This mouse can't keep a secret about the “secretome”

The “secretoma” refers to the proteins which are secreted by a cell, a tissue or an organism. In a new study published in Open Up Biology, Andy McMahon, scientist on the stem cells of the USC, and his collaborators present an elegant new way of labeling and studying the secretomity in a living organism.

“The secretoma orchestra The subtle and complex processes of embryonic development, maintains the function of the individual organs and coordinates the activity of the organs thanks to the inter-organization interaction”, said McMahon, president of the Biology Department of Stem Cells and Regenerative Medicine at the USC. “However, it can be difficult to know which cells are secreting proteins and which cells are being targeted.”

To address this challenge, co-first authors Rui Yang and Amanda S. Meyer at the USC and Ilia A. Droujinine formerly at the Harvard Health Care Faculty and now Scripps Analysis have generated mice with an integrated system to label and follow the secreto.

“This integrated system is like a ‘passport system in the body, because we identify where proteins come from and where they go,'” said Druzhinin, who is a Scripps Investigation researcher and principal investigator in the Department of Molecular Research. Medicine.

To establish this system, the research team began by genetically editing mice embryonic stem cells to code an enzyme designed in the Alice Ting laboratory ‘Stanford University. The enzyme, BIRA*G3, marks neighboring proteins without difference with the derivative of vitamin B7, biotin. The reason biotin is a useful tag is that it binds tightly to the protein streptavidin, so biotin-tagged proteins can be separated from other proteins in the cell and blood using a readily available technology called “affinity purification of streptavidin”.

The next step was to ensure that BirA*G3 specifically labeled only the proteins in the secretome. These proteins come from a framework inside the cell known as the endoplasmic reticulum, or ER. Some of these proteins remain in the re, while others are either secreted or incorporated into the surrounding membrane of the cell.

to specifically mark these proteins, BIRA *G3 has itself been marked with four additional protein construction blocks, or peptides. These four peptides, known as Kdel, served as a signal to the cell to retain BIRA*G3 in the RE. Thus, when biotin was added, BirA*G3 only added biotin markers to proteins traveling through the ER.

using these genetically modified stem cells, the team then produced transgenic mice. When these mice were given biotin, the scientists were able to demonstrate BirA*G3 labeling and identify secretomes from a number of organs, including the brain, liver and kidneys. Scientists also identified proteins that were in any case secreted, even if they were not marked with the typical signal indicating that the cell should secrete them.

These transgenic mice allow Scientists to label and study specific cell spells and organs, thus facilitating inter-organization interaction studies.

“Our new mouse model demonstrates efficiency enhanced labeling of secreted and ