Related Experiment Video

Updated: May 14, 2026

Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice
10:50

Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice

Published on: November 3, 2013

Loss of SPARC in mouse skeletal muscle causes myofiber atrophy

Katsuyuki Nakamura1, Shin-Ichi Nakano, Takahiro Miyoshi

  • 1Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.

Muscle & Nerve
|February 21, 2013
PubMed
Abstract

Insights

Secreted protein acidic and rich in cysteine (SPARC) loss in skeletal muscle increases atrogin1 and enhances TGFβ signaling, potentially causing muscle atrophy. This study investigated SPARC

Area of Science:

  • Muscle physiology
  • Molecular biology
  • Aging research

Background:

  • Secreted protein acidic and rich in cysteine (SPARC) expression declines in skeletal muscle with age.
  • Understanding SPARC's role in muscle health is crucial for age-related conditions.

Purpose of the Study:

  • To investigate the functional role of SPARC in skeletal muscle.
  • To determine the effects of reduced SPARC expression on muscle characteristics and signaling pathways.

Main Methods:

  • SPARC expression was suppressed in mouse tibialis anterior muscle using short interfering RNA (siRNA).
  • Analyzed myofiber diameter, atrogin1, MuRF1 expression, and TNFα and TGFβ signaling pathways.

Main Results:

  • Reduced SPARC expression led to decreased myofiber diameter, particularly in fast-twitch fibers.
  • Atrogin1 expression was upregulated, while MuRF1 remained unaffected.
  • Increased Smad3 phosphorylation indicated enhanced TGFβ signaling, without affecting TNFα or p38 pathways.

Conclusions:

  • Loss of SPARC upregulates atrogin1 and enhances TGFβ signaling.
  • These molecular changes suggest a mechanism by which SPARC deficiency contributes to skeletal muscle atrophy.
Keywords:
SPARCSmad3TGFβatrogin1myofiber atrophy

More Related Videos

Dissection of the Transversus Abdominis Muscle for Whole-mount Neuromuscular Junction Analysis06:12

Dissection of the Transversus Abdominis Muscle for Whole-mount Neuromuscular Junction Analysis

Published on: January 11, 2014

Myo-mechanical Analysis of Isolated Skeletal Muscle08:42

Myo-mechanical Analysis of Isolated Skeletal Muscle

Published on: February 22, 2011

Related Concept Videos

Cross-bridge Cycle01:26

Cross-bridge Cycle

As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
Satellite Stem Cells and Muscular Dystrophy01:21

Satellite Stem Cells and Muscular Dystrophy

Satellite stem cells or myosatellite cells are quiescent stem cells that Alexander Mauro first identified in 1961. These cells are located between the sarcolemma, the plasma membrane of muscle fibers, and the basal lamina, the connective tissue sheath covering it. These mononucleated cells are activated in response to muscle injury, can transform into myoblasts, and may form or repair muscle fibers. Myosatellite cells can provide additional myonuclei for muscle regeneration or return to a...
Disorders of the Skeletal Muscle01:28

Disorders of the Skeletal Muscle

The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...