonical proteins, and alternative translational isoforms. However, conditions under which start-codon selection is altered remain poorly defined. Here, using transcriptome-wide translation initiation site profiling, we reveal a global increase in the stringency of start-codon selection during mammalian mitosis. Low-efficiency initiation sites are preferentially repressed in mitosis, resulting in pervasive changes in the translation of thousands of start sites and their corresponding protein products. This increased stringency of start-codon selection during mitosis results from increased interactions between the key regulator of start-codon selection, eIF1, and the 40S ribosome. We find that increased eIF1-40S ribosome interactions during mitosis are mediated by the release of a nuclear pool of eIF1 upon nuclear envelope breakdown. Selectively depleting the nuclear pool of eIF1 eliminates the changes to translational stringency during mitosis, resulting in altered mitotic proteome composition. In addition, preventing mitotic translational rewiring results in substantially increased cell death and decreased mitotic slippage following treatment with anti-mitotic chemotherapeutics. Thus, cells globally control translation initiation stringency with critical roles during the mammalian cell cycle to preserve mitotic cell physiology.

Patients with persistent symptoms after COVID-19 attending a multidisciplinary evaluation: Characteristics, medical conclusions, and satisfaction

OBJECTIVE

Among patients attending a multidisciplinary day-hospital program for persistent symptoms after COVID-19, we aimed i) to describe their characteristics ii) to present the medical conclusions (diagnoses and recommendations) and iii) to assess the patients' satisfaction and its correlates.

METHODS

For this retrospective chart review study, frequent symptoms were systematically assessed. Standardized questionnaires explored fatigue (Pichot scale), physical activity (Ricci & Gagnon scale), health-related quality of life (Short-Form Health Survey), anxiety and depressive symptoms (Hospital Anxiety and Depression scale) and associated psychological burden (Somatic-Symptom-Disorder B criteria Scale). Medical record conclusions were collected and a satisfaction survey was performed at 3-months follow-up.

RESULTS

Among 286 consecutive patients (median age: 44 years; 70% women), the most frequent symptoms were fatigue (86%), breathlessness (65%), joint/muscular pain (61%) and cognitive dysfunction (58%), with a median duration of 429 days (Inter-quartile range (IqR): 216-624). Questionnaires revealed low levels of physical activity and quality of life, and high levels of fatigue, anxiety, depression, and psychological burden, with 32% and 23% meeting the diagnostic criteria for a depressive or anxiety disorder, respectively. Positive arguments for a functional somatic disorder were found in 76% of patients, including 96% with no abnormal clinical or test findings that may explain the symptoms. Physical activity rehabilitation was recommended for 91% of patients. Patients' median satisfaction was 8/10 (IqR: 6-9).

CONCLUSION

Most patients attending this program presented with long-lasting symptoms and severe quality of life impairment, received a diagnosis of functional somatic disorder, and reported high levels of satisfaction regarding the program.

Polymer Complex Fiber: Property, Functionality, and Applications

Polymer complex fibers (PCFs) are a novel kind of fiber material processed from polymer complexes that are assembled through noncovalent interactions. These can realize the synergy of functional components and miscibility on the molecular level. The dynamic character of noncovalent interactions endows PCFs with remarkable properties, such as reversibility, stimuli responsiveness, self-healing, and recyclability, enabling them to be applied in multidisciplinary fields. The objective of this article is to provide a review of recent progress in the field of PCFs. The classification based on chain interactions will be first introduced followed by highlights of the fabrication technologies and properties of PCFs. The effects of composition and preparation method on fiber properties are also discussed, with some emphasis on utilizing these for rational design. Finally, we carefully summarize recent advanced applications of PCFs in the fields of energy storage and sensors, water treatment, biomedical materials, artificial actuators, and biomimetic platforms. This review is expected to deepen the comprehension of PCF materials and open new avenues for developing PCFs with tailor-made properties for advanced application.

Development and validation of an individualized nomogram for predicting the high-volume (> 5) central lymph node metastasis in papillary thyroid microcarcinoma

PURPOSE

Papillary thyroid microcarcinoma (PTMC) frequently presents a favorable clinical outcome, while aggressive invasiveness can also be found in some of this population. Identifying the risk clinical factors of high-volume (> 5) central lymph node metastasis (CLNM) in PTMC patients could help oncologists make a better-individualized clinical decision.

METHODS

We retrospectively reviewed the clinical characteristics of adult patients with PTC in the Surveillance, Epidemiology, and End Results (SEER) database between Jan 2010 and Dec 2015 and in one medical center affiliated to Chongqing Medical University between Jan 2018 and Oct 2020. Univariate and multivariate logistic regression analyses were used to determine the risk factors for high volume of CLNM in PTMC patients.

RESULTS

The male gender (OR = 2.02, 95% CI 1.46-2.81), larger tumor size (> 5 mm, OR = 1.64, 95% CI 1.13-2.38), multifocality (OR = 1.87, 95% CI 1.40-2.51), and extrathyroidal invasion (OR = 3.67; 95% CI 2.64-5.10) were independent risk factors in promoting high-volume of CLNM in PTMC patients. By contrast, elderly age (≥ 55 years) at diagnosis (OR = 0.57, 95% CI 0.40-0.81) and PTMC-follicular variate (OR = 0.60, 95% CI 0.42-0.87) were determined as the protective factors. Based on these indicators, a nomogram was further constructed with a good concordance index (C-index) of 0.702, supported by an external validating cohort with a promising C-index of 0.811.

CONCLUSION

A nomogram was successfully established and validated with six clinical indicators. This model could help surgeons to make a better-individualized clinical decision on the management of PTMC patients, especially in terms of whether prophylactic central lymph node dissection and postoperative radiotherapy should be warranted.

Construction and validation of a nomogram for predicting cervical lymph node metastasis in classic papillary thyroid carcinoma

PURPOSE

Patients with papillary thyroid carcinoma (PTC) frequently present a relatively poor prognosis when they coexist with cervical lymph node metastasis (LNM). Moreover, it remains controversial whether prophylactic lymph node dissection (LND) should be performed for patients without clinically lymph node metastasis. Thus, we hereby develop a nomogram for predicting the cervical LNM (including central and lateral LNM) in patients with PTC.

METHODS

We retrospectively reviewed the clinical characteristics of adult patients with PTC in the surveillance, epidemiology, and end results (SEER) database between 2010 and 2015 and in our Department of Breast and Thyroid Surgery in the Second Affiliated Hospital of Chongqing Medical University between 2019 and 2020.

RESULT

A total of 21,972 patients in the SEER database and 747 patients in our department who met the inclusion criteria were enrolled in this study. Ultimately, six clinical features including age, gender, race, extrathyroidal invasion, multifocality, and tumor size were identified to be associated with cervical LNM in patients with PTC, which were screened to develop a nomogram. This model had satisfied discrimination with a concordance index (C-index) of 0.733, supported by both internal and external validation with a C-index of 0.731 and 0.716, respectively. A decision curve analysis was subsequently made to evaluate the feasibility of this nomogram for predicting cervical LNM. Besides, a positive correlation between nomogram score and the average number of lymph node metastases was observed in all groups.

CONCLUSION

This visualized multipopulational-based nomogram model was successfully established. We determined that various clinical characteristics were significantly associated with cervical LNM, which would be better helping clinicians make individualized clinical decisions for PTC patients.

The molecular basis of coupling between poly(A)-tail length and translational efficiency

In animal oocytes and early embryos, mRNA poly(A)-tail length strongly influences translational efficiency (TE), but later in development this coupling between tail length and TE disappears. Here, we elucidate how this coupling is first established and why it disappears. Overexpressing cytoplasmic poly(A)-binding protein (PABPC) in Xenopus oocytes specifically improved translation of short-tailed mRNAs, thereby diminishing coupling between tail length and TE. Thus, strong coupling requires limiting PABPC, implying that in coupled systems longer-tail mRNAs better compete for limiting PABPC. In addition to expressing excess PABPC, post-embryonic mammalian cell lines had two other properties that prevented strong coupling: terminal-uridylation-dependent destabilization of mRNAs lacking bound PABPC, and a regulatory regime wherein PABPC contributes minimally to TE. Thus, these results revealed three fundamental mechanistic requirements for coupling and defined the context-dependent functions for PABPC, which promotes TE but not mRNA stability in coupled systems and mRNA stability but not TE in uncoupled systems.

Cells are microscopic biological factories that are constantly creating new proteins. To do so, a cell must first convert its master genetic blueprint, the DNA, into strands of messenger RNA or mRNA. These strands are subsequently translated to make proteins. Cells have two ways to adjust the number of proteins they generate so they do not produce too many or too few: by changing how many mRNA molecules are available for translation, and by regulating how efficiently they translate these mRNA molecules into proteins.

