Ubiquitin-specific proximity labeling for the identification of E3 ligase substrates.

Protein ubiquitylation controls diverse processes within eukaryotic cells, including protein degradation, and is often dysregulated in disease. Moreover, small-molecule degraders that redirect ubiquitylation activities toward disease targets are an emerging and promising therapeutic class. Over 600 E3 ubiquitin ligases are expressed in humans, but their substrates remain largely elusive, necessitating the development of new methods for their discovery. Here we report the development of E3-substrate tagging by ubiquitin biotinylation (E-STUB), a ubiquitin-specific proximity labeling method that biotinylates ubiquitylated substrates in proximity to an E3 ligase of interest. E-STUB accurately identifies the direct ubiquitylated targets of protein degraders, including collateral targets and ubiquitylation events that do not lead to substrate degradation. It also detects known substrates of E3 ligase CRBN and VHL with high specificity. With the ability to elucidate proximal ubiquitylation events, E-STUB may facilitate the development of proximity-inducing therapeutics and act as a generalizable method for E3-substrate mapping.

Birth Weight, Cardiometabolic Factors, and Coronary Heart Disease: A Mendelian Randomization Study.

CONTEXT: Observational studies have shown associations of birth weight (BW) with coronary heart disease (CHD), but results are inconsistent and do not distinguish the fetal or maternal effect of BW. OBJECTIVE: This study aims to explore the causal association between BW and CHD, analyze the fetal and maternal contribution, and quantify mediating effects of cardiometabolic factors. METHODS: Genetic variants from genome-wide association study summary-level data of own BW (N = 298 142), offspring BW (N = 210 267 mothers), and 16 cardiometabolic (anthropometric, glycemic, lipidemic, and blood pressure) factors were extracted as instrumental variables. We used two-sample Mendelian randomization study (MR) to estimate the causal effect of BW on CHD (60 801 cases and 123 504 controls from mixed ancestry) and explore the fetal and maternal contributions. Mediation analyses were conducted to analyze the potential mediating effects of 16 cardiometabolic factors using two-step MR. RESULTS: Inverse variance weighted analysis showed that lower BW raised the CHD risk (ß -.30; 95% CI: -0.40, -0.20) and consistent results were observed in fetal-specific/maternal-specific BW. We identified 5 mediators in the causal pathway from BW to CHD, including body mass index-adjusted hip circumference, triglycerides, fasting insulin, diastolic blood pressure, and systolic blood pressure (SBP), with mediated proportion ranging from 7.44% for triglycerides to 27.75% for SBP. Causality between fetal-specific and maternal-specific BW and CHD was mediated by glycemic factors and SBP, respectively. CONCLUSION: Our findings supported that lower BW increased CHD risk and revealed that fetal-specific and maternal-specific BW may both contribute to this effect. The causality between BW and CHD was mediated by several cardiometabolic factors.

[Expression of the pulmonary surfactant in rat with paraquat-induced acute lung injury].

OBJECTIVE: To explore the expression of pulmonary surfactant in rats with paraquat-induced acute lung injury. METHODS: A total of 36 SD rats were randomly divided into the control group (n=6) and paraquat group at 6, 12, 24, 48, 72 h five time points, each time points 6 rats. All of the rats were injected with paraquat (80 mg/kg) for once. The specimens were collected at 0 h (instant) after paraquat intoxication in the control group, and at the corresponding point in time in the paraquat each time point groups. The pathology changes of lung tissue were observed by HE staining, thiobarbituric acid method was used to detect malondialdehyde (MDA) level, and Western blot method was used to analyze the relative expression of surfactant protein (SP)-A and SP-D in bronchoalveolar lavage fluid (BALF) with time. RESULTS: As compared to control, the levels of MDA in BALF were significantly higher at 6, 24, 48 h after paraquat intoxication ((4.19 ± 0.12), (3.33 ± 0.08), (3.52 ± 0.08) vs (2.82 ± 0.15) nmol/mg, all P<0.01), no significantly different at 12, 72 h ((2.76 ± 0.13), (2.79 ± 0.10) nmol/mg, both P>0.05); the relative expression of SP-A in BALF were significantly higher at 6 h after paraquat intoxication (1.32 ± 0.19 vs 1.00 ± 0.19, P<0.01), lower at 24, 48 h (0.43 ± 0.07, 0.67 ± 0.08, both P<0.01), and no significantly different at 12, 72 h (0.98 ± 0.15, 0.79 ± 0.18, both P>0.05); the relative expression of SP-D in BALF were significantly higher at 6, 12 h after paraquat intoxication (1.54 ± 0.33, 1.64 ± 0.37 vs 1.00 ± 0.23, both P<0.01), no significantly different at 24, 48 h (1.07 ± 0.19, 0.97 ± 0.15, both P>0.05), and reached the peak at 72 h (2.15 ± 0.26, P<0.01); the expression of MDA, SP-A and SP-D were characterized by the state of fluctuation with increased first, reduced after, and finally increased. CONCLUSION: The expression of SP-A, SP-D increase at the early stage of the paraquat-induced acute lung injury in rat, which can reflect the degree of lung injury.