# Myosin Va Cargo Transport: In Vitro Model Systems

> **NIH NIH R01** · UNIVERSITY OF VERMONT & ST AGRIC COLLEGE · 2020 · $361,094

## Abstract

SUMMARY
Intracellular cargo transport, such as insulin granules destined for secretion in pancreatic β-cells, relies on
myosin Va (myoVa) molecular motors. This double-headed molecular motor carries its cargo by stepping
processively for considerable distances along actin tracks. To successfully deliver cargo, a team of myoVa
motors must overcome the physical challenges presented by the 3-dimensional (3D) complex networks of
branched and bundled actin filaments that comprise the actin cytoskeleton. To determine how efficient myoVa
cargo transport and delivery are accomplished despite the physical challenges presented by the cell's
multitude of actin structures and complex networks, we will develop complex but well-defined, 3-dimensional
(3D) actin networks formed in vitro using multifunctional actin-binding proteins, and; 2) create structurally-
defined “designer” actin networks inside cultured cells. By using state-of-the-art single molecule biophysical
techniques with high spatial (6nm) and temporal (10ms) resolution, we will define how myoVa motor teams
respond to these physical challenges. To begin simulating the complex 3D intracellular cytoskeleton, in Aim #1,
we will suspend actin filaments to create actin filament intersections in 3D. Similarly, branched actin filaments
formed by Arp2/3 will also be suspended. These 3D actin filament intersections and branch points will then
challenge a team of myoVa motors carrying a lipid-bound, liposome cargo. Knowing the precise spatial relation
between the cargo and the actin tracks using super-resolution STORM imaging, and by varying the number of
motors and the fluidity of the cargo's lipid coating, we will provide a mechanistic basis for the directional
outcome as the cargo and its team of motors maneuvers through the intersection or branch point. These
studies will inform the studies in Aim #2 in which we will create structurally and mechanically defined 3D actin
networks of branched and bundled actin filaments as models of the cell's complex actin cytoskeleton. The
cellular structures to be modeled are the actin cortex with its Arp2/3 branched filaments and filopodia and
stress fibers that are parallel actin bundles formed by fascin and α-actinin cross-linkers, respectively. We
propose that a functional interplay exists between the properties of the actin tracks, motors, and cargos, which
determines how teams of myoVa motors meet the cellular demands placed on them by this multitude of actin
structures. The data obtained will provide a rich, mechano-spatial knowledgebase for the field and serve as a
foundation for understanding myoVa transport in the complex architectural environment of the cell, which we
will control by culturing cells on patterned substrates so as to create “designer” actin cytoskeletons. Thus, the
proposed studies will provide a mechanistic understanding of how efficient myoVa transport system is
designed for delivery and retention of cargo at its destination, such as insulin...

## Key facts

- **NIH application ID:** 9843149
- **Project number:** 5R01GM094229-08
- **Recipient organization:** UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
- **Principal Investigator:** David M Warshaw
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $361,094
- **Award type:** 5
- **Project period:** 2011-04-01 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9843149

## Citation

> US National Institutes of Health, RePORTER application 9843149, Myosin Va Cargo Transport: In Vitro Model Systems (5R01GM094229-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9843149. Licensed CC0.

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