In animals, both unfertilized eggs and early-stage embryos lack the ability to create or destroy mRNAs, and consequently cannot adjust the number of mRNA molecules available for translation. These cells can therefore only regulate how efficiently each mRNA is translated. They do this by changing the length of the so-called poly(A) tail at the end of each mRNA molecule, which is made up of a long stretch of repeating adenosine nucleotides. The mRNAs with longer poly(A) tails are translated more efficiently than those with shorter poly(A) tails. However, this difference disappears in older embryos, when both long and short poly(A) tails are translated with equal efficiency, and it is largely unknown why.

To find out more, Xiang and Bartel studied frog eggs, and discovered that artificially raising levels of a protein that binds poly(A) tails, also known as PABPC, improved the translation of short-tailed mRNAs to create a situation in which both short- and long-tailed mRNAs were translated with near-equal efficiency. This suggested that short- and long-tailed mRNAs compete for limited amounts of the translation-enhancing PABPC, and that long-tailed mRNAs are better at it than short-tailed mRNAs. Further investigation revealed that eggs also had to establish the right conditions for PABPC to enhance translation and had to protect mRNAs not associated with PABPC from being destroyed before they could be translated.

Overall, Xiang and Bartel found that in eggs and early embryos, PABPC and poly(A) tails enhanced the translation of mRNAs but did not influence their stability, whereas later in development, they enhanced mRNA stability but not translation.

This research provides new insights into how protein production is controlled at different stages of animal development, from unfertilized eggs to older embryos. Understanding how this process is regulated during normal development is crucial for gaining insights into how it can become dysfunctional and cause disease. These findings may therefore have important implications for research into areas such as infertility, reproductive medicine and rare genetic diseases.

P1021Comparative efficacy of microfidelity technology vs standard ablation for atrioventricular nodal ablation

Background

Microfidelity Cateter Technology has proven efficacy in ablating atrial arrhythmias in multiple pilot studies. Closely spaced radial microelectrodes render a focused near-field electrogram. Case series suggest that this catheter design facilitates accurate ablations with fewer radiofrequency (RF) lesions. Atrioventricular junction (AVJ) ablation is regarded as a straightforward procedure, but case records show wide variance in procedure times and number of RF lesions required.

Methods

Twenty-four patients scheduled for AVJ ablation were randomized to treatment with either the Microfidelity technology or standard 8mm/8 French ablation catheter. Both groups located the AVJ by fluoroscopic landmarks and His electrograms, and the MiFi group used electroanatomical mapping to create the location of his electrograms. The primary endpoints were development of Junctional Rhythm (JR) or Complete Heart Block (CHB), and time from first RF lesion until rhythm change. Secondary endpoints included number of RF applications.

Results

Patients were randomized one-to-one to the MiFi arm or standard ablation arm. JR or CHB was achieved in all patients. Time from first RF lesion until JR/CHB was: (Median/IQR) 325 sec/250–1270 sec. vs 287 sec/101–406 sec. Number of RF applications was 5/3–15 applications vs 4.5/1–5 applications. Total procedure time in the lab was 134 min/73.5–172.5 min vs 58 min/52–146 min.

Microfidelity Technology vs Standard

Conclusion

Analysis suggests that the MiFi catheter is efficacious in ablating the AVJ, but requires greater RF duration and number of lesions, with wider case-by-case variability to achieve JR or CHB. Microfidelity technology and electroanatomical mapping did not result in faster time to completion than using fluoroscopic landmarks and His electrograms alone. Preoperative choice of sheath for catheter stability and contact may also play a role in a more efficient timely successful ablation of the AV node.

Acknowledgement/Funding

Boston Scientific

Abstract B197: Translational control in macrophages during inflammatory response

Translational control has been increasingly appreciated as a critical gene-regulatory mechanism during immune responses. Previous studies suggested that translation of select cytokines could be regulated by mRNA poly(A)-tail lengths in memory T-cells and macrophages. We carried out transcriptome-wide analysis with mRNA sequencing, ribosome-footprinting profiling as well as poly(A)-tail length profiling in both RAW264.7 cells and mouse thioglycollate-elicited peritoneal macrophages. No coupling between poly(A)-tail length and translational efficiency (TE) was observed in either cell type, arguing against a global translational-regulatory regime mediated by poly(A)-tail lengths. Immune activation with the treatment of lipopolysaccharides (LPS) to these cells did not change the uncoupled regime. Moreover, gene expression landscape in LPS-treated macrophages was dominated by mRNA level changes, with little contribution from TE changes. The up- or down-regulation of TE was not accompanied by concerted lengthening or shortening of poly(A) tails, implying existence of yet unclear translational control mechanisms in these immune cells. Finally, our studies in other biologic systems, including HeLa cells, Xenopus oocytes and yeast suggest that saturating levels of poly(A)-binding proteins might suppress poly(A) tail length-mediated translational control in various uncoupled systems, including immune cells.

Citation Format: Kehui Xiang, David P. Bartel. Translational control in macrophages during inflammatory response [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B197.

Abstract B132: Importance and mechanism of poly(A) tail length-mediated translational control in different immune cells

Translational control is an essential regulatory mechanism in immune cells. Although it has been suggested that poly(A) tail length-mediated translational control plays important roles in regulating select cytokine production in memory T cells and macrophages, whether this is a transcriptome-wide regulatory principle in all immune cells remains unknown. We set out to perform RNA-seq, ribosome-footprint profiling and poly(A) tail length profiling across major types of immune cells to examine the relationship between poly(A) tail length and translational efficiency in these systems. We also plan to delineate the transcriptome-wide landscape of poly(A) tail length before and after immune activation, and investigate if the coupling of poly(A) tail length and translational efficiency plays a regulatory role in this process.

Meanwhile, to understand the general mechanistic details of how poly(A) tail length affects translational efficiency in a cell context-dependent manner, we carried out RNA pull-down experiments and isolated proteins from known coupled (Xenopus oocytes) and uncoupled (rabbit reticulocyte lysates) systems. By quantitative mass spectrometry analysis, we identified key factors that are responsible for coupling translational efficiency to poly(A) tail length. Among these candidates, poly(A) binding protein (PABPC1) plays an essential role. Overexpression of PABPC1 in Xenopus oocytes renders the translation of reporter RNAs with either a short poly(A) tail or a long poly(A) tail equally well, turning a coupled system into an uncoupled system. We have also generated an effective degron-induced PABPC1-knockdown cell line and are performing analysis to see if the coupling can be established in a normally uncoupled system. Our results suggest that cells can modify the expression of PABPC1 to help determine if poly(A) tail length regulates translational efficiency.

Citation Format: Kehui Xiang, David Bartel. Importance and mechanism of poly(A) tail length-mediated translational control in different immune cells [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B132.

Extended solid solutions and coherent transformations in nanoscale olivine cathodes

Nanoparticle LiFePO4, the basis for an entire class of high power Li-ion batteries, has recently been shown to exist in binary lithiated/delithiated states at intermediate states of charge. The Mn-bearing version, LiMn(y)Fe(1-y)PO4, exhibits even higher rate capability as a lithium battery cathode than LiFePO4 of comparable particle size. To gain insight into the cause(s) of this desirable performance, the electrochemically driven phase transformation during battery charge and discharge of nanoscale LiMn0.4Fe0.6PO4 of three different average particle sizes, 52, 106, and 152 nm, is investigated by operando synchrotron radiation powder X-ray diffraction. In stark contrast to the binary lithiation states of pure LiFePO4 revealed in recent investigations, the formations of metastable solid solutions covering a remarkable wide compositional range, including while in two-phase coexistence, are observed. Detailed analysis correlates this behavior with small elastic misfits between phases compared to either pure LiFePO4 or LiMnPO4. On the basis of time- and state-of-charge dependence of the olivine structure parameters, we propose a coherent transformation mechanism. These findings illustrate a second, completely different phase transformation mode for pure well-ordered nanoscale olivines compared to the well-studied case of LiFePO4.

Association between KCNQ1 genetic variants and QT interval in a Chinese population

AIM

There is a close link between electrocardiographic ventricular repolarization QT parameters and Type 2 diabetes. The aim of the present study was to assess the effects of QT-related and diabetes-related variants in KCNQ1 on QT interval in a Chinese population.

METHODS

We recruited 2415 patients with Type 2 diabetes and 1163 subjects with normal glucose regulation in the present study. QT interval was obtained and the heart rate-corrected QT interval (QTc) was calculated using Bazett's formula. Four single nucleotide polymorphisms in KCNQ1 were selected (rs12296050, rs12576239, rs2237892 and rs2237895) and genotyped.

RESULTS

In participants with normal glucose regulation, the minor allele T of rs12296050 was associated with a 3.46-ms QTc prolongation under an additive model (P = 0.0109, empirical P = 0.0498). In patients with Type 2 diabetes, we did not find any association for the single nucleotide polymorphisms.

CONCLUSIONS

Our findings indicate that KCNQ1 is associated with QT interval in a Chinese population with normal glucose regulation.

Genome-wide association study in a Chinese population identifies a susceptibility locus for type 2 diabetes at 7q32 near PAX4

AIMS/HYPOTHESIS

Most genetic variants identified for type 2 diabetes have been discovered in European populations. We performed genome-wide association studies (GWAS) in a Chinese population with the aim of identifying novel variants for type 2 diabetes in Asians.

