Association of plasma ceramide with decline in kidney function in patients with type 2 diabetes.

Circulating ceramide levels are dysregulated in kidney disease. However, their associations with rapid decline in kidney function (RDKF) and end-stage kidney disease (ESKD) in patients with type 2 diabetes (T2D) are unknown. In this prospective study of 1746 T2D participants, we examined the association of plasma ceramide Cer16:0, Cer18:0, Cer24:0, and Cer24:1 with RDKF, defined as an estimated glomerular filtration rate (eGFR) decline of 5 ml/min/1.73 m2 per year or greater, and ESKD defined as eGFR <15/min/1.73 m2 for at least 3 months, on dialysis or renal death at follow-up. During a median follow-up period of 7.7 years, 197 patients experienced RDKF. Ceramide Cer24:0 (odds ratio [OR] = 0.71, 95% CI 0.56-0.90) and ratios Cer16:0/Cer24:0 (OR = 3.54 [1.70-7.35]), Cer18:0/Cer24:0 (OR = 1.89 [1.10-3.25]), and Cer24:1/Cer24:0 (OR = 4.01 [1.93-8.31]) significantly associated with RDKF in multivariable analysis; 124 patients developed ESKD. The ratios Cer16:0/Cer24:0 (hazard ratio [HR] = 3.10 [1.44-6.64]) and Cer24:1/Cer24:0 (HR = 4.66 [1.93-11.24]) significantly associated with a higher risk of ESKD. The Cer24:1/Cer24:0 ratio improved risk discrimination for ESKD beyond traditional risk factors by small but statistically significant margin (Harrell C-index difference: 0.01; P = 0.022). A high ceramide risk score also associated with RDKF (OR = 2.28 [1.26-4.13]) compared to lower risk score. In conclusion, specific ceramide levels and their ratios are associated with RDKF and conferred an increased risk of ESKD, independently of traditional risk factors, including baseline renal functions in patients with T2D.

Incident heart failure and the subsequent risk of progression to end stage kidney disease in individuals with type 2 diabetes.

BACKGROUND: Diabetic kidney disease is an established risk factor for heart failure. However, the impact of incident heart failure on the subsequent risk of renal failure has not been systematically assessed in diabetic population. We sought to study the risk of progression to end stage kidney disease (ESKD) after incident heart failure in Asian patients with type 2 diabetes. METHODS: In this prospective cohort study, 1985 outpatients with type 2 diabetes from a regional hospital and a primary care facility in Singapore were followed for a median of 8.6 (interquartile range 6.2-9.6) years. ESKD was defined as a composite of progression to sustained eGFR below 15 ml/min/1.73m2, maintenance dialysis or renal death, whichever occurred first. RESULTS: 180 incident heart failure events and 181 incident ESKD events were identified during follow-up. Of 181 ESKD events, 38 (21%) occurred after incident heart failure. Compared to those did not progress to ESKD after incident heart failure (n = 142), participants who progressed to ESKD after heart failure occurrence were younger, had higher HbA1c and higher urine albumin-to-creatinine ratio at baseline. The excess risk of ESKD manifested immediately after heart failure occurrence, persisted for two years and was moderated thereafter. Cox regression suggested that, compared to counterparts with no heart failure event, participants with heart failure occurrence had 9.6 (95% CI 5.0- 18.3) fold increased risk for incident ESKD after adjustment for baseline cardio-renal risk factors including eGFR and albuminuria. It appeared that heart failure with preserved ejection fraction had a higher risk for ESKD as compared to those with reduced ejection fraction (adjusted HR 13.7 [6.3-29.5] versus 6.5 [2.3-18.6]). CONCLUSION: Incident heart failure impinges a high risk for progression to ESKD in individuals with type 2 diabetes. Our data highlight the need for intensive surveillance of kidney function after incident heart failure, especially within the first two years after heart failure diagnosis.

Association of plasma angiogenin with risk of major cardiovascular events in type 2 diabetes.

