THE HUMAN TISSUE PROTEOMES

Lactating breast



The Tissue atlas is based on immunohistochemical staining of tissue microarrays from 44 different normal tissue types. In addition to the standard setup, extended tissue profiling is performed for selected proteins, to give a more complete overview on where the protein is expressed. Extended tissue samples include mouse brain, human lactating breast, eye and additional samples of adrenal gland, skin and brain. For lactating breast, both tissue microarrays with 1 mm diameter cores and large tissue sections (20 x 30 mm) are used.

The full list of proteins analyzed in lactating breast is found in Table 1.


Background


The breasts are mainly composed of mammary glands, adipose tissue and connective tissue. An adult woman has 15-20 lobes in each breast and each lobe consist of 20-40 lobules. Inside of each lobule are structures called acini or alveoli. These are connected to a duct system, the lactiferous duct, which eventually accumulates in lactiferous sinuses and finally reaches the nipple.

The main purpose of the breast is to provide nutritious milk for infants. A fully developed breast can either be lactating or non-lactating and during pregnancy, the mammary glands undergo a morphological transformation, in preparation for lactation. Some proteins can only be detected after this transformation. An example of a protein expressed in lactating breast is alpha-lactalbumin (LALBA), a principal protein of milk required for lactose synthesis in the mammary gland (Figure 1).

Figure 1. Immunohistochemical staining of human lactating breast using an antibody toward LALBA shows moderate cytoplasmic positivity in glandular cells.


Table 1. The following 10 genes have been analyzed using extended lactating breast tissue samples.

Gene

Gene description

Staining pattern

BTN1A1 Butyrophilin, subfamily 1, member A1 Immunohistochemical staining of human lactating breast shows strong membranous positivity in glandular cells.
CEL Carboxyl ester lipase Immunohistochemical staining of human lactating breast shows moderate cytoplasmic positivity in glandular cells.
CSN1S1 Casein alpha s1 Immunohistochemical staining of human lactating breast shows strong cytoplasmic positivity in glandular cells. Ductal cells showed membranous staining.
CSN2 Casein beta Immunohistochemical staining of human lactating breast shows strong cytoplasmic positivity in glandular cells and ductal cells.
CSN3 Casein kappa Immunohistochemical staining of human lactating breast shows strong cytoplasmic positivity in glandular cells.
LALBA Lactalbumin, alpha- Immunohistochemical staining of human lactating breast shows moderate cytoplasmic positivity in glandular cells and ductal cells.
LTF Lactotransferrin Immunohistochemical staining of human lactating breast shows moderate membranous positivity with additional plasma positivity.
PLIN2 Perilipin 2 Immunohistochemical staining of human lactating breast shows strong membranous positivity in glandular cells.
SCGB2A2 Secretoglobin, family 2A, member 2 Immunohistochemical staining of human lactating breast shows moderate cytoplasmic positivity in ductal cells with additional plasma positivity.
XDH Xanthine dehydrogenase Immunohistochemical staining of human lactating breast shows strong cytoplasmic positivity in glandular cells.


Relevant links and publications


UhlÚn M et al, 2015. Tissue-based map of the human proteome. Science
PubMed: 25613900 DOI: 10.1126/science.1260419

Yu NY et al, 2015. Complementing tissue characterization by integrating transcriptome profiling from the Human Protein Atlas and from the FANTOM5 consortium. Nucleic Acids Res.
PubMed: 26117540 DOI: 10.1093/nar/gkv608

Fagerberg L et al, 2014. Analysis of the human tissue-specific expression by genome-wide integration of transcriptomics and antibody-based proteomics. Mol Cell Proteomics.
PubMed: 24309898 DOI: 10.1074/mcp.M113.035600