scholarly journals Alternative splicing of auxiliary β2-subunits stabilizes Cav2.3 Ca2+ channel activity in continuously active midbrain dopamine neurons

2021 ◽  
Author(s):  
Anita Siller ◽  
Nadja T. Hofer ◽  
Giulia Tomagra ◽  
Nicole Wiederspohn ◽  
Simon Hess ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Splice Variants ◽  
Brain Slices ◽  
Physiological Role ◽  
Neuronal Firing ◽  
Dopamine Neurons ◽  
Channel Activity ◽  
Channel Inactivation ◽  
Midbrain Dopamine

AbstractIn dopaminergic (DA) substantia nigra (SN) neurons Cav2.3 R-type Ca2+-currents contribute to somatodendritic Ca2+-oscillations. These may contribute to the selective degeneration of these neurons in Parkinson’s disease (PD) since Cav2.3-knockout is neuroprotective in a PD mouse model. However, the typical Cav2.3 gating would predict complete channel inactivation during SN DA neuronal firing. Here we show that in tsA-201-cells the membrane-anchored β2-splice variants β2a and β2e stabilize Cav2.3 gating properties allowing sustained Cav2.3 availability during simulated pacemaking and enhanced Ca2+-currents during bursts. We confirmed the expression of β2a and β2e-subunits in the SN and identified SN DA neurons. Patch-clamp recordings of SN DA neurons in mouse brain slices revealed R-type Ca2+-currents similar to β2a- or β2e-stabilized Cav2.3-currents and recordings in cultured murine DA neurons confirmed their activity during pacemaking. Taken together, our data support an important (patho)physiological role of β-subunit alternative splicing for Cav2.3 Ca2+-signaling in highly vulnerable SN DA neurons.

scholarly journals Modified Sawhorse Waveform for the Voltammetric Detection of Oxytocin

2022 ◽  
Author(s):  
Favian Liu ◽  
Negar Ghasem Ardabili ◽  
Izaiah Brown ◽  
Harmain Rafi ◽  
Clarice Cook ◽  
...  
Keyword(s):  
Brain Slices ◽  
Physiological Role ◽  
Peptide Hormone ◽  
Protective Effects ◽  
Fast Scan Cyclic Voltammetry ◽  
The Past ◽  
Voltammetric Detection ◽  
Carbon Fiber Microelectrodes

Abstract Carbon fiber microelectrodes (CFMEs) have been used to detect neurotransmitters and other biomolecules using fast-scan cyclic voltammetry (FSCV) for the past few decades. This technique measures neurotransmitters such as dopamine and, more recently, physiologically relevant neuropeptides. Oxytocin, a pleiotropic peptide hormone, is physiologically important for adaptation, development, reproduction, and social behavior. This neuropeptide functions as a stress-coping molecule, an anti-inflammatory agent, and serves as an antioxidant with protective effects especially during adversity or trauma. Here, we measure tyrosine using the Modified Sawhorse Waveform (MSW), enabling enhanced electrode sensitivity for the amino acid and oxytocin peptide. Applying the MSW, decreased surface fouling and enabled codetection with other monoamines. As oxytocin contains tyrosine, the MSW was also used to detect oxytocin. The sensitivity of oxytocin detection was found to be 3.99 ± 0.49 nA/µM, (n=5). Additionally, we demonstrate that applying the MSW on CFMEs allows for real time measurements of exogenously applied oxytocin on rat brain slices. These studies may serve as novel assays for oxytocin detection in a fast, sub-second timescale with possible implications for in vivo measurements and further understanding of the physiological role of oxytocin.

Intracellular ADP-ribose inhibits ATP-sensitive K+ channels in rat ventricular myocytes

1996 ◽  
Vol 271 (2) ◽  
pp. C464-C468 ◽  
Author(s):  
Y. G. Kwak ◽  
S. K. Park ◽  
U. H. Kim ◽  
M. K. Han ◽  
J. S. Eun ◽  
...  
Keyword(s):  
Single Channel ◽  
Ventricular Myocytes ◽  
Physiological Role ◽  
Hill Coefficient ◽  
K Channel ◽  
Channel Activity ◽  
Rat Ventricular Myocytes ◽  
Cyclic Adp Ribose ◽  
The Hill

Cyclic ADP-ribose (cADPR), an NAD metabolite, has been shown to be a messenger for Ca2+ mobilization from intracellular Ca2+ stores. However, the physiological role of ADP-ribose (ADPR), another metabolite of NAD, is not known. We examined the effects of cADPR and ADPR on the ATP-sensitive K+ channel (KATP) activity in rat ventricular myocytes by use of the inside-out patch-clamp configuration. ADPR, but not cADPR, inhibited the channel activity at micromolar range with an inhibitor constant (Ki) of 38.4 microM. The Hill coefficient was 0.9. ATP inhibited the K+ channel with a Ki of 77.8 microM, and the Hill coefficient was 1.8. Single-channel conductance was not affected by ADPR. These findings strongly suggest that ADPR may act as a regulator of KATP channel activity.

