scholarly journals Functional Analyses of the Two Distinctive Types of Two-Pore Channels (TPCs) and the Slow Vacuolar Channel in Marchantia polymorpha

2021 ◽  
Author(s):  
Kenji Hashimoto ◽  
Mateusz Koselski ◽  
Shoko Tsuboyama ◽  
Halina Dziubinska ◽  
Kazimierz Trębacz ◽  
...  
Keyword(s):  
Vascular Plants ◽  
Double Mutant ◽  
Plant Evolution ◽  
Marchantia Polymorpha ◽  
Pore Channel ◽  
Channel Activity ◽  
Slow Vacuolar Channel ◽  
Sv Channel

Abstract The two-pore channel (TPC) family is widely conserved in eukaryotes. Many vascular plants, including Arabidopsis and rice, possess a single TPC gene which functions as a slow vacuolar (SV) channel—voltage-dependent cation-permeable channel located in the vacuolar membrane (tonoplast). On the other hand, a liverwort Marchantia polymorpha genome encodes three TPC homologs: MpTPC1 is similar to TPCs in vascular plants (type 1 TPC), while MpTPC2 and MpTPC3 are classified into a distinctive group (type 2 TPC). Phylogenetic analysis suggested that the type 2 TPC emerged before the land colonization in plant evolution and was lost in vascular plants and hornworts. All of the three MpTPCs were shown to be localized at the tonoplast. We generated knockout mutants of tpc1, tpc2, tpc3, and tpc2 tpc3 double mutant by CRISPR/Cas9 genome editing and performed patch-clamp analyses of isolated vacuoles. The SV channel activity was abolished in the Mptpc1 loss-of-function mutant (Mptpc1-1KO), while Mptpc2-1KO, Mptpc3-1KO, and Mptpc2-2/tpc3-2KO double mutant exhibited similar activity to the wild type, indicating that MpTPC1 (type 1) is solely responsible for the SV channel activity. Activators of mammalian TPC channels, PI(3,5)P2, and, NAADP, did not affect the ion channel activity of any MpTPCs. These results indicate that the type 1 TPCs, which are well conserved in all land plant species, encode the SV channel, while the type 2 TPCs likely encode other tonoplast cation channel(s) distinct from the SV channel and animal TPC channels.

scholarly journals Angiotensin II type 2 receptor regulates ROMK-like K+ channel activity in the renal cortical collecting duct during high dietary K+ adaptation

2014 ◽  
Vol 307 (7) ◽  
pp. F833-F843 ◽  
Author(s):  
Yuan Wei ◽  
Yi Liao ◽  
Beth Zavilowitz ◽  
Jin Ren ◽  
Wen Liu ◽  
...  
Keyword(s):  
Collecting Duct ◽  
No Synthase ◽  
K Channel ◽  
Ang Ii ◽  
Cortical Collecting Duct ◽  
Channel Activity ◽  
High K ◽  
Pka Pathway

The kidney adjusts K+ excretion to match intake in part by regulation of the activity of apical K+ secretory channels, including renal outer medullary K+ (ROMK)-like K+ channels, in the cortical collecting duct (CCD). ANG II inhibits ROMK channels via the ANG II type 1 receptor (AT1R) during dietary K+ restriction. Because AT1Rs and ANG II type 2 receptors (AT2Rs) generally function in an antagonistic manner, we sought to characterize the regulation of ROMK channels by the AT2R. Patch-clamp experiments revealed that ANG II increased ROMK channel activity in CCDs isolated from high-K+ (HK)-fed but not normal K+ (NK)-fed rats. This response was blocked by PD-123319, an AT2R antagonist, but not by losartan, an AT1R antagonist, and was mimicked by the AT2R agonist CGP-42112. Nitric oxide (NO) synthase is present in CCD cells that express ROMK channels. Blockade of NO synthase with N-nitro-l-arginine methyl ester and free NO with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt completely abolished ANG II-stimulated ROMK channel activity. NO enhances the synthesis of cGMP, which inhibits phosphodiesterases (PDEs) that normally degrade cAMP; cAMP increases ROMK channel activity. Pretreatment of CCDs with IBMX, a broad-spectrum PDE inhibitor, or cilostamide, a PDE3 inhibitor, abolished the stimulatory effect of ANG II on ROMK channels. Furthermore, PKA inhibitor peptide, but not an activator of the exchange protein directly activated by cAMP (Epac), also prevented the stimulatory effect of ANG II. We conclude that ANG II acts at the AT2R to stimulate ROMK channel activity in CCDs from HK-fed rats, a response opposite to that mediated by the AT1R in dietary K+-restricted animals, via a NO/cGMP pathway linked to a cAMP-PKA pathway.

