The skeletal muscle cell type enriched transcriptome Skeletal muscle cell type enriched transcriptome: Summary Skeletal muscle cell type enriched transcriptome: Illustrative examples

The skeletal muscle cell type enriched transcriptome

The main function of skeletal muscle is to provide stability, posture and movement throughout the body. It handles this by contracting and relaxing in a manner coordinated directly by impulses from the brain, i.e., it is under voluntary control, as opposed to cardiac and smooth muscle, where movement is involuntary. Another important function of skeletal muscle is to regulate body temperature. The heat is generated when the muscles contract and cause blood vessels in the skin to dilate.

1225 genes were predicted to have cell type specificity in the skeletal muscle.

9 cell types profiled
131 very highly enriched genes
305 highly enriched genes
811 moderately enriched genes

Skeletal muscle cell type enriched transcriptome: Summary

Genes with predicted cell type specificity within skeletal muscle are detailed in Table 1. Identified genes are subdivided into 3 specificity categories, based on the difference between the enrichment score in the corresponding cell type, compared to the other cell types profiled in the tissue (see Methods Summary page for details):

Predicted specificity: ´Very high´ - Differential score vs. other profiled cell types within the tissue >0.35
Predicted specificity: ´High´ - Differential score vs. other profiled cell types within the tissue >0.25
Predicted specificity: ´Moderate´ - Differential score vs. other profiled cell types within the tissue >0.15

Table 1. Number of genes in each specificity category in the skeletal muscle cell types.

Cell type	Very high	High	Moderate	Total enriched
Skeletal myocytes	63	107	180	328
Endothelial cells	4	37	196	237
Smooth muscle cells	3	12	26	41
Fibroblasts	0	53	285	338
Macrophages	25	55	98	178
Neutrophils	13	9	12	34
Plasma cells	23	32	14	69
All cell types	131	305	811	1225

Figure 1. Bar plot of the number of enriched genes in the cell types of the skeletal muscle, divided by specificity category

Skeletal muscle cell type enriched transcriptome: Illustrative examples

Skeletal myocytes

Skeletal muscle cells consist of many individual striated muscle cells that are fused together into long, multinuclear myofibers. The contractile function of muscle cells is controlled by actin and myosin myofilaments, which form small repeating subunits known as sarcomeres which are then arranged together and aligned to form very long, repeating myofibrils, which give skeletal muscle its distinctive striated or striped pattern. Skeletal muscle myofibers can be separated into two main types, termed fast-twitch and slow-twitch.

Myocyte 1

Genes classified as having specificity in the Myocyte_1 group include the contractile protein Myosin light chain 6B (MYL6B), the regulatory protein Troponin C1, slow type (TNNC1), as well as the uncharacterized protein C12orf75, with unknown function.

MYL6B - Skeletal muscle
MYL6B
TNNC1 - Skeletal muscle
TNNC1
C12orf75 - Skeletal muscle
C12orf75

Myocyte 2

Genes classified as having specificity in the Myocyte_2 group include the sarcoglycan complex subunit Sarcoglycan gamma (SGCG), which links the myocyte cytoskeleton to the extracellular matrix, as well as Calcium voltage-gated channel subunit alpha1 S (CACNA1S), involved in calcium regulation, and Protein phosphatase 1 regulatory subunit 3A (PPP1R3A), which is important for the metabolism of glycogen in muscle fibers.

SGCG - Skeletal muscle
SGCG
CACNA1S - Skeletal muscle
CACNA1S
PPP1R3A - Skeletal muscle
PPP1R3A

Myocyte 3

Genes classified as having specificity in the Myocyte_3 group include the regulatory proteins Troponin C2, fast type (TNNC2), Myosin binding protein C2, fast isoform (MYBPC2), and ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 1 (ATP2A1), responsible for calcium reuptake into the sarcoplasmic reticulum.

TNNC2 - Skeletal muscle
TNNC2
MYBPC2 - Skeletal muscle
MYBPC2
ATP2A1 - Skeletal muscle
ATP2A1