METHODS

We performed a meta-analysis of three GWAS comprising 684 patients with type 2 diabetes and 955 controls of Southern Han Chinese descent. We followed up the top signals in two independent Southern Han Chinese cohorts (totalling 10,383 cases and 6,974 controls), and performed in silico replication in multiple populations.

RESULTS

We identified CDKN2A/B and four novel type 2 diabetes association signals with p < 1 × 10(-5) from the meta-analysis. Thirteen variants within these four loci were followed up in two independent Chinese cohorts, and rs10229583 at 7q32 was found to be associated with type 2 diabetes in a combined analysis of 11,067 cases and 7,929 controls (p meta = 2.6 × 10(-8); OR [95% CI] 1.18 [1.11, 1.25]). In silico replication revealed consistent associations across multiethnic groups, including five East Asian populations (p meta = 2.3 × 10(-10)) and a population of European descent (p = 8.6 × 10(-3)). The rs10229583 risk variant was associated with elevated fasting plasma glucose, impaired beta cell function in controls, and an earlier age at diagnosis for the cases. The novel variant lies within an islet-selective cluster of open regulatory elements. There was significant heterogeneity of effect between Han Chinese and individuals of European descent, Malaysians and Indians.

CONCLUSIONS/INTERPRETATION

Our study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.

Genetic variants of LPIN1 indicate an association with Type 2 diabetes mellitus in a Chinese population

AIMS

Metabolic disorders are independent risk factors for the development of Type 2 diabetes. The aim of the study is to test the association of LPIN1 variants with Type 2 diabetes and clinical characteristics in large samples of the Chinese population.

METHODS

In the first stage, 15 single nucleotide polymorphisms within the LPIN1 region were selected and genotyped in 3700 Chinese Han participants. In the second stage, the single nucleotide polymorphisms showing significant association or trends towards association were genotyped in an additional 3122 samples for replication. Meta-analyses and genotype-phenotype association studies were performed after combining the data from the two stages.

RESULTS

In the first stage, we detected that rs16857876 was significantly associated with Type 2 diabetes with an odds ratio of 0.806 (95% CI 0.677-0.958, P = 0.015), while rs11695610 showed a trend with Type 2 diabetes (odds ratio 0.846, 95% CI 0.709-1.009, P = 0.062). In the second stage, a similar effect of rs11695610 on Type 2 diabetes was observed (odds ratio 0.849, 95% CI 0.700-1.030, P = 0.096). The meta-analyses combining the information from the two stages showed a significant effect of rs11695610 on Type 2 diabetes with an odds ratio of 0.847 (95% CI 0.744-0.965, P = 0.012). Finally, the phenotype-genotype association analyses showed that rs11695610 was associated with 2-h plasma glucose (P = 0.040) and triglyceride levels (P = 0.034).

CONCLUSIONS

Our data implied that common single nucleotide polymorphisms within the LPIN1 region were associated with Type 2 diabetes and metabolic traits in the Chinese population.

An unexpected binding mode for a Pol II CTD peptide phosphorylated at Ser7 in the active site of the CTD phosphatase Ssu72

Ssu72, an RNA polymerase II C-terminal domain (CTD) phospho-Ser5 (pSer5) phosphatase, was recently reported to have pSer7 phosphatase activity as well. We report here the crystal structure of a ternary complex of the N-terminal domain of human symplekin, human Ssu72, and a 10-mer pSer7 CTD peptide. Surprisingly, the peptide is bound in the Ssu72 active site with its backbone running in the opposite direction compared with a pSer5 peptide. The pSer7 phosphatase activity of Ssu72 is ∼4000-fold lower than its pSer5 phosphatase activity toward a peptide substrate, consistent with the structural observations.

Functional analyses of the mutation nt-128 T→G in the hepatocyte nuclear factor-1α promoter region in Chinese diabetes pedigrees

AIMS

Hepatocyte nuclear factor-1α (HNF-1α) regulates the expression of genes encoding proteins involved in glucose metabolism and insulin secretion. Mutations in the HNF-1α gene cause maturity-onset diabetes of the young Type 3. However, the mechanism leading to this disease has not been completely ascertained. Previously, we found a novel mutation in the regulatory element of the human HNF-1α gene in two Chinese diabetes pedigrees. The nucleotide at position -128 T was substituted by G (nt-128 T→G). In this study, we analysed the functional defect of nt-128 T→G in HNF-1α transcription activity.

METHODS

Luciferase reporter gene assays were carried out to examine the functional characteristics of this mutant. Electrophoretic mobility shift assays and chromatin immunoprecipitation were performed to confirm the binding of nuclear proteins to oligonucleotides.

RESULTS

The variant construct (nt-128 T→G) had a 1.65-fold increase in promoter activity compared with that of the wild-type construct in HepG2 cells and a 1.33-fold increase in MIN6 cells, respectively. The variant resided at a FOXA/HNF-3 binding site identified by a series of competitive electrophoretic mobility shift assays and antibody supershift analyses. The assays showed a differential binding affinity in the wild-type and the nt-128 T→G mutant fragments by FOXA/HNF-3. Chromatin immunoprecipitation indicated that FOXA/HNF-3 bound to this region in vivo. One nucleotide substitution in the FOXA/HNF-3 site in the human HNF-1α regulatory element caused an increase of HNF-1α transcriptional activity.

CONCLUSIONS

Our data suggested that this substitution in the promoter region affects DNA-protein interaction and HNF-1α gene transcription. The mutant may contribute to the development of diabetes in these two nt-128 T→G pedigrees of Chinese.

Association between KCNQ1 genetic variants and obesity in Chinese patients with type 2 diabetes

AIMS/HYPOTHESIS

There is evidence of overlap between susceptibility loci for type 2 diabetes and obesity. The aim of this study is to explore the association between the established type 2 diabetes locus KCNQ1 and obesity in Han Chinese.

METHODS

We recruited 6,667 and 6,606 diabetic case-control samples from Shanghai and Hong Kong, respectively. Of the samples, 7.5% and 6.3% were excluded because of genotyping failure or data missing in the association analyses of rs2237892 and rs2237895 with obesity/BMI, respectively.

RESULTS

We found that rs2237892 was associated with lower BMI and lower incidence of overweight/obesity in diabetic patients from Hong Kong (BMI, β = -0.0060 per diabetes risk C allele for log(10)BMI [95% CI -0.0088, -0.0032; p = 2.83 × 10(-5)]; overweight/obesity, OR 0.880 for C allele [95% CI 0.807, 0.960; p = 0.004]) and in the meta-analysis of cases from the two regions (BMI, combined β = -0.0048 per C allele for log(10)BMI [95% CI -0.0070, -0.0026; p = 2.20 × 10(-5)]; overweight/obesity, combined OR 0.890 for C allele [95% CI 0.830, 0.955; p = 0.001]). rs2237895 was also related to decreased BMI (combined β = -0.0042 per diabetes risk C allele for log(10)BMI [95% CI -0.0062, -0.0022; p = 4.30 × 10(-5)]). A significant association with waist circumference was detected for rs2237892 in the pooled analyses (β = -0.0026 per C allele for log(10)[waist circumference] [95% CI -0.0045, -0.0007; p = 0.007]). However, neither an association with the risk of being overweight or obese nor associations with quantitive traits were detected for rs2237892 or rs2237895 in controls.

CONCLUSION

Our findings indicate that KCNQ1 is associated with obesity in Chinese patients with type 2 diabetes.

The yeast regulator of transcription protein Rtr1 lacks an active site and phosphatase activity

The activity of RNA polymerase II (Pol II) is controlled in part by the phosphorylation state of the C-terminal domain (CTD) of its largest subunit. Recent reports have suggested that yeast regulator of transcription protein, Rtr1, and its human homologue RPAP2, possess Pol II CTD Ser5 phosphatase activity. Here we report the crystal structure of Kluyveromyces lactis Rtr1, which reveals a new type of zinc finger protein and does not have any close structural homologues. Importantly, the structure does not show evidence of an active site, and extensive experiments to demonstrate its CTD phosphatase activity have been unsuccessful, suggesting that Rtr1 has a non-catalytic role in CTD dephosphorylation.

Increment of 30-min post-challenge plasma glucose is associated with urine albumin excretion in men with normal glucose regulation

AIMS

The overwhelming majority of subjects with normal glucose regulation have the highest plasma glucose concentration at 30 minutes during oral glucose tolerance. We aimed to examine the association between increment of 30-min post-challenge glucose and albuminuria in participants with normal glucose regulation.

METHODS

A population-based cross-sectional study was conducted in six communities in Shanghai between 2007 and 2008. A total of 3508 subjects with normal glucose regulation had complete data and were enrolled into the analysis. Among the selected subjects, only 1525 individuals (581 men, 944 women) were examined for their serum insulin levels. We assessed post-challenge blood glucose and insulin at 0, 30 and 120 min, urinary albumin and creatinine. The 30-min post-challenge glucose increment (Δ) was calculated as 30-min post-challenge glucose minus fasting plasma glucose, and albumin/creatinine ratio was used to reflect urinary albumin excretion.

