👤 John E Dick

Individual variation in the physiological response to alcohol is predictive of an individual's likelihood to develop alcohol use disorder (AUD). Evidence from diverse model organisms indicates that the levels of long-chain polyunsaturated omega-3 fatty acids (ω-3 LC-PUFAs) can modulate the behavioral response to ethanol and therefore may impact the propensity to develop AUD. While most ω-3 LC-PUFAs come from diet, humans can produce these fatty acids from shorter chain precursors through a series of enzymatic steps. Natural variation in the genes encoding these enzymes has been shown to affect ω-3 LC-PUFA levels. We hypothesized that variation in these genes could contribute to the susceptibility to develop AUD. We identified nine genes (FADS1, FADS2, FADS3, ELOVL2, GCKR, ELOVL1, ACOX1, APOE, and PPARA) that are required to generate ω-3 LC-PUFAs and/or have been shown or predicted to affect ω-3 LC-PUFA levels. Using both set-based and gene-based analyses we examined their association with AUD and two AUD-related phenotypes, alcohol consumption, and an externalizing phenotype. We found that the set of nine genes is associated with all three phenotypes. When examined individually, GCKR, FADS2, and ACOX1 showed significant association signals with alcohol consumption. GCKR was significantly associated with AUD. ELOVL1 and APOE were associated with externalizing. Taken together with observations that dietary ω-3 LC-PUFAs can affect ethanol-related phenotypes, this work suggests that these fatty acids provide a link between the environmental and genetic influences on the risk of developing AUD. Show less

DREAM (Dp, Rb-like, E2F, and MuvB) is a transcriptional repressor complex that regulates cell proliferation, and its loss causes neonatal lethality in mice. To investigate DREAM function in adult mice, we used an assembly-defective p107 protein and conditional deletion of its redundant family member p130. In the absence of DREAM assembly, mice displayed shortened survival characterized by systemic amyloidosis but no evidence of excessive cellular proliferation. Amyloid deposits were found in the heart, liver, spleen, and kidneys but not the brain or bone marrow. Using laser-capture microdissection followed by mass spectrometry, we identified apolipoproteins as the most abundant components of amyloids. Intriguingly, apoA-IV was the most detected amyloidogenic protein in amyloid deposits, suggesting apoA-IV amyloidosis (AApoAIV). AApoAIV is a recently described form, whereby WT apoA-IV has been shown to predominate in amyloid plaques. We determined by ChIP that DREAM directly regulated Apoa4 and that the histone variant H2AZ was reduced from the Apoa4 gene body in DREAM's absence, leading to overexpression. Collectively, we describe a mechanism by which epigenetic misregulation causes apolipoprotein overexpression and amyloidosis, potentially explaining the origins of nongenetic amyloid subtypes. Show less

Hypoxia of the retina is a common pathogenic drive leading to vision loss as a result of tissue ischemia, increased vascular permeability and ultimately retinal neovascularisation. Here we tested the hypothesis that Müller cells stabilize the neurovascular unit, microvasculature by suppression of HIF-1α activation as a result of hypoxic preconditioning. Tube Formation Assay and In vitro Vascular Permeability Image Assay were used to analyze angiogenesis and vascular integrity. Seahorse XF Cell Mito Stress Test was used to measure mitochondrial respiration. Gene and protein expression were examined by qRTPCR, ELISA and western blot. Hypoxic insult induces a significant induction of proangiogenic factors including vascular endothelial growth factor (VEGF) and angiopoietinlike 4 (ANGPTL-4) resulting in angiogenesis and increased vascular permeability of vascular endothelial cells. Hypoxic preconditioning of a human retinal Müller glia cell line significantly attenuates HIF-1α activation through the inhibition of mTOR and concomitant induction of aerobic glycolysis, stabilizing endothelial cells. Hypoxic preconditioning of Müller cells confers a robust protection to endothelial cells, through the suppression of HIF1α activation and its downstream regulation of VEGF and ANGPTL-4. Show less

