Scientists have discovered 193 hidden human proteins in an initiative that has produced the first comprehensive map of the human proteome, a research tool that may help drive new findings against disease.
Proteins are complex molecules that carry out the instructions of genes, performing the work needed to build and regulate the body’s tissues and organs. A directory of the body’s proteins may help refine research in diagnostics and drug development, building on the work from the Human Genome Project years earlier, the scientists said.
The research, reported today in the journal Nature, studied tissue from both adults and fetuses, potentially opening a new window into diseases that begin early in life. The 193 novel proteins identified were a surprise, found in regions of the genome not normally thought to include them.
“Some of the proteins expressed during development in ovary and testis can serve as potential biological markers for identifying cancers of different lineages in the future,” the researchers wrote in the paper.
The project, which involved 72 researchers, used mass spectrometry to identify the proteins, and cost less than $1 million to achieve, said Akhilesh Pandey, the lead author and a professor of genetic medicine, pathology, oncology and biological chemistry at Johns Hopkins University in Baltimore.
“Researchers will now know which parts of the genome truly code for proteins,” Pandey said. “Scientists can now also find out which protein is located where and which proteins are restricted to one organ or cell type.’
The team studied 30 normal human cell and tissue types, from organs that included the spinal cord, retina and brain in adults. They also reviewed tissue from fetuses that including their ovaries, testes, placenta, brain, heart, gut and liver.
Because it’s known that a number of proteins are expressed during fetal development but not in adult cells, earlier studies have focused on only a few fetal tissues. Today’s research detected proteins encoded by 735 genes that are expressed more than tenfold in fetal samples compared with adults, researchers said.
Though not the first work to detail human proteins, the project is the largest coverage of the human proteome so far, researchers said. The Swedish Human Protein Atlas project, has been exploring the human proteome since 2003, using antibodies to recognize proteins.
‘‘We have basically done it on a shoe-string budget,” Pandey said in a telephone interview. “That tells you how far public money can go if used appropriately.”
The Human Genome Project, completed in 2003, cost about $2.7 billion, with funding established by Congress in 1990. The human proteome project was funded through U.S. and other grants.
The findings may also bring new enlightenment on non-coding regions of the genome, once referred to as “junk DNA.” One of the very small proteins identified, dubbed “Suppresyn,’ was found to affect cell-cell fusion, a biological process that in the placenta aids in diffusion of nutrients and hormones from the mother to the fetus.
Another team from the Technical University of Munich created a public database that covers 92 percent of genes in human genome thought to make proteins, according to a second report in Nature. While Pandey generated new data from tissue samples, the German researchers assembled a proteome using mass spectrometry data from experiments involving human repositories and other contributions.