BACKGROUND: Angiogenin, an enzyme belonging to the ribonucleases A superfamily, plays an important role in vascular biology. Here, we sought to study the association of plasma angiogenin and major adverse cardiovascular events (MACEs) in patients with type 2 diabetes (T2D). METHODS: This prospective study included 1083 T2D individuals recruited from a secondary hospital and a primary care facility. The primary outcome was a composite of four-point MACE (nonfatal myocardial infarction, stroke, unstable angina pectoris leading to hospitalization and cardiovascular death). Circulating angiogenin was measured by a proximity extension assay. Cox regression models were used to evaluate the association of baseline plasma angiogenin with the risk of MACE. RESULTS: During a median follow-up of 9.3 years, 109 (10%) MACE were identified. Plasma angiogenin was significantly higher in participants with MACE than in those without MACE (P < 0.001). Doubling of plasma angiogenin concentration was associated with a 3.10-fold (95% CI 1.84-5.22) increased risk for MACE. The association was only moderately attenuated after adjustment for demographic and cardiometabolic risk factors (adjusted HR 2.38, 95% CI 1.34-4.23) and remained statistically significant after additional adjustment for estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (uACR) (adjusted HR 1.90, 95% CI 1.02-3.53). A consistent outcome was obtained when plasma angiogenin was analysed as a categorical variable in tertiles. CONCLUSIONS: Plasma angiogenin was associated with the risk of future cardiovascular events in patients with T2D and may be a promising novel biomarker for identifying high-risk T2D patients for early management.

A Reversible Association between Smc Coiled Coils Is Regulated by Lysine Acetylation and Is Required for Cohesin Association with the DNA.

Cohesin is a ring-shaped protein complex that is capable of embracing DNA. Most of the ring circumference is comprised of the anti-parallel intramolecular coiled coils of the Smc1 and Smc3 proteins, which connect globular head and hinge domains. Smc coiled coil arms contain multiple acetylated and ubiquitylated lysines. To investigate the role of these modifications, we substituted lysines for arginines to mimic the unmodified state and uncovered genetic interaction between the Smc arms. Using scanning force microscopy, we show that wild-type Smc arms associate with each other when the complex is not on DNA. Deacetylation of the Smc1/Smc3 dimers promotes arms' dissociation. Smc arginine mutants display loose packing of the Smc arms and, although they dimerize at the hinges, fail to connect the heads and associate with the DNA. Our findings highlight the importance of a "collapsed ring," or "rod," conformation of cohesin for its loading on the chromosomes.

Clinical variable-based cluster analysis identifies novel subgroups with a distinct genetic signature, lipidomic pattern and cardio-renal risks in Asian patients with recent-onset type 2 diabetes.

AIMS/HYPOTHESIS: We sought to subtype South East Asian patients with type 2 diabetes by de novo cluster analysis on clinical variables, and to determine whether the novel subgroups carry distinct genetic and lipidomic features as well as differential cardio-renal risks. METHODS: Analysis by k-means algorithm was performed in 687 participants with recent-onset diabetes in Singapore. Genetic risk for beta cell dysfunction was assessed by polygenic risk score. We used a discovery-validation approach for the lipidomics study. Risks for cardio-renal complications were studied by survival analysis. RESULTS: Cluster analysis identified three novel diabetic subgroups, i.e. mild obesity-related diabetes (MOD, 45%), mild age-related diabetes with insulin insufficiency (MARD-II, 36%) and severe insulin-resistant diabetes with relative insulin insufficiency (SIRD-RII, 19%). Compared with the MOD subgroup, MARD-II had a higher polygenic risk score for beta cell dysfunction. The SIRD-RII subgroup had higher levels of sphingolipids (ceramides and sphingomyelins) and glycerophospholipids (phosphatidylethanolamine and phosphatidylcholine), whereas the MARD-II subgroup had lower levels of sphingolipids and glycerophospholipids but higher levels of lysophosphatidylcholines. Over a median of 7.3 years follow-up, the SIRD-RII subgroup had the highest risks for incident heart failure and progressive kidney disease, while the MARD-II subgroup had moderately elevated risk for kidney disease progression. CONCLUSIONS/INTERPRETATION: Cluster analysis on clinical variables identified novel subgroups with distinct genetic, lipidomic signatures and varying cardio-renal risks in South East Asian participants with type 2 diabetes. Our study suggests that this easily actionable approach may be adapted in other ethnic populations to stratify the heterogeneous type 2 diabetes population for precision medicine.

Association of Plasma Leucine-Rich Alpha-2 Glycoprotein 1 (LRG1) with All-Cause and Cause-Specific Mortality in Individuals with Type 2 Diabetes.