The Role of Vitamin D3 in the Development and Neuroprotection of Midbrain Dopamine Neurons

2016 ◽  
pp. 273-297 ◽  
Author(s):  
Rowan P. Orme ◽  
Charlotte Middleditch ◽  
Lauren Waite ◽  
Rosemary A. Fricker
Keyword(s):  
Vitamin D3 ◽  
Dopamine Neurons ◽  
Midbrain Dopamine ◽  
Midbrain Dopamine Neurons

scholarly journals A role of midbrain dopamine neurons in negative punishment

IBRO Reports ◽  
2019 ◽  
Vol 6 ◽  
pp. S193
Author(s):  
Constance Peng ◽  
Philip Jean-Richard Dit Bressel ◽  
Gavan Mcnally
Keyword(s):  
Dopamine Neurons ◽  
Midbrain Dopamine ◽  
Midbrain Dopamine Neurons

scholarly journals Instantiation of incentive value and movement invigoration by distinct midbrain dopamine circuits

2017 ◽  
Author(s):  
Benjamin T. Saunders ◽  
Jocelyn M. Richard ◽  
Elyssa B. Margolis ◽  
Patricia H. Janak
Keyword(s):  
Dopamine Neuron ◽  
Dopamine Neurons ◽  
Neuron Activity ◽  
Temporal Association ◽  
Conditioned Stimuli ◽  
Incentive Value ◽  
Pavlovian Learning ◽  
Midbrain Dopamine ◽  
Dopamine Circuits

Environmental cues, through Pavlovian learning, become conditioned stimuli that guide animals towards the acquisition of “rewards” (i.e., food) that are necessary for survival. Here, we test the fundamental role of midbrain dopamine neurons in conferring predictive or motivational properties to cues, independent of external rewards. We demonstrate that phasic optogenetic excitation of dopamine neurons throughout the midbrain, when presented in temporal association with discrete sensory cues, is sufficient to instantiate those cues as conditioned stimuli that subsequently both evoke dopamine neuron activity on their own, and elicit cue-locked conditioned behaviors. Critically, we identify highly parcellated behavioral functions for dopamine neuron subpopulations projecting to discrete regions of striatum, revealing dissociable mesostriatal systems for the generation of incentive value and movement invigoration. These results show that dopamine neurons orchestrate Pavlovian conditioning via functionally heterogeneous, circuit-specific motivational signals to shape cue-controlled behavior.

scholarly journals Dopamine neuron-derived IGF-1 controls dopamine neuron firing, skill learning, and exploration

2019 ◽  
Vol 116 (9) ◽  
pp. 3817-3826 ◽  
Author(s):  
Alessandro Pristerà ◽  
Craig Blomeley ◽  
Emanuel Lopes ◽  
Sarah Threlfell ◽  
Elisa Merlini ◽  
...  
Keyword(s):  
Cognitive Processes ◽  
Skill Learning ◽  
Dopamine Neuron ◽  
Dopamine Neurons ◽  
Neuron Firing ◽  
Adult Mice ◽  
Conditional Deletion ◽  
Dopamine Content ◽  
Midbrain Dopamine

Midbrain dopamine neurons, which can be regulated by neuropeptides and hormones, play a fundamental role in controlling cognitive processes, reward mechanisms, and motor functions. The hormonal actions of insulin-like growth factor 1 (IGF-1) produced by the liver have been well described, but the role of neuronally derived IGF-1 remains largely unexplored. We discovered that dopamine neurons secrete IGF-1 from the cell bodies following depolarization, and that IGF-1 controls release of dopamine in the ventral midbrain. In addition, conditional deletion of dopamine neuron-derived IGF-1 in adult mice leads to decrease of dopamine content in the striatum and deficits in dopamine neuron firing and causes reduced spontaneous locomotion and impairments in explorative and learning behaviors. These data identify that dopamine neuron-derived IGF-1 acts as a regulator of dopamine neurons and regulates dopamine-mediated behaviors.

Alternative splicing of Krüppel-like factor 6 (KLF6) enriched in human androgen-deprived prostate cancer (PC).

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e15191-e15191
Author(s):  
XiaoMei Liu ◽  
Alejandro Gomez-Pinillos ◽  
Charisse Loder ◽  
Enrique Carrillo-de Santa Pau ◽  
Rui Fang Quiao ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Transcriptional Activity ◽  
Splice Variants ◽  
Tissue Banks ◽  
Lncap Cells ◽  
Transactivation Activity ◽  
Castrate Resistant ◽  
Mtt Assays ◽  
Proliferative Advantage

