👤 Emma Mead

A deep multi-omic analysis of post mortem human brains has identified a new co-expression protein network - Module 42 (M42), strongly corelated with Alzheimer's disease (AD) pathology. M42 comprises 32 transmembrane and extracellular matrix (ECM)-associated proteins, including the amyloid precursor protein (APP) and apolipoprotein E (apoE), and its members have been implicated in amyloid beta (Aβ) pathology. We systematically evaluated the Aβ-independent effects of M42 on immune function in vitro. Recombinant M42 proteins were expressed and purified. Their effects on phagocytosis, intracellular signaling, and cell viability were assessed in human induced pluripotent stem cell-derived macrophages. Treatment with Midkine (MDK) reduced phagocytosis, while treatment with the ectodomain of Transmembrane protein with EGF-like and two follistatin-like domains 2 (TMEFF2) had the opposite effect. Both proteins promoted intracellular Ca Our results suggest an additional role for M42 in AD via regulating immune functions. We tested M42 proteins for their effects on immune functions in vitro. Five proteins altered phagocytosis, and seven altered Ca Show less

The PromarkerD test accurately predicts diabetic kidney disease. We aimed to determine whether PromarkerD and/or its constituent biomarkers would also identify an increased risk of distal sensory polyneuropathy (DSPN) complicating type 2 diabetes (T2D). We selected 160 community-based adults without baseline DSPN (mean age 69 years, 56% males), 80 of whom were free of DSPN after four years and 80 who developed DSN based on the vibration perception threshold. Baseline plasma apolipoprotein A-IV (ApoA4), CD5 antigen-like protein (CD5L) and insulin-like growth factor binding protein 3 (IBP3) concentrations were measured and PromarkerD risk scores were generated. Logistic regression modelling assessed associations between PromarkerD risk and its component proteins and incident DSPN. At Year 4, 77 of 151 with valid data (51%) had developed DSPN. The PromarkerD area under the receiver operating characteristic curve was 0.53 (95% CI 0.43-0.62). The odds ratio for the PromarkerD score for identifying incident DSPN was 0.97 (95% CI 0.82-1.16, P = 0.76), with similar non-significant results for plasma ApoA4, CD5L, and IBP3. PromarkerD and its constituent protein concentrations, each with some preclinical or epidemiological evidence of an association with DSPN, did not predict incident DSPN over 4 years of follow-up. These data support microangiopathy-specific pathophysiological mechanisms in T2D. Show less

Genome- and epigenome-wide association studies have associated variants and methylation status of CPT1a (carnitine palmitoyltransferase 1a) to reductions in VLDL (very low-density lipoprotein) cholesterol and triglyceride levels. The objective of this study was to determine the mechanisms by which CPT1a-dependent mitochondrial fatty acid oxidation influences hepatic and lipoprotein metabolism. Eight-week-old male and female We report significant associations between the presence of These studies provide mechanistic insight linking genetic variants and methylation status of Show less

Protein truncating variants (PTVs) in To identify high-priority missense variants (HPVs), we applied ‘domain mapping of disease mutations’ for the 637 unique coding In this sample, PTVs and HPVs associated with respectively a 35- and 10-fold increased risk of early onset AD and 17- and 6-fold increased risk of overall AD. The median age at onset (AAO) of PTV- and HPV-carriers was 62 and 64 years, and Our results justify a debate on whether HPV carriers should be considered for clinical counseling. The online version contains supplementary material available at 10.1186/s13024-025-00907-z. Show less

Genome- and epigenome-wide association studies have associated variants and methylation status of carnitine palmitoyltransferase 1a (CPT1a) to reductions in very low-density lipoprotein (VLDL) cholesterol and triglyceride levels. We report significant associations between the presence of Loss-of-function SNPs in Show less

Genome and epigenome wide association studies identified variants in carnitine palmitoyltransferase 1a (CPT1a) that associate with lipid traits. The goal of this study was to determine the role of liver-specific CPT1a on hepatic lipid metabolism. Male and female liver-specific knockout (LKO) and littermate controls were placed on a low-fat or high-fat diet (60% kcal fat) for 15 weeks. Mice were necropsied after a 16 h fast, and tissues were collected for lipidomics, matrix-assisted laser desorption ionization mass spectrometry imaging, kinome analysis, RNA-sequencing, and protein expression by immunoblotting. Female LKO mice had increased serum alanine aminotransferase levels which were associated with greater deposition of hepatic lipids, while male mice were not affected by CPT1a deletion relative to male control mice. Mice with CPT1a deletion had reductions in DHA-containing phospholipids at the expense of monounsaturated fatty acids (MUFA)-containing phospholipids in whole liver and at the level of the lipid droplet (LD). Male and female LKO mice increased RNA levels of genes involved in LD lipolysis (Plin2, Cidec, G0S2) and in polyunsaturated fatty acid metabolism (Elovl5, Fads1, Elovl2), while only female LKO mice increased genes involved in inflammation (Ly6d, Mmp12, Cxcl2). Kinase profiling showed decreased protein kinase A activity, which coincided with increased PLIN2, PLIN5, and G0S2 protein levels and decreased triglyceride hydrolysis in LKO mice. Liver-specific deletion of CPT1a promotes sexually dimorphic steatotic liver disease (SLD) in mice, and here we have identified new mechanisms by which females are protected from HFD-induced liver injury. Show less