RESULTS

Multivariable logistic regression analysis revealed that the Δ30-min post-challenge glucose was independently associated with increased albumin/creatinine ratio in men with normal glucose regulation (OR = 1.08, P = 0.025), but not in women. Furthermore, multivariable linear regression analysis revealed that early-phase glucose disposition index was the main factor responsible for Δ30-min post-challenge glucose and explained 14-20% of the variance of Δ30-min post-challenge glucose in the two subgroups (P < 0.05). Notably, men had higher Δ30-min post-challenge glucose and lower early-phase glucose disposition index than women (all P < 0.001).

CONCLUSIONS

The 30-min post-challenge plasma glucose increment is associated with urine albumin excretion in men with normal glucose regulation.

Effects of KCNQ1 polymorphisms on the therapeutic efficacy of oral antidiabetic drugs in Chinese patients with type 2 diabetes

The aim of this study was to explore the impact of KCNQ1 variants on the responses to oral antidiabetic drugs in a Chinese study population. A 48-week randomized pharmacogenetics study compared the effects of repaglinide and rosiglitazone in 209 newly diagnosed patients with type 2 diabetes. In the repaglinide cohort, individuals who were rs2237892 TT homozygotes exhibited lower 2-h glucose levels and significantly higher cumulative attainment rates of target 2-h glucose levels (P(log-rank) = 0.0383) than the C allele carriers; patients with a greater number of rs2237892 C alleles showed larger augmentations in both fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) (P = 0.0166 and 0.0026, respectively); moreover, the rs2237895 C allele was also associated with greater increments in both fasting insulin and HOMA-IR (P = 0.0274 and 0.0259, respectively). In contrast, only an association between rs2237897 and decrease in 2-h glucose levels was detected in the rosiglitazone cohort (P = 0.0321). Our results indicated that KCNQ1 polymorphisms are associated with repaglinide efficacy, and might also be associated with rosiglitazone response, in Chinese patients with type 2 diabetes.

Crystal structure of the human symplekin-Ssu72-CTD phosphopeptide complex

Symplekin (Pta1 in yeast) is a scaffold in the large protein complex that is required for 3′-end cleavage and polyadenylation of eukaryotic messenger RNA precursors (pre-mRNAs) 1–4, and also participates in transcription initiation and termination by RNA polymerase II (Pol II) 5,6. Symplekin mediates interactions among many different proteins in this machinery 1,2,7–9, although the molecular basis for its function is not known. Here we report the crystal structure at 2.4 Å resolution of the N-terminal domain (residues 30–340) of human symplekin (Symp-N) in a ternary complex with the Pol II C-terminal domain (CTD) Ser⁵ phosphatase Ssu72 7,10–17 and a CTD Ser⁵ phosphopeptide. The N-terminal domain of symplekin has the ARM or HEAT fold, with seven pairs of anti-parallel α-helices arranged in the shape of an arc. The structure of Ssu72 has some similarity to that of low-molecular-weight phosphotyrosine protein phosphatase 18,19, although Ssu72 has a unique active site landscape as well as extra structural features at the C-terminus that is important for interaction with symplekin. Ssu72 is bound to the concave face of symplekin, and engineered mutations in this interface can abolish interactions between the two proteins. The CTD peptide is bound in the active site of Ssu72, unexpectedly with the pSer⁵-Pro⁶ peptide bond in the cis configuration, which contrasts with all other known CTD peptide conformations 20,21. While the active site of Ssu72 is about 25 Å away from the interface with symplekin, we found that the symplekin N-terminal domain stimulates Ssu72 CTD phosphatase activity in vitro. Furthermore, the N-terminal domain of symplekin inhibits polyadenylation in vitro, but importantly only when coupled to transcription. As catalytically active Ssu72 overcomes this inhibition, our results demonstrate a role for mammalian Ssu72 in transcription-coupled pre-mRNA 3′-end processing.

A common variant of NOS1AP is associated with QT interval duration in a Chinese population with Type 2 diabetes

AIMS

Electrocardiographic ventricular repolarization QT parameters are independent risk factors for cardiovascular events and sudden cardiac death in diabetic patients. The aim of the study was to investigate the association of polymorphisms of the nitric oxide synthase 1 adaptor protein (NOS1AP) gene with QT interval in Chinese subjects with or without Type 2 diabetes.

METHODS

Three single nucleotide polymorphisms (SNPs) (rs10494366, rs12143842 and rs12029454) were genotyped in 1240 Type 2 diabetic patients (631 men and 609 women) and 1196 normal controls (433 men and 763 women). Individuals with overt diseases other than diabetes were excluded. Heart-rate corrected QT interval (QTc) was determined by standard 12-lead ECG and Bazett formula. Sex-pooled analysis and sex-specific analysis for genotype-phenotype association were both conducted.

RESULTS

In the diabetic group, the rs12143842 T allele was associated with a 3.87-ms (P = 0.014, empirical P = 0.039) increase in QTc duration for each additional allele copy, while rs10494366 and rs12029454 exhibited no significant association with QTc. We found no evidence of association for the three SNPs in subjects with normal glucose regulation. No significant SNP-gender and -diabetes affection interaction was observed.

CONCLUSIONS

The genetic variant rs12143842 in NOS1AP is associated with QT interval duration in a Chinese population with Type 2 diabetes. Future studies in different populations are needed to validate this finding and to evaluate the impact of NOS1AP variants on cardiovascular events and sudden cardiac death in diabetic patients.

A novel non-radioactive assay for HIV-RT (RdDp) based on pyrosequencing for high-throughput drug screening

Current in vitro assays for the activity of HIV-RT (reverse transcriptase) require radio-labeled or chemically modified nucleotides to detect reaction products. However, these assays are inherently end-point measurements and labor intensive. Here we describe a novel non-radioactive assay based on the principle of pyrosequencing coupled-enzyme system to monitor the activity of HIV-RT by indirectly measuring the release of pyrophosphate (PP(i)), which is generated during nascent strand synthesis. The results show that our assay could monitor HIV-RT activity with high sensitivity and is suitable for rapid high-throughput drug screening targeting anti-HIV therapies due to its high speed and convenience. Moreover, this assay can be used to measure primase activity in an easy and sensitive manner, which suggests that this novel approach could be wildly used to analyze the activity of PP(i)-generated and ATP-free enzyme reactions.

Association of genetic variants of NOS1AP with type 2 diabetes in a Chinese population

AIMS/HYPOTHESIS

Chromosome 1q21-q24 has been shown to be linked to type 2 diabetes. The International Type 2 Diabetes 1q Consortium showed that one of the nominal associations was located in the NOS1AP gene. Although this association was not replicated in additional samples of European descent, it remains unknown whether NOS1AP plays a role in Chinese individuals.

METHODS

In stage 1 analyses, 79 single nucleotide polymorphisms (SNPs) of the NOS1AP gene were successfully genotyped in a group of Shanghai Chinese individuals, comprising 1,691 type 2 diabetes patients and 1,720 control participants. In stage 2 analyses, the SNP showing the strongest association was genotyped in additional Chinese individuals, including 1,663 type 2 diabetes patients and 1,408 control participants.

RESULTS

In stage 1 analyses, 20 SNPs were nominally associated with type 2 diabetes (p < 0.05), with SNP rs12742393 showing the strongest association (OR 1.24 [95% CI 1.11-1.38]; p = 0.0002, empirical p = 0.019). Haplotype analysis also confirmed the association between rs12742393 and type 2 diabetes. In stage 2 analyses, the difference in allele frequency distribution of rs12742393 did not reach statistical significance (p = 0.254). However, the meta-analysis showed a significant association between rs12742393 and type 2 diabetes with an OR of 1.17 (95% CI 1.07-1.26; p = 0.0005).

CONCLUSIONS/INTERPRETATION

Our data suggest that NOS1AP variants may not play a dominant role in susceptibility to type 2 diabetes, but a minor effect cannot be excluded.

Variations in KCNQ1 are associated with type 2 diabetes and beta cell function in a Chinese population

AIMS/HYPOTHESIS

Recent genome-wide association studies in East Asian populations reported that single nucleotide polymorphisms (SNPs) in KCNQ1 are associated with type 2 diabetes. The aim of this study was to validate this finding in a Chinese population.

METHODS

We genotyped four SNPs, rs2074196, rs2237892, rs2237895 and rs2237897, in a group of 3,503 Shanghai Chinese individuals, comprising 1,769 type 2 diabetic patients and 1,734 normoglycaemic controls. Both the cases and the controls were extensively phenotyped for anthropometric and biochemical traits related to glucose metabolism. Arginine stimulation tests under fasting conditions were performed in a subgroup of 466 cases.