BACKGROUND: Leucine-rich alpha-2 glycoprotein 1 (LRG1) is a circulating protein in the transforming growth factor-beta superfamily. We sought to study whether LRG1 might predict risk for all-cause and cause-specific mortality in individuals with type 2 diabetes. METHODS: 2012 outpatients with type 2 diabetes were followed for a median of 7.2 years and 188 death events were identified. Association of LRG1 with risk for mortality was assessed by multivariable Cox regression models. RESULTS: Participants with a higher concentration of LRG1 had an increased risk for all-cause mortality [HR (95% CI), 1.76 (1.03-3.01), 1.75 (1.03-2.98), and 4.37 (2.72-7.02) for quartiles 2, 3, and 4, respectively, compared to quartile 1]. The association remained significant after adjustment for known cardio-renal risk factors including estimated glomerular filtration rate and albuminuria [adjusted HR 2.76 (1.66-4.59), quartile 4 versus 1]. As a continuous variable, a 1-SD increment in LRG1 was associated with 1.34 (1.14-1.57)-fold adjusted risk for all-cause mortality. High plasma LRG1 was independently associated with mortality attributable to cardiovascular disease, infection, and renal diseases. Adding LRG1 into a clinical variable-based model improved discrimination (c statistics from 0.828 to 0.842, P = 0.006) and reclassification (net reclassification improvement 0.47, 95% CI 0.28-0.67) for prediction of 5-year all-cause mortality. CONCLUSION: Plasma LRG1 predicts risk for all-cause mortality and mortality attributable to cardiovascular disease, infection, and renal disease independent of known cardio-renal risk factors. It may be a potential novel biomarker to improve risk stratification in individuals with type 2 diabetes.

Association between depressive symptoms and pulse wave velocity is mediated by increased adiposity in older adults with type 2 diabetes.

Background: Studies investigating the association between depression and aortic stiffness in older patients with type 2 diabetes are lacking. We postulated an association between depressive symptoms and aortic stiffness, and this relationship may be mediated by increased adiposity. Methods: We analyzed participants with type 2 diabetes aged 55 years or older (n = 958). We measured aortic stiffness using carotid-femoral pulse wave velocity (cut-off ≥ 12 m/s) using the tonometry method. We defined depressive symptoms as a score of greater than 5 on the Geriatric Depression Scale-15 (GDS-15). Adiposity indices we assessed were body mass index, waist circumference, waistto-height ratio, visceral fat area and fat mass. Results: Among the participants, 27.2% had aortic stiffness, of whom 6.5% had depressive symptoms. Score on the GDS-15 was correlated with pulse wave velocity, and both variables were correlated with the adiposity markers we analyzed (all p < 0.05). Depressive symptoms were associated with pulse wave velocity (B = 1.79, 95% confidence interval [CI] 0.83-2.75) or aortic stiffness (risk ratio 1.60, 95% CI 1.10-2.33) in the unadjusted model. The association persisted after controlling for demographics, duration of diabetes, glycated hemoglobin, comorbidities and medications. Further adjustment for visceral fat area and fat mass in separate models reduced the association between depressive symptoms and pulse wave velocity or aortic stiffness. Mediation models revealed that the mediation proportions of fat mass and visceral fat area on the association between depressive symptoms and pulse wave velocity were 11.8% and 9.7%, respectively. A preliminary analysis of longitudinal data (n = 184) showed similar findings. Limitations: Causality cannot be inferred from the associations we observed. Conclusion: Depressive symptoms are associated with elevated pulse wave velocity in older people with type 2 diabetes, and this relationship may be partially mediated by increased adiposity.

Role of endothelium-independent vasodilation in the relationship between visceral adiposity and reduced cognitive performance in older adults with type 2 diabetes.

