Nebulin-deficient mice exhibit shorter thin filament lengths and reduced contractile function in skeletal muscle.

Abstract

Nebulin is a giant modular sarcomeric protein that has been proposed to play critical roles in myofibrillogenesis, thin filament length regulation, and muscle contraction. To investigate the functional role of nebulin in vivo, we generated nebulin-deficient mice by using a Cre knock-in strategy. Lineage studies utilizing this mouse model demonstrated that nebulin is expressed uniformly in all skeletal muscles. Nebulin-deficient mice die within 8-11 d after birth, with symptoms including decreased milk intake and muscle weakness. Although myofibrillogenesis had occurred, skeletal muscle thin filament lengths were up to 25% shorter compared with wild type, and thin filaments were uniform in length both within and between muscle types. Ultrastructural studies also demonstrated a critical role for nebulin in the maintenance of sarcomeric structure in skeletal muscle. The functional importance of nebulin in skeletal muscle function was revealed by isometric contractility assays, which demonstrated a dramatic reduction in force production in nebulin-deficient skeletal muscle.

• Authors: Marie-Louise Bang, Xiaodong Li, Ryan Littlefield, Shannon Bremner, Andrea Thor, Kirk U Knowlton, Richard L Lieber, Ju Chen
• Journal: The Journal of cell biology (J Cell Biol) Vol. 173 Issue 6 Pg. 905-16 (Jun 19 2006) ISSN: 0021-9525 [Print] United States
• PMID: 16769824 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Muscle Proteins
• nebulin

Topics

• Actin Cytoskeleton (metabolism, ultrastructure)
• Animals
• Cells, Cultured
• Diaphragm (ultrastructure)
• Gene Targeting
• Mice
• Microscopy, Electron, Transmission
• Muscle Contraction (genetics, physiology)
• Muscle Proteins (genetics, metabolism, physiology)
• Muscle, Skeletal (metabolism, physiology)
• Myocytes, Cardiac (metabolism, ultrastructure)
• Myofibrils (metabolism, ultrastructure)
• RNA Interference
• Sarcomeres (metabolism, ultrastructure)