Ankyrin-G mediates targeting of both Na+ and KATP channels to the rat cardiac intercalated disc
Abstract
We investigated targeting mechanisms of Na+ and KATP channels to the intercalated disk (ICD) of cardiomyocytes. Patch clamp and surface biotinylation data show reciprocal downregulation of each other's surface density. Mutagenesis of the Kir6.2 ankyrin binding site disrupts this functional coupling. Duplex patch clamping and Angle SICM recordings show that INa and IKATP functionally co-localize at the rat ICD, but not at the lateral membrane. Quantitative STORM imaging show that Na+ and KATP channels are localized close to each other and to AnkG, but not to AnkB, at the ICD. Peptides corresponding to Nav1.5 and Kir6.2 ankyrin binding sites dysregulate targeting of both Na+ and KATP channels to the ICD, but not to lateral membranes. Finally, a clinically relevant gene variant that disrupts KATP channel trafficking also regulates Na+ channel surface expression. The functional coupling between these two channels need to be considered when assessing clinical variants and therapeutics.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Funding
National Institutes of Health (HL126905)
- William A Coetzee
National Institutes of Health (HL145911)
- Mario Delmar
National Institutes of Health (HL126802)
- Julia Gorelik
Leducq Foundation
- Eli Rothenberg
- Mario Delmar
Rafael del Pino Foundation
- Marta Pérez-Hernández
Biotechnology and Biological Sciences Research Council (BB/M022080)
- Andriy Shevchuk
British Heart Foundation (RG/17/13/33173)
- Jose Sanchez-Alonso
- Julia Gorelik
American Heart Association (17POST33370050)
- Hua-Qian Yang
National Institutes of Health (HL146514)
- William A Coetzee
National Institutes of Health (HL134328)
- Mario Delmar
National Institutes of Health (HL136179)
- Mario Delmar
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Baron Chanda, University of Wisconsin-Madison, United States
Ethics
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of New York University School of Medicine (protocol s17-00352).
Version history
- Received: October 2, 2019
- Accepted: January 11, 2020
- Accepted Manuscript published: January 14, 2020 (version 1)
- Version of Record published: January 24, 2020 (version 2)
Copyright
© 2020, Yang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Further reading
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- Medicine
- Microbiology and Infectious Disease
Background:
End-stage renal disease (ESRD) patients experience immune compromise characterized by complex alterations of both innate and adaptive immunity, and results in higher susceptibility to infection and lower response to vaccination. This immune compromise, coupled with greater risk of exposure to infectious disease at hemodialysis (HD) centers, underscores the need for examination of the immune response to the COVID-19 mRNA-based vaccines.
Methods:
The immune response to the COVID-19 BNT162b2 mRNA vaccine was assessed in 20 HD patients and cohort-matched controls. RNA sequencing of peripheral blood mononuclear cells was performed longitudinally before and after each vaccination dose for a total of six time points per subject. Anti-spike antibody levels were quantified prior to the first vaccination dose (V1D0) and 7 d after the second dose (V2D7) using anti-spike IgG titers and antibody neutralization assays. Anti-spike IgG titers were additionally quantified 6 mo after initial vaccination. Clinical history and lab values in HD patients were obtained to identify predictors of vaccination response.
Results:
Transcriptomic analyses demonstrated differing time courses of immune responses, with prolonged myeloid cell activity in HD at 1 wk after the first vaccination dose. HD also demonstrated decreased metabolic activity and decreased antigen presentation compared to controls after the second vaccination dose. Anti-spike IgG titers and neutralizing function were substantially elevated in both controls and HD at V2D7, with a small but significant reduction in titers in HD groups (p<0.05). Anti-spike IgG remained elevated above baseline at 6 mo in both subject groups. Anti-spike IgG titers at V2D7 were highly predictive of 6-month titer levels. Transcriptomic biomarkers after the second vaccination dose and clinical biomarkers including ferritin levels were found to be predictive of antibody development.
Conclusions:
Overall, we demonstrate differing time courses of immune responses to the BTN162b2 mRNA COVID-19 vaccination in maintenance HD subjects comparable to healthy controls and identify transcriptomic and clinical predictors of anti-spike IgG titers in HD. Analyzing vaccination as an in vivo perturbation, our results warrant further characterization of the immune dysregulation of ESRD.
Funding:
F30HD102093, F30HL151182, T32HL144909, R01HL138628. This research has been funded by the University of Illinois at Chicago Center for Clinical and Translational Science (CCTS) award UL1TR002003.
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- Medicine
Background:
Among its extragonadal effects, follicle-stimulating hormone (FSH) has an impact on body composition and bone metabolism. Since androgen deprivation therapy (ADT) has a profound impact on circulating FSH concentrations, this hormone could potentially be implicated in the changes of fat body mass (FBM), lean body mass (LBM), and bone fragility induced by ADT. The objective of this study is to correlate FSH serum levels with body composition parameters, bone mineral density (BMD), and bone turnover markers at baseline conditions and after 12 months of ADT.
Methods:
Twenty-nine consecutive non-metastatic prostate cancer (PC) patients were enrolled from 2017 to 2019 in a phase IV study. All patients underwent administration of the luteinizing hormone-releasing hormone antagonist degarelix. FBM, LBM, and BMD were evaluated by dual-energy x-ray absorptiometry at baseline and after 12 months of ADT. FSH, alkaline phosphatase, and C-terminal telopeptide of type I collagen were assessed at baseline and after 6 and 12 months. For outcome measurements and statistical analysis, t-test or sign test and Pearson or Spearman tests for continuous variables were used when indicated.
Results:
At baseline conditions, a weak, non-significant, direct relationship was found between FSH serum levels and FBM at arms (r = 0.36) and legs (r = 0.33). Conversely, a stronger correlation was observed between FSH and total FBM (r = 0.52, p = 0.006), fat mass at arms (r = 0.54, p = 0.004), and fat mass at trunk (r = 0.45, p = 0.018) assessed after 12 months. On the other hand, an inverse relationship between serum FSH and appendicular lean mass index/FBM ratio was observed (r = −0.64, p = 0.001). This is an ancillary study of a prospective trial and this is the main limitation.
Conclusions:
FSH serum levels after ADT could have an impact on body composition, in particular on FBM. Therefore, FSH could be a promising marker to monitor the risk of sarcopenic obesity and to guide the clinicians in the tailored evaluation of body composition in PC patients undergoing ADT.
Funding:
This research was partially funded by Ferring Pharmaceuticals. The funder had no role in design and conduct of the study, collection, management, analysis, and interpretation of the data and in preparation, review, or approval of the manuscript.
Clinical trial number:
clinicalTrials.gov NCT03202381, EudraCT Number 2016-004210-10.