OBJECTIVE: In this cross-sectional analysis, we sought to assess the relationship of adiposity and forearm microvascular reactivity with cognitive dysfunction among older Asians with type 2 diabetes (T2D). METHODS: Subjects with T2D aged ≥ 55 years were analyzed (N = 907). Cognitive performance was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Mini-Mental State Exam (MMSE). Visceral fat area (VFA) was estimated by tetrapolar multi-frequency bioimpedance. Forearm microvascular endothelium-dependent vasodilation (EDV) and endothelium-independent vasodilation (EIV) were assessed by laser Doppler imaging with iontophoresis. RESULTS: RBANS total score was correlated with VFA, EDV, and EIV (all P < .05). However, VFA was correlated with EIV, but not with EDV. Multivariable linear regression showed significant association between VFA and RBANS total score (B = -0.02, 95% CI= -0.03 to -0.01) or memory (immediate and delayed) index scores. These associations were attenuated after adjustment for EIV. Mediation analysis showed that EIV partially mediated the relationship between visceral adiposity and RBANS scores (all Sobel tests P < .05). EIV also mediated the relationship between VFA and MMSE score. CONCLUSIONS: Impaired endothelium-independent vascular smooth muscle reactivity may exert a mediatory effect on the association between increased visceral adiposity and decreased cognitive performance in older adults with T2D.

Risk of progressive chronic kidney disease in individuals with early-onset type 2 diabetes: a prospective cohort study.

BACKGROUND: The progression trajectory of renal filtration function has not been well characterized in patients with early-onset type 2 diabetes mellitus (T2DM) although albuminuria is often reported in this population. We aim to study the risk of progressive chronic kidney disease (CKD) in individuals with early-onset T2DM. METHODS: In total, 1189 T2DM participants were followed for 3.9 (interquartile range 3.2-4.7) years. Progressive CKD was defined as estimated glomerular filtration rate (eGFR) decline of ≥5 mL/min/1.73 m2 per year. Early-onset T2DM was defined as age at T2DM diagnosis between 18 and 30 years. RESULTS: Compared with later-onset counterparts (N = 1032), participants with early-onset T2DM (N = 157) were more obese and had poorer glycaemic control at baseline. In the follow-up, 24.2% and 15.6% experienced progressive CKD in early-onset and later-onset participants, respectively (P = 0.007). Logistic regression suggested that participants with early-onset T2DM had 2.63-fold [95% confidence interval (CI) 1.46-4.75] higher risk of progressive CKD after accounting for multiple traditional risk factors. Furthermore, the excess risk of progressive CKD associated with early-onset T2DM mainly occurred in participants with preserved renal function [eGFR ≥60 mL/min/1.73 m2, odds ratio (OR) 2.85, 95% CI 1.50-5.42] and was more pronounced in those with diabetes duration <10 years (OR 3.67, 95% CI 1.51-8.90). CONCLUSIONS: Individuals with early-onset T2DM have a higher risk of progressive CKD. The excess risk mainly exhibits in early stage of CKD and cannot be solely attributed to traditional risk factors and a longer diabetes duration.

Arterial Stiffness Modulates the Association of Resting Heart Rate With Rapid Renal Function Decline in Individuals With Type 2 Diabetes Mellitus.

OBJECTIVE: Resting heart rate (RHR) has been associated with cardiovascular risk, but data on renal outcomes are still scarce. We aimed to study the association of RHR with rapid renal function decline (RRFD) and to explore whether the association of RHR with RRFD is modulated by arterial stiffness in individuals with type 2 diabetes mellitus. Approach and Results: One thousand one hundred forty-two Asian people with type 2 diabetes mellitus were followed for 3.9±0.9 years in a regional hospital and a primary care facility. RRFD was defined as eGFR decline of 5 mL/min per 1.73 m2 or greater per year. Arterial stiffness was assessed by carotid-femoral pulse wave velocity. One hundred sixty-eight participants (15%) were classified as having RRFD. Participants with elevated RHR were younger, had higher levels of HbA1c, albuminuria, C-reactive protein, and pulse wave velocity. Compared with the lowest quartile, participants in quartile 4 had a higher risk for RRFD after adjustment for known risk factors (adjusted odds ratio 1.91 [1.11-3.28]). RHR improved discrimination and net reclassification for prediction of RRFD above traditional risk factors. Remarkably, arterial stiffness modulated the association of RHR with RRFD (P for interaction =0.03). RHR was significantly associated with risk of RRFD only in those with increased arterial stiffness (pulse wave velocity above age-reference value 7.7 m/s). CONCLUSIONS: RHR independently predicts RRFD, and the association is modulated by arterial stiffness. An elevated heart rate may be one factor in the spectrum of cardiovascular risk factors associated with renal functional impairment, especially in those with type 2 diabetes mellitus and an increased arterial stiffness.

