👤 David Feldman

G protein-coupled receptors (GPCRs) play key roles in physiology and are central targets for drug discovery and development, yet the design of protein agonists and antagonists has been challenging as GPCRs are integral membrane proteins and conformationally dynamic. Here we describe computational Show less

Changes in low-density lipoprotein cholesterol (LDL-C) among people following a ketogenic diet (KD) are heterogeneous. Prior work has identified an inverse association between body mass index and change in LDL-C. However, the cardiovascular disease risk implications of these lipid changes remain unknown. The aim of the study was to examine the association between plaque progression and its predicting factors. A total of 100 individuals exhibiting KD-induced LDL-C ≥190 mg/dL, high-density lipoprotein cholesterol ≥60 mg/dL, and triglycerides ≤80 mg/dL were followed for 1 year using coronary artery calcium and coronary computed tomography angiography. Plaque progression predictors were assessed with linear regression and Bayes factors. Diet adherence and baseline cardiovascular disease risk sensitivity analyses were performed. High apolipoprotein B (ApoB) (median 178 mg/dL, Q1-Q3: 149-214 mg/dL) and LDL-C (median 237 mg/dL, Q1-Q3: 202-308 mg/dL) with low total plaque score (TPS) (median 0, Q1-Q3: 0-2.25) were observed at baseline. The median change in NCPV was 18.9 mm In lean metabolically healthy people on KD, neither total exposure nor changes in baseline levels of ApoB and LDL-C were associated with changes in plaque. Conversely, baseline plaque was associated with plaque progression, supporting the notion that, in this population, plaque predicts plaque but ApoB does not. (Diet-induced Elevations in LDL-C and Progression of Atherosclerosis [Keto-CTA]; NCT05733325). Show less

The relationship between atherogenic lipoproteins and subclinical coronary atherosclerosis has not been thoroughly evaluated in low-risk adults. The purpose of this study was to assess the association of low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (HDL-C), and apolipoprotein B (apoB) with coronary atherosclerosis in adults without traditional risk factors. We assessed atherosclerosis on coronary computed tomography angiography among asymptomatic adults in the Miami Heart Study not taking lipid-lowering therapy and without hypertension, diabetes, or active tobacco use. Prevalence of atherosclerosis was evaluated based on serum LDL-C, non-HDL-C, and apoB, and multivariable logistic regression with forward selection was used to assess variables associated with coronary plaque. Among 1,033 adults 40 to 65 years of age, 55.0% were women and 86.3% had estimated 10-year atherosclerotic cardiovascular disease risk <5%. Coronary atherosclerosis prevalence was 35.9% (50.6% in men; 23.8% in women) and 3.4% had ≥1 high-risk plaque feature. Atherosclerosis prevalence increased with LDL-C, ranging from 13.2% in adults with LDL-C <70 mg/dL up to 48.2% with ≥160 mg/dL. Higher LDL-C (adjusted OR [aOR]: 1.13 [95% CI: 1.08-1.18] per 10 mg/dL), age (aOR: 1.43 [95% CI: 1.28-1.60] per 5 years), male sex (aOR: 3.81 [95% CI: 2.86-5.10]), and elevated lipoprotein(a) (aOR: 1.46 [95% CI: 1.01-2.09]) were associated with atherosclerosis. Higher serum non-HDL-C and apoB were similarly associated with atherosclerosis. In adults with optimal risk factors, 21.2% had atherosclerosis with greater prevalence at higher lipoprotein levels. Among asymptomatic middle-aged adults without traditional risk factors, coronary atherosclerosis is common and increasingly prevalent at higher levels of atherogenic lipoproteins. These findings emphasize the importance of lipid-lowering strategies to prevent development and progression of atherosclerosis regardless of risk factors. Show less

Metabolomics genome wide association study (GWAS) help outline the genetic contribution to human metabolism. However, studies to date have focused on relatively healthy, population-based samples of White individuals. Here, we conducted a GWAS of 537 blood metabolites measured in the Chronic Renal Insufficiency Cohort (CRIC) Study, with separate analyses in 822 White and 687 Black study participants. Trans-ethnic meta-analysis was then applied to improve fine-mapping of potential causal variants. Mean estimated glomerular filtration rate was 44.4 and 41.5 mL/min/1.73m Show less

