Absence of BBSome function leads to astrocyte reactivity in the brain.

In humans, dysfunctional primary cilia result in Bardet-Biedl syndrome (BBS), which presents with clinical features including intellectual disabilities, obesity, and retinal degeneration, and, in mouse models, the added feature of hydrocephalus. We observed increased Glial Fibrillary Acidic Protein (GFAP) immunoreactivity in BBS mouse brains. Increased GFAP expression is a hallmark of astrocyte reactivity that is associated with microglia activation and neuro-inflammation. To gain a better understanding of reactive astrocytes observed in BBS mice, we used two mouse models of BBS8, a BBSome protein, to characterize the reactive astrocyte phenotype. The finding of reactive astrocytes in young BBS mouse brains led us to hypothesize that loss of BBSome function leads to reactive astrocytes prior to hydrocephalus and obesity. By using two mouse models of BBS8, a congenital BBS8 knockout with hydrocephalus, and a tamoxifen-inducible BBS8 knockout without hydrocephalus, we were able to molecularly phenotype the reactive astrocytes. Molecular phenotype of reactive astrocytes shows differential regulation of inducers of Pan, A1 neurotoxic, and A2 neuroprotective astrocytes that are significantly altered in brains of both congenital and induced knockouts of BBS8, but without microglia activation. We find evidence for neuroinflammation in the brains of congenital knockout mice, but not in induced knockout mice. Protein levels of GFAP, SERPINA3N and post-synaptic density 95 (PSD95) are significantly increased in congenital knockout mice, but remain unchanged in induced knockout mice. Thus, despite the reactive astrocyte phenotype being present in both models, the molecular signature of reactive astrocytes in BBS8 mice models are distinct. Together, these findings suggest that BBS8, and by extension the BBSome, plays a role in neuro-astrocyte functions independent of hydrocephalus, and its dysregulation is associated with astrocyte reactivity without microglia activation. (Total word count 278).

Mood, food, and obesity.

Food is a potent natural reward and food intake is a complex process. Reward and gratification associated with food consumption leads to dopamine (DA) production, which in turn activates reward and pleasure centers in the brain. An individual will repeatedly eat a particular food to experience this positive feeling of gratification. This type of repetitive behavior of food intake leads to the activation of brain reward pathways that eventually overrides other signals of satiety and hunger. Thus, a gratification habit through a favorable food leads to overeating and morbid obesity. Overeating and obesity stems from many biological factors engaging both central and peripheral systems in a bi-directional manner involving mood and emotions. Emotional eating and altered mood can also lead to altered food choice and intake leading to overeating and obesity. Research findings from human and animal studies support a two-way link between three concepts, mood, food, and obesity. The focus of this article is to provide an overview of complex nature of food intake where various biological factors link mood, food intake, and brain signaling that engages both peripheral and central nervous system signaling pathways in a bi-directional manner in obesity.

Dysregulated A to I RNA editing and non-coding RNAs in neurodegeneration.

RNA editing is an alteration in the primary nucleotide sequences resulting from a chemical change in the base. RNA editing is observed in eukaryotic mRNA, transfer RNA, ribosomal RNA, and non-coding RNAs (ncRNA). The most common RNA editing in the mammalian central nervous system is a base modification, where the adenosine residue is base-modified to inosine (A to I). Studies from ADAR (adenosine deaminase that act on RNA) mutants in Caenorhabditis elegans, Drosophila, and mice clearly show that the RNA editing process is an absolute requirement for nervous system homeostasis and normal physiology of the animal. Understanding the mechanisms of editing and findings of edited substrates has provided a better knowledge of the phenotype due to defective and hyperactive RNA editing. A to I RNA editing is catalyzed by a family of enzymes knows as ADARs. ADARs modify duplex RNAs and editing of duplex RNAs formed by ncRNAs can impact RNA functions, leading to an altered regulatory gene network. Such altered functions by A to I editing is observed in mRNAs, microRNAs (miRNA) but other editing of small and long ncRNAs (lncRNAs) has yet to be identified. Thus, ncRNA and RNA editing may provide key links between neural development, nervous system function, and neurological diseases. This review includes a summary of seminal findings regarding the impact of ncRNAs on biological and pathological processes, which may be further modified by RNA editing. NcRNAs are non-translated RNAs classified by size and function. Known ncRNAs like miRNAs, smallRNAs (smRNAs), PIWI-interacting RNAs (piRNAs), and lncRNAs play important roles in splicing, DNA methylation, imprinting, and RNA interference. Of note, miRNAs are involved in development and function of the nervous system that is heavily dependent on both RNA editing and the intricate spatiotemporal expression of ncRNAs. This review focuses on the impact of dysregulated A to I editing and ncRNAs in neurodegeneration.

