Septin regulation of Orai-mediated Ca entry - a novel target for neurodegeneration.

Aberrant Ca signaling is an early hallmark of multiple neurodegenerative syndromes including Alzheimer's and Parkinson's disease (AD and PD) as well as classes of rare genetic disorders such as Spinocebellar Ataxias. Therapeutic strategies that target aberrant Ca signals whilst allowing normal neuronal Ca signals have been a challenge. In a recent study Princen et al.

IPRs and nSOCE-Tied Together at Two Ends.

All living organisms need to respond appropriately to changes in the extracellular milieu. Cellular mechanisms that enable such responses evolved in parallel with organismal complexity and intracellular Ca signaling is one such mechanism where extracellular signals received at the cell membrane communicate with endoplasmic reticular stores of Ca, to stimulate appropriate Ca-mediated changes in cellular physiology. The amplitude and dynamics of endoplasmic reticulum (ER)-Ca release in response to extracellular signals determines the nature of the cellular response.

Orai-mediated calcium entry determines activity of central dopaminergic neurons by regulation of gene expression.

Maturation and fine-tuning of neural circuits frequently require neuromodulatory signals that set the excitability threshold, neuronal connectivity, and synaptic strength. Here, we present a mechanistic study of how neuromodulator-stimulated intracellular Ca signals, through the store-operated Ca channel Orai, regulate intrinsic neuronal properties by control of developmental gene expression in flight-promoting central dopaminergic neurons (fpDANs). The fpDANs receive cholinergic inputs for release of dopamine at a central brain tripartite synapse that sustains flight (Sharma and Hasan, 2020).

Regulation of store-operated Ca entry by IP receptors independent of their ability to release Ca.

Loss of endoplasmic reticular (ER) Ca activates store-operated Ca entry (SOCE) by causing the ER localized Ca sensor STIM to unfurl domains that activate Orai channels in the plasma membrane at membrane contact sites (MCS). Here, we demonstrate a novel mechanism by which the inositol 1,4,5 trisphosphate receptor (IPR), an ER-localized IP-gated Ca channel, regulates neuronal SOCE. In human neurons, SOCE evoked by pharmacological depletion of ER-Ca is attenuated by loss of IPRs, and restored by expression of IPRs even when they cannot release Ca, but only if the IPRs can bind IP.

A STIM dependent dopamine-neuropeptide axis maintains the larval drive to feed and grow in Drosophila.

Appropriate nutritional intake is essential for organismal survival. In holometabolous insects such as Drosophila melanogaster, the quality and quantity of food ingested as larvae determines adult size and fecundity. Here we have identified a subset of dopaminergic neurons (THD') that maintain the larval motivation to feed.

Generation of feeder-independent transgene-free iPSC lines from a young-onset Parkinson's disease (YOPD) patient with a homozygous PLA2G6: c.2222G>A (p. Arg741Gln) mutation (NCBSi003-A) and unaffected heterozygous parent (NCBSi004-A).

Phospholipase A2 group 6 (PLA2G6, iPLA2β or PARK14) gene encodes a calcium-independent group 6 phospholipase A2 enzyme and is associated with young-onset autosomal recessive Parkinson's disease (PD). We generated human induced pluripotent stem cell (iPSC) lines from a patient with young-onset PD carrying a homozygous PLA2G6: c.2222G>A (p.

ER-Ca stores and the regulation of store-operated Ca entry in neurons.

Key components of endoplasmic reticulum (ER) Ca release and store-operated Ca entry (SOCE) are likely expressed in all metazoan cells. Due to the complexity of canonical Ca entry mechanisms in neurons, the functional significance of ER-Ca release and SOCE has been difficult to identify and establish. In this review we present evidence of how these two related mechanisms of Ca signalling impact multiple aspects of neuronal physiology and discuss their interaction with the better understood classes of ion channels that are gated by either voltage changes or extracellular ligands in neurons.

Store-operated Ca entry regulates neuronal gene expression and function.

