Differential transcriptional modulation of duplicated fatty acid-binding protein genes by dietary fatty acids in zebrafish (Danio rerio): evidence for subfunctionalization or neofunctionalization of duplicated genes

<p>Abstract</p> <p>Background</p> <p>In the Duplication-Degeneration-Complementation (DDC) model, subfunctionalization and neofunctionalization have been proposed as important processes driving the retention of duplicated genes in the genome. These processes are thought to occur by gain or loss of regulatory elements in the promoters of duplicated genes. We tested the DDC model by determining the transcriptional induction of fatty acid-binding proteins (Fabps) genes by dietary fatty acids (FAs) in zebrafish. We chose zebrafish for this study for two reasons: extensive bioinformatics resources are available for zebrafish at zfin.org and zebrafish contains many duplicated genes owing to a whole genome duplication event that occurred early in the ray-finned fish lineage approximately 230-400 million years ago. Adult zebrafish were fed diets containing either fish oil (12% lipid, rich in highly unsaturated fatty acid), sunflower oil (12% lipid, rich in linoleic acid), linseed oil (12% lipid, rich in linolenic acid), or low fat (4% lipid, low fat diet) for 10 weeks. FA profiles and the steady-state levels of <it>fabp </it>mRNA and heterogeneous nuclear RNA in intestine, liver, muscle and brain of zebrafish were determined.</p> <p>Result</p> <p>FA profiles assayed by gas chromatography differed in the intestine, brain, muscle and liver depending on diet. The steady-state level of mRNA for three sets of duplicated genes, <it>fabp1a/fabp1b.1/fabp1b.2</it>, <it>fabp7a/fabp7b</it>, and <it>fabp11a</it>/<it>fabp11b</it>, was determined by reverse transcription, quantitative polymerase chain reaction (RT-qPCR). In brain, the steady-state level of <it>fabp7b </it>mRNAs was induced in fish fed the linoleic acid-rich diet; in intestine, the transcript level of <it>fabp1b.1 </it>and <it>fabp7b </it>were elevated in fish fed the linolenic acid-rich diet; in liver, the level of <it>fabp7a </it>mRNAs was elevated in fish fed the low fat diet; and in muscle, the level of <it>fabp7a </it>and <it>fabp11a </it>mRNAs were elevated in fish fed the linolenic acid-rich or the low fat diets. In all cases, induction of the steady-state level of <it>fabp </it>mRNAs by dietary FAs correlated with induced levels of hnRNA for a given <it>fabp </it>gene. As such, up-regulation of the steady-state level of <it>fabp </it>mRNAs by FAs occurred at the level of initiation of transcription. None of the sister duplicates of these <it>fabp </it>genes exhibited an increase in their steady-state transcript levels in a specific tissue following feeding zebrafish any of the four experimental diets.</p> <p>Conclusion</p> <p>Differential induction of only one of the sister pair of duplicated <it>fabp </it>genes by FAs provides evidence to support the DDC model for retention of duplicated genes in the zebrafish genome by either subfunctionalization or neofunctionalization.</p

Evidence that the fragmented ribosomal RNAs of Chlamydomonas mitochondria are associated with ribosomes

AbstractThe discontinuous and scrambled organization of the small subunit and large subunit rRNA coding regions in Chlamydomonas mitochondrial DNA has been well documented. Our goals were to demonstrate that the small transcripts produced by these coding regions in Chlamydomonas eugametos are assembled into mitochondrial ribosomes and to characterize the sedimentation properties of these ribosomes and their subunits in sucrose gradients. Putative mitochondrial ribosomes (60–66S) and their large (44–50S) and small (35–39S) subunits were identified by slot blot hybridization which sedimented independently of the chloroplast and cytosolic ribosomes. A crude mitochondrial pellet prepared from C. eugametos was enriched for mitochondrial small subunit and large subunit rRNA subfragments thereby providing independent confirmation of the mitochondrial association of these rRNA molecules

Sustained striatal ciliary neurotrophic factor expression negatively affects behavior and gene expression in normal and R6/1 mice