Aortic pulse wave velocity, central pulse pressure, augmentation index and chronic kidney disease progression in individuals with type 2 diabetes: a 3- year prospective study.

BACKGROUND: Pulse wave velocity (PWV), central pulse pressure and augmentation index are arterial stiffness- related hemodynamic parameters but their associations with renal outcome are still controversial. We hereby aim to study, 1) which hemodynamic parameter is independently associated with progressive chronic kidney disease (CKD), 2) the association of 3-year change in PWV with CKD progression and, 3) the additive predictive value of PWV for progressive CKD. METHODS: Carotid- femoral PWV, central pulse pressure and augmentation index were measured in 1444 participants with type 2 diabetes at baseline and 3 years apart. Progressive CKD was defined as confirmed eGFR decline 40% or greater. RESULTS: In the follow-up, 102 participants experienced progressive CKD. All 3 hemodynamic parameters were significantly associated with progressive CKD In univariable analysis. However, only PWV remained statistically significant after adjustment for known clinical risk factors and the other 2 hemodynamic parameters (OR 1.14 [95% CI 1.01-1.29] per m/s increment). One m/s regression (decrement) in PWV in the 3-year follow-up was associated with 26% lower adjusted- risk of progressive CKD (OR 0.74, 95% CI 0.56-0.97). Adding PWV onto traditional risk factor- based model significantly improved classification (net reclassification improvement 0.25, 95% CI 0.05-0.45, P = 0.01) and positive prediction rate (24.5 to 32.3%). CONCLUSIONS: Of 3 arterial stiffness- related hemodynamic parameters, only PWV is independently associated with progressive CKD. PWV may be a potential intervention target to mitigate risk of CKD progression and also a biomarker to improve risk-stratification of adverse renal outcome in individuals with type 2 diabetes.

Association of haptoglobin phenotype with incident acute myocardial infarction in Chinese patients with type 2 diabetes.

BACKGROUND: Haptoglobin (Hp) is an abundant plasma protein with anti-oxidant properties. Hp polymorphism is associated with cardio-metabolic dysfunction but the allele conferring risk of developing acute myocardial infarction (AMI) in type 2 diabetes (T2D) patients is unclear. This study aimed to investigate the association of Hp phenotype (Hp 1-1, 2-1 and 2-2) with incident AMI in Chinese T2D patients. METHODS: This prospective study included Chinese T2D participants from the Singapore Study of Macro-angiopathy and Micro-vascular Reactivity in Type 2 Diabetes (SMART2D) and Diabetic Nephropathy (DN) cohorts. Information on incidence of non-fatal AMI was collected by data linkage with the Singapore Myocardial Infarction Registry. Hp phenotype was determined using enzyme-linked immunosorbent assay. Cox proportional hazards regression models were used to evaluate the association of Hp phenotype with incident AMI, adjusted for traditional risk factors separately in two cohorts, then meta-analysed. RESULTS: In total, 2324 Chinese participants (SMART2D; N = 1034, mean age [SD] of 59 [11]) and (DN: N = 1290, mean age [SD] of 58 [12]) were included in this study. There were total of 30 (56 events per 10,000 patient-years) and 99 (128 events per 10,000 patient-years) AMI events in SMART2D and DN cohorts respectively. In meta-analysis, presence of Hp 1 allele conferred 43% (hazard ratio [HR] = 1.43 [95% CI 1.10-1.87], P = 0.008, Phet = 0.413) increased risk of incident AMI, independent of age, sex, smoking, body mass index, HbA1c, diabetes duration, lipids, hypertension, renal function and usage of insulin and RAS antagonist. In adjusted model, compared to Hp 2-2 groups, individuals with Hp 1-1 (HR = 2.18 [95% CI 1.19-3.76], P = 0.010, Phet = 0.193) and Hp 2-1 (HR = 1.45 [95% CI 0.98-2.14], P = 0.065, Phet = 0.576) were at a higher risk of incident AMI. Moreover, compared to Hp 2-2 groups, non-Hp 2-2 groups (Hp 1-1 and Hp 2-1) were at 55% increased risk of incident AMI (HR = 1.55 [95% CI 1.07-2.24], P = 0.021, Phet = 0.940). CONCLUSIONS: Hp 1-1 phenotype was associated with increased risk of incident AMI, independent of traditional risk factors, in Chinese patients with T2D. Hp phenotyping may allow for identification of T2D individuals at higher risk for onset of AMI. However, further studies are needed to understand the underlying mechanism between Hp alleles and risk for AMI.