The COMPASS trial showed a reduction of ischemic events with low-dose rivaroxaban and aspirin in chronic coronary syndromes (CCS) compared with aspirin alone, at the expense of increased bleeding. The CHA We identified the COMPASS-eligible population within the CLARIFY registry (>30.000 patients with CCS). High-bleeding risk patients (REACH BRS > 10) were excluded, as in the COMPASS trial. Patients were categorized as low (0-1) or high (≥ 2) CHA The COMPASS-eligible population comprised 5.142 patients with ischemic and bleeding outcome of 2.3 (2.1-2.5) and 0.5 (0.4-0.6) per 100 patient-years, respectively. Patients with intermediate REACH RIS (n = 1934 [37.6%]) had the higher ischemic risk (3.0 [2.6-3.4]) with similar bleeding risk (0.5 [0.4-0.7]) as the overall population. Patients with low CHA Intermediate REACH RIS identified potential optimal candidates for adjunction of low-dose rivaroxaban while patients with low CHA Show less

Microtubules are polarized intracellular polymers that play key roles in the cell, including in transport, polarity, and cell division. Across eukaryotic cell types, microtubules adopt diverse intracellular organization to accommodate these distinct functions coordinated by specific cellular sites called microtubule-organizing centers (MTOCs). Over 50 years of research on MTOC biology has focused mainly on the centrosome; however, most differentiated cells employ non-centrosomal MTOCs (ncMTOCs) to organize their microtubules into diverse arrays, which are critical to cell function. To identify essential ncMTOC components, we developed the biotin ligase-based, proximity-labeling approach TurboID for use in C. elegans. We identified proteins proximal to the microtubule minus end protein PTRN-1/Patronin at the apical ncMTOC of intestinal epithelial cells, focusing on two conserved proteins: spectraplakin protein VAB-10B/MACF1 and WDR-62, a protein we identify as homologous to vertebrate primary microcephaly disease protein WDR62. VAB-10B and WDR-62 do not associate with the centrosome and instead specifically regulate non-centrosomal microtubules and the apical targeting of microtubule minus-end proteins. Depletion of VAB-10B resulted in microtubule mislocalization and delayed localization of a microtubule nucleation complex ɣ-tubulin ring complex (γ-TuRC), while loss of WDR-62 decreased the number of dynamic microtubules and abolished γ-TuRC localization. This regulation occurs downstream of cell polarity and in conjunction with actin. As this is the first report for non-centrosomal roles of WDR62 family proteins, we expand the basic cell biological roles of this important disease protein. Our studies identify essential ncMTOC components and suggest a division of labor where microtubule growth and localization are distinctly regulated. Show less

Cisplatin is a first-line chemotherapeutic for many cancers, but causes neurotoxicity including hearing loss, tinnitus, and peripheral sensory neuropathy. However, no study has comprehensively characterized risk factors for developing multiple (>1) severe neurotoxicities. The relationship between multiple severe neurotoxicities and age, cumulative cisplatin dose, medical history, and lifestyle/behavioral factors was evaluated in 300 cisplatin-treated testicular cancer survivors using logistic regression. Case-control genome-wide association study (GWAS; cases, Age at clinical examination ( Certain survivors are more susceptible to cisplatin-induced neurotoxicity, markedly increasing likelihood of developing numerous neuro-otological symptoms that affect quality of life. Genome-wide analysis identified genetic variation in Show less

Cardiovascular (CV)- and lifestyle-associated risk factors (RFs) are increasingly recognized as important for Alzheimer's disease (AD) pathogenesis. Beyond the ε4 allele of apolipoprotein E (APOE), comparatively little is known about whether CV-associated genes also increase risk for AD. Using large genome-wide association studies and validated tools to quantify genetic overlap, we systematically identified single nucleotide polymorphisms (SNPs) jointly associated with AD and one or more CV-associated RFs, namely body mass index (BMI), type 2 diabetes (T2D), coronary artery disease (CAD), waist hip ratio (WHR), total cholesterol (TC), triglycerides (TG), low-density (LDL) and high-density lipoprotein (HDL). In fold enrichment plots, we observed robust genetic enrichment in AD as a function of plasma lipids (TG, TC, LDL, and HDL); we found minimal AD genetic enrichment conditional on BMI, T2D, CAD, and WHR. Beyond APOE, at conjunction FDR < 0.05 we identified 90 SNPs on 19 different chromosomes that were jointly associated with AD and CV-associated outcomes. In meta-analyses across three independent cohorts, we found four novel loci within MBLAC1 (chromosome 7, meta-p = 1.44 × 10 Show less

