Inositol 1,4,5-trisphosphate receptor and dSTIM function in Drosophila insulin-producing neurons regulates systemic intracellular calcium homeostasis and flight

Calcium (Ca2+) signaling is known to regulate the development, maintenance and modulation of activity in neuronal circuits that underlie organismal behavior. In Drosophila, intracellular Ca2+ signaling by the inositol 1,4,5-trisphosphate receptor and the store-operated channel (dOrai) regulates the formation and function of neuronal circuits that control flight. Here, we show that restoring InsP3R activity in insulin-producing neurons of flightless InsP3R mutants (itpr) during pupal development can rescue systemic flight ability. Expression of the store operated Ca2+ entry (SOCE) regulator dSTIM in insulin-producing neurons also suppresses compromised flight ability of InsP3R mutants suggesting that SOCE can compensate for impaired InsP3R function. Despite restricted expression of wild-type InsP3R and dSTIM in insulin-producing neurons, a global restoration of SOCE and store Ca2+ is observed in primary neuronal cultures from the itpr mutant. These results suggest that restoring InsP3R-mediated Ca2+ release and SOCE in a limited subset of neuromodulatory cells can influence systemic behaviors such as flight by regulating intracellular Ca2+ homeostasis in a large population of neurons through a non-cell-autonomous mechanism

Mtrr hypomorphic mutation alters liver morphology, metabolism and fuel storage in mice.

Nonalcoholic fatty liver disease (NAFLD) is associated with dietary folate deficiency and mutations in genes required for one‑carbon metabolism. However, the mechanism through which this occurs is unclear. To improve our understanding of this link, we investigated liver morphology, metabolism and fuel storage in adult mice with a hypomorphic mutation in the gene methionine synthase reductase (Mtrrgt ). MTRR enzyme is a key regulator of the methionine and folate cycles. The Mtrrgt mutation in mice was previously shown to disrupt one‑carbon metabolism and cause a wide-spectrum of developmental phenotypes and late adult-onset macrocytic anaemia. Here, we showed that livers of Mtrrgt/gt female mice were enlarged compared to control C57Bl/6J livers. Histological analysis of these livers revealed eosinophilic hepatocytes with decreased glycogen content, which was associated with down-regulation of genes involved in glycogen synthesis (e.g., Ugp2 and Gsk3a genes). While female Mtrrgt/gt livers showed evidence of reduced β-oxidation of fatty acids, there were no other associated changes in the lipidome in female or male Mtrrgt/gt livers compared with controls. Defects in glycogen storage and lipid metabolism often associate with disruption of mitochondrial electron transfer system activity. However, defects in mitochondrial function were not detected in Mtrrgt/gt livers as determined by high-resolution respirometry analysis. Overall, we demonstrated that adult Mtrrgt/gt female mice showed abnormal liver morphology that differed from the NAFLD phenotype and that was accompanied by subtle changes in their hepatic metabolism and fuel storage

New insights into the efficient charge transfer of ternary chalcogenides composites of TiO2

Abstract A two-step solvothermal synthesis was adopted to prepare AgXSe2-TiO2 (X = In, Bi) composites. DFT study of the pristine parent samples showed the formation of the hexagonal phase of AgBiSe2, and tetragonal phase of AgInSe2 and TiO2, which corroborated the experimentally synthesised structures. Both the AgBiSe2-TiO2 and AgInSe2-TiO2 composites displayed enhanced visible light absorption and reduced band gap in the UV-DRS patterns. The XPS results exhibited a shift in binding energy values and the TEM results showed the formation of spherical nanoparticles of both AgBiSe2 and AgInSe2. The PL signals displayed delayed recombination of the photogenerated excitons. The as synthesised materials were studied for their photocatalytic efficiency, by hydrogen generation, degradation of doxycycline, and antimicrobial disinfection (E. coli and S. aureus). The composite samples illustrated more than 95 % degradation results within 180 min and showed 5 log reductions of bacterial strains within 30 min of light irradiation. The hydrogen production outcomes were significantly improved as the AgBiSe2 and AgInSe2 based composites illustrated 180-fold and 250-fold enhanced output compared to their parent samples. The enhanced photocatalytic efficiency displayed is attributed to the delayed charge recombination of the photogenerated electron-hole pairs in the AgXSe2-TiO2 interface. Formation of a p-n nano heterojunction for AgBiSe2-TiO2 and type II heterojunction for AgInSe2-TiO2 composite are explained

Mutation in Folate Metabolism Causes Epigenetic Instability and Transgenerational Effects on Development