e15191 Background: Inactivation of KLF6 by mutations and alternative splicing has been implicated in PC. However, there are significant discrepancies among human PC studies concerning the prevalence and significance of KLF6 mutations, and the prevalence of splice variants (SVs) has not been established. The objective of this study was to assess the prevalence and role of KLF6 splicing in human PC progression. Methods: Human specimens were obtained from the tissue banks of three institutions. Representative epithelium of 74 frozen PC specimens [25 primary hormone-naïve (HN) PCs, 21 primary hormone-deprived (HD) PCs, 6 castrate-resistant metastases] and 22 normal prostates (NPs) were microdissected. KLF6 cDNA was amplified by PCR, cloned and sequenced in both forward and reverse directions and compared to the KLF6 GenBank sequence. The transcriptional activity of KLF6 SVs was evaluated in co-transfection assays with a p21-reporter, and their effect on LNCaP cell growth was determined by MTT assays. Results: Sixteen different SVs were identified: 13 were novel; 14 affected the DNA binding domain (DBD) and were transcriptionally inactive. The incidence of SVs was increased in PC versus NP (75% vs 45%; p=0.01) and in HD-PC versus HN-PC (90% vs 64%; p=0.04) HD-PC were significantly enriched in SVs lacking the DBD. Forced expression of dysfunctional KLF6 SVs increased growth of LNCaP cells in androgen-depleted media. Conclusions: KLF6 SVs lacking p21-reporter transactivation activity occur in NP epithelium but are markedly increased in incidence, variety and level of expression in PC tissues that survive androgen-deprivation. This enrichment may enable resistance to hormone therapy and a proliferative advantage under castrate conditions.

Evidence for a modulatory role of Ih on the firing of a subgroup of midbrain dopamine neurons

Neuroreport ◽  
2001 ◽  
Vol 12 (2) ◽  
pp. 255-258 ◽  
Author(s):  
Vincent Seutin ◽  
Laurent Massotte ◽  
Michel-François Renette ◽  
Albert Dresse
Keyword(s):  
Dopamine Neurons ◽  
Midbrain Dopamine ◽  
Midbrain Dopamine Neurons

Effect of mutation of a calmodulin binding site on Ca2+ regulation of inositol trisphosphate receptors

2001 ◽  
Vol 360 (2) ◽  
pp. 395-400 ◽  
Author(s):  
Xianchao ZHANG ◽  
Suresh K. JOSEPH
Keyword(s):  
Splice Variants ◽  
Binding Motif ◽  
Type I ◽  
Channel Activity ◽  
Wild Type ◽  
Binding Assays ◽  
Ip3 Receptor ◽  
Calmodulin Binding ◽  
Mutant Receptors

Several studies have shown that calmodulin (CaM) modulates d-myo-inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) channel activity and ligand binding to IP3Rs. It has been proposed that CaM may act as the Ca2+ sensor for mediating Ca2+ inhibition of IP3R channel activity. However, the functional role of CaM binding sites and the mechanism by which CaM regulates IP3R activities remains unclear. Tryptophan at position 1577 of type I IP3R has been shown to be part of a motif that is responsible for CaM binding to IP3Rs and we have mutated this residue to alanine in the long (neuronal) and short (peripheral) SII splice variants of the type I IP3R. CaM–Sepharose binding assays using COS-7 cell lysates confirmed that the W1577A mutant in both splice variants completely eliminated CaM binding. Functional measurements of IP3-mediated 45Ca2+ fluxes indicated that there was no change in the IP3 sensitivity of the channel induced by the W1577A mutation. Such measurements also indicated that the W1577A mutants of both splice variants have a dependence on external [Ca2+] that was indistinguishable from the corresponding wild-types. Although subtle differences in the Ca2+ and CaM sensitivity of [3H]IP3 binding were noted between wild-type and mutant receptors, our data suggest that the CaM binding motif involving the W1577A locus does not play a role in Ca2+ regulation of IP3R channel activity.

Role of RYR3 splice variants in calcium signaling in mouse nonpregnant and pregnant myometrium

2007 ◽  
Vol 293 (3) ◽  
pp. C848-C854 ◽  
Author(s):  
Fabrice Dabertrand ◽  
Nicolas Fritz ◽  
Jean Mironneau ◽  
Nathalie Macrez ◽  
Jean-Luc Morel
Keyword(s):  
Alternative Splicing ◽  
Antisense Oligonucleotides ◽  
Splice Variants ◽  
Pregnant Mouse ◽  
Receptor Subtype ◽  
Hek 293 ◽  
Physiological Regulation ◽  
293 Cells ◽  
Subtype 3

Alternative splicing of ryanodine receptor subtype 3 (RYR3) may generate a short isoform (RYR3S) without channel function and a functional full-length isoform (RYR3L). The RYR3S isoform has been shown to negatively regulate the native RYR2 subtype in smooth muscle cells as well as the RYR3L isoform when both isoforms were coexpressed in HEK-293 cells. Mouse myometrium expresses only the RYR3 subtype, but the role of RYR3 isoforms obtained by alternative splicing and their activation by cADP-ribose during pregnancy have never been investigated. Here, we show that both RYR3S and RYR3L isoforms are differentially expressed in nonpregnant and pregnant mouse myometrium. The use of antisense oligonucleotides directed against each isoform indicated that only RYR3L was activated by caffeine and cADP-ribose in nonpregnant myometrium. These RYR3L-mediated Ca2+ releases were negatively regulated by RYR3S expression. At the end of pregnancy, the relative expression of RYR3L versus RYR3S and its ability to respond to cADP-ribose were increased. Therefore, our results suggest that physiological regulation of RYR3 alternative splicing may play an essential role at the end of pregnancy.

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