Out of millions of ejaculated sperm, a few reach the fertilization site in mammals. Flagellar Ca2+ signaling nanodomains, organized by multi-subunit CatSper calcium channel complexes, are pivotal for sperm migration in the female tract, implicating CatSper-dependent mechanisms in sperm selection. Here using biochemical and pharmacological studies, we demonstrate that CatSper1 is an O-linked glycosylated protein, undergoing capacitation-induced processing dependent on Ca2+ and phosphorylation cascades. CatSper1 processing correlates with protein tyrosine phosphorylation (pY) development in sperm cells capacitated in vitro and in vivo. Using 3D in situ molecular imaging and ANN-based automatic detection of sperm distributed along the cleared female tract, we demonstrate that spermatozoa past the utero-tubal junction possess the intact CatSper1 signals. Together, we reveal that fertilizing mouse spermatozoa in situ are characterized by intact CatSper channel, lack of pY, and reacted acrosomes. These findings provide molecular insight into sperm selection for successful fertilization in the female reproductive tract.
- MeSH
- akrozomální reakce MeSH
- glykosylace MeSH
- molekulární zobrazování metody MeSH
- myši MeSH
- regulace genové exprese MeSH
- spermie fyziologie MeSH
- vápníková signalizace MeSH
- vápníkové kanály genetika metabolismus MeSH
- ženské pohlavní orgány diagnostické zobrazování MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
T-type channels are low-voltage-activated calcium channels that contribute to a variety of cellular and physiological functions, including neuronal excitability, hormone and neurotransmitter release as well as developmental aspects. Several human conditions including epilepsy, autism spectrum disorders, schizophrenia, motor neuron disorders and aldosteronism have been traced to variations in genes encoding T-type channels. In this short review, we present the genetics of T-type channels with an emphasis on structure-function relationships and associated channelopathies.
- MeSH
- autonomní denervace metody MeSH
- beta blokátory farmakologie terapeutické užití MeSH
- defibrilátory implantabilní MeSH
- dospělí MeSH
- draslíkový kanál KCNQ1 genetika MeSH
- elektrokardiografie MeSH
- kardiostimulace umělá metody MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- náhlá srdeční smrt etiologie patologie MeSH
- sporty MeSH
- syndrom dlouhého QT * farmakoterapie genetika mortalita patofyziologie MeSH
- vápníkové kanály genetika MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- Publikační typ
- přehledy MeSH
Ca2+ release-activated Ca2+ (CRAC) channels constitute the major Ca2+ entry pathway into the cell. They are fully reconstituted via intermembrane coupling of the Ca2+-selective Orai channel and the Ca2+-sensing protein STIM1. In addition to the Orai C terminus, the main coupling site for STIM1, the Orai N terminus is indispensable for Orai channel gating. Although the extended transmembrane Orai N-terminal region (Orai1 amino acids 73-91; Orai3 amino acids 48-65) is fully conserved in the Orai1 and Orai3 isoforms, Orai3 tolerates larger N-terminal truncations than Orai1 in retaining store-operated activation. In an attempt to uncover the reason for these isoform-specific structural requirements, we analyzed a series of Orai mutants and chimeras. We discovered that it was not the N termini, but the loop2 regions connecting TM2 and TM3 of Orai1 and Orai3 that featured distinct properties, which explained the different, isoform-specific behavior of Orai N-truncation mutants. Atomic force microscopy studies and MD simulations suggested that the remaining N-terminal portion in the non-functional Orai1 N-truncation mutants formed new, inhibitory interactions with the Orai1-loop2 regions, but not with Orai3-loop2. Such a loop2 swap restored activation of the N-truncation Orai1 mutants. To mimic interactions between the N terminus and loop2 in full-length Orai1 channels, we induced close proximity of the N terminus and loop2 via cysteine cross-linking, which actually caused significant inhibition of STIM1-mediated Orai currents. In aggregate, maintenance of Orai activation required not only the conserved N-terminal region but also permissive communication of the Orai N terminus and loop2 in an isoform-specific manner.
