MicroRNA-208b progressively declines after spinal cord injury in humans and is inversely related to myostatin expression

Physiol Rep, 2015 · DOI: 10.14814/phy2.12622 · Published: November 1, 2015

Simple Explanation

This study investigates the impact of long-term physical inactivity, specifically due to spinal cord injury, on microRNAs involved in regulating skeletal muscle mass. The researchers focused on microRNA-208b and microRNA-499-5p, which are associated with muscle fiber type and growth, and their relationship with myostatin, a protein that inhibits muscle growth. The study found that the expression of microRNA-208b and microRNA-499-5p decreased in individuals with spinal cord injury, while myostatin expression increased, suggesting an inverse relationship.

Study Duration

12 Months

Participants

Spinal cord injured subjects and able-bodied controls

Evidence Level

Original Research

Key Findings

1
Skeletal muscle expression of microRNA-208b and microRNA-499-5p progressively declined within the first year after cervical spinal cord injury in humans, with changes maintained in long-standing injury.
2
Myostatin expression was inversely correlated with microRNA-208b and microRNA-499-5p in human skeletal muscle following spinal cord injury, coincident with skeletal muscle atrophy.
3
In vivo overexpression of microRNA-208b, but not microRNA-499-5p directly reduced myostatin gene expression in mouse skeletal muscle.

Research Summary

The study examined the expression of microRNAs and myostatin in skeletal muscle of humans with spinal cord injury. It found a progressive decline in microRNA-208b and microRNA-499-5p expression after spinal cord injury, correlated with increased myostatin expression. Overexpression of microRNA-208b in mouse muscle decreased myostatin gene expression, suggesting a regulatory role.

Practical Implications

Potential Therapeutic Target

MicroRNA-208b could be a potential therapeutic target for mitigating muscle atrophy in spinal cord injury patients.

Understanding Muscle Atrophy

The study contributes to a better understanding of the molecular mechanisms underlying skeletal muscle atrophy following spinal cord injury.

Exercise and Rehabilitation Strategies

Findings may inform the development of targeted exercise and rehabilitation strategies to preserve muscle mass and function in individuals with spinal cord injury.

Study Limitations

1
The study has a limited sample size.
2
The study focuses primarily on cervical spinal cord injuries, limiting generalizability to other injury levels.
3
The molecular mechanisms regulating intronic microRNA expression are complex and require further investigation.

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