Comparative gene expression profiling between human cultured myotubes and skeletal muscle tissue

Area of Science:

• Molecular Biology
• Genomics
• Cell Biology

Background:

• High-sensitivity DNA microarrays enable transcriptome analysis of individual skeletal muscle (SM) tissue samples using nanograms of RNA.
• Culturing SM cells from biopsies allows for investigation of transcriptional defects and therapeutic strategies.

Purpose of the Study:

• To compare the transcriptome of aneurally cultured human SM cells with that of tissue biopsies.
• To identify transcriptional differences and pathways affected by in vitro culture.

Main Methods:

• Illumina expression BeadChips were used to analyze transcriptomic differences between tissue and cultured SM samples from five individuals.
• Gene expression changes were validated using QuantiGene Plex assay and reverse transcription real-time PCR.

Main Results:

• 1216 genes were differentially expressed in cultured myotubes compared to tissue (583 downregulated, 633 upregulated).
• Downregulated genes were associated with mitochondrial function, metabolism, and muscle contraction; upregulated genes with endoplasmic reticulum and extracellular matrix.
• Key downregulated genes included metabolic proteins (e.g., AMPD1, PYGM) and muscle proteins (e.g., TMOD4, MYBPC1).
• Upregulated genes included senescence/apoptosis markers (e.g., CDKN1A) and regulatory factors (e.g., HIF1A).
• Mitochondrial dysfunction was the most significantly regulated pathway, with apoptosis genes also modulated.

Conclusions:

• Cultured muscle cells exhibit transcriptome adaptations mirroring muscle atrophy, including reduced metabolic and muscle-system gene expression.
• In vitro culture induces tissue-remodeling and senescence/apoptosis processes in skeletal muscle cells.