Myotubular myopathy (MTM) is a devastating pediatric neuromuscular disorder of phosphoinositide (PIP) metabolism resulting from mutations of the PIP phosphatase MTM1 for which there are no treatments. We have previously shown phosphatidylinositol-3-phosphate (PI3P) accumulation in animal models of MTM. Here, we tested the hypothesis that lowering PI3P levels may prevent or reverse the MTM disease process. To test this, we targeted class II and III PI3 kinases (PI3Ks) in an MTM1-deficient mouse model. Muscle-specific ablation of Pik3c2b, but not Pik3c3, resulted in complete prevention of the MTM phenotype, and postsymptomatic targeting promoted a striking rescue of disease. We confirmed this genetic interaction in zebrafish, and additionally showed that certain PI3K inhibitors prevented development of the zebrafish mtm phenotype. Finally, the PI3K inhibitor wortmannin improved motor function and prolonged lifespan of the Mtm1-deficient mice. In all, we have identified Pik3c2b as a genetic modifier of Mtm1 mutation and demonstrated that PIK3C2B inhibition is a potential treatment strategy for MTM. In addition, we set the groundwork for similar reciprocal inhibition approaches for treating other PIP metabolic disorders and highlight the importance of modifier gene pathways as therapeutic targets. Show less

During the course of normal wound healing, fibroblasts at the wound edge are exposed to electric fields (EFs) ranging from 40 to 200 mV/mm. Various forms of EFs influence fibroblast migration, proliferation, and protein synthesis. Thus, EFs may contribute to fibroblast activation during wound repair. To elucidate the role of EFs during the normal progression of healing, this study compares gene expression in normal adult dermal fibroblasts exposed to a 100 mV/mm EF for 1 h to non-stimulated controls. Significantly increased expression of 162 transcripts and decreased expression of 302 transcripts was detected using microarrays, with 126 transcripts above the level of 1.4-fold increases or decreases compared to the controls. Above the level of twofold, only 11 genes were significantly increased or decreased compared to controls. Many of these significantly regulated genes are associated with wound repair through the processes of matrix production, cellular signaling, and growth. Activity within specific cellular signaling pathways is noted, including TGF-beta, G-proteins, and inhibition of apoptosis. In addition, RT-PCR analysis of the expression of KLF6, FN1, RGS2, and JMJD1C over continued stimulation and at different field strengths suggests that there are specific windows of field characteristics for maximum induction of these genes. EFs thus appear to have an important role in controlling fibroblast activity in the process of wound healing. Show less

We undertook studies of the association between common genomic variations in APOC3, APOA5, APOE and PON1 genes and variation in biochemical phenotypes in a sample of Greenlanders. Genetic association study of quantitative lipoprotein traits. In a sample of 1,310 adult Greenlanders, fasting plasma lipid, lipoprotein and apolipoprotein (apo) concentrations were assessed for association with known functional genomic variants of APOC3, APOA5, APOE and PON1. For significantly associated polymorphisms, between-genotype differences were examined in closer detail. We found that (1) the APOE restriction isotype was associated with variation in plasma total and LDL cholesterol and apo B (all p < .0001); (2) the APOC3 promoter genotype was associated with variation in plasma triglycerides, HDL cholesterol and apo A-I (all p < .002); (3) the APOA5 codon 19 genotype was associated with variation in plasma triglycerides (p = .027); and (4) the PON1 codon 192 genotype was associated with variation in total and LDL cholesterol and apo B (all p < .05). Taken together, our results suggest that common genetic variations in APOC3, APOA5, APOE and PON1 are associated with significant variation in intermediate traits in plasma lipoprotein metabolism in Greenlanders; the associations are similar to those observed for these variants in other populations. Show less