@article {17522, title = {CRISPR-Cas-Induced Mutants Identify a Requirement for dSTIM in Larval Dopaminergic Cells of Drosophila melanogaster.}, journal = {G3 (Bethesda)}, volume = {7}, year = {2017}, month = {2017 Mar 10}, pages = {923-933}, abstract = {

Molecular components of store-operated calcium entry have been identified in the recent past and consist of the endoplasmic reticulum (ER) membrane-resident calcium sensor STIM and the plasma membrane-localized calcium channel Orai. The physiological function of STIM and Orai is best defined in vertebrate immune cells. However, genetic studies with RNAi strains in Drosophila suggest a role in neuronal development and function. We generated a CRISPR-Cas-mediated deletion for the gene encoding STIM in Drosophila (dSTIM), which we demonstrate is larval lethal. To study STIM function in neurons, we merged the CRISPR-Cas9 method with the UAS-GAL4 system to generate either tissue- or cell type-specific inducible STIM knockouts (KOs). Our data identify an essential role for STIM in larval dopaminergic cells. The molecular basis for this cell-specific requirement needs further investigation.

}, issn = {2160-1836}, doi = {10.1534/g3.116.038539}, author = {Pathak, Trayambak and Trivedi, Deepti and Hasan, Gaiti} } @article {3906, title = {Store-independent modulation of Ca(2+) entry through Orai by Septin 7.}, journal = {Nat Commun}, volume = {7}, year = {2016}, month = {2016}, abstract = {

Orai channels are required for store-operated Ca(2+) entry (SOCE) in multiple cell types. Septins are a class of GTP-binding proteins that function as diffusion barriers in cells. Here we show that Septin 7 acts as a {\textquoteright}molecular brake{\textquoteright} on activation of Orai channels in Drosophila neurons. Lowering Septin 7 levels results in dOrai-mediated Ca(2+) entry and higher cytosolic Ca(2+) in resting neurons. This Ca(2+) entry is independent of depletion of endoplasmic reticulum Ca(2+) stores and Ca(2+) release through the inositol-1,4,5-trisphosphate receptor. Importantly, store-independent Ca(2+) entry through Orai compensates for reduced SOCE in the Drosophila flight circuit. Moreover, overexpression of Septin 7 reduces both SOCE and flight duration, supporting its role as a negative regulator of Orai channel function in vivo. Septin 7 levels in neurons can, therefore, alter neural circuit function by modulating Orai function and Ca(2+) homeostasis.

}, issn = {2041-1723}, doi = {10.1038/ncomms11751}, author = {Deb, BipanKumar and Pathak, Trayambak and Hasan, Gaiti} } @article {1033, title = {Store-Operated Calcium Entry through Orai Is Required for Transcriptional Maturation of the Flight Circuit in Drosophila.}, journal = {J Neurosci}, volume = {35}, year = {2015}, month = {2015 Oct 7}, pages = {13784-99}, abstract = {

UNLABELLED: Store operated calcium entry (SOCE) is thought to primarily regulate calcium homeostasis in neurons. Subsequent to identification of Orai as the SOCE channel in nonexcitable cells, investigation of Orai function in neurons demonstrated a requirement for SOCE in Drosophila flight. Here, by analysis of an Orai mutant and by controlled expression of a dominant-negative Drosophila Orai transgene, we show that Orai-mediated SOCE is required in dopaminergic interneurons of the flight circuit during pupal development. Expression of dominant-negative Orai in dopaminergic neurons of pupae abolished flight. The loss of Orai-mediated SOCE alters transcriptional regulation of dopaminergic neurons, leading to downregulation of the enzyme tyrosine hydroxylase, which is essential for dopamine synthesis, and the dopamine transporter, which is required for dopamine uptake after synaptic release. These studies suggest that modulation of SOCE could serve as a novel mechanism for restoring dopamine levels in dopaminergic neurons.

SIGNIFICANCE STATEMENT: The specificity of an animal{\textquoteright}s response to an environmental stimulus is determined in part by the release of neurotransmitters, which are sensed by responding neurons through cognate receptors on their surface. One way by which neurons respond is through release of calcium from intracellular stores followed by store refilling from extracellular calcium sources. This mechanism is called store-operated calcium entry (SOCE). The function of SOCE in neurons has been debated. Here we describe a new function for SOCE in the regulation of neurotransmitter levels in Drosophila flight neurons. This cell-signaling mechanism is required to maintain optimal levels of a key enzyme for dopamine synthesis and may serve as a mechanism for restoring dopamine levels in relevant pathological conditions.

}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1680-15.2015}, author = {Pathak, Trayambak and Agrawal, Tarjani and Richhariya, Shlesha and Sadaf, Sufia and Hasan, Gaiti} }