SummaryThe importance of maternal folate consumption for normal development is well established, yet the molecular mechanism linking folate metabolism to development remains poorly understood. The enzyme methionine synthase reductase (Mtrr) is necessary for utilization of methyl groups from the folate cycle. We found that a hypomorphic mutation of the mouse Mtrr gene results in intrauterine growth restriction, developmental delay, and congenital malformations, including neural tube, heart, and placental defects. Importantly, these defects were dependent upon the Mtrr genotypes of the maternal grandparents. Furthermore, we observed widespread epigenetic instability associated with altered gene expression in the placentas of wild-type grandprogeny of Mtrr-deficient maternal grandparents. Embryo transfer experiments revealed that Mtrr deficiency in mice lead to two distinct, separable phenotypes: adverse effects on their wild-type daughters’ uterine environment, leading to growth defects in wild-type grandprogeny, and the appearance of congenital malformations independent of maternal environment that persist for five generations, likely through transgenerational epigenetic inheritance.PaperFlic

Inositol 1,4,5- Trisphosphate Receptor Function in Drosophila Insulin Producing Cells

The Inositol 1,4,5- trisphosphate receptor (InsP3R) is an intracellular ligand gated channel that releases calcium from intracellular stores in response to extracellular signals. To identify and understand physiological processes and behavior that depends on the InsP3 signaling pathway at a systemic level, we are studying Drosophila mutants for the InsP3R (itpr) gene. Here, we show that growth defects precede larval lethality and both are a consequence of the inability to feed normally. Moreover, restoring InsP3R function in insulin producing cells (IPCs) in the larval brain rescues the feeding deficit, growth and lethality in the itpr mutants to a significant extent. We have previously demonstrated a critical requirement for InsP3R activity in neuronal cells, specifically in aminergic interneurons, for larval viability. Processes from the IPCs and aminergic domain are closely apposed in the third instar larval brain with no visible cellular overlap. Ubiquitous depletion of itpr by dsRNA results in feeding deficits leading to larval lethality similar to the itpr mutant phenotype. However, when itpr is depleted specifically in IPCs or aminergic neurons, the larvae are viable. These data support a model where InsP3R activity in non-overlapping neuronal domains independently rescues larval itpr phenotypes by non-cell autonomous mechanisms

Target genes, variants, tissues and transcriptional pathways influencing human serum urate levels.

Elevated serum urate levels cause gout and correlate with cardiometabolic diseases via poorly understood mechanisms. We performed a trans-ancestry genome-wide association study of serum urate in 457,690 individuals, identifying 183 loci (147 previously unknown) that improve the prediction of gout in an independent cohort of 334,880 individuals. Serum urate showed significant genetic correlations with many cardiometabolic traits, with genetic causality analyses supporting a substantial role for pleiotropy. Enrichment analysis, fine-mapping of urate-associated loci and colocalization with gene expression in 47 tissues implicated the kidney and liver as the main target organs and prioritized potentially causal genes and variants, including the transcriptional master regulators in the liver and kidney, HNF1A and HNF4A. Experimental validation showed that HNF4A transactivated the promoter of ABCG2, encoding a major urate transporter, in kidney cells, and that HNF4A p.Thr139Ile is a functional variant. Transcriptional coregulation within and across organs may be a general mechanism underlying the observed pleiotropy between urate and cardiometabolic traits.The Genotype-Tissue Expression (GTEx) Project was supported by the Common Fund of the Office of the Director of the National Institutes of Health, and by NCI, NHGRI, NHLBI, NIDA, NIMH, and NINDS. Variant annotation was supported by software resources provided via the Caché Campus program of the InterSystems GmbH to Alexander Teumer

Overlap of <i>DdcGAL4</i> and Ddc labeled cells in larval brains.

<p>Three-dimensional projections of confocal Z-stacks of a wild-type <i>Drosophila</i> 3^rd instar larval brain (A–C) expressing mCD8GFP with <i>DdcGAL4</i> and immunostained with an anti-Ddc antibody (A) and anti-GFP antibody (B). A majority of <i>DdcGAL4::UASmCD8GFP</i> labeled cells overlap with those stained with the Ddc antibody, though there are some cells in both cases that do not overlap (green arrows in B). These do not appear in the region of the IPCs. Green arrowhead in (B) indicates <i>DdcGAL4::UASmCD8GFP</i> expression in Ddc stained cells in the sub-esophageal ganglia that lie in close proximity to IPC projections. Scale bars A–C, 50 µm.</p

Ddc and serotonin labeled cells in larval brains do not overlap with IPCs.

