👤 Nicole L Walters

The APOE-ε4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease. However, APOE-ε4 is not deterministic, highlighting the need to identify additional genetic and environmental factors. APOE-ε4 has been linked to accelerated cognitive decline, so we sought to investigate genetic factors that modify APOE-ε4-associated cognitive decline. We conduct cross-ancestry APOE-ε4-stratified and interaction GWAS using harmonized cognitive data from 32,778 participants, including 29,354 non-Hispanic White and 3,424 non-Hispanic Black individuals. Our primary outcome is late-life cognition, measured using harmonized composite scores for memory, executive function, and language, modeled as continuous traits reflecting both normative cognitive aging and disease-related decline. We identify two genome-wide significant loci in APOE-ε4 carriers, reaching genome-wide significance for executive function. These loci also demonstrate nominal associations across the other domains, suggesting broad effects on cognition. In non-carriers, we identify a genome-wide significant association at ITGB8 restricted to executive function, and another locus associated with language. We further link these loci to SEMA6D, GRIN3A, and ITGB8 through expression and methylation databases. Post-GWAS analyses implicate additional genes including SLCO1A2, and DNAH11. Genetic correlation analyses reveal differences by APOE-ε4 status for immune-related traits, suggesting immune-related predispositions may exacerbate cognitive risk in APOE-ε4 carriers. Show less

Obesity is associated with adverse effects on health and quality of life. Improved understanding of its underlying pathophysiology is essential for developing counteractive measures. To search for sequence variants with large effects on BMI, we perform a multi-ancestry meta-analysis of 13 genome-wide association studies on BMI, including data derived from 1,534,555 individuals of European ancestry, 339,657 of Asian ancestry, and 130,968 of African ancestry. We identify an intergenic 262,760 base pair deletion at the MC4R locus that associates with 4.11 kg/m Show less

Little is known about the importance of blood lipids for risk of myocardial infarction (MI) in Chinese vs. European populations. We compared the associations with MI of apolioprotein B (ApoB) vs. low-density lipoprotein cholesterol (LDL-C) and remnant-cholesterol (remnant-C) vs. triglycerides in the China Kadoorie Biobank (CKB) and UK Biobank (UKB). Plasma levels of LDL-C, high-density lipoprotein-cholesterol (HDL-C), apolipoprotein B (ApoB), apolipoprotein A1 (ApoA1), non-HDL-C, remnant-C, LDL-C/ApoB, and HDL-C/ApoA1 ratios were measured in a nested case-control study of MI (948 cases, 6101 controls) in CKB and a prospective study (5344 cases in 279 989 participants) in UKB. Associations of lipids with MI were assessed using logistic regression in CKB and Cox regression in UKB after adjustment for confounders and correction for regression dilution. The mean levels of LDL-C were about 30% lower in CKB than in UKB [2.3 (0.6) vs. 3.7 (0.8) mmol/L], but mean levels of HDL-C were comparable [1.3 (0.3) vs. 1.5 (0.4) mmol/L], as were those for triglycerides [1.8 (1.1) vs. 1.7 (1.1) mmol/L]. While the rate ratios (RRs) of MI for 1 SD higher usual levels of LDL-C in Chinese were about half those in Europeans (1.27; 1.13-1.44 vs. 1.55; 1.49-1.61), the corresponding RRs for ApoB or non-HDL with MI were comparable between Chinese and Europeans. The findings reinforce current guidelines for primary prevention of atherosclerotic cardiovascular disease (ASCVD) in China that advocate initiation of statin treatment in individuals at high-risk of ASCVD rather than high levels of LDL-C. Show less

Many emerging service delivery models triage genetic counselor time with patients to postgenetic testing, including population genomic screening followed by genetic counseling (GC). To prime patients and help genetic counselors tailor such visits, a previsit (PV) chatbot was created to assess patient understanding, emotional response to, and family communication about genetic results. This study explored patients' perceptions of the PV chatbot and how they would use it. User testing was conducted via videoconference with patients who had completed GC. A codebook thematic analysis informed by Proctor's Conceptual Model of Implementation Research in a postpositivist paradigm was conducted. In total, 16 participants completed user testing, of whom 12 were women and 4 were men with a mean age of 55.4 (range 32-69). Participants had a variety of genetic results out of 78 genes among cancer (PMS2 n = 2; PALB2 n = 4; BRCA2 n = 1) and cardiovascular (LDLR n = 1; MYBPC3 n = 1; DSP n = 1; TTN n = 5; MYH7 n = 1) conditions. Participants reported high acceptability (M = 4.53/5, SD = 0.45) and feasibility (M = 4.43/5, SD = 1.04) of the chatbot. Participants reported liking the chatbot because of its ease of use and anticipated benefit to GC. Participants viewed the chatbot as complementary to GC and shared that the chatbot would have helped prepare them for GC in ways they may not have considered, including inviting a family member to join the appointment. Participants desired more personalization within the chatbot, including responsiveness to their personal/family history, optional supplementary education, and more emotionally supportive language. Some participants described challenges with certain aspects of the chatbot, including the repetitiveness and phrasing of validated scaled measures. Overall, participants perceived the PV chatbot to be of value in educating and preparing them for GC and reflected on how the PV chatbot may have enhanced GC. Many of the perceived benefits of this chatbot are applicable across GC settings. Show less