RESULTS

All four of the SNPs were associated with type 2 diabetes, with rs2237892 showing strongest evidence for association (OR 1.532, 95% CI 1.381-1.698, p = 5.0 x 10(-16)). The SNP rs2237897 was associated with both acute insulin and C-peptide response after arginine stimulation in a subgroup of cases (p = 0.0471 and p = 0.0156, respectively). The SNP rs2237895 was associated with both first- and second-phase insulin secretion in the controls (p = 0.0334 and p = 0.0002, respectively).

CONCLUSIONS/INTERPRETATION

In this study we found that KCNQ1 was associated with type 2 diabetes susceptibility in a Chinese population, possibly through its effect on beta cell function.

A genetic variant of G6PC2 is associated with type 2 diabetes and fasting plasma glucose level in the Chinese population

AIMS/HYPOTHESIS

Single nucleotide polymorphisms (SNPs) in G6PC2 have been reported to be associated with fasting plasma glucose level in several populations of European descent. However, whether G6PC2 variants have a similar effect in other ethnic groups is unknown. The aim of this study was to investigate the effect of common variants of G6PC2 on type 2 diabetes and related clinical features in a Chinese population.

METHODS

We selected four SNPs, rs13387347, rs2232316, rs492594 and rs16856187, tagging all the common variants spanning the G6PC2 gene (r(2) >or= 0.8) based on HapMap Chinese data, and genotyped them in a group of 3,676 Shanghai Chinese individuals, comprising 1,876 cases and 1,800 controls.

RESULTS

Three SNPs were nominally associated with type 2 diabetes, with rs16856187 showing the strongest evidence for association (p = 0.0009, empirical p = 0.0047). Further conditional analysis revealed that the association signal arose from an individual SNP, rs16856187. This SNP was also associated with fasting plasma glucose level in participants with normal glucose regulation (p = 0.0002), with the fasting plasma glucose level observed to increase by 0.067 mmol/l with each copy of the rare C allele.

CONCLUSIONS/INTERPRETATION

In this study we identified a novel risk-conferring G6PC2 SNP for type 2 diabetes in a Chinese population and confirmed the previous finding that G6PC2 variants are associated with fasting plasma glucose concentration.

Chronic benzodiazepine-induced reduction in GABA(A) receptor-mediated synaptic currents in hippocampal CA1 pyramidal neurons prevented by prior nimodipine injection

One week oral flurazepam (FZP) administration in rats results in reduced GABA(A) receptor-mediated synaptic transmission in CA1 pyramidal neurons associated with benzodiazepine tolerance in vivo and in vitro. Since voltage-gated calcium channel (VGCC) current density is enhanced twofold during chronic FZP treatment, the role of L-type VGCCs in regulating benzodiazepine-induced changes in CA1 neuron GABA(A) receptor-mediated function was evaluated. Nimodipine (10 mg/kg, i.p.) or vehicle (0.5% Tween 80, 2 ml/kg) was injected 1 day after ending FZP treatment and 24 h prior to hippocampal slice preparation for measurement of mIPSC characteristics and in vitro tolerance to zolpidem. The reduction in GABA(A) receptor-mediated mIPSC amplitude and estimated unitary channel conductance measured 2 days after drug removal was no longer observed following prior nimodipine injection. However, the single nimodipine injection failed to prevent in vitro tolerance to zolpidem's ability to prolong mIPSC decay in FZP-treated neurons, suggesting multiple mechanisms may be involved in regulating GABA(A) receptor-mediated synaptic transmission following chronic FZP administration. As reported previously in recombinant receptors, nimodipine inhibited synaptic GABA(A) receptor currents only at high concentrations (>30 muM), significantly greater than attained in vivo (1 muM) 45 min after a single antagonist injection. Thus, the effects of nimodipine were unlikely to be related to direct effects on GABA(A) receptors. As with nimodipine injection, buffering intracellular free [Ca(2+)] with BAPTA similarly prevented the effects on GABA(A) receptor-mediated synaptic transmission, suggesting intracellular Ca(2+) homeostasis is important to maintain GABA(A) receptor function. The findings further support a role for activation of L-type VGCCs, and perhaps other Ca(2+)-mediated signaling pathways, in the modulation of GABA(A) receptor synaptic function following chronic benzodiazepine administration, independent of modulation of the allosteric interactions between benzodiazepine and GABA binding sites.

Effect of RBP4 gene variants on circulating RBP4 concentration and type 2 diabetes in a Chinese population

AIMS

Retinol binding protein 4 (RBP4) is a newly discovered adipokine, which plays a role in insulin resistance and obesity. The aim of this study was to determine the relationship between genetic variants of the RBP4 gene, circulating RBP4 concentrations and phenotypes related to glucose and lipid metabolism in the Chinese population.

METHODS

We sequenced exons and the putative promoter region to identify single nucleotide polymorphisms (SNPs) in the RBP4 gene in 32 Chinese subjects. Additional SNPs were selected from a public database to increase marker density. Taking account of the pairwise linkage disequilibrium and minor allele frequencies, a subset of SNPs was further genotyped in 255 Type 2 diabetic patients and 372 normal control subjects. Circulating RBP4 concentrations and phenotypes related to glucose and lipid metabolism were measured.

RESULTS

Ten SNPs were identified and five were further genotyped in the full sample. No individual SNP was significantly associated with Type 2 diabetes, but a rare haplotype CAA formed by +5388 C>T, +8201 T>A and +8204 T>A was more frequent in diabetic patients (P = 0.0343, empirical P = 0.0659 on 10 000 permutations). In both groups, non-coding SNPs were associated with circulating RBP4 concentrations (P < 0.05). In the normal control subjects, the SNP +5388 C>T was associated with serum C-peptide levels both fasting and 2 h after an oral glucose tolerance test (P = 0.0162 and P = 0.0075, respectively).

CONCLUSION

Our findings suggest that genetic variants in the RBP4 gene may be associated with circulating RBP4 concentration and phenotypes related to glucose metabolism.

The molecular genetics of diabetes mellitus

Diabetes mellitus is a clinically heterogeneous disorder which is characterized by hyperglycaemia due to an absolute or relative deficiency of insulin. Both genetic and non-genetic factors contribute to its development and, as such, it represents a multifactorial disorder. In addition, it may also be, in some instances, a polygenic disorder resulting from the cumulative effects of several genes with or without environmental factors. Serological and/or DNA markers for genes that confer susceptibility to the insulin-dependent form of the disorder (IDDM; type 1) have been identified in the HLA-D region of chromosome 6 and near the insulin gene on chromosome 11. Patients with non-insulin-dependent diabetes mellitus (NIDDM; type 2) make up a more heterogeneous group than those with IDDM and it is likely that in these patients similar clinical phenotypes may be produced by different genetic defects. The synthesis of either an abnormal insulin/proinsulin molecule or an abnormal insulin receptor can confer susceptibility to NIDDM. The genes encoding insulin and the insulin receptor are on chromosomes 11 and 19, respectively. In addition, studies of restriction fragment length polymorphism and disease associations suggest that two other genes may contribute to the development of NIDDM on chromosome 11, one near the insulin gene on the short arm of this chromosome and the other near the apolipoprotein A-I gene on the long arm. None of the susceptibility genes that have been identified to date causes diabetes in the absence of other genetic or non-genetic contributing factors, which is consistent with a multifactorial or polygenic origin for this disorder.

Peroxisome proliferator-activated receptor (PPAR) delta genetic polymorphism and its association with insulin resistance index and fasting plasma glucose concentrations in Chinese subjects

AIMS

Previous studies have shown that the peroxisome proliferator-activated receptor delta (PPARD) genetic polymorphism affects cholesterol metabolism in Whites. This association was not observed in a Korean population in a separate study, but this study showed a link between the PPARD polymorphism and body weight and fasting plasma glucose. The purpose of this study was to determine whether polymorphisms of PPARD influence glucose and cholesterol metabolism in Chinese subjects. We investigated the association between the polymorphism (-87T/C) of the human PPARD gene and phenotypes related to body weight, insulin sensitivity, glucose and lipid metabolism in Chinese subjects.

METHODS

Unrelated Chinese subjects (n = 663) in Shanghai were studied; 287 had newly diagnosed Type 2 diabetes mellitus and 376 were non-diabetic control subjects over 40 years old. Clinical parameters were collected and genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

In normal glucose tolerant (NGT) subjects, the C allele carriers had higher fasting plasma glucose concentrations (P = 0.0078) and a lower insulin sensitivity index (ISI) (P = 0.0365). The C allele carriers also showed higher concentrations of low-density lipoprotein cholesterol (P = 0.0261) and percentage of body fat (P = 0.0357). There was a trend towards higher visceral adiposity in C allele carriers, but the difference was not significant (P = 0.0830). In diabetes patients, similar results were detected for plasma glucose concentrations (fasting plasma glucose P < 0.0001, 2-h plasma glucose P = 0.0052) and insulin sensitivity (homeostasis model assessment of insulin resistance P = 0.0094; ISI P = 0.0058).

CONCLUSION

The PPARD-87T/C polymorphism is associated with higher fasting plasma glucose concentrations in both NGT and diabetic subjects, largely due to impaired insulin sensitivity.