Microvascular endothelial function is an independent predictor for albuminuria progression among Asians with type 2 diabetes-A prospective cohort study.

OBJECTIVE: We aim to investigate whether microvascular endothelial dysfunction is an independent predictor for future albuminuria progression in T2DM cohort. METHODS: A total of 1098 patients with T2DM were clinically assessed at baseline and 3.2-year follow-up. Progression was defined as transition from normoalbuminuria (ACR <30 mg/g) to microalbuminuria (ACR = 30-299 mg/g) or macroalbuminuria (ACR >300 mg/g), or microalbuminuria to macroalbuminuria. Microvascular endothelial vasodilation at baseline was quantified using LDF. The increase in perfusion in response to ACh and NaNP was calculated. Logistic regression model was used to estimate the OR for albuminuria progression. RESULTS: Albuminuria progression occurred in 226 (20.6%) patients. Baseline ACh was significantly higher in nonprogression than progression group (80.0 ± 53.2% vs 72.0 ± 49.7%, P = .04). There is no significant difference in NaNP between the two groups (111.1 ± 80.3% vs 121.1 ± 87.4%, P = .12). After multivariable adjustment, 1-SD increase in ACh was marginally associated with albuminuria progression (OR = 0.87, 95% CI, 0.72-1.02, P = .08) in all patients. When stratified by baseline albuminuria, 1-SD increase in ACh was significantly associated with albuminuria progression in normoalbuminuria (OR = 0.76, 95% CI, 0.59-0.97, P = .03), but not in microalbuminuria patients (OR = 1.18, 95% CI, 0.81-1.70, P = .39). CONCLUSIONS: Impaired endothelial-dependent microvascular reactivity predicts the onset of albuminuria progression among T2DM patients with normoalbuminuria.

Excess visceral adiposity is associated with diabetic retinopathy in a multiethnic Asian cohort with longstanding type 2 diabetes.

Purpose/Aim: Diabetic retinopathy (DR) is the most common diabetic microvascular complication, and it typically develops after 10 years of diabetes diagnosis. The primary aim of this study was to evaluate the association between adiposity and DR susceptibility among individuals with longstanding type 2 diabetes mellitus (T2D). MATERIALS AND METHODS: In this cross-sectional study, DR was assessed by fundus photography in 953 T2D subjects. DR prevalence by categories of T2D duration was evaluated. In a sub-cohort analysis, subjects having T2D for ≥10 years were divided into DR (N = 241) and non-DR (N = 377) groups. Measures of adiposity including body mass index (BMI), waist circumference (WC), and visceral fat area (VFA) were analyzed. Urinary albumin:creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were measured. RESULTS: DR prevalence markedly increased 10 years after T2D diagnosis (p < 0.001). Among subjects with T2D duration ≥10 years, BMI, WC, and VFA were elevated in DR compared with non-DR (all p < 0.05). Contrasting with BMI and WC, the association between VFA and DR sustained adjustment for demographics, metabolic factors, and insulin treatment (OR: 1.060, 95% CI: 1.004-1.119, p = 0.035). However, the association became insignificant after controlling for ACR and eGFR. Mediation analysis revealed that ACR and eGFR explained 47.3% of the relationship between VFA and DR. CONCLUSIONS: The findings suggest that visceral adiposity is associated with DR in individuals with longstanding T2D. This relationship may be attributable to generalized vascular injury as reflected by coexisting renal burden. Therefore, effective management of visceral adiposity and ameliorating renal burden may ameliorate susceptibility to DR.

Mediator acts upstream of the transcriptional activator Gal4.

