Genomic knockout of alms1 in zebrafish recapitulates Alström syndrome and provides insight into metabolic phenotypes.

Alström syndrome (OMIM #203800) is an autosomal recessive obesity ciliopathy caused by loss-of-function mutations in the ALMS1 gene. In addition to multi-organ dysfunction, such as cardiomyopathy, retinal degeneration and renal dysfunction, the disorder is characterized by high rates of obesity, insulin resistance and early-onset type 2 diabetes mellitus (T2DM). To investigate the underlying mechanisms of T2DM phenotypes, we generated a loss-of-function deletion of alms1 in the zebrafish.

An APOO Pseudogene on Chromosome 5q Is Associated With Low-Density Lipoprotein Cholesterol Levels.

Background: Elevated levels of low-density lipoprotein cholesterol (LDL-C) are a major risk factor for cardiovascular disease via its contribution to the development and progression of atherosclerotic lesions. Although the genetic basis of LDL-C has been studied extensively, currently known genetic variants account for only ≈20% of the variation in LDL-C levels.

Methods: Through an array-based association analysis in 1102 Amish subjects, we identified a variant strongly associated with LDL-C levels.

Use of Immunolabeling to Analyze Stable, Dynamic, and Nascent Microtubules in the Zebrafish Embryo.

Microtubules (MTs) are dynamic and fragile structures that are challenging to image in vivo, particularly in vertebrate embryos. Immunolabeling methods are described here to analyze distinct populations of MTs in the developing neural tube of the zebrafish embryo. While the focus is on neural tissue, this methodology is broadly applicable to other tissues.

TM6SF2 rs58542926 impacts lipid processing in liver and small intestine.

Unlabelled: The transmembrane 6 superfamily member 2 (TM6SF2) loss-of-function variant rs58542926 is a genetic risk factor for nonalcoholic fatty liver disease and progression to fibrosis but is paradoxically associated with lower levels of hepatically derived triglyceride-rich lipoproteins. TM6SF2 is expressed predominantly in liver and small intestine, sites for triglyceride-rich lipoprotein biogenesis and export. In light of this, we hypothesized that TM6SF2 may exhibit analogous effects on both liver and intestine lipid homeostasis.

Microtubule-associated protein 1b is required for shaping the neural tube.

Background: Shaping of the neural tube, the precursor of the brain and spinal cord, involves narrowing and elongation of the neural tissue, concomitantly with other morphogenetic changes that contribue to this process. In zebrafish, medial displacement of neural cells (neural convergence or NC), which drives the infolding and narrowing of the neural ectoderm, is mediated by polarized migration and cell elongation towards the dorsal midline. Failure to undergo proper NC results in severe neural tube defects, yet the molecular underpinnings of this process remain poorly understood.

Changes in the Distribution of the α 3 Na(+)/K(+) ATPase Subunit in Heterozygous Lurcher Purkinje Cells as a Genetic Model of Chronic Depolarization during Development.

A common assumption of excitotoxic mechanisms in the nervous system is that the ionic imbalance resulting from overstimulation of glutamate receptors and increased Na(+) and Ca(++) influx overwhelms cellular energy metabolic systems leading to cell death. The goal of this study was to examine how a chronic Na(+) channel leak current in developing Purkinje cells in the heterozygous Lurcher mutant (+/Lc) affects the expression and distribution of the α 3 subunit of the Na(+)/K(+) ATPase pump, a key component of the homeostasis system that maintains ionic equilibrium in neurons. The expression pattern of the catalytic α 3 Na(+)/K(+) ATPase subunit was analyzed by immunohistochemistry, histochemistry, and Western Blots in wild type (WT) and +/Lc cerebella at postnatal days P10, P15, and P25 to determine if there are changes in the distribution of active Na(+)/K(+) ATPase subunits in degenerating Purkinje cells.

Enhanced survival of wild-type and Lurcher Purkinje cells in vitro following inhibition of conventional PKCs or stress-activated MAP kinase pathways.

Recent studies using both dissociated and organotypic cell cultures have shown that heterozygous Lurcher (Lc/+) Purkinje cells (PCs) grown in vitro share many of the same survival and morphological characteristics as Lc/+ PCs in vivo. We have used this established tissue culture system as a valuable model for studying cell death mechanisms in a relatively simple system where neurodegeneration is induced by a constitutive cation leak mediated by the Lurcher mutation in the δ2 glutamate receptor (GluRδ2). In this study, Ca(++) imaging and immunocytochemistry studies indicate that intracellular levels of Ca(++) are chronically increased in Lc/+ PCs and the concentration and/or distribution of the conventional PKCγ isoform is altered in degenerating Lc/+ PCs.

Altered spatial learning, cortical plasticity and hippocampal anatomy in a neurodevelopmental model of schizophrenia-related endophenotypes.

Adult rats exposed to the DNA-methylating agent methylazoxymethanol on embryonic day 17 show a pattern of neurobiological deficits that model some of the neuropathological and behavioral changes observed in schizophrenia. Although it is generally assumed that these changes reflect targeted disruption of embryonic neurogenesis, it is unknown whether these effects generalise to other antimitotic agents administered at different stages of development. In the present study, neurochemical, behavioral and electrophysiological techniques were used to determine whether exposure to the antimitotic agent Ara-C later in development recapitulates some of the changes observed in methylazoxymethanol (MAM)-treated animals and in patients with schizophrenia.

Mechanisms of compartmental purkinje cell death and survival in the lurcher mutant mouse.

The Lurcher mutant mouse is characterized by its ataxic gait and loss of cerebellar Purkinje cells and their afferents, granule cells and olivary neurons, during the first weeks of postnatal development. For the 50 years since its discovery, the heterozygous Lurcher mutant has served as an important model system for studying neuron-target interactions in the developing cerebellum and cerebellar function. The identification of the Lurcher (Lc) gene over 10 years ago as a gain-of-function mutation in the δ2 glutamate receptor (GluRδ2) led to extensive studies of cell death mechanisms in the Lc/+ cerebellum.

Death and survival of heterozygous Lurcher Purkinje cells in vitro.

The differentiation and survival of heterozygous Lurcher (+/Lc) Purkinje cells in vitro was examined as a model system for studying how chronic ionic stress affects neuronal differentiation and survival. The Lurcher mutation in the delta2 glutamate receptor (GluRdelta2) converts an orphan receptor into a membrane channel that constitutively passes an inward cation current. In the GluRdelta2(+/Lc) mutant, Purkinje cell dendritic differentiation is disrupted and the cells degenerate following the first week of postnatal development.

Oxidative stress, nitric oxide, and the mechanisms of cell death in Lurcher Purkinje cells.

Oxidative stress is postulated to play a role in cell death in many neurodegenerative diseases. As a model of neonatal neuronal cell death, we have examined the role of oxidative stress in Purkinje cell death in the heterozygous Lurcher mutant (+/Lc). Lurcher is a gain of function mutation in the delta2 glutamate receptor (GluRdelta2) that turns the receptor into a leaky membrane channel, resulting in chronic depolarization of +/Lc Purkinje cells starting around the first week of postnatal development.