Bromodomain and extra-terminal domain (BET) proteins are therapeutic targets in several cancers including the most common malignant adult brain tumor glioblastoma (GBM). Multiple small molecule inhibitors of BET proteins have been utilized in preclinical and clinical studies. Unfortunately, BET inhibitors have not shown efficacy in clinical trials enrolling GBM patients. One possible reason for this may stem from resistance mechanisms that arise after prolonged treatment within a clinical setting. However, the mechanisms and timeframe of resistance to BET inhibitors in GBM is not known. To identify the temporal order of resistance mechanisms in GBM we performed quantitative proteomics using multiplex-inhibitor bead mass spectrometry and demonstrated that intrinsic resistance to BET inhibitors in GBM treatment occurs rapidly within hours and involves the fibroblast growth factor receptor 1 (FGFR1) protein. Additionally, small molecule inhibition of BET proteins and FGFR1 simultaneously induces synergy in reducing GBM tumor growth in vitro and in vivo. Further, FGFR1 knockdown synergizes with BET inhibitor mediated reduction of GBM cell proliferation. Collectively, our studies suggest that co-targeting BET and FGFR1 may dampen resistance mechanisms to yield a clinical response in GBM. Show less

Integrated analyses of plasma proteomics and genetic data in prospective studies can help assess the causal relevance of proteins, improve risk prediction, and discover novel protein drug targets for type 2 diabetes (T2D). We measured plasma levels of 2,923 proteins using Olink Explore among ∼2,000 randomly selected participants from China Kadoorie Biobank (CKB) without prior diabetes at baseline. Cox regression assessed associations of individual protein with incident T2D (n = 92 cases). Proteomic-based risk models were developed with discrimination, calibration, reclassification assessed using area under the curve (AUC), calibration plots, and net reclassification index (NRI), respectively. Two-sample Mendelian randomization (MR) analyses using cis-protein quantitative trait loci identified in a genome-wide association study of CKB and UK Biobank for specific proteins were conducted to assess their causal relevance for T2D, along with colocalization analyses to examine shared causal variants between proteins and T2D. Overall, 33 proteins were significantly associated (false discovery rate <0.05) with risk of incident T2D, including IGFBP1, GHR, and amylase. The addition of these 33 proteins to a conventional risk prediction model improved AUC from 0.77 (0.73-0.82) to 0.88 (0.85-0.91) and NRI by 38%, with predicted risks well calibrated with observed risks. MR analyses provided support for the causal relevance for T2D of ENTR1, LPL, and PON3, with replication of ENTR1 and LPL in Europeans using different genetic instruments. Moreover, colocalization analyses showed strong evidence (pH4 > 0.6) of shared genetic variants of LPL and PON3 with T2D. Proteomic analyses in Chinese adults identified novel associations of multiple proteins with T2D with strong genetic evidence supporting their causal relevance and potential as novel drug targets for prevention and treatment of T2D. Show less

Tissue fluidification and collective motility are pivotal in regulating embryonic morphogenesis, wound healing, and tumor metastasis. These processes frequently require that each cell constituent of a tissue coordinates its migration activity and directed motion through the oriented extension of lamellipodium cell protrusions, promoted by RAC1 activity. While the upstream RAC1 regulators in individual migratory cells or leader cells during invasion or wound healing are well characterized, how RAC1 is controlled in follower cells remains unknown. Here, we identify a MYO6-DOCK7 axis essential for spatially restricting RAC1 activity in a planar polarized fashion in model tissue monolayers. The MYO6-DOCK7 axis specifically controls the extension of cryptic lamellipodia required to drive tissue fluidification and cooperative-mode motion in otherwise solid and static carcinoma cell collectives. Show less