Crystal structures of Nipah and Hendra virus fusion core proteins

The Nipah and Hendra viruses are highly pathogenic paramyxoviruses that recently emerged from flying foxes to cause serious disease outbreaks in humans and livestock in Australia, Malaysia, Singapore and Bangladesh. Their unique genetic constitution, high virulence and wide host range set them apart from other paramyxoviruses. These characteristics have led to their classification into the new genus Henpavirus within the family Paramyxoviridae and to their designation as Biosafety Level 4 pathogens. The fusion protein, an enveloped glycoprotein essential for viral entry, belongs to the family of class I fusion proteins and is characterized by the presence of two heptad repeat (HR) regions, HR1 and HR2. These two regions associate to form a fusion-active hairpin conformation that juxtaposes the viral and cellular membranes to facilitate membrane fusion and enable subsequent viral entry. The Hendra and Nipah virus fusion core proteins were crystallized and their structures determined to 2.2 A resolution. The Nipah and Hendra fusion core structures are six-helix bundles with three HR2 helices packed against the hydrophobic grooves on the surface of a central coiled coil formed by three parallel HR1 helices in an oblique antiparallel manner. Because of the high level of conservation in core regions, it is proposed that the Nipah and Hendra virus fusion cores can provide a model for membrane fusion in all paramyxoviruses. The relatively deep grooves on the surface of the central coiled coil represent a good target site for drug discovery strategies aimed at inhibiting viral entry by blocking hairpin formation.

Scanning for MODY5 gene mutations in Chinese early onset or multiple affected diabetes pedigrees

Mutation of HNF-1beta gene has been reported in early onset diabetes or MODY families and this gene has been defined as MODY5 gene. The aim of our study was to examine whether HNF-1beta mutation contribute to early onset or multiple affected diabetes pedigrees in Chinese. Molecular scanning of HNF-1beta gene promoter region, nine exons and flanking introns was performed in 154 unrelated probands from early onset and multiple affected diabetes Chinese pedigrees. The family members of probands with mutations or variants and 58 nondiabetics were also examined. Clinical examinations of renal morphology, renal function and beta-cell function were performed in the HNF-1beta gene mutation carriers and family members. Mutation of HNF-1beta gene causing the substitution S36F was found in two subjects of an early onset diabetic family. One carrier has early onset diabetes, renal function impairment and renal cyst, while the other has impaired glucose tolerance only. This is the first case of MODY5 gene mutation diabetes found in the Chinese. Three HNF-1beta variants were identified and no significant differences in allele frequencies for these variants were detected between the nondiabetic and diabetic groups. Nucleotide 66 of intron 8 of HNF-1beta gene was G in the Chinese population rather than A as noted in the GenBank sequence. These results suggest that HNF-1beta gene mutations may be associated with nondiabetic renal dysfunction and diabetes in Chinese, but they are responsible for only a small percentage of early onset or multiple affected diabetes pedigrees including MODY.

[The impact of calpain-10 gene combined-SNP variation on type 2 diabetes mellitus and its related metabolic traits]

OBJECTIVE

To investigate the impact of calpain-10 gene (CAPN-10) combined single nucleotide polymorphism (SNP) variation on type 2 diabetes mellitus (T2DM) and its related clinical metabolic traits in Chinese.

METHODS

The study population consisted of 268 Chinese residents in Shanghai. Among them, 144 were subjects with normal glucose tolerance (NGT) and 124, with T2DM. Plasma glucose (PG), insulin (INS), c-peptide (CP) and free fatty acids (FFA) levels were measured at fasting and 30, 60, 120, and 180 minutes after oral 75 g glucose challenge. The islet beta-cell insulin secretion and tissue insulin sensitivity were assessed. CAPN-10 UCSNP44,-43,-19 and -63 were genotyped.

RESULTS

(1) In Chinese NGT subjects, the major allele of UCSNP-44 was allele T (frequency=91%), of UCSNP43 was G(89%), of UCSNP-19 was I (3 repeats of a 32 bp sequence) (67%) and of UCSNP-63 was C allele (79%). Significant differences were observed in comparison of these allele frequencies in Chinese to those in other ethnic groups reported in the literature. (2) 14 genotype combinations of these four SNPs were observed in Chinese NGT subjects. 69% of the NGT population was composed of four genotype combinations, in the order of UCSNP44,-43,-19 and -63, i.e., combination A:TT-GG-DI-CC(haplotype combination was 1121/1111) (frequency=10%), combination B:TT-GA-II-CC(1121/1221)(10%), combination C:TT-GG-II-CC(1121/1121)(26%) and combination D:TT-GG-DI-CT(1121/1112)(22%).(3) The frequencies of the above mentioned SNP in single or in combinations were not different significantly between NGT and T2DM groups. (4) The variation of clinical metabolic parameter levels shifted from completely normal towards abnormal glucose intolerance among genotype combination subgroups. In comparison between combination A and combination D, subjects in the former subgroups had: higher PG levels with delayed peak after glucose challenge; less and lower decrement of FFA levels after challenge with no rising in late stage; higher insulin levels with delayed peak after challenge; and the tendency of decreased insulin sensitivity. More than half of the comparisons remained statistically significant after adjusted with age, gender, body mass index and waist circumference.

CONCLUSION

The variation of calpain-10 gene has impact on the variation of clinical metabolic parameter levels related to type 2 diabetes mellitus. Such impact depends upon the haplotypes as well as the haplotype combination of calpain-10 gene variations.

[Dyslipidaemia and insulin resistance in Chinese in Shanghai]

OBJECTIVE

To investigate the impact of dyslipidaemia on insulin resistance in Chinese individuals in Shanghai.

METHODS

830 individuals aged over 40 years (male 300, female 530) were divided into normal and dyslipidaemia groups. The latter included 7 subgroups as follows: low high density lipoprotein (L-HDL)-subgroup I, high triglycerides (H-TG)-subgroup II, high total cholesterol or high low density lipoprotein (H-TC/H-LDL)-subgroup III, low high density lipoprotein with high triglycerides (L-HDL + H-TG)-subgroup IV, low high density lipoprotein with high total cholesterol or high low density lipoprotein (L-HDL + H-TC/H-LDL)-subgroup V, high triglycerides with high total cholesterol or high low density lipoprotein(H-TG + H-TC/H-LDL)-subgroup VI, low high density lipoprotein with high triglycerides and high total cholesterol or high low density lipoprotein (L-HDL + H-TG + H-TC/H-LDL)-subgroup VII. Homeostasis model assessment (HOMA) was applied to estimate the degree of insulin resistance (IR).

RESULTS

(1) Adjusted with age, sex and body mass index (BMI), HOMA-IR was increased in the dyslipidaemia subgroups with high triglycerides. (2) Hypertriglyceridemia was more closely related to raised BMI and waist-hip ratio (WHR). (3) Both body fat (BMI, WHR) and triglycerides were independent risk factors accounting for HOMA-IR.

CONCLUSION

Hypertriglycerides could be regarded as an independent risk factor for insulin resistance.

Gene regulatory networks generating the phenomena of additivity, dominance and epistasis

We show how the phenomena of genetic dominance, overdominance, additivity, and epistasis are generic features of simple diploid gene regulatory networks. These regulatory network models are together sufficiently complex to catch most of the suggested molecular mechanisms responsible for generating dominant mutations. These include reduced gene dosage, expression or protein activity (haploinsufficiency), increased gene dosage, ectopic or temporarily altered mRNA expression, increased or constitutive protein activity, and dominant negative effects. As classical genetics regards the phenomenon of dominance to be generated by intralocus interactions, we have studied two one-locus models, one with a negative autoregulatory feedback loop, and one with a positive autoregulatory feedback loop. To include the phenomena of epistasis and downstream regulatory effects, a model of a three-locus signal transduction network is also analyzed. It is found that genetic dominance as well as overdominance may be an intra- as well as interlocus interaction phenomenon. In the latter case the dominance phenomenon is intimately connected to either feedback-mediated epistasis or downstream-mediated epistasis. It appears that in the intra- as well as the interlocus case there is considerable room for additive gene action, which may explain to some degree the predictive power of quantitative genetic theory, with its emphasis on this type of gene action. Furthermore, the results illuminate and reconcile the prevailing explanations of heterosis, and they support the old conjecture that the phenomenon of dominance may have an evolutionary explanation related to life history strategy.

Relationship between the renin-angiotensin system genes and diabetic nephropathy in the Chinese

OBJECTIVE

To clarify whether genetic variants of the renin-angiotensin system (RAS) contribute to the development of diabetic nephropathy (DN) in the Chinese.

METHODS

Totally 173 Chinese subjects of Han nationality from Shanghai were classified into! control, DN (-) and DN (+) groups. The latter was subdivided according to diabetic duration at the onset of DN and the stage of DN. Genotyping of five polymorphic sites in four key genes of the RAS: the AGT-T174M, AGT-M235T and AGTR1 genotypes were determined by PCR/restriction enzyme digestion. The insertion/deletion (I/D) and [ACAC] n-STR microsatellite polymorphic markers were used for ACE and REN genotyping, respectively. Statistical analysis showed comparisons of gene frequencies between any two groups were made with Fisher's exact test or Chi-square test. Logistic regression analysis was performed to identify predictors of DN.

