👤 Rand Wilcox

Physical activity (PA) and sedentary behavior (SB) are associated with many diseases, including Alzheimer's disease and all-cause dementia. However, the specific biological mechanisms through which PA protects against disease are not entirely understood. This study aims to address this gap, with a specific focus on all-cause dementia. We first assessed the conventional observational associations of three self-reported and three device-based PA/SB measures with circulating levels of 2,911 plasma proteins measured in the UK Biobank (n max =39,160) and assessed functional enrichment of identified proteins. We then used bi-directional Mendelian randomization (MR) to further evaluate the evidence for causal relationships of PA/SB with protein levels. Finally, we performed mediation analyses to identify proteins that may mediate the relationship of PA with incident all-cause dementia. Our findings revealed 41 proteins consistently associated with all PA measures and 1,027 proteins associated with at least one PA measure. Both conventional observational and MR study designs converged on proteins that appear to increase as a result of PA, including integrins such as ITGAV and ITGAM, as well as MXRA8, CLEC4A, CLEC4M, LPL, and ADGRG2; on proteins that appear to decrease as a result of PA such as LEP, INHBC, CLMP, PTGDS, ADM, OGN, and PI3; and on proteins that are more responsive to high-intensity PA, such as CA14, CA6, CA4, KIT, and ANGPT2. Functional enrichment analyses revealed processes such as cell-matrix adhesion, integrin-mediated signaling, and collagen binding. Finally, GDF15, ITGAV, ITGAM, ITGA11, HPGDS, GFAP, ADM, AHNAK, and DPP4 were among 21 unique proteins found to mediate the relationship of PA with all-cause dementia, implicating processes such as synaptic plasticity, neurogenesis, and inflammation. Our results provide insights into how PA affects biological processes and protects against dementia, and provide avenues for future research into the health-promoting effects of PA. Show less

Physical activity (PA), including sedentary behavior, is associated with many diseases, including Alzheimer's disease and all-cause dementia. However, the specific biological mechanisms through which PA protects against disease are not entirely understood. To address this knowledge gap, we first assessed the conventional observational associations of three self-reported and three device-based PA measures with circulating levels of 2,911 plasma proteins measured in the UK Biobank (n Show less

Identifying population-specific genetic variants associated with disease and disease-predisposing traits is important to provide insights into the genetic determinants of health and disease between populations, as well as furthering genomic justice. Various common pan-population polymorphisms at Show less

Insulin coordinately up-regulates lipogenic gene transcription via induction of sterol regulatory element binding protein-1c (SREBP-1c). Conversely, polyunsaturated fatty acids (PUFA) decrease lipogenic gene transcription via suppression of SREBP-1c. We therefore examined the ability of n-3 PUFA to mitigate induction of SREBP-1c and its downstream lipogenic targets by insulin in primary rat hepatocyte cultures. Insulin induced expression of SREBP-1c mRNA 5-6 fold as well as rat SREBP-1c promoter activity. These effects were prevented by the n-3 fatty acids eicosapentaenoic acid (20:5 n-3; EPA) and docosahexaenoic acid (22:6 n-3, DHA), but not by the monounsaturated fatty acid oleic acid (18:1 n-6, OLA). N-3 fatty acids also effectively prevented insulin induction of the downstream lipogenic enzyme targets fatty acid synthase (FAS) and acetyl carboxyl coenzyme acetyltransferase-1 (ACC-1), and reduced de novo lipogenesis. The SREBP-1c promoter contains an insulin response unit consisting of tandem LXRalpha response elements (LXREs) as well as sites for NF-Y, Sp1, and SREBP-1c itself. The LXREs were identified as a primary site mediating suppression of SREBP-1c transcription by n-3 PUFA. DHA effectively prevented LXRalpha-dependent activation of both the wild type SREBP-1c promoter and the synthetic LXRE-driven promoter, and significantly blunted LXRalpha-dependent activation of a Gal4-LXRalpha chimeric protein thus demonstrating that n-3 PUFA effectively mitigate induction of SREBP-1c by insulin via reduced trans-activation of LXRalpha. Show less

Nonsyndromic deafness locus (DFNB48) segregating as an autosomal recessive trait has been mapped to the long arm of chromosome 15 in bands q23-q25.1 in five large Pakistani families. The deafness phenotype in one of these five families (PKDF245) is linked to D15S1005 with a lod score of 8.6 at theta=0, and there is a critical linkage interval of approximately 7 cM on the Marshfield human genetic map, bounded by microsatellite markers D15S216 (70.73 cM) and D15S1041 (77.69 cM). MYO9A, NR2E3, BBS4, and TMC3 are among the candidate genes in the DFNB48 region. The identification of another novel nonsyndromic recessive deafness locus demonstrates the high degree of locus heterogeneity for hearing impairment, particularly in the Pakistani population. Show less