Tissue fluidification and collective motility are pivotal in regulating embryonic morphogenesis, wound healing and tumor metastasis. These processes frequently require that each cell constituent of a tissue coordinates its migration activity and directed motion through the oriented extension of lamellipodia cell protrusions, promoted by RAC1 activity. While the upstream RAC1 regulators in individual migratory cells or leader cells during invasion or wound healing are well characterized, how RAC1 is controlled in follower cells remains unknown. Here, we identify a novel MYO6-DOCK7 axis that is critical for spatially restriction of RAC1 activity in a planar polarized fashion in model tissue monolayers. The MYO6-DOCK7 axis specifically controls the extension of cryptic lamellipodia required to drive tissue fluidification and cooperative mode motion in otherwise solid and static carcinoma cell collectives. Collective motion of jammed epithelia requires myosin VI activityThe MYO6-DOCK7 axis is critical to restrict the activity of RAC1 in a planar polarized fashionMYO6-DOCK7-RAC1 activation ensures long-range coordination of movements by promoting orientation and persistence of cryptic lamellipodiaMyosin VI overexpression is exploited by infiltrating breast cancer cells. Show less

Among many causes of hypertriglyceridemia (HTG), familial chylomicronemia syndrome (FCS) is a rare monogenic disorder that manifests as severe HTG and acute pancreatitis. Among the known causal genes for FCS, mutations in We present the challenging care of a 43-year-old man with FCS with apoC-II deficiency and the results of two types of TPE and of investigational TG-lowering biologic therapies. The patient's lipid profile was consistent with FCS. A novel homozygous variant was identified in Our case demonstrates the importance of delineating and defining the underlying etiology of a rare disorder to optimize therapy and to minimize unfavorable outcomes. Show less

Increasing levels of high-density lipoprotein (HDL) cholesterol through pharmacologic inhibition of cholesteryl ester transfer protein (CETP) is a potentially important strategy for prevention and treatment of cardiovascular disease (CVD). To use genetic variants in the CETP gene to assess potential risks and benefits of lifelong lower CETP activity on CVD and other outcomes. This prospective biobank study included 151 217 individuals aged 30 to 79 years who were enrolled from 5 urban and 5 rural areas of China from June 25, 2004, through July 15, 2008. All participants had baseline genotype data, 17 854 of whom had lipid measurements and 4657 of whom had lipoprotein particle measurements. Median follow-up of 9.2 years (interquartile range, 8.2-10.1 years) was completed January 1, 2016, through linkage to health insurance records and death and disease registries. Five CETP variants, including an East Asian loss-of-function variant (rs2303790), combined in a genetic score weighted to associations with HDL cholesterol levels. Baseline levels of lipids and lipoprotein particles, cardiovascular risk factors, incidence of carotid plaque and predefined major vascular and nonvascular diseases, and a phenome-wide range of diseases. Among the 151 217 individuals included in this study (58.4% women and 41.6% men), the mean (SD) age was 52.3 (10.9) years. Overall, the mean (SD) low-density lipoprotein (LDL) cholesterol level was 91 (27) mg/dL; HDL cholesterol level, 48 (12) mg/dL. CETP variants were strongly associated with higher concentrations of HDL cholesterol (eg, 6.1 [SE, 0.4] mg/dL per rs2303790-G allele; P = 9.4 × 10-47) but were not associated with lower LDL cholesterol levels. Within HDL particles, cholesterol esters were increased and triglycerides reduced, whereas within very low-density lipoprotein particles, cholesterol esters were reduced and triglycerides increased. When scaled to 10-mg/dL higher levels of HDL cholesterol, the CETP genetic score was not associated with occlusive CVD (18 550 events; odds ratio [OR], 0.98; 95% CI, 0.91-1.06), major coronary events (5767 events; OR, 1.08; 95% CI, 0.95-1.22), myocardial infarction (3118 events; OR, 1.14; 95% CI, 0.97-1.35), ischemic stroke (13 759 events; OR, 0.94; 95% CI, 0.86-1.02), intracerebral hemorrhage (6532 events; OR, 0.94; 95% CI, 0.83-1.06), or other vascular diseases or carotid plaque. Similarly, rs2303790 was not associated with any vascular diseases or plaque. No associations with nonvascular diseases were found other than an increased risk for eye diseases with rs2303790 (4090 events; OR, 1.43; 95% CI, 1.13-1.80; P = .003). CETP variants were associated with altered HDL metabolism but did not lower LDL cholesterol levels and had no significant association with risk for CVD. These results suggest that in the absence of reduced LDL cholesterol levels, increasing HDL cholesterol levels by inhibition of CETP may not confer significant benefits for CVD. Show less

Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ∼ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10⁻⁸), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation. Show less