RESULTS

The frequencies of ACE-DD genotype and ACE-D allele were much higher in DN(+) group than in DN (-) group (0.25 vs 0.05, 0.47 vs 0.29, respectively), so were the frequencies of TT genotype and T allele in AGT-M235T (0.73 vs 0.54, 0.85 vs 0.68, respectively). DN (+) DUR < 5 years group had greatly increased frequencies of AGT-M235T allele and ACE-DD genotype in comparison with DN(-) group (0.92 vs 0.68 and 0.28 vs 0.05, respectively). Logistic regression analysis further identified these two genes as contributing factors to DN. Although AGTR1 and AGT-T174M genotyping analysis revealed differences in frequency distribution between DN (+) and DN (-) or control groups, logistic regression analysis failed to implicate them in the development of DN.

CONCLUSIONS

Our study revealed RAS genes, ACE and AGT-M235T but not AGT-T174M, AGTR1 or REN genotypes, as contributing factors for DN in type 2 diabetes mellitus in Chinese.

[The association between A55V variant in UCP2 gene and body fat distribution, serum lipid profile in Chinese]

OBJECTIVE

Uncoupling protein 2(UCP2) could play an important role in energy metabolism and body weight regulation. The aim of this study was to investigate Ala55Val(A55V) variant in the UCP2 gene has effects on serum lipid profile, body fat and its distribution in Chinese.

METHODS

The genotypes of A55V variant in the UCP2 gene were determined by a PCR-RFLP assay in 359 unrelated Chinese [including 193 normal glucose tolerance(NGT) and 166 type 2 diabetic subjects by ADA 97' criteria]. The parameters for regional adipose tissue distribution were measured by magnetic resonance imaging(MRI).

RESULTS

In NGT group, an association between A55V variant in the UCP2 gene and body mass index(BMI) (P=0.0246), as well as femoral subcutaneous adipose tissue area (FA) (P=0.0017), was noted in females. A55V variant in the UCP2 gene was also associated with serum triglyceride (TG) level (P=0.0072) in males. However, in type 2 diabetes group, an association between A55V variant in the UCP2 gene and FA (P=0.0150) was replicated in females too. Those females who were homozygotes of AA in the UCP2 gene had decreased FA not only in NGT group but also in type 2 diabetes group. Furthermore, logistic regression analysis indicated that FA (P=0.0098 in NGT females, P=0.0071 in type 2 diabetic females) and BMI (P=0.0016 in NGT females), as well as TG level (P=0.0040 in NGT males) were associated with this variant in the UCP2 gene.

CONCLUSION

A55V variant in the UCP2 gene is associated not only with FA (in NGT females and type 2 diabetic females) but also with BMI (in NGT females). Therefore A55V variant in the UCP2 gene appears to play a role in body fat and its distribution in Chinese females.

[The mechanism of tumor necrosis factor-alpha (TNF-alpha) induced insulin resistance by variation in promoter region of TNF-alpha gene]

OBJECTIVE

To investigate the relationship between the G to A variant at the--308 bp of the promoter region of tumor necrosis factor-alpha gene (TNF-alpha-P) and the body adiposity, the insulin secretion and action, and the glucose and lipid levels in Chinese population.

METHOD

359 Chinese were genotyped for the TNF-alpha-P by using PCR/Nco I digestion. Fasting blood lipid profile and the levels of plasma glucose (PG), insulin (INS), c-peptide (CP) and the free fatty acids (FFA) at 0, 1/2, 1, 2 and 3 hours after glucose challenge were measured.

RESULTS

Genotype frequencies of TNF-alpha-P were not associated with diabetes and obesity. The genotype frequency of the G/A heterozygotes was significantly increased in non-diabetic subgroups with less decreased levels of 2 h-FFA and AUC-FFA after glucose challenge (Fisher exact P = 0.002 and 0.041 respectively). The FFA levels in non-diabetics with G/A heterozygotes were higher than those with G/G homozygotes, especially in the comparisons of the 2 h and 3 h FFA levels after glucose challenge (P = 0.029 and 0.030 respectively). Similar tendency was also observed in diabetics.

CONCLUSION

Circulation FFA level reflects the degree of lipolysis in adipose tissue. The difference in the degree of lipolysis led by the variant of the promoter region of TNF-alpha may be one of the mechanisms for the variation in the degree of insulin resistance in general population.

[Association of Gln223Arg variant in leptin receptor gene with metabolic abnormalities and hypertension in type II diabetes mellitus in Shanghai "Han" population]

OBJECTIVE

To investigate the association of Gln223Arg variant in leptin receptor gene with metabolic abnormalities and hypertension in type II diabetes mellitus.

METHODS

The genotypes of Gln223Arg variant in leptin receptor gene were determined by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) assay in 359 unrelated subjects of Shanghai "Han" population (including 193 subjects with normal glucose tolerance and 166 type II diabetic patients). The clinical data were also analyzed. The parameters for regional adipose tissue distribution were measured by magnetic resonance imaging (MRI).

RESULTS

Significant difference of genotype frequency of Gln223Arg variant in leptin receptor gene was observed between hypertensive and normotensive type II diabetic male patients (P = 0.008). "A" allele was associated with increased systolic blood pressure (P = 0.0026) and diastolic blood pressure (P = 0.0084) in type II diabetic male patients. Logistic regression analysis showed that this gene variant was an independent risk factor of type II diabetic male patients accompanied with hypertension (P = 0.0031), and it was associated with elevation of systolic blood pressure (P = 0.0054). The odds ratio of hypertension in type II diabetic male patients with "A" allele was 2.825 (95% CI 1.418, 5.627).

CONCLUSION

Gln223Arg variant in leptin receptor gene is associated with hypertension in type II diabetic male patients, especially with elevation of systolic blood pressure.

The impact of codon 54 variation in intestinal fatty acid binding protein gene on the pathogenesis of diabetes mellitus in Chinese

OBJECTIVE

To investigate whether or not the intestinal fatty acid binding protein gene (FABP2)-Ala54Thr variation is related to non-insulin dependent diabetes mellitus (NIDDM), obesity, dyslipidemia and glucose stimulated insulin secretion (GSIS) in Chinese.

METHODS

The FABP2-Ala54Thr variation was detected by PCR/Hhal digestion in 231 Chinese subjects (116 with normal glucose tolerance (NGT), 54 with impaired glucose tolerance (IGT) and 61 with NIDDM). Plasma glucose, insulin and C-peptide levels before and after 75 g glucose load as well as fasting lipid profile were determined.

RESULTS

(1) The Ala54 and Thr54 allele frequencies in Chinese were 0.71 and 0.29 respectively; (2) The FABP2-Ala54Thr variation was neither associated with fasting and post-challenged plasma glucose levels nor with NIDDM; (3) This variation was neither associated with fasting lipid profile nor with obesity; (4) The IGT subjects with genotype Thr54(+) (Thr54 homozygotes and heterozygotes) had lower fasting, 2-hour and total C-peptide levels and smaller AUC representing lesser C-peptide secretion after glucose challenge than those with genotype Thr54(-) (Ala54 homozygotes) (P = 0.04, 0.03, 0.01 and 0.01 respectively). The serum insulin levels changed in the same tendency.

CONCLUSIONS

The glucose stimulated insulin secretion (GSIS) reserve of islet beta-cells is more limited in subjects with FABP2-Thr54(+) genotype than in those with FABP2-Thr54(-) genotype. It suggests that FABP2-codon 54 variation might contribute to the insufficient insulin secretion in the development of NIDDM in Chinese.

[Effects of Trp64Arg mutation in the beta 3-adrenergic receptor gene on body fat, plasma glucose level, lipid profile, insulin secretion and action in Chinese]

OBJECTIVE

To ascertain the association of the Trp64Arg mutation in the beta 3-adrenergic receptor (ADRB3) gene with the total body fat and fat distribution, plasma glucose level, lipid profile, insulin secretion and action in Chinese.

METHODS

Genotyping of the Trp64Arg mutation in the ADRB3 gene as well as measurment of clinical variables body mass index(BMI), percent of desirable weight(PDW), area of regional adipose tissue depots, fasting lipid profile, and also, plasma glucose, insulin, C-peptide, free fatty acids levels before and after glucose challenge and blood pressure were performed in 308 Chinese, of whom, 161 were nondiabetics and 147, type 2 diabetic subjects.