Alcohol dependence is a complex disease, and although linkage and candidate gene studies have identified several genes associated with the risk for alcoholism, these explain only a portion of the risk. We carried out a genome-wide association study (GWAS) on a case-control sample drawn from the families in the Collaborative Study on the Genetics of Alcoholism. The cases all met diagnostic criteria for alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition; controls all consumed alcohol but were not dependent on alcohol or illicit drugs. To prioritize among the strongest candidates, we genotyped most of the top 199 single nucleotide polymorphisms (SNPs) (p < or = 2.1 x 10(-4)) in a sample of alcohol-dependent families and performed pedigree-based association analysis. We also examined whether the genes harboring the top SNPs were expressed in human brain or were differentially expressed in the presence of ethanol in lymphoblastoid cells. Although no single SNP met genome-wide criteria for significance, there were several clusters of SNPs that provided mutual support. Combining evidence from the case-control study, the follow-up in families, and gene expression provided strongest support for the association of a cluster of genes on chromosome 11 (SLC22A18, PHLDA2, NAP1L4, SNORA54, CARS, and OSBPL5) with alcohol dependence. Several SNPs nominated as candidates in earlier GWAS studies replicated in ours, including CPE, DNASE2B, SLC10A2, ARL6IP5, ID4, GATA4, SYNE1, and ADCY3. We have identified several promising associations that warrant further examination in independent samples. Show less

The t(11;17)(q23;q21) translocation is associated with a retinoic acid (RA)-insensitive form of acute promyelocytic leukemia (APL), involving the production of reciprocal fusion proteins, promyelocytic leukemia zinc finger-retinoic acid receptor alpha (PLZF-RARalpha) and RARalpha-PLZF. Using a combination of chromatin immunoprecipitation promotor arrays (ChIP-chip) and gene expression profiling, we identify novel, direct target genes of PLZF-RARalpha that tend to be repressed in APL compared with other myeloid leukemias, supporting the role of PLZF-RARalpha as an aberrant repressor in APL. In primary murine hematopoietic progenitors, PLZF-RARalpha promotes cell growth, and represses Dusp6 and Cdkn2d, while inducing c-Myc expression, consistent with its role in leukemogenesis. PLZF-RARalpha binds to a region of the c-MYC promoter overlapping a functional PLZF site and antagonizes PLZF-mediated repression, suggesting that PLZF-RARalpha may act as a dominant-negative version of PLZF by affecting the regulation of shared targets. RA induced the differentiation of PLZF-RARalpha-transformed murine hematopoietic cells and reduced the frequency of clonogenic progenitors, concomitant with c-Myc down-regulation. Surviving RA-treated cells retained the ability to be replated and this was associated with sustained c-Myc expression and repression of Dusp6, suggesting a role for these genes in maintaining a self-renewal pathway triggered by PLZF-RARalpha. Show less

A major question in hematopoiesis is how the system maintains long-term homeostasis whereby the generation of large numbers of differentiated cells is balanced with the requirement for maintenance of progenitor pools, while remaining sufficiently flexible to respond to periods of perturbed cellular output during infection or stress. We focused on the development of the myeloid lineage and present evidence that promyelocytic leukemia zinc finger (PLZF) provides a novel function that is critical for both normal and stress-induced myelopoiesis. During homeostasis, PLZF restricts proliferation and differentiation of human cord blood-derived myeloid progenitors to maintain a balance between the progenitor and mature cell compartments. Analysis of PLZF promoter-binding sites revealed that it represses transcription factors involved in normal myeloid differentiation, including GFI-1, C/EBPalpha, and LEF-1, and induces negative regulators DUSP6 and ID2. Loss of ID2 relieves PLZF-mediated repression of differentiation identifying it as a functional target of PLZF in myelopoiesis. Furthermore, induction of ERK1/2 by myeloid cytokines, reflective of a stress response, leads to nuclear export and inactivation of PLZF, which augments mature cell production. Thus, negative regulators of differentiation can serve to maintain developmental systems in a primed state, so that their inactivation by extrinsic signals can induce proliferation and differentiation to rapidly satisfy increased demand for mature cells. Show less