Genome and epigenome wide association studies identified variants in carnitine palmitoyltransferase 1a (CPT1a) that associate with lipid traits. The goal of this study was to determine the impact by which liver-specific CPT1a deletion impacts hepatic lipid metabolism. Six-to-eight-week old male and female liver-specific knockout (LKO) and littermate controls were placed on a low-fat or high-fat diet (HFD; 60% kcal fat) for 15 weeks. Mice were necropsied after a 16 hour fast, and tissues were collected for lipidomics, matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), kinome analysis, RNA-sequencing, and protein expression by immunoblotting. Female LKO mice had increased serum alanine aminotransferase (ALT) levels which were associated with greater deposition of hepatic lipids, while male mice were not affected by CPT1a deletion relative to male control mice. Mice with CPT1a deletion had reductions in DHA-containing phospholipids at the expense of monounsaturated fatty acids (MUFA)-containing phospholipids in both whole liver and at the level of the lipid droplet (LD). Male and female LKO mice increased RNA levels of genes involved in LD lipolysis ( Liver-specific deletion of CPT1a promotes sexually dimorphic steatotic liver disease (SLD) in mice, and here we have identified new mechanisms by which females are protected from HFD-induced liver injury. Show less

APOE ɛ4, the most significant genetic risk factor for Alzheimer disease (AD), may mask effects of other loci. We re-analyzed genome-wide association study (GWAS) data from the International Genomics of Alzheimer's Project (IGAP) Consortium in APOE ɛ4+ (10 352 cases and 9207 controls) and APOE ɛ4- (7184 cases and 26 968 controls) subgroups as well as in the total sample testing for interaction between a single-nucleotide polymorphism (SNP) and APOE ɛ4 status. Suggestive associations (P<1 × 10(-4)) in stage 1 were evaluated in an independent sample (stage 2) containing 4203 subjects (APOE ɛ4+: 1250 cases and 536 controls; APOE ɛ4-: 718 cases and 1699 controls). Among APOE ɛ4- subjects, novel genome-wide significant (GWS) association was observed with 17 SNPs (all between KANSL1 and LRRC37A on chromosome 17 near MAPT) in a meta-analysis of the stage 1 and stage 2 data sets (best SNP, rs2732703, P=5·8 × 10(-9)). Conditional analysis revealed that rs2732703 accounted for association signals in the entire 100-kilobase region that includes MAPT. Except for previously identified AD loci showing stronger association in APOE ɛ4+ subjects (CR1 and CLU) or APOE ɛ4- subjects (MS4A6A/MS4A4A/MS4A6E), no other SNPs were significantly associated with AD in a specific APOE genotype subgroup. In addition, the finding in the stage 1 sample that AD risk is significantly influenced by the interaction of APOE with rs1595014 in TMEM106B (P=1·6 × 10(-7)) is noteworthy, because TMEM106B variants have previously been associated with risk of frontotemporal dementia. Expression quantitative trait locus analysis revealed that rs113986870, one of the GWS SNPs near rs2732703, is significantly associated with four KANSL1 probes that target transcription of the first translated exon and an untranslated exon in hippocampus (P ⩽ 1.3 × 10(-8)), frontal cortex (P ⩽ 1.3 × 10(-9)) and temporal cortex (P⩽1.2 × 10(-11)). Rs113986870 is also strongly associated with a MAPT probe that targets transcription of alternatively spliced exon 3 in frontal cortex (P=9.2 × 10(-6)) and temporal cortex (P=2.6 × 10(-6)). Our APOE-stratified GWAS is the first to show GWS association for AD with SNPs in the chromosome 17q21.31 region. Replication of this finding in independent samples is needed to verify that SNPs in this region have significantly stronger effects on AD risk in persons lacking APOE ɛ4 compared with persons carrying this allele, and if this is found to hold, further examination of this region and studies aimed at deciphering the mechanism(s) are warranted. Show less