The proteasome inhibitor MG132 had been shown to prevent galactose induction of the S. cerevisiae GAL1 gene, demonstrating that ubiquitin proteasome-dependent degradation of transcription factors plays an important role in the regulation of gene expression. The deletion of the gene encoding the F-box protein Mdm30 had been reported to stabilize the transcriptional activator Gal4 under inducing conditions and to lead to defects in galactose utilization, suggesting that recycling of Gal4 is required for its function. Subsequently, however, it was argued that Gal4 remains stably bound to the enhancer under inducing conditions, suggesting that proteolytic turnover of Gal4 might not be required for its function. We have performed an alanine-scanning mutagenesis of ubiquitin and isolated a galactose utilization-defective ubiquitin mutant. We have used it for an unbiased suppressor screen and identified the inhibitor Gal80 as a suppressor of the transcriptional defects of the ubiquitin mutant, indicating that the protein degradation of the inhibitor Gal80, and not of the activator Gal4, is required for galactose induction of the GAL genes. We also show that in the absence of Gal80, Mdm30 is not required for Gal4 function, strongly supporting this hypothesis. Furthermore, we have found that Mediator controls the galactose-induced protein degradation of Gal80, which places Mediator genetically upstream of the activator Gal4. Mediator had originally been isolated by its ability to respond to transcriptional activators, and here we have discovered a leading role for Mediator in the process of transcription. The protein kinase Snf1 senses the inducing conditions and transduces the signal to Mediator, which initiates the degradation of the inhibitor Gal80 with the help of the E3 ubiquitin ligase SCF(Mdm30). The ability of Mediator to control the protein degradation of transcriptional inhibitors indicates that Mediator is actually able to direct its own recruitment to gene promoters.

Plasma proteomics of diabetic kidney disease among Asians with younger-onset type 2 diabetes.

CONTEXT: Patients with younger onset of type 2 diabetes (YT2D) have increased risk for kidney failure compared to those with late onset. However, the mechanism of diabetic kidney disease (DKD) progression in this high-risk group is poorly understood. OBJECTIVES: To identify novel biomarkers and potential causal proteins associated with DKD progression in patients with YT2D. DESIGN AND PARTICIPANTS: Among YT2D (T2D onset age ≤ 40 years), 144 DKD progressors (cases) were matched for T2D onset age, sex, and ethnicity with 292 non-progressors (controls) and divided into discovery and validation sets. DKD progression was defined as decline of estimated glomerular filtration rate (eGFR) of 3ml/min/1.73m2 or greater or 40% decline in eGFR from baseline. 1472 plasma proteins were measured through a multiplex immunoassay that uses a proximity extension assay technology. Multivariable logistic regression was used to identify proteins associated with DKD progression. Mendelian randomization (MR) was used to evaluate causal relationship between plasma proteins and DKD progression. RESULTS: 42 plasma proteins were associated with DKD progression, independent of traditional cardio-renal risk factors, baseline eGFR and urine albumin-to-creatinine ratio (uACR). The proteins identified were related to inflammatory and remodelling biological processes. Our findings suggested angiogenin as one of the top signals (odds ratio =5.29, 95% CI 2.39-11.73, P = 4.03 × 10-5). Furthermore, genetically determined plasma angiogenin level was associated with increased odds of DKD progression. CONCLUSION: Large-scale proteomic analysis identified novel proteomic biomarkers for DKD progression in YT2D. Genetic evidence suggest a causal role of plasma angiogenin in DKD progression.

Plasma ceramides predict all-cause and cause-specific mortality in individuals with type 2 diabetes.

CONTEXT: The CERT1 (Cardiovascular Event Risk Test) score derived from plasma ceramides has been applied clinically for cardiovascular risk assessment. OBJECTIVE: To study whether plasma ceramides predict risk of mortality in patients with type 2 diabetes. DESIGN, SETTING AND PARTICIPANTS: A prospective study which included 1903 outpatients with type 2 diabetes in a regional hospital and a primary care facility in Singapore. EXPOSURE AND OUTCOME: Plasma ceramides (d18:1/16:0, d18:1/18:0, d18:1/24:0, d18:1/24:1) were measured by mass spectrometry and CERT1 score was calculated accordingly. Main outcomes were all-cause and cause-specific mortality. RESULTS: 252 death events were identified during median of 9.3 years of follow-up. Compared to those with low score (≤ 2), participants with a high CERT1 score (≥ 7) had 1.86 (95% CI 1.30-3.65) fold increased risk for all-cause death after adjustment for cardio-renal risk factors including eGFR and albuminuria. As continuous variable, one- unit increment in CERT1 was associated with 8% increased risk for all-cause death (adjusted HR 1.08 [1.04-1.13]). Adding CERT1 onto RECODe (Risk Equations for Complications Of type 2 Diabetes) mortality risk engine significantly improved prediction of 10- year risk of all-cause death (AUC 0.810 to 0.823, delta 0.013 [0.005-0.022]). The association between CERT1 and non-cardiovascular death remained significant (adjusted HR 2.12 [1.32-3.42]), whereas its association with cardiovascular death became non-significant after adjustment for kidney measurements (adjusted HR 1.41 [0.78-2.56]). CONCLUSION: CERT1 score predicts mortality risk independent of clinical cardio-renal risk factors. Further studies are warranted to elucidate the mechanistic linkage between ceramide and mortality, especially non-cardiovascular mortality.