Type 2 Diabetes Overtakes Type 1 in Hispanic Girls

2008 ◽  
Vol 38 (15) ◽  
pp. 18
Author(s):  
SHERRY BOSCHERT
Keyword(s):  
Type 2 Diabetes

Molecular analysis of FVIII gene in severe HA patients of Costa Rica

2010 ◽  
Vol 30 (S 01) ◽  
pp. S150-S152
Author(s):  
G. Jiménez-Cruz ◽  
M. Mendez ◽  
P. Chaverri ◽  
P. Alvarado ◽  
W. Schröder ◽  
...  
Keyword(s):  
Factor Viii ◽  
Coagulation Factor ◽  
Costa Rican ◽  
Factor Viii Gene ◽  
Intron 22 Inversion ◽  
Intron 1 ◽  
Polymerase Chain ◽  
Inversion Analysis

SummaryHaemophilia A (HA) is X-chromosome linked bleeding disorders caused by deficiency of the coagulation factor VIII (FVIII). It is caused by FVIII gene intron 22 inversion (Inv22) in approximately 45% and by intron 1 inversion (Inv1) in 5% of the patients. Both inversions occur as a result of intrachromosomal recombination between homologous regions, in intron 1 or 22 and their extragenic copy located telomeric to the FVIII gene. The aim of this study was to analyze the presence of these mutations in 25 HA Costa Rican families. Patients, methods: We studied 34 HA patients and 110 unrelated obligate members and possible carriers for the presence of Inv22or Inv1. Standard analyses of the factor VIII gene were used incl. Southern blot and long-range polymerase chain reaction for inversion analysis. Results: We found altered Inv22 restriction profiles in 21 patients and 37 carriers. It was found type 1 and type 2 of the inversion of Inv22. During the screening for Inv1 among the HA patient, who were Inv22 negative, we did not found this mutation. Discussion: Our data highlight the importance of the analysis of Inv22 for their association with development of inhibitors in the HA patients and we are continuous searching of Inv1 mutation. This knowledge represents a step for genetic counseling and prevention of the inhibitor development.

Polymorphisms of the Plasminogen Activator Inhibitor- 1 Gene in Type 1 and Type 2 Diabetes, and in Patients with Diabetic Retinopathy

1994 ◽  
Vol 71 (06) ◽  
pp. 731-736 ◽  
Author(s):  
M W Mansfield ◽  
M H Stickland ◽  
A M Carter ◽  
P J Grant
Keyword(s):  
Diabetic Retinopathy ◽  
Plasminogen Activator Inhibitor ◽  
Allelic Frequency ◽  
Repeat Sequence ◽  
Dinucleotide Repeat ◽  
Plasminogen Activator Inhibitor 1 ◽  
The Difference ◽  
Pai 1

SummaryTo identify whether genotype contributes to the difference in PAI-1 levels in type 1 and type 2 diabetic subjects and whether genotype relates to the development of retinopathy, a Hind III restriction fragment length polymorphism and two dinucleotide repeat polymorphisms were studied. In 519 Caucasian diabetic subjects (192 type 1, 327 type 2) and 123 Caucasian control subjects there were no differences in the frequency of the Hind III restriction alleles (type 1 vs type 2 vs control: allele 1 0.397 vs 0.420 vs 0.448; allele 2 0.603 vs 0.580 vs 0.552) nor in the allelic frequency at either dinucleotide repeat sequence. In 86 subjects with no retinopathy at 15 years or more from diagnosis of diabetes and 190 subjects with diabetic retinopathy there was no difference in the frequency of Hind III restriction alleles (retinopathy present vs retinopathy absent: allele 1 0.400 vs 0.467; allele 2 0.600 vs 0.533) nor in the allelic frequencies at either dinucleotide repeat sequence. The results indicate that there is no or minimal influence of the PAI-1 gene on either PAI-1 levels or the development of diabetic retinopathy in patients with diabetes mellitus.

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