Huntington's disease (HD) is a neurodegenerative disorder caused by an elongation of CAG repeats in the HD gene, which encodes a mutant copy of huntingtin with an expanded polyglutatmine repeat. Individuals who are affected by the disease suffer from motor, cognitive, and emotional impairments. Levels of certain striatal-enriched mRNAs decrease in both HD patients and transgenic HD mice prior to the development of motor symptoms and neuronal cell death. Ciliary neurotrophic factor (CNTF) has been shown to protect neurons against chemically induced toxic insults in vitro and in vivo. To test the hypothesis that CNTF might protect neurons from the negative effects of the mutant huntingtin protein in vivo, CNTF was continuously expressed following transduction of the striatum by recombinant adeno-associated viral vectors (rAAV2). Wild-type and R6/1 HD transgenic (R6/1) mice that received bilateral or unilateral intrastriatal injections of rAAV2-CNTF experienced weight loss. The CNTF-treated R6/1 HD transgenic mice experienced motor impairments at an earlier age than expected compared with age-matched control R6/1 HD transgenic animals. CNTF also caused abnormal behavior in WT mice. In addition to behavioral impairments, in situ hybridization showed that, in both WT and R6/1 mice, CNTF expression caused a significant decrease in the levels of striatal-enriched transcripts. Overall, continuous expression of striatal CNTF at the dose mediated by the expression cassette used in this study was detrimental to HD and wild-type mice. © 2008 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58641/1/21636_ftp.pd

Biased Type 1 Cannabinoid Receptor Signaling Influences Neuronal Viability in a Cell Culture Model of Huntington Disease

ABSTRACT Huntington disease (HD) is an inherited, autosomal dominant, neurodegenerative disorder with limited treatment options. Prior to motor symptom onset or neuronal cell loss in HD, levels of the type 1 cannabinoid receptor (CB 1 ) decrease in the basal ganglia. Decreasing CB 1 levels are strongly correlated with chorea and cognitive deficit. CB 1 agonists are functionally selective (biased) for divergent signaling pathways. In this study, six cannabinoids were tested for signaling bias in in vitro models of medium spiny projection neurons expressing wild-type (STHdh Q7/Q7 ) or mutant huntingtin protein (STHdh Q111/Q111 ). Signaling bias was assessed using the Black and Leff operational model. Relative activity [DlogR (t/K A )] and system bias (DDlogR) were calculated relative to the reference compound WIN55,212-2 for Ga i/o , Ga s , Ga q , Gbg, and b-arrestin1 signaling following treatment with 2-arachidonoylglycerol (2-AG), anandamide (AEA), CP55,940, D 9 -tetrahydrocannabinol (THC), cannabidiol (CBD), and THC1CBD (1:1), and compared between wild-type and HD cells. The E max of Ga i/o -dependent extracellular signal-regulated kinase (ERK) signaling was 50% lower in HD cells compared with wild-type cells. 2-AG and AEA displayed Ga i/o /Gbg bias and normalized CB 1 protein levels and improved cell viability, whereas CP55,940 and THC displayed b-arrestin1 bias and reduced CB 1 protein levels and cell viability in HD cells. CBD was not a CB 1 agonist but inhibited THC-dependent signaling (THC1CBD). Therefore, enhancing Ga i/o -biased endocannabinoid signaling may be therapeutically beneficial in HD. In contrast, cannabinoids that are b-arrestin-biased-such as THC found at high levels in modern varieties of marijuana-may be detrimental to CB 1 signaling, particularly in HD where CB 1 levels are already reduced

Novel Electrophilic and Photoaffinity Covalent Probes for Mapping the Cannabinoid 1 Receptor Allosteric Site(s)

ACKNOWLEDGMENTS The work was supported by National Institutes of Health grants DA027113 and EY024717 to G.A.T. and DA09158 to A.M. A portion of this work was submitted in 2011 by A. Kulkarni in partial fulfillment of M.S. degree requirements from Northeastern University, Boston, MA.Peer reviewedPublisher PD

Divergent evolution of cis-acting peroxisome proliferator-activated receptor elements that differentially control the tandemly-duplicated fatty acid-binding protein genes, fabp1b.1 and fabp1b.2, in zebrafish

