Triiodothyronine maintains cardiac transverse-tubule structure and function

Nimra Gilani; Kaihao Wang; Adam Muncan; Jerrin Peter; Shimin An; Simran Bhatti; Khushbu Pandya; Youhua Zhang; Yi-Da Tang; A Martin Gerdes; Randy F Stout; Kaie Ojamaa

doi:10.1016/j.yjmcc.2021.06.010

Triiodothyronine maintains cardiac transverse-tubule structure and function

J Mol Cell Cardiol. 2021 Nov:160:1-14. doi: 10.1016/j.yjmcc.2021.06.010. Epub 2021 Jun 24.

Authors

Nimra Gilani¹, Kaihao Wang², Adam Muncan³, Jerrin Peter⁴, Shimin An², Simran Bhatti⁵, Khushbu Pandya⁶, Youhua Zhang⁷, Yi-Da Tang⁸, A Martin Gerdes⁹, Randy F Stout¹⁰, Kaie Ojamaa¹¹

Affiliations

¹ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: ngilani@nyit.edu.
² Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA; Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
³ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: amuncan@nyit.edu.
⁴ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: jpeter@nyit.edu.
⁵ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: sbhatt12@nyit.edu.
⁶ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: kpandy04@nyit.edu.
⁷ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: yzhang49@nyit.edu.
⁸ Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
⁹ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: martin.gerdes@nyit.edu.
¹⁰ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA; NYIT Imaging Center, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: rstout@nyit.edu.
¹¹ Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA. Electronic address: kojamaa@nyit.edu.

Abstract

Subclinical hypothyroidism and low T3 syndrome are commonly associated with an increased risk of cardiovascular disease (CVD) and mortality. We examined effects of T3 on T-tubule (TT) structures, Ca²⁺ mobilization and contractility, and clustering of dyadic proteins. Thyroid hormone (TH) deficiency was induced in adult female rats by propyl-thiouracil (PTU; 0.025%) treatment for 8 weeks. Rats were then randomized to continued PTU or triiodo-L-thyronine (T3; 10 μg/kg/d) treatment for 2 weeks (PTU + T3). After in vivo echocardiographic and hemodynamic recordings, cardiomyocytes (CM) were isolated to record Ca²⁺ transients and contractility. TT organization was assessed by confocal microscopy, and STORM images were captured to measure ryanodine receptor (RyR2) cluster number and size, and L-type Ca²⁺ channel (LTCC, Ca_v1.2) co-localization. Expressed genes including two integral TT proteins, junctophilin-2 (Jph-2) and bridging integrator-1 (BIN1), were analyzed in left ventricular (LV) tissues and cultured CM using qPCR and RNA sequencing. The T3 dosage used normalized serum T3, and reversed adverse effects of TH deficiency on in vivo measures of cardiac function. Recordings of isolated CM indicated that T3 increased rates of Ca²⁺ release and re-uptake, resulting in increased velocities of sarcomere shortening and re-lengthening. TT periodicity was significantly decreased, with reduced transverse tubules but increased longitudinal tubules in TH-deficient CMs and LV tissue, and these structures were normalized by T3 treatment. Analysis of STORM data of PTU myocytes showed decreased RyR2 cluster numbers and RyR localizations within each cluster without significant changes in Ca_v1.2 localizations within RyR clusters. T3 treatment normalized RyR2 cluster size and number. qPCR and RNAseq analyses of LV and cultured CM showed that Jph2 expression was T3-responsive, and its increase with treatment may explain improved TT organization and RyR-LTCC coupling.

Keywords: Ca(2+); Junctophilin-2; Ryanodine receptors; STORM; Thyroid hormone; Transverse-tubules.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Animals
Calcium / metabolism
Calcium Channels, L-Type / metabolism
Calcium Signaling / drug effects*
Cells, Cultured
Disease Models, Animal
Female
Gene Expression
Heart Ventricles / drug effects*
Heart Ventricles / metabolism*
Hypothyroidism / blood
Hypothyroidism / chemically induced
Hypothyroidism / drug therapy*
Membrane Proteins / genetics
Membrane Proteins / metabolism
Myocytes, Cardiac / metabolism
Rats
Ryanodine Receptor Calcium Release Channel / metabolism
Sarcolemma / metabolism
Sarcomeres / metabolism
Treatment Outcome
Triiodothyronine / administration & dosage*
Triiodothyronine / blood
Ventricular Function / drug effects

Substances

Calcium Channels, L-Type
Membrane Proteins
RyR2 protein, rat
Ryanodine Receptor Calcium Release Channel
junctophilin
Triiodothyronine
Calcium

Grants and funding

R15 HL154068/HL/NHLBI NIH HHS/United States