# Lysosome Regulation of Exosome Release and Function in Arterial Smooth Muscle

> **NIH NIH R01** · VIRGINIA COMMONWEALTH UNIVERSITY · 2021 · $488,375

## Abstract

Project Summary
Exosomes are from the intraluminal vesicles (ILV) of multivesicular bodies (MVBs) produced via endocytic
process. Mature MVBs can fuse with lysosomes to deliver their contents for degradation and recycling or fuse
with the plasma membrane where ILVs are released as exosomes. Recent studies have indicated that
enhanced exosome excretion in arterial smooth muscle cells (SMCs) is an essential mechanism triggering or
promoting calcifying nidus formation and extracellular matrix (ECM) mineralization in the arterial wall under
different pathological conditions. However, little is known so far how MVB fate and exosome excretion are
controlled by lysosomes in SMCs and whether lysosomal dysfunction increases exosome excretion from SMCs
to activate or accelerate vascular calcification process. The present grant proposal will test a central
hypothesis that lysosomal acid ceramidase (AC)-mediated sphingolipid metabolism plays a crucial role in the
control of lysosome trafficking or fusion to MVBs and subsequent exosome excretion, maintaining the normal
phenotype and function of SMCs. AC gene defect or functional deficiency may disturb lysosome degradation of
MVBs, increasing exosome excretion and resulting in calcifying nidus formation and ultimate vascular
calcification under pathological conditions. To test this hypothesis, three Specific Aims are proposed. Specific
Aim 1 will determine whether exosome excretion in arterial SMCs is fine controlled by lysosomal AC activity
and whether the deficiency of this AC regulation causes arterial calcification in smooth muscle-specific AC
gene knockout mice (Asah1fl/fl/SMcre) with analysis of exosomes, SMC phenotypes, and calcification in the
arterial wall and cultured coronary arterial SMCs. Specific Aim 2 attempts to test whether lysosomal AC-
mediated sphingolipid signaling regulates lysosome trafficking to and fusion with MVBs to limit exosome
excretion from SMCs with gene deletion (Asah1fl/fl/SMcre), CRISPR-Cas9 gene editing, and SM22α promoter-
driven gene rescuing. In Specific Aim 3, we will address whether the AC regulation of lysosome trafficking or
fusion to MVBs is attributed to its action on lysosomal TRPML1 channel activity and associated Ca2+ release
using patch clamping of isolated lysosomes and lysosome-specific Ca2+ imaging with GCaMP3-ML as an
indicator. To our knowledge, these proposed studies will represent the first effort to investigate the lysosome
regulation of exosome excretion from SMCs and associated pathogenic role in vascular calcification. The
findings will provide new insights into the pathogenesis of arterial calcification and identify lysosomal AC as a
therapeutic target for prevention or treatment of vascular calcification.

## Key facts

- **NIH application ID:** 10092204
- **Project number:** 5R01HL057244-23
- **Recipient organization:** VIRGINIA COMMONWEALTH UNIVERSITY
- **Principal Investigator:** PinLan Li
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $488,375
- **Award type:** 5
- **Project period:** 1997-01-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10092204

## Citation

> US National Institutes of Health, RePORTER application 10092204, Lysosome Regulation of Exosome Release and Function in Arterial Smooth Muscle (5R01HL057244-23). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10092204. Licensed CC0.

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