- MeSH
- HEK293 buňky MeSH
- lidé MeSH
- nádorové proteiny chemie genetika metabolismus MeSH
- protein ORAI1 chemie genetika metabolismus MeSH
- protein STIM1 chemie genetika metabolismus MeSH
- proteinové domény MeSH
- sekundární struktura proteinů MeSH
- vápníkové kanály chemie genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
INTRODUCTION: Episodic ataxias (EAs) are rare dominantly inherited neurological disorders characterized by recurrent episodes of ataxia lasting minutes to hours. The most common subtype is EA type 2 (EA2) caused by pathogenic variants of calcium voltage-gated channel subunit alpha1 A gene (CACNA1A) on chromosome 19p13. SUBJECTS AND METHODS: We examined a Slovak three-generation family. Genomic DNA of the family members was extracted from peripheral blood and amplified by polymerase chain reaction. CACNA1A variants were screened by Sanger sequencing. RESULTS: We identified four family members with recurrent episodes of ataxia. Complex differential diagnosis was performed. Genetic analysis with direct sequencing revealed a novel heterozygous variant of CACNA1A - c.5264A>G (p.Glu1755Gly) located in the pore loop of domain IV of calcium channel alpha-1A subunit. CONCLUSION: We identified a novel missense variant of a voltage-dependent P/Q-type calcium channel alpha-1A subunit in a Slovak three-generation family with recurrent episodes of ataxia. The heterozygous missense variant resulted in changing a highly conserved glutamic acid within the pore loop of domain IV.
- MeSH
- ataxie genetika MeSH
- heterozygot MeSH
- lidé středního věku MeSH
- lidé MeSH
- missense mutace genetika MeSH
- mladý dospělý MeSH
- recidiva MeSH
- rodokmen MeSH
- vápníkové kanály genetika MeSH
- věk při počátku nemoci MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- Geografické názvy
- Slovenská republika MeSH
- MeSH
- cévní mozková příhoda MeSH
- dítě MeSH
- fosfotransferasy * chemie nedostatek MeSH
- kanálopatie genetika MeSH
- lidé MeSH
- nemoci mozečku diagnostické zobrazování MeSH
- prognóza MeSH
- vápníkové kanály genetika MeSH
- vrozené poruchy glykosylace diagnostické zobrazování genetika patofyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The ankyrin transient receptor potential channel TRPA1 is a polymodal sensor for noxious stimuli, and hence a promising target for treating chronic pain. This tetrameric six-transmembrane segment (S1-S6) channel can be activated by various pungent chemicals, such as allyl isothiocyanate or cinnamaldehyde, but also by intracellular Ca(2+) or depolarizing voltages. Within the S4-S5 linker of human TRPA1, a gain-of-function mutation, N855S, was recently found to underlie familial episodic pain syndrome, manifested by bouts of severe upper body pain, triggered by physical stress, fasting, or cold. To clarify the structural basis for this channelopathy, we derive a structural model of TRPA1 by combining homology modeling, molecular dynamics simulations, point mutagenesis and electrophysiology. In the vicinity of N855, the model reveals inter-subunit salt bridges between E854 and K868. Using the heterologous expression of recombinant wild-type and mutant TRPA1 channels in HEK293T cells, we indeed found that the charge-reversal mutants E854R and K868E exhibited dramatically reduced responses to chemical and voltage stimuli, whereas the charge-swapping mutation E854R/K868E substantially rescued their functionalities. Moreover, mutation analysis of highly conserved charged residues within the S4-S5 region revealed a gain-of-function phenotype for R852E with an increased basal channel activity, a loss of Ca(2+)-induced potentiation and an accelerated Ca(2+)-dependent inactivation. Based on the model and on a comparison with the recently revealed atomic-level structure of the related channel TRPV1, we propose that inter-subunit salt bridges between adjacent S4-S5 regions are crucial for stabilizing the conformations associated with chemically and voltage-induced gating of the TRPA1 ion channel.
