# Tsg101 and endosomes in cardiac surgery-induced injury

> **NIH NIH R01** · UNIVERSITY OF CINCINNATI · 2021 · $304,950

## Abstract

Heart surgery for both coronary artery bypass graft (CABG) and transplantation often involves cardiac
ischemia/reperfusion (I/R), which leads to a switch of the myocardial energy source from fatty acid β-
oxidation to anaerobic glycolysis. As an adaptation, Glut-4, a major isoform of the glucose transporters in the
heart, is recruited to the cardiomyocyte surface (also called sarcolemma) to take up glucose and stimulate
cardiac ATP production. Nonetheless, such compensatory Glut4 translocation is not sufficient to meet cardiac
glucose demands for ATP generation in I/R hearts and thereby, results in an energy crisis. Notably, recent
multiple large clinical trials involving infusion of glucose-insulin-potassium (GIK) solution into patients
undergoing cardiac surgery have not shown any positive results (or even worse). Therefore, exploring how
to augment Glut-4 translocation and glucose utilization, independent of insulin, is desperately needed to
counter I/R-triggered cardiac energy loss. We recently made the novel findings that the tumor susceptibility
gene 101 (Tsg101), a central component of the ESCRT (endosomal sorting complexes required for transport)
machinery, is able to regulate the endosomal recycling of membrane receptors in animal hearts. Our newest
data further showed that: 1) Tsg101 binds directly to Glut-4 in adult mouse hearts; 2) forced expression of
Tsg101 in cultured myocytes resulted in higher levels of sarcolemma Glut-4 and improved cell survival when
challenged with hypoxia/reoxygenation; and 3) Tsg101 up-regulates the expression of Rab11a and FIP3
(Rab11-family interacting protein 3), two key factors involved in endosomal recycling. Most importantly, our
pilot data also showed that a group of naturally-occurring nano-vesicles, exosomes, released by bone-
marrow stem cells, can effectively deliver Tsg101 into cardiac myocytes. Based on these initial findings, we
hypothesize that Tsg101 can reduce or prevent cardiac I/R-induced energy crisis/injury by promoting Rab11a/
FIP3-mediated endosomal recycling of Glut-4. Treatment of mouse hearts with Tsg101-containing exosomes
before ischemia or during early reperfusion can elevate myocardial Tsg101, thereby limiting I/R-triggered
cardiac damage. The work proposed here will address three specific aims: 1) Define the role of Tsg101 in
glucose-dependent energy generation and cardio-protection from I/R injury, using both heart-specific
Tsg101-overexpressing and inducible knockdown mouse models; 2) Identify whether Tsg101-induced
cardio-protection is dependent on Rab11a/FIP3-mediated endosomal recycling of Glut-4; and 3)
Investigate the therapeutic potential of Tsg101 to prevent/reduce I/R-induced cardiac energy stress
and injury, using Tsg101-loaded exosomes. The proposed studies are expected to identify Tsg101 as a
novel regulator of Glut-4 translocation and as a major cardio-protector against I/R-induced energy stress. If
verified, the findings from this proposal should provide new and ...

## Key facts

- **NIH application ID:** 10066356
- **Project number:** 5R01GM126061-04
- **Recipient organization:** UNIVERSITY OF CINCINNATI
- **Principal Investigator:** Guo-Chang Fan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $304,950
- **Award type:** 5
- **Project period:** 2017-12-10 → 2022-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10066356

## Citation

> US National Institutes of Health, RePORTER application 10066356, Tsg101 and endosomes in cardiac surgery-induced injury (5R01GM126061-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10066356. Licensed CC0.

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