RESULTS

(1) The frequency of Arg64 allele of ADRB3 gene in Chinese was similar to that in Japanese but slightly higher than that in Caucasians. (2) No association of any of the clinical varaibles with Trp64Arg mutation was observed in nondiabetics. (3) The Trp64Arg mutation in the ADRB3 gene was associated with BMI(P=0.019), PDW(P=0.001) and waist circumference (P=0.045) in type 2 diabetic subjects. In female diabetic subjects, more significant association with BMI(P=0.001), PDW(P=0.001), waist circumference(P=0.023), and also, association with abdominal and femoral subcutaneous fat area(P=0.032 and P=0.023) were observed. The frequencies of Arg64 allele were 21%, 14% and 4% in female diabetics with obesity, over-weight and normal-weight respectively (P=0.026). Logistic regression analysis showed that BMI was the only independent clinical variable related to the Trp64Arg mutation in the ADRB3 gene (P=0.0027).

CONCLUSION

The Trp64Arg mutation in ADRB3 gene contributes to the variation of total body fat in Chinese type 2 diabetic subjects.

[The impact of the missense mutation-ser20gly in islet amyloid polypeptide gene on NIDDM in Chinese]

OBJECTIVES

To ascertain the presence of the Ser 20Gly mutation of islet amyloid polypeptide (IAPP) gene and its impact on NIDDM in Chinese.

METHODS

In 896 Chinese, 825 were unrelated subjects (NIDDM in 609 and non-diabetics, 216) and 71 were family members of the pedigrees with IAPP gene-Ser 20Gly carrier probands detected from population screening. The mutation was examined by PCR-RFLP MspI digestion in population screening and the results was randomly checked by direct DNA sequencing. Data were analyzed through association as well as linkage approaches.

RESULTS

The Ser20Gly mutation of the IAPP gene was observed in Chinese. It was more prevalent in NIDDM (17 cases, 2.8%) than in non-diabetics (1 cases, 0.5%) (Fisher two-tailed exact P = 0.05). The mutation carrier detected by PCR-RFLP was confirmed to be the A to G point mutation in nucleotide 582 of IAPP gene cDNA encoding the amino acid codon 20. All the mutation carriers detected in population screening were heterozygotes. Analysis of the family members of the 12 NIDDM pedigrees with the IAPP gene Ser20Gly mutation showed that in two families, the mutation was not cosegregated with the affection status. The older was the age of Ser20Gly mutant carrier, the more prevalent was the diabetes in families (P = 0.0001). The highest total lod score of this 12 pedigree was 0.021(theta = 0) in parametric linkage analysis with the model of autosomal dominance with incomplete penetrance.

CONCLUSION

The Ser20Gly mutation of IAPP gene was present in Chinese. This mutation does not cause monogenic inheritance diabetes, but may be a pathogenetic factor for the development of NIDDM, the complex genetic disease.

[The relationship between angiotensin II type 1 receptor gene and coronary heart disease, hypertension and diabetes mellitus in Chinese]

OBJECTIVE

To ascertain whether the angiotensin II type 1 receptor (AGTR1) gene is associated with coronary heart disease (CHD), hypertension (HTN) and non-insulin-dependent diabetes mellitus (NIDDM) in Chinese and to observe the interaction of AGTR1 gene and angiotensin I converting enzyme(ACE) gene to the development of the associated disease in Chinese.

METHODS

270 cases of Chinese with CHD, HTN or NIDDM in single or in different combinations were genotyped for the A1166C variation at the 3'-untranslated region of AGTR1 gene by using PCR/Dde I restriction endonuclease digestion. And also, the insertion/deletion polymorphism at the intron 16 of ACE gene was typed by PCR.

RESULTS

(1) AGTR1 gene was associated with CHD (logistic regression analysis, P=0.02), but not with HTN and NIDDM; (2) The attributable risk of AGTR1 gene for CHD was 12.5% and the odds ratio was 4.55. Both AGTR1 gene and ACE gene were independent variation factors for CHD (P=0.032 and P=0.002 respectively); (3) The contribution of AGTR1 gene to the development of CHD was independent of total body adiposity, blood lipid profile and blood pressure; (4) The analysis of individual combined genotypes of AGTR1 gene and ACE gene showed significant difference in frequency distribution between patients with CHD and controls.

CONCLUSION

AGTR1 gene contributes to the development of CHD and is an independent risk factor for CHD in Chinese.

Mitochondrial tRNA(Leu(UUR)) gene mutation diabetes mellitus in Chinese

OBJECTIVE

To ascertain the prevalence and clinical features of mitochondrial tRNALeu(UUR) gene nucleotide (nt) 3243 A-->G mutation diabetes mellitus in Chinese and to establish the approaches for genetic diagnosis of this subtype of diabetes during routine daily clinical practice.

METHODS

Mitochondrial nt 3243 A-->G mutation was screened among 207 unrelated non-insulin-dependent diabetes mellitus (NIDDM) patients by using polymerase chain reaction (PCR)/Apa I restriction endonuclease digestion. Samples with positive result were confirmed by DNA sequence analysis. Genetic and clinical analysis were carried out in family members of the proband with positive genetic diagnosis.

RESULTS

Positive results were found in two subjects during screening of unrelated NIDDM patients, which account for 2.4%-11.1% of NIDDM subjects with uncommon clinical features (with early age-of-onset, with low body-mass-index and on insulin therapy) or with positive family history of diabetes consistent with or unable to exclude from maternal inheritance. Genetic diagnosis was positive in 10 out of 25 family members in the pedigrees of these two probands.

CONCLUSIONS

Mitochondrial tRNALeu(UUR) gene nt 3242 A-->G mutation should be considered in diabetic patients with the above-mentioned clinical features. The genetic diagnosis in daily clinical practice can be performed with allele specific priming amplification, or PCR/Hae III or Apa I digestion which are technically simple to perform and diagnostically easy to define.

[Relationship between angiotensin 1 converting enzyme gene polymorphism and diabetic nephropathy]

OBJECTIVE

To clarify if ACE gene I/D polymorphism attributes to the development of non-insulin dependent diabetes mellitus (NIDDM) and renal complication.

METHODS

A fragment of 287 bp Alu sequence in inron 16 of ACE gene was used as I/D polymorphic marker. After PCR amplification of DNA fragment, 12% non-denatured polyacrylamide gel electrophoresis was undertaken to analyze the PCR products.

RESULTS

Allele D was the prominent one (frequency 0.75) in the subgroup of DN which was complicated in the earliest stage of NIDDM without HTN, CHD and diabetic retinopathy. However, the frequency of allele D was low (0.39) in the subgroup of NIDDM without DN, HTN, CHD and diabetic retinopathy, in which the duration of each subject was over 5 years. It was significant to compare these two mentioned subgroups (P < 0.02, continuity-adjusted X2test, P < 0.05). The distribution of genotype in the whole NIDDM group without HTN and CHD (69 cases) was very similar to the normal control (110 subjects) (I 0.60 to 0.59, D 0.40 to 0.41).

CONCLUSION

The I/D polymorphism of ACE gene may be the factor of genetic predisposition of early-onset diabetic nephropathy in Chinese NIDDM.

Glucokinase gene variants in Chinese subjects with the common form of NIDDM

OBJECTIVE

To determine whether mutation of the coding or junction region of glucokinase gene (GCK) is also the pathogenic cause of the common form of non-insulin-dependent diabetes mellitus (NIDDM) in Chinese.

METHODS

Single strand conformation polymorphism (SSCP) analysis was performed after the 12 exons and junction regions of GCK of each subject studied were separately amplified with polymerase chain reaction (PCR). The molecular scanning was carried out in 30 Chinese subjects with common form NIDDM having the age of onset at or before 45 years, and/or with positive family history of diabetes mellitus (NIDDM-A group). Further screening of the mutation/variation found was conducted in 56 NIDDM subjects (NIDDM-B group) and 134 non-diabetes subjects (ND group) in order to define their frequencies.

RESULTS

No mutation was found by molecular scanning in coding or junction region of GCK in NIDDM-A group. A variant of intron I b was detected in GCK of NIDDM subjects, especially in those with early age of onset and/or with positive family history of diabetes. Significant difference in incidences was found between ND group and NIDDM-A+B group (0% vs 4.7%, Fisher exact P = 0.022).

CONCLUSIONS

(1) Mutation of coding and junction regions of GCK is not the main pathogenic factor of common form NIDDM in Chinese subjects. (2) A variant of GCK intron I b may be found in NIDDM in Chinese, especially in those with early age of onset and/or with positive family history of diabetes. Its role in the expression of GCK remain to be elucidated.

A genome-wide search for human non-insulin-dependent (type 2) diabetes genes reveals a major susceptibility locus on chromosome 2

Non-insulin-dependent (type 2) diabetes mellitus (NIDDM) is a common disorder of middle-aged individuals characterized by high blood glucose levels which, if untreated, can cause serious medical complications and lead to early death. Genetic factors play an important role in determining susceptibility to this disorder. However, the number of genes involved, their chromosomal location and the magnitude of their effect on NIDDM susceptibility are unknown. We have screened the human genome for susceptibility genes for NIDDM using non-and quasi-parametric linkage analysis methods in a group of Mexican American affected sib pairs. One marker, D2S125, showed significant evidence of linkage to NIDDM and appears to be a major factor affecting the development of diabetes mellitus in Mexican Americans. We propose that this locus be designated NIDDM1.