Protective actions of estrogen on angiotensin II-induced hypertension: role of central nitric oxide.

The present study tested the hypotheses that 1) nitric oxide (NO) is involved in attenuated responses to ANG II in female mice, and 2) there is differential expression of neuronal NO synthase (nNOS) in the subfornical organ (SFO) and paraventricular nucleus (PVN) in response to systemic infusions of ANG II in males vs. females. Aortic blood pressure (BP) was measured in conscious mice with telemetry implants. N(G)-nitro-l-arginine methyl ester (l-NAME; 100 microg x kg(.-1)day(-1)), an inhibitor of NOS, was administrated into the lateral cerebral ventricle for 14 days before and during ANG II pump implantation. Central infusion of l-NAME augmented the pressor effects of systemic ANG II in females (Delta21.5 + or - 2.2 vs. Delta9.2 + or - 1.5 mmHg) but not in males (Delta29.4 + or - 2.5 vs. Delta30.1 + or - 2.5 mmHg). Central administration of N(5)-(1-imino-3-butenyl)-l-ornithine (l-VNIO), a selective nNOS inhibitor, also significantly potentiated the increase in BP induced by ANG II in females (Delta17.5 + or - 3.2 vs. Delta9.2 + or - 1.5 mmHg). In gonadectomized mice, central l-NAME infusion did not affect the pressor response to ANG II in either males or females. Ganglionic blockade after ANG II infusion resulted in a greater reduction in BP in central l-NAME- or l-VNIO-treated females compared with control females. Western blot analysis of nNOS protein expression indicated that levels were approximately 12-fold higher in both the SFO and PVN of intact females compared with those in intact males. Seven days of ANG II treatment resulted in a further increase in nNOS protein expression only in intact females (PVN, to approximately 51-fold). Immunohistochemical studies revealed colocalization of nNOS and estrogen receptors in the SFO and PVN. These results suggest that NO attenuates the increase in BP induced by ANG II through reduced sympathetic outflow in females and that increased nNOS protein expression associated with the presence of female sex hormones plays a protective role against ANG II-induced hypertension in female mice.

Affect-related behaviors in mice misexpressing the RNA editing enzyme ADAR2.

Misediting of the serotonin (5HT) 2C receptor (5HT(2C)R) has been implicated in both depression and anxiety. The adenosine deaminases that act on double stranded RNAs (ADARs) are reported to modify the 5HT(2C)R by RNA editing. Transgenic mice misexpressing the RNA editing enzyme ADAR2 show an adult onset obese phenotype due to chronic hyperphagia, but little more than this is known about the behavior of these animals. The present experiments examined whether affect-associated behaviors are also altered in ADAR2 transgenic mice. Age- and weight-matched transgenic mice misexpressing ADAR2 were tested for signs of behavioral despair with the forced swim (FST) and tail suspension (TST) tests, and for anxiety by evaluating spontaneous exploration in a novel environment and by elevated plus maze performance. Plasma corticosterone was also determined by radioimmunoassay. Transgenic mice of both sexes displayed indications of increased behavioral despair on first exposures to the TST and the FST. Behavioral despair persisted in ADAR2 mice in that it was also observed in the FST in tests administered 24 h and 1 week following the initial TST and FST. ADAR2 transgenic mice also displayed behaviors associated with anxiety as indicated by decreased entry into the open arms in an elevated plus maze test. Both sexes of ADAR2 transgenic mice displayed elevated plasma corticosterone. Taken together, the results suggest that ADAR2 transgenic mice represent a novel rodent model of endogenous behavioral despair and anxiety accompanied by elevated hypothalamo-pituitary adrenal axis activity.

Ca2+/calmodulin-dependent kinase II triggers cell membrane injury by inducing complement factor B gene expression in the mouse heart.