Perfluorooctanoic acid (PFOA), with an array of industrial uses, is one of the most common perfluoroalkyl acids. Resistance to biological degradation and a global distribution are characteristics that have caused PFOA to become a frequent subject of toxicological studies. PFOA treatment in rodents causes peroxisome proliferation, mitochondrial biogenesis, and transactivation of PPARs. Prior work has shown urea cycle gene expression to be reduced in mice by another PPARalpha ligand, WY14643. In light of these findings, the aim of our investigation was to determine if PFOA treatment in rats alters expression of genes responsible for ureogenesis. 30 mg/kg of PFOA was administered to adult male Sprague-Dawley rats via oral gavage for 28 days and their livers were harvested. Gene transcription was measured using real time PCR and protein expression was determined through western blotting. We observed a decrease in mRNA for the coordinately expressed urea cycle genes Cps1, Ass1, and Asl; mRNA of the ammonia generating Gls2 was also reduced. Protein amounts for CPS1, ASS1, and OTC were all decreased in the PFOA treated rats, and interestingly there was an increase in the amount of S133 phosphorylated CREB, which is a regulator of urea cycle gene transcription. We conclude that the transactivation of PPARalpha by PFOA leads to a metabolic shift that favors the catabolism of lipids over proteins, thereby suppressing urea cycle gene expression. Our findings provide further evidence of the effect of PFOA on intermediary metabolism in rodents and add valuable information in assessing the potential risks of PFOA exposure. Show less

Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes. Show less

Activated tyrosine kinases have been frequently implicated in the pathogenesis of cancer, including acute myeloid leukemia (AML), and are validated targets for therapeutic intervention with small-molecule kinase inhibitors. To identify novel activated tyrosine kinases in AML, we used a discovery platform consisting of immunoaffinity profiling coupled to mass spectrometry that identifies large numbers of tyrosine-phosphorylated proteins, including active kinases. This method revealed the presence of an activated colony-stimulating factor 1 receptor (CSF1R) kinase in the acute megakaryoblastic leukemia (AMKL) cell line MKPL-1. Further studies using siRNA and a small-molecule inhibitor showed that CSF1R is essential for the growth and survival of MKPL-1 cells. DNA sequence analysis of cDNA generated by 5'RACE from CSF1R coding sequences identified a novel fusion of the RNA binding motif 6 (RBM6) gene to CSF1R gene generated presumably by a t(3;5)(p21;q33) translocation. Expression of the RBM6-CSF1R fusion protein conferred interleukin-3 (IL-3)-independent growth in BaF3 cells, and induces a myeloid proliferative disease (MPD) with features of megakaryoblastic leukemia in a murine transplant model. These findings identify a novel potential therapeutic target in leukemogenesis, and demonstrate the utility of phosphoproteomic strategies for discovery of tyrosine kinase alleles. Show less

The metabolism of apolipoprotein (apo) A-IV in diabetes mellitus (DM) is poorly understood. Several factors, such as dietary fat intake, fat malabsorption, acute inflammation, and hormonal dysregulation can disturb the plasma apo A-IV concentration. We have compared the plasma apo A-IV concentrations in patients with type 1 DM and DM secondary to chronic pancreatitis to determine the effects of combinations of these factors. We examined 4 groups of male patients with chronic pancreatitis without diabetes (ND-CP) (n = 12), diabetes secondary to chronic pancreatitis and insulin-treated (CP-DM) (n = 32), type 1 diabetes (n = 25), and controls (n = 20). Plasma apo A-IV was significantly lower in the chronic pancreatitis patients (ND-CP and CP-DM) than in the other patients. Inflammatory proteins (fibrinogen, ceruloplasmin, and haptoglobin) were significantly elevated in the 2 chronic pancreatitis groups. The apo A-IV concentration was positively correlated with hemoglobin A(1c) (HbA(1c)) percentage in each group of diabetic patients (CP-DM, r =.35; P =.046; type 1 DM, r =.53; P =.010), in both groups of diabetic patients (r =.472; P <.0001) and negatively correlated with ceruloplasmin concentration in each group of diabetic patients (CP-DM, r = -.48; P =.0052; type 1 DM, r = -.66; P =.003), in both groups of diabetic patients (r = -.561; P <.0001), and in the whole population (r = -.463; P <.0001). Apo A-IV was also negatively correlated with haptoglobin in type 1 DM patients (r = -.434; P =.0435), in the both groups of diabetic patients (r = -.349; P =.0154), and in the whole population (r = -.351; P =.0019). Multiple linear regression analysis revealed that only HbA(1c) and ceruloplasmin were independent explanatory variables. Plasma apo A-IV is positively correlated with HbA(1c) suggesting that hyperglycemia per se selectively affects apo A-IV metabolism. The correlation between the concentrations of inflammatory protein and apo A-IV suggest a link between chronic inflammation and apo A-IV synthesis or catabolism. As apo A-IV is involved in reverse cholesterol transport, its low level in CP-DM may contribute to the accelerated development of atherosclerosis in these patients. Show less