Recent studies with mutants of STIM and Orai have identified store-operated Ca entry as an important regulator of neuronal function in Drosophila and mouse. Cellular Ca imaging and electrophysiological studies demonstrate changes in ion channel function in neurons with loss of store-operated Ca entry. Importantly, such changes are specific to neuronal subtypes.

Two photon imaging of calcium responses in murine Purkinje neurons.

Purkinje neurons (PNs) are an important component of the motor learning and coordination circuit and are affected in spino-cerebellar ataxias. Maintaining healthy PNs in cerebellar slices and recording their Ca transients can be challenging. Here, we describe a protocol for measuring Ca transients in PNs from adult mice, including problem-solving tips.

Deficits Associated With Loss of STIM1 in Purkinje Neurons Including Motor Coordination Can Be Rescued by Loss of Septin 7.

Septins are cytoskeletal proteins that can assemble to form heteromeric filamentous complexes and regulate a range of membrane-associated cellular functions. SEPT7, a member of the septin family, functions as a negative regulator of the plasma membrane-localized store-operated Ca entry (SOCE) channel, Orai in neurons, and in human neural progenitor cells. Knockdown of STIM, a Ca sensor in the endoplasmic reticulum (ER) and an integral component of SOCE, leads to flight deficits in that can be rescued by partial loss of SEPT7 in neurons.

IP3-mediated Ca2+ signals regulate larval to pupal transition under nutrient stress through the H3K36 methyltransferase Set2.

Persistent loss of dietary protein usually signals a shutdown of key metabolic pathways. In Drosophila larvae that have reached a 'critical weight' and can pupariate to form viable adults, such a metabolic shutdown would needlessly lead to death. Inositol 1,4,5-trisphosphate-mediated calcium (IP3/Ca2+) release in some interneurons (vGlutVGN6341) allows Drosophila larvae to pupariate on a protein-deficient diet by partially circumventing this shutdown through upregulation of neuropeptide signaling and the expression of ecdysone synthesis genes.

Purkinje Neurons with Loss of STIM1 Exhibit Age-Dependent Changes in Gene Expression and Synaptic Components.

The stromal interaction molecule 1 (STIM1) is an ER-Ca sensor and an essential component of ER-Ca store operated Ca entry. Loss of STIM1 affects metabotropic glutamate receptor 1 (mGluR1)-mediated synaptic transmission, neuronal Ca homeostasis, and intrinsic plasticity in Purkinje neurons (PNs). Long-term changes of intracellular Ca signaling in PNs led to neurodegenerative conditions, as evident in individuals with mutations of the ER-Ca channel, the inositol 1,4,5-triphosphate receptor.

Modulation of flight and feeding behaviours requires presynaptic IPRs in dopaminergic neurons.

Innate behaviours, although robust and hard wired, rely on modulation of neuronal circuits, for eliciting an appropriate response according to internal states and external cues. flight is one such innate behaviour that is modulated by intracellular calcium release through inositol 1,4,5-trisphosphate receptors (IPRs). Cellular mechanism(s) by which IPRs modulate neuronal function for specific behaviours remain speculative, in vertebrates and invertebrates.

SEPT7 regulates Ca entry through Orai channels in human neural progenitor cells and neurons.

Human neural progenitor cells (hNPCs) are self-renewing cells of neural lineage that can be differentiated into neurons of different subtypes. Here we show that SEPT7, a member of the family of filament-forming GTPases called septins, prevents constitutive Ca entry through the store-operated Ca entry channel, Orai in hNPCs and in differentiated neurons and is thus required for neuronal calcium homeostasis. Previous work in Drosophila neurons has shown that loss of one copy of the evolutionarily-conserved dSEPT7 gene leads to elevated Ca entry via Orai, in the absence of ER-Ca store depletion.

Surviving nutritional deprivation during development: neuronal intracellular calcium signaling is critical.