Gene duplication is thought to facilitate increasing complexity in the evolution of life. The fate of most duplicated genes is nonfunctionalization: functional decay resulting from the accumulation of mutations. According to the duplication-degeneration-complementation (DDC) model, duplicated genes are retained by subfunctionalization, where the functions of the ancestral gene are sub-divided between duplicate genes, or by neofunctionalization, where one of the duplicates acquires a new function. Here, we report the differential regulation of the zebrafish tandemly-duplicated fatty acid-binding protein genes, fabp1b.1 and fabp1b.2 by peroxisome proliferator-activated receptors (PPAR). fabp1b.1 mRNA levels were induced in tissue explants of liver, but not intestine, by PPAR agonists. fabp1b.1 promoter activity was inducedto a greater extent by rosiglitazone (PPARγ-selective agonist) compared to WY 14,643 (PPARα-selective agonist) in HEK293A cells. Mutation of a peroxisome proliferator response element (PPRE) at -1,232 bp in the fabp1b.1 promoter reduced PPAR-dependent activation. fabp1b.2 promoter activity was not affected by PPAR agonists. Differential regulation of the duplicated fabp1b promoters may be the result of PPRE loss in fabp1b.2 during a meiotic crossing-over event. Retention of PPAR inducibility in fabp1b.1 and not fabp1b.2 suggests unique regulation and function of the fabp1b duplicates.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Effect of interacting nonsteroidal anti-inflammatory agents (NSAIDs) and opioids on mood: pharmacodynamic considerations in misuse and abuse

Clinical reality shows that pharmacodynamic interactions, as well as the pharmacokinetic interactions, might be used to increase effectiveness when treatment resistance to monotherapy presents. Nonsteroidal anti-inflammatory agents and opioids are among the most common drugs used in clinical practice to treat a heterogeneous spectrum of conditions, ranging from inflammation and fever to pain. Both classes of drugs appear to have mood-altering effects. Thus, their use, individually or concomitant, might determine an alteration of the clinical course of mood disorders, with the manifestation of which might be more severe in those patients who present comorbid substance use disorders and therefore are more prone to abusing/misusing these treatments. In this chapter we aim to provide a series of pharmacodynamic considerations concerning the interacting effects of nonsteroidal anti-inflammatory agents and opioids, and identify the implications of this pharmacodynamic synergism on mood and on the risk of developing abuse and misuse

Data from: Subfunctionalization of peroxisome proliferator response elements accounts for retention of duplicated fabp1 genes in zebrafish

Background: In the duplication-degeneration-complementation (DDC) model, a duplicated gene has three possible fates: it may lose functionality through the accumulation of mutations (non-functionalization), acquire a new function (neo-functionalization), or each duplicate gene may retain a subset of functions of the ancestral gene (sub-functionalization). The role that promoter evolution plays in retention of duplicated genes in eukaryotic genomes is not well understood. Fatty acid-binding proteins (Fabp) belong to a multigene family that are highly conserved in sequence and function, but differ in their gene regulation, suggesting selective pressure is exerted via regulatory elements in the promoter. A previous report showed that zebrafish fabp1b.1 and fabp1b.2 promoters underwent sub-functionalization of transcriptional control by peroxisome proliferator-activated receptors (PPAR). The fabp1b.1 promoter retained a functional PPAR response element (PPRE), while fabp1b.2 did not. Results: In this study, we describe the divergent PPAR regulation of zebrafish fabp1a, fabp1b.1, and fabp1b.2 promoters from the ancestral fabp1 gene. Promoter evolution was assessed by sequence analysis, and differential PPAR-agonist activation of fabp1 promoter activity in zebrafish liver and intestine ex vivo cells, and in HEK293 cells transiently transfected with wild-type and mutated fabp1promoter-reporter gene constructs. Spotted gar fabp1, representative of the ancestral fabp1, was responsive to both PPARα and PPARγ, and displayed a biphasic response to PPARα activation. Zebrafish fabp1a was PPARα-selective, fabp1b.1 was PPARγ-selective, while fabp1b.2 was not regulated by PPAR. Conclusions: The zebrafish fabp1 promoters underwent two successive rounds of PPAR-selective subfunctionalization leading to retention of three zebrafish fabp1 genes that display stimuli-specific regulation