All living things are made of cells, and the molecular machinery within them is imperative to survival. Different biomolecules,\u00a0including RNA,\u00a0proteins\u00a0and more,\u00a0have specialized roles and\u00a0perform a range of\u00a0functions. Proteins support living states by\u00a0acquiring\u00a0and metabolizing nutrients from external environments, synthesizing new material molecules for growth and division, and transmitting information to respond to the environment.\u00a0Given their importance, researchers strive to characterize how\u00a0protein abundances\u00a0change under\u00a0different\u00a0conditions, and how\u00a0the abundances\u00a0are coordinated\u00a0within\u00a0cells.\u00a0<\/p>\n
“To\u00a0explore the\u00a0abundance\u00a0of proteins\u00a0in\u00a0cells,\u00a0the technique known as\u00a0‘proteomics’\u00a0is often used\u00a0to create a dataset called a proteome\u00a0profile. However, the standard approach requires extracting proteins to quantify them, which is destructive\u00a0and\u00a0takes many\u00a0laborious steps.\u00a0But,\u00a0we have found a better way,” said Professor Yuichi Wakamoto from the Department of Basic Science\u00a0at\u00a0the\u00a0University of Tokyo. “We\u00a0demonstrated that cellular proteome profiles can be\u00a0nondestructively\u00a0inferred by simply exposing cells to light and analyzing their\u00a0so-called\u00a0Raman spectra, a type of scattered light from cells that\u00a0conveys\u00a0their molecular profiles.”\u00a0<\/p>\n
After they discovered this,\u00a0Wakamoto, with\u00a0Project Researcher\u00a0Ken-ichiro\u00a0F. Kamei\u00a0and\u00a0their\u00a0team,\u00a0wanted to understand why it is possible to predict a\u00a0cell’s\u00a0protein makeup from Raman light measurements or spectra. They found that\u00a0abundance ratios of\u00a0many proteins\u00a0are globally coordinated\u00a0across\u00a0a range of\u00a0conditions.\u00a0A pattern\u00a0emerged\u00a0with a large core of proteins\u00a0whose\u00a0abundance\u00a0ratios\u00a0stay\u00a0consistent\u00a0and support basic cellular functions.\u00a0Smaller groups of proteins\u00a0tend to vary\u00a0more depending on environmental changes,\u00a0and this is what\u00a0helps a\u00a0cell adapt.\u00a0This\u00a0hierarchical\u00a0structure explains how cells can remain stable while still responding flexibly to new conditions, and this study proves that Raman spectroscopy can be a powerful tool for exploring the complex world of cellular\u00a0machinery.\u00a0<\/p>\n
“The biggest challenge for us was connecting and unifying the two distant fields of study, optics, in this case Raman spectroscopy, and omics, or the proteome,\u00a0which have developed independently. Many measurements, data analyses\u00a0and mathematical analyses were necessary to convince ourselves that the correspondence between cellular Raman spectra and omics profiles is real and has a firm foundation,” said\u00a0Kamei. “It’s\u00a0possible that by applying our method, we may be able to predict the early changes in cellular states associated with diseases and the molecular underpinnings that drive such changes.\u00a0It’s\u00a0also\u00a0important to dig deeper into how this pattern of protein ratios, which we call\u00a0stoichiometry\u00a0conservation,\u00a0emerges. It is\u00a0apparent\u00a0in cell types beyond\u00a0E.\u00a0coli, including human cells, so\u00a0it’s\u00a0intriguing and\u00a0likely important.”\u00a0<\/p>\n
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