CORDIS - EU research results
CORDIS

Elucidating the Molecular Mechanism of Myoblast Fusion in Vertebrates

Project description

Dissecting cell fusion in muscle

Skeletal muscle consists of functional contractile units known as myofibers, which emerge from the fusion of muscle cells, the myoblasts. Myofiber formation requires the remodelling and fusion of plasma membranes, processes that currently are incompletely characterised. To address this gap in knowledge, the EU-funded MYOCLEM project is developing 3D light and electron microscopy methods and using them to elucidate the molecular players and their function in driving the changes associated with membrane remodelling during fusion. Insight into mechanism and regulation of fusion will not only improve our understanding of this key process but also help design novel treatments against muscle diseases.

Objective

Cell-to-cell fusion is a ubiquitous phenomenon essential for the physiological function of numerous tissues. A striking example is the fusion of myoblasts to form multinucleated myofibers during skeletal muscle development and regeneration. During myoblast fusion, membrane architecture must be radically remodeled. Yet, how membrane remodeling occurs on the molecular level is poorly understood as, until now, there was no approach available for visualizing dynamic changes in the cellular ultrastructure and the organization of the fusion machinery in situ.
To fill this gap, we have developed correlative light and 3D electron microscopy (CLEM) methods that allow us to identify fluorescent signals within EM samples with high sensitivity and subsequently localize the source of these signals with high precision. In this proposal, we will apply these methods in combination with live-cell imaging, biochemistry and cryo-electron tomography (ET) to deliver fundamental knowledge about the mechanism of myoblast fusion. Our specific aims are:
Aim 1: To resolve the molecular and ultrastructural events underlying cell fusion, by revealing how plasma membrane architecture is remodeled at sites of fusion using 3D EM.
Aim 2: To dissect the mechanism driving membrane remodeling during fusion, by visualizing how the fusion machinery assembles at sites of fusion and how its assembly is mirrored by changes in membrane shape, using biochemistry and live-cell imaging.
Aim 3: To determine the structure of the fusion machinery in situ, by using cryo-ET and subtomogram averaging.
Our synergetic experimental strategy will generate a quantitative, dynamic high-resolution view of the fusogenic synapse of vertebrate muscle, revealing how the fusion machinery remodels the plasma membrane at sites of fusion. These data are vital for deriving a biophysical model of myoblast fusion, understanding the general mechanism of cell fusion, and developing strategies to treat primary muscle diseases.

Host institution

WEIZMANN INSTITUTE OF SCIENCE
Net EU contribution
€ 1 500 000,00
Address
HERZL STREET 234
7610001 Rehovot
Israel

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Activity type
Higher or Secondary Education Establishments
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Total cost
€ 1 500 000,00

Beneficiaries (1)