# Heart Function Decline and Aging

> **NIH VA I01** · VA SAN DIEGO HEALTHCARE SYSTEM · 2020 · —

## Abstract

Heart failure (HF) is a significant health problem in the elderly population, including in Veterans. The basis for
the diminished function of the old heart (OH, 19-22 month) and increased propensity to develop HF is only
incompletely explored and poorly treated. Preliminary results show that in OH cardiac function is diminished,
cardiac myocytes (CM) contract poorly, and decreased Mitochondrial (Mito) respiratory function occurs. Our
preliminary results also show novel findings that in CM from OH versus young heart (YH, 2-3 month) the
Mitochondrial Calcium Uniporter (MCU) Complex (MCUC) has markedly decreased calcium (Ca2+) conductance
resulting in decreased Mito matrix freeCa2+ concentration ([Ca2+]m) which leads to decreased Mito respiratory,
cardiac metabolic, and contractile function. Specific MCUC member proteins show decreased levels in OH CM.
The level of the Essential MCU Regulator (EMRE) is decreased by 70% in OH CM. In the absence of EMRE,
MCUC Ca2+ conductance is lost. In addition MCU shows a more modest 30% decline in OH CM. The principle
hypothesis is that the performance of the OH can be markedly improved by restoring EMRE and MCU
levels in OH CM (OH+EMRE+MCU) using adeno-associated viral vector (AAV)-based expression of
transgenes (tges) encoding EMRE and MCU or pharmacological inhibition of Mito Ca2+ export. To test this
hypothesis we pursue three closely linked Aims. In Aim 1 we enhance MCUC Ca2+ conductance by restoring
EMRE and MCU in OH towards the YH range and determine its influence on Mito and cytosolic Ca2+ handling,
Mito respiratory, cardiac metabolic and contractile function, and animal survival. We also inhibit the Mito sodium-
Ca2+ exchanger (mNCLX) and Mito Ca2+ export with a pharmacological compound, returning [Ca2+]m to the YH
level and improving CM contraction. In Aim 2 we determine if maladaptive consequences occur in
OH+EMRE+MCU, especially increased CM death and increased myocardial infarct size (MI) with
ischemia/reperfusion (I/R). Preliminary results show a decrease in MI size in OH+EMRE+MCU versus (vs) OH.
Influences of dominant negative (dn) dnEMRE and dnMCU expression on Mito Ca2+ handling and CM contraction
in YH and OH are investigated. We compare rescue effects in OH+EMRE+MCU vs expression of a SERCa2 tge
in OH (OH+SERCa2). Preliminary results show similar basal and maximal ex vivo cardiac function in
OH+EMRE+MCU and OH+SERCa2. In Aim 3 we explore molecular mechanisms mediating the marked
decrease in EMRE protein levels in OH CM. Preliminary results point to an interaction of miRNA 215, which is
3.4-fold increased in OH CM, with the 5' UTR of EMRE mRNA inhibiting translation initiation. We also explore if
chromatin remodeling to a more open state occurs in OH+EMRE+MCU vs OH with increased DNA accessibility
enabling increased gene transcription, including of the SERCa2 gene. Chromatin remodeling involves chromatin
remodeling motors which require ATP hydrolysis. Studies in YH, OH, and OH+EMRE+MCU are condu...

## Key facts

- **NIH application ID:** 9852296
- **Project number:** 5I01BX003429-02
- **Recipient organization:** VA SAN DIEGO HEALTHCARE SYSTEM
- **Principal Investigator:** Wolfgang H Dillmann
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2019-01-01 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9852296

## Citation

> US National Institutes of Health, RePORTER application 9852296, Heart Function Decline and Aging (5I01BX003429-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9852296. Licensed CC0.

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