<p>(A) A schematic drawing depicting a third instar larval brain with the relative positions of the IPCs and their processes (in green) and the Ddc labeled cells and their processes (in red). The cellular processes from the two domains seem to intermingle in the sub-esophageal ganglia region. (B–H) Three-dimensional projections of confocal Z-stacks of a wild-type <i>Drosophila</i> larval brain from a wandering third instar larva expressing mCD8GFP with <i>Dilp2GAL4</i> and immunostained with anti-serotonin antibody (E), anti-Ddc antibody (B, F) and anti-GFP antibody, (C, G). (D) is a merge of (B) and (C) while (H) is a merge of (E),(F) and (G). In (D) and (H), anti-Ddc staining is in red and anti-GFP in green while anti-serotonin is blue in (H). Red arrowheads in (B, F) indicate Ddc stained cells in the sub-esophageal ganglia that lie in close proximity to IPC projections (bottom green arrows in C, G). Smaller red arrowheads indicate cells which send out processes (marked with red arrows) that seem to intermingle with these IPC projections. Green arrowheads in (C, G) mark the IPCs in the two brain lobes. Green arrows indicate the projections of the IPCs towards the lateral protocerebrum (top green arrows) and sub-esophageal ganglion (bottom green arrows). Ddc marked cells (indicated by big red arrowheads in B, F) stain with the anti-serotonin antibody (E, marked by blue arrowheads), but have lesser serotonin staining than some neighboring cells (for example, cells in the lateral protocerebrum indicated by blue asterisk in E). Scale bars B–H 20 µm.</p

Delayed pupation in <i>Dilp2GAL4</i> and <i>DdcGAL4</i> rescue conditions results in larger body size.

<p>(A) From left to right: <i>UASitpr⁺/+;Dilp2GAL4/+; P0163GAL4,itpr^sv35/ug3</i> (<i>Dilp2GAL4 P0163GAL4</i> rescue), wild-type (<i>Canton-S</i>) and <i>UASitpr⁺/+</i>;<i>Dilp2GAL4/+</i>;<i>itpr^sv35/ug3</i> (<i>Dilp2GAL4</i> rescue) pupae. (E) Only <i>UASitpr⁺</i> expression with <i>Dilp2GAL4</i> in <i>itpr^sv35/ug3</i> background causes a significant increase (*p<0.005; Student's t-test) in pupal length as compared to controls of all the indicated genotypes. Pupal length is restored close to wild-type in <i>Dilp2GAL4::P0163GAL4</i> rescue condition. (B) From left to right: wild-type and <i>Dilp2GAL4</i> rescued flies. (F) Body length of <i>Dilp2GAL4</i> rescued flies is significantly more than wild-type flies (*p<0.05; Student's t-test). (C, D) From left to right: <i>UASitpr⁺/+;DdcGAL4/+;P0163GAL4,itpr^sv35/ug3</i> (<i>DdcGAL4 P0163GAL4</i> rescue), wild-type (<i>Canton-S</i>) and <i>UASitpr⁺/+</i>;<i>DdcGAL4/+</i>;<i>itpr^sv35/ug3</i> (<i>DdcGAL4</i> rescue) pupae (C) and flies (D). (G) Only <i>UASitpr⁺</i> expression with <i>DdcGAL4</i> in <i>itpr^sv35/ug3</i> background causes a significant increase (*p<0.005; Student's t-test) in pupal length as compared to controls of all the indicated genotypes. Pupal length (G) and adult weight per fly (H) is increased in the <i>DdcGAL4</i> rescued condition (*p<0.005; Student's t-test) but is restored close to wild-type in <i>DdcGAL4::P0163GAL4</i> rescue condition. n = 10 or more for each individual genotype for (A–G). For (H), the following numbers of male flies (n) in batches of around 3 flies each were weighed for each genotype: <i>DdcGAL4 P0163GAL4</i> rescue n = 26, wild-type n = 30 and <i>DdcGAL4</i> rescue n = 54. (I) Total number of larvae that undergo pupation is significantly increased on introducing a prothoracic gland GAL4 (<i>P0163GAL4)</i> in <i>DdcGAL4</i> and <i>Dilp2GAL4</i> rescued conditions (*p<0.05, **p<0.005; Student's t-test). (J) Time AEL for 50% pupal formation is significantly reduced with <i>P0163GAL4</i> in <i>DdcGAL4</i> and <i>Dilp2GAL4</i> rescued conditions (*p<0.005; Student's t-test). However the 50% pupation time in all single and double GAL4 conditions remained longer than the 50% pupation time of wild-type. For (I) and (J) 25 larvae in the following number of batches (N) were assayed for pupation for each genotype: wild-type N = 11, <i>Dilp2GAL4</i> rescue N = 10, <i>Dilp2GAL4 P0163GAL4</i> rescue N = 5, <i>DdcGAL4</i> rescue N = 13 and <i>DdcGAL4 P0163GAL4</i> rescue N = 9. (K) <i>DdcGAL4</i> rescued <i>itpr^sv35/ug3</i> larvae pupated earlier on being fed 20-hydroxyecdysone (∼150 hrs AEL) than larvae without 20-hydroxyecdysone (∼200 hrs AEL) (*p<0.05; Student's t-test). A minimum of 75 animals were screened in batches of 25 each. Differences in pupation rate are not apparent upon 20-hydroxyecdysone feeding in <i>Dilp2GAL4</i> rescue animals due to increased lethality in this condition in late third instar larvae. The <i>DdcGAL4</i> rescued condition which were not fed ecdysone, pupated at a slower rate than those observed in (J). This is very likely due to differences in culture conditions in the two cases. Results are expressed as mean±SEM.</p