The heart muscle cell type enriched transcriptome Heart muscle cell type enriched transcriptome: Summary Heart muscle cell type enriched transcriptome: Illustrative examples

The heart muscle cell type enriched transcriptome

The main function of the heart is to pump blood around the body and maintain the pressure needed for adequate circulation. The heart predominantly consists of a specialized form of striated muscle called cardiomyocytes.

1902 genes were predicted to have cell type specificity in the heart muscle.

9 cell types profiled
79 very highly enriched genes
457 highly enriched genes
1366 moderately enriched genes

Heart muscle cell type enriched transcriptome: Summary

Genes with predicted cell type specificity within heart 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 heart muscle cell types.

Cell type	Very high	High	Moderate	Total enriched
Cardiomyocytes	1	183	732	916
Mitotic cells (Heart)	7	15	34	56
Endothelial cells	9	44	138	191
Smooth muscle cells	2	10	26	38
Fibroblasts	12	98	251	361
Macrophages	3	21	111	135
Neutrophils	11	22	19	52
T-cells	6	27	42	75
Plasma cells	28	37	13	78
All cell types	79	457	1366	1902

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

Heart muscle cell type enriched transcriptome: Illustrative examples

Cardiomyocytes

Cardiomyocytes are the predominant muscle type present in the heart. Cardiomyocytes share many features with myocytes in skeletal muscle, both have a striated appearance due to the regular alignment of actin and myosin myofilaments, and have large energy requirements, and so are heavily enriched for mitochondria and proteins related to energy production. Cardiomyocytes differ from skeletal myocytes in that they are a much smaller size, with only a single nucleus per cell, and are connected by specialized structures called intercalated discs, allowing adjacent cardiomyocytes to act together. Cardiomyocytes are also specialized to allow for the repetitive and continuous beating of the heart, and are under involuntary nervous control, as opposed to the voluntary control of skeletal muscles.

Genes classified as having specificity in cardiomyocytes include fumarate hydratase FH, an important component of the energy producing citric acid cycle, as well as myosin binding protein C MYBPC3, which is important for regulating the extent of cardiac contraction.

FH - Heart muscle
FH
MYBPC3 - Heart muscle
MYBPC3