Proteomics profiling and association with cardiorenal complications in type 2 diabetes subtypes in Asian population.

AIM: Among multi-ethnic Asians, type 2 diabetes (T2D) clustered in three subtypes; mild obesity-related diabetes (MOD), mild age-related diabetes with insulin insufficiency (MARD-II) and severe insulin-resistant diabetes with relative insulin insufficiency (SIRD-RII) had differential cardio-renal complication risk. We assessed the proteomic profiles to identify subtype specific biomarkers and its association with diabetes complications. METHODS: 1448 plasma proteins at baseline were measured and compared across the T2D subtypes. Multivariable cox regression was used to assess associations between significant proteomics features and cardio-renal complications. RESULTS: Among 645 T2D participants (SIRD-RII [19%], MOD [45%], MARD-II [36%]), 295 proteins expression differed significantly across the groups. These proteins were enriched in cell adhesion, neurogenesis and inflammatory response processes. In SIRD-RII group, ADH4, ACY1, THOP1, IGFBP2, NEFL, ENTPD2, CALB1, HAO1, CTSV, ITGAV, SCLY, EDA2R, ERBB2 proteins significantly associated with progressive CKD and LILRA5 protein with incident heart failure (HF). In MOD group, TAFA5, RSPO3, EDA2R proteins significantly associated with incident HF. In MARD-II group, FABP4 protein significantly associated with progressive CKD and PTPRN2 protein with major adverse cardiovascular events. Genetically determined NEFL and CALB1 were associated with kidney function decline. CONCLUSIONS: Each T2D subtype has unique proteomics signature and association with clinical outcomes and underlying mechanisms.

Association Between Plasma LRG1 and Lower Cognitive Function in Asians With Type 2 Diabetes Mellitus.

CONTEXT: Leucine-rich α-2-glycoprotein 1 (LRG1) has been implicated in the pathogenesis of diabetic complications, but its association with cognitive function remains unclear. OBJECTIVE: Our primary objective is to investigate the longitudinal association between LRG1 and cognitive function in patients with type 2 diabetes mellitus (T2DM). Secondarily, we determine the causal relationship using Mendelian randomization (MR) and the role of arterial stiffness as a potential mediator. METHODS: T2DM patients (n = 1039; age = 64.1 ± 6.4 years) were followed-up for 5.3 ± 1.2 years. Plasma LRG1 was measured at baseline using enzyme-linked immunosorbent assay. Baseline and follow-up cognitive function was assessed using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). One-sample MR was performed with rs4806985 as plasma LRG1-associated single-nucleotide polymorphism. Mediation analysis was performed to examine if pulse wave velocity (PWV), an arterial stiffness index, mediated the association between plasma LRG1 and follow-up cognitive function. RESULTS: Elevated baseline natural log (Ln)-transformed LRG1 was inversely associated with baseline and follow-up RBANS total score with adjusted coefficients -1.38 (95% CI -2.55 to -.21; P = .021) and -1.38 (95% CI -2.70 to -.07; P = .039), respectively. Genetically predicted higher levels of plasma LRG1 was associated with lower follow-up RBANS total score with coefficient -7.44 (95% CI -14.14 to -.74; P = .030) per unit increase in LnLRG1. Higher PWV accounted for 27.7% of the association between LnLRG1 and follow-up RBANS total score. CONCLUSION: Baseline plasma LRG1 was associated with lower cognitive function at follow-up in patients with T2DM, mediated by PWV. MR analysis provided evidence of an association between genetically influenced plasma LRG1 and lower cognitive function at follow-up.