Myocardial Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibition improves cardiac function following myocardial infarction (MI), but the CaMKII-dependent pathways that participate in myocardial stress responses are incompletely understood. To address this issue, we sought to determine the transcriptional consequences of myocardial CaMKII inhibition after MI. We performed gene expression profiling in mouse hearts with cardiomyocyte-delimited transgenic expression of either a CaMKII inhibitory peptide (AC3-I) or a scrambled control peptide (AC3-C) following MI. Of the 8,600 mRNAs examined, 156 were substantially modulated by MI, and nearly half of these showed markedly altered responses to MI with CaMKII inhibition. CaMKII inhibition substantially reduced the MI-triggered upregulation of a constellation of proinflammatory genes. We studied 1 of these proinflammatory genes, complement factor B (Cfb), in detail, because complement proteins secreted by cells other than cardiomyocytes can induce sarcolemmal injury during MI. CFB protein expression in cardiomyocytes was triggered by CaMKII activation of the NF-kappaB pathway during both MI and exposure to bacterial endotoxin. CaMKII inhibition suppressed NF-kappaB activity in vitro and in vivo and reduced Cfb expression and sarcolemmal injury. The Cfb-/- mice were partially protected from the adverse consequences of MI. Our findings demonstrate what we believe is a novel target for CaMKII in myocardial injury and suggest that CaMKII is broadly important for the genetic effects of MI in cardiomyocytes.

Protective roles of alpha-calcitonin and beta-calcitonin gene-related peptide in spontaneous and experimentally induced colitis.

Calcitonin gene-related peptide (CGRP) is thought to be involved in the regulation of gastric and mesenteric blood flow, in the control of gastric acid secretion and in the modulation of intestinal motility, yet the precise physiological roles of CGRP remain to be elucidated. To further examine the role(s) of CGRP in gastrointestinal function, we examined mutant mice lacking alphaCGRP or betaCGRP expression. Mutant mice did not demonstrate any overt phenotypic changes, yet exhibited a spontaneous, adult-onset colitis and increased colonic damage using a dextran sulfate sodium model of experimental colitis. Surprisingly, mice lacking betaCGRP show no obvious alterations in CGRP immunoreactivity in the gut, accompanied by an increase in alphaCGRP messenger RNA expression, suggesting an adaptive mechanism to compensate for the lack of betaCGRP. These data demonstrate that both alphaCGRP and betaCGRP play a protective role in the generation of spontaneous colitis, supporting a role for both extrinsic and intrinsic CGRP-containing neurons.

Hyperphagia-mediated obesity in transgenic mice misexpressing the RNA-editing enzyme ADAR2.

ADAR2 is a double-stranded RNA-specific adenosine deaminase involved in the editing of mammalian RNAs by the site-specific conversion of adenosine to inosine. To examine the physiologic consequences resulting from ADAR2 misexpression, we have generated mutant mice expressing either wild-type or deaminase-deficient ADAR2 transgenes under the control of the human cytomegalovirus promoter. Transgenic mice expressing either wild-type or inactive ADAR2 isoforms demonstrated adult onset obesity characterized by hyperglycemia, hyperleptinemia, and increased adiposity. Paired feeding analysis revealed that mutant mice on caloric restriction had a growth rate and body composition indistinguishable from wild-type littermates, indicating that the observed obesity predominantly results from hyperphagia rather than a metabolic derangement. The observation that expression of catalytically inactive ADAR2 also is capable of producing an obese phenotype in mutant animals suggests that ADAR2 may possess additional biological activities beyond those required for the site-selective deamination of adenosine or may interfere with the actions of other double-stranded RNA-specific binding proteins in the cell.

Altered RNA editing in mice lacking ADAR2 autoregulation.

ADAR2 is a double-stranded-RNA-specific adenosine deaminase involved in the editing of mammalian RNAs by the site-selective conversion of adenosine to inosine. Previous studies from our laboratory have demonstrated that ADAR2 can modify its own pre-mRNA to create a proximal 3' splice site containing a noncanonical adenosine-inosine dinucleotide. Alternative splicing to this proximal acceptor adds 47 nucleotides to the mature ADAR2 transcript, thereby resulting in the loss of functional ADAR2 protein expression due to premature translation termination in an alternate reading frame. To examine whether the editing of ADAR2 transcripts represents a negative autoregulatory strategy to modulate ADAR2 protein expression, we have generated genetically modified mice in which the ability of ADAR2 to edit its own pre-mRNA has been selectively ablated by deletion of a critical sequence (editing site complementary sequence [ECS]) required for adenosine-to-inosine conversion. Here we demonstrate that ADAR2 autoediting and subsequent alternative splicing are abolished in homozygous deltaECS mice and that ADAR2 protein expression is increased in numerous tissues compared to wild-type animals. The observed increases in ADAR2 protein expression correlate with the extent of ADAR2 autoediting observed with wild-type tissues and correspond to increases in the editing of ADAR2 substrates, indicating that ADAR2 autoediting is a key regulator of ADAR2 protein expression and activity in vivo.