- MeSH
- asparagin genetika MeSH
- elektrická stimulace MeSH
- gating iontového kanálu účinky léků fyziologie MeSH
- HEK293 buňky MeSH
- isothiokyanatany farmakologie MeSH
- kationtové kanály TRP chemie genetika metabolismus MeSH
- lidé MeSH
- membránové potenciály genetika MeSH
- metoda terčíkového zámku MeSH
- molekulární modely * MeSH
- mutace genetika MeSH
- mutageneze MeSH
- proteiny nervové tkáně chemie genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- serin genetika MeSH
- terciární struktura proteinů MeSH
- transfekce MeSH
- vápník metabolismus MeSH
- vápníkové kanály chemie genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Gain-of-function (GOF) mutations in ion channels are rare events, which lead to increased agonist sensitivity or altered gating properties, and may render the channel constitutively active. Uncovering and following characterization of such mutants contribute substantially to the understanding of the molecular basis of ion channel functioning. Here we give an overview of some GOF mutants in polymodal ion channels specifically involved in transduction of painful stimuli--TRPV1 and TRPA1, which are scrutinized by scientists due to their important role in development of some pathological pain states. Remarkably, a substitution of single amino acid in the S4-S5 region of TRPA1 (N855S) has been recently associated with familial episodic pain syndrome. This mutation increases chemical sensitivity of TRPA1, but leaves the voltage sensitivity unchanged. On the other hand, mutations in the analogous region of TRPV1 (R557K and G563S) severely affect all aspects of channel activation and lead to spontaneous activity. Comparison of the effects induced by mutations in homologous positions in different TRP receptors (or more generally in other distantly related ion channels) may elucidate the gating mechanisms conserved during evolution.
- MeSH
- bolest patofyziologie MeSH
- kationtové kanály TRP chemie genetika metabolismus MeSH
- kationtové kanály TRPV chemie genetika metabolismus MeSH
- lidé MeSH
- mícha patofyziologie MeSH
- mutace genetika MeSH
- percepce bolesti MeSH
- proteiny nervové tkáně chemie genetika metabolismus MeSH
- vápníkové kanály chemie genetika metabolismus MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Previously we have shown that inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) are abundantly expressed in the atria of rat hearts. Since arrangement of atria is very heterogeneous, in this work we focused on the precise localization of IP3 receptors in the left atrium, where the gene expression of the type 1 IP3R was the highest. The mRNA levels of the IP3 type 1 receptors in the left atrium, left ventricle and myocytes were determined using real-time polymerase chain reaction and Taqman probe. For precise localization, immunohistochemistry with the antibody against type 1 IP3Rs was performed. The mRNA of type 1 IP3 receptor was more than three times higher in the left atrium than in the left ventricle, as determined by real-time PCR. Expression of the type 1 IP3 receptor mRNA was higher in the atria, especially in parts containing cardiac ganglion cells. The atrial auricles, which are particularly free of ganglion cells, and the ventricles (wall of the right and left ventricle and ventricular septum) contained four to five times less IP3 receptors than atrial samples with ganglia. IP3R type 1 immunoreactivity detected by a confocal microscope attributed the most condensed signal on ganglionic cells, although light immunoreactivity was also seen in cardiomyocytes. These results show that type 1IP3 receptors predominate in intrinsic neuronal ganglia of cardiac atria.
- MeSH
- exprese genu MeSH
- financování organizované MeSH
- ganglia parasympatická cytologie chemie metabolismus MeSH
- imunohistochemie MeSH
- inositol-1,4,5-trisfosfát - receptory MeSH
- krysa rodu rattus MeSH
- messenger RNA analýza metabolismus MeSH
- potkani Wistar MeSH
- receptory cytoplazmatické a nukleární analýza genetika MeSH
- srdce inervace MeSH
- srdeční síně inervace MeSH
- vápníkové kanály analýza genetika MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- MeSH
- finanční podpora výzkumu jako téma MeSH
- membránové glykoproteiny genetika MeSH
- mozek metabolismus účinky léků MeSH
- receptory cytoplazmatické a nukleární genetika MeSH
- regulace genové exprese genetika MeSH
- tretinoin farmakologie metabolismus MeSH
- vápníkové kanály genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