Developing cells and tissues in a growing animal need to sense food quality and integrate this information with on-going time-bound developmental programs. The integration of metabolism with development requires cellular and systemic coordination. Work in our laboratory has focused on Ca signaling arising from the release of Ca stored in the endoplasmic reticulum (ER), which triggers store-operated Ca entry.

Implications of the null mutation for synapsin phosphorylation, longevity, climbing proficiency and behavioural plasticity in adult .

The gene of encodes a highly abundant 47 kDa synaptic vesicle-associated protein. null mutants show defects in synaptic plasticity and larval olfactory associative learning but the molecular function of Sap47 at the synapse is unknown. We demonstrate that Sap47 modulates the phosphorylation of another highly abundant conserved presynaptic protein, synapsin.

ER-Ca2+ sensor STIM regulates neuropeptides required for development under nutrient restriction in Drosophila.

Neuroendocrine cells communicate via neuropeptides to regulate behaviour and physiology. This study examines how STIM (Stromal Interacting Molecule), an ER-Ca2+ sensor required for Store-operated Ca2+ entry, regulates neuropeptides required for Drosophila development under nutrient restriction (NR). We find two STIM-regulated peptides, Corazonin and short Neuropeptide F, to be required for NR larvae to complete development.

Measurement of Store-Operated Calcium Entry in Human Neural Cells: From Precursors to Differentiated Neurons.

Calcium imaging in an ex-vivo setup is used to understand the calcium status of isolated cells or tissue. In this chapter we explain the use of the ratiometric chemical indicator Fura-2 which can be loaded into isolated cells in the form of lipophilic acetomethyl (AM) esters. Fura-2 is a combination of calcium chelator and fluorophore, and can be used with dual wavelength excitation (340/380 nm) for quantitative calcium concentrations.

Extended Flight Bouts Require Disinhibition from GABAergic Mushroom Body Neurons.

Insect flight is a complex behavior that requires the integration of multiple sensory inputs with flight motor output. Although previous genetic studies identified central brain monoaminergic neurons that modulate Drosophila flight, neuro-modulatory circuits underlying sustained flight bouts remain unexplored. Certain classes of dopaminergic and octopaminergic neurons that project to the mushroom body, a higher integrating center in the insect brain, are known to modify neuronal output based on contextual cues and thereby organismal behavior.

IP receptors and Ca entry.

Inositol 1,4,5-trisphosphate receptors (IPR) are the most widely expressed intracellular Ca release channels. Their activation by IP and Ca allows Ca to pass rapidly from the ER lumen to the cytosol. The resulting increase in cytosolic [Ca] may directly regulate cytosolic effectors or fuel Ca uptake by other organelles, while the decrease in ER luminal [Ca] stimulates store-operated Ca entry (SOCE).

A Multicomponent Neuronal Response Encodes the Larval Decision to Pupariate upon Amino Acid Starvation.

Organisms need to coordinate growth with development, particularly in the context of nutrient availability. Thus, multiple ways have evolved to survive extrinsic nutrient deprivation during development. In , growth occurs during larval development.

Store-Operated Ca Entry in Drosophila Primary Neuronal Cultures.

Intracellular calcium signals in neurons frequently derive from the stimulation of G protein-coupled receptors (GPCR) by neurotransmitters, neuropeptides, and neurohormones. GPCR stimulation in neurons leads to generation of inositol 1,4,5-trisphosphate (IP), which in turn activates endoplasmic reticulum (ER)-localized IP receptors. The IP receptor (IPR) is a ligand-gated Ca channel, which releases Ca from ER stores.

FMRFa receptor stimulated Ca2+ signals alter the activity of flight modulating central dopaminergic neurons in Drosophila melanogaster.

Neuropeptide signaling influences animal behavior by modulating neuronal activity and thus altering circuit dynamics. Insect flight is a key innate behavior that very likely requires robust neuromodulation. Cellular and molecular components that help modulate flight behavior are therefore of interest and require investigation.

Publisher Correction: Store-independent modulation of Ca entry through Orai by Septin 7.

This corrects the article DOI: 10.1038/ncomms11751.