AZG1 is a cytokinin transporter that interacts with auxin transporter PIN1 and regulates the root stress response.

An environmentally responsive root system is crucial for plant growth and crop yield, especially in suboptimal soil conditions. This responsiveness enables the plant to exploit regions of high nutrient density while simultaneously minimizing abiotic stress. Despite the vital importance of root systems in regulating plant growth, significant gaps of knowledge exist in the mechanisms that regulate their architecture. Auxin defines both the frequency of lateral root (LR) initiation and the rate of LR outgrowth. Here, we describe a search for proteins that regulate root system architecture (RSA) by interacting directly with a key auxin transporter, PIN1. The native separation of Arabidopsis plasma membrane protein complexes identified several PIN1 co-purifying proteins. Among them, AZG1 was subsequently confirmed as a PIN1 interactor. Here, we show that, in Arabidopsis, AZG1 is a cytokinin (CK) import protein that co-localizes with and stabilizes PIN1, linking auxin and CK transport streams. AZG1 expression in LR primordia is sensitive to NaCl, and the frequency of LRs is AZG1-dependent under salt stress. This report therefore identifies a potential point for auxin:cytokinin crosstalk, which shapes RSA in response to NaCl.

Comprehensive research synopsis and systematic meta-analyses in Parkinson's disease genetics: The PDGene database.

More than 800 published genetic association studies have implicated dozens of potential risk loci in Parkinson's disease (PD). To facilitate the interpretation of these findings, we have created a dedicated online resource, PDGene, that comprehensively collects and meta-analyzes all published studies in the field. A systematic literature screen of -27,000 articles yielded 828 eligible articles from which relevant data were extracted. In addition, individual-level data from three publicly available genome-wide association studies (GWAS) were obtained and subjected to genotype imputation and analysis. Overall, we performed meta-analyses on more than seven million polymorphisms originating either from GWAS datasets and/or from smaller scale PD association studies. Meta-analyses on 147 SNPs were supplemented by unpublished GWAS data from up to 16,452 PD cases and 48,810 controls. Eleven loci showed genome-wide significant (P < 5 × 10(-8)) association with disease risk: BST1, CCDC62/HIP1R, DGKQ/GAK, GBA, LRRK2, MAPT, MCCC1/LAMP3, PARK16, SNCA, STK39, and SYT11/RAB25. In addition, we identified novel evidence for genome-wide significant association with a polymorphism in ITGA8 (rs7077361, OR 0.88, P  =  1.3 × 10(-8)). All meta-analysis results are freely available on a dedicated online database (www.pdgene.org), which is cross-linked with a customized track on the UCSC Genome Browser. Our study provides an exhaustive and up-to-date summary of the status of PD genetics research that can be readily scaled to include the results of future large-scale genetics projects, including next-generation sequencing studies.

The role of TREM2 R47H as a risk factor for Alzheimer's disease, frontotemporal lobar degeneration, amyotrophic lateral sclerosis, and Parkinson's disease.

A rare variant in TREM2 (p.R47H, rs75932628) was recently reported to increase the risk of Alzheimer's disease (AD) and, subsequently, other neurodegenerative diseases, i.e. frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). Here we comprehensively assessed TREM2 rs75932628 for association with these diseases in a total of 19,940 previously untyped subjects of European descent. These data were combined with those from 28 published data sets by meta-analysis. Furthermore, we tested whether rs75932628 shows association with amyloid beta (Aß42) and total-tau protein levels in the cerebrospinal fluid (CSF) of 828 individuals with AD or mild cognitive impairment. Our data show that rs75932628 is highly significantly associated with the risk of AD across 24,086 AD cases and 148,993 controls of European descent (odds ratio or OR = 2.71, P = 4.67 × 10(-25)). No consistent evidence for association was found between this marker and the risk of FTLD (OR = 2.24, P = .0113 across 2673 cases/9283 controls), PD (OR = 1.36, P = .0767 across 8311 cases/79,938 controls) and ALS (OR = 1.41, P = .198 across 5544 cases/7072 controls). Furthermore, carriers of the rs75932628 risk allele showed significantly increased levels of CSF-total-tau (P = .0110) but not Aß42 suggesting that TREM2's role in AD may involve tau dysfunction.

Closing the case of APOE in multiple sclerosis: no association with disease risk in over 29 000 subjects.

BACKGROUND: Single nucleotide polymorphisms (SNPs) rs429358 (ε4) and rs7412 (ε2), both invoking changes in the amino-acid sequence of the apolipoprotein E (APOE) gene, have previously been tested for association with multiple sclerosis (MS) risk. However, none of these studies was sufficiently powered to detect modest effect sizes at acceptable type-I error rates. As both SNPs are only imperfectly captured on commonly used microarray genotyping platforms, their evaluation in the context of genome-wide association studies has been hindered until recently. METHODS: We genotyped 12 740 subjects hitherto not studied for their APOE status, imputed raw genotype data from 8739 subjects from five independent genome-wide association studies datasets using the most recent high-resolution reference panels, and extracted genotype data for 8265 subjects from previous candidate gene assessments. RESULTS: Despite sufficient power to detect associations at genome-wide significance thresholds across a range of ORs, our analyses did not support a role of rs429358 or rs7412 on MS susceptibility. This included meta-analyses of the combined data across 13 913 MS cases and 15 831 controls (OR=0.95, p=0.259, and OR 1.07, p=0.0569, for rs429358 and rs7412, respectively). CONCLUSION: Given the large sample size of our analyses, it is unlikely that the two APOE missense SNPs studied here exert any relevant effects on MS susceptibility.

Alzheimer's disease pathology explains association between dementia with Lewy bodies and APOE-ε4/TOMM40 long poly-T repeat allele variants.

INTRODUCTION: The role of TOMM40-APOE 19q13.3 region variants is well documented in Alzheimer's disease (AD) but remains contentious in dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). METHODS: We dissected genetic profiles within the TOMM40-APOE region in 451 individuals from four European brain banks, including DLB and PDD cases with/without neuropathological evidence of AD-related pathology and healthy controls. RESULTS: TOMM 40-L/APOE-ε4 alleles were associated with DLB (OR TOMM40 -L = 3.61; P value = 3.23 × 10-9; OR APOE -ε4 = 3.75; P value = 4.90 × 10-10) and earlier age at onset of DLB (HR TOMM40 -L = 1.33, P value = .031; HR APOE -ε4 = 1.46, P value = .004), but not with PDD. The TOMM40-L/APOE-ε4 effect was most pronounced in DLB individuals with concomitant AD pathology (OR TOMM40 -L = 4.40, P value = 1.15 × 10-6; OR APOE - ε 4 = 5.65, P value = 2.97 × 10-8) but was not significant in DLB without AD. Meta-analyses combining all APOE-ε4 data in DLB confirmed our findings (ORDLB = 2.93, P value = 3.78 × 10-99; ORDLB+AD = 5.36, P value = 1.56 × 10-47). DISCUSSION: APOE-ε4/TOMM 40-L alleles increase susceptibility and risk of earlier DLB onset, an effect explained by concomitant AD-related pathology. These findings have important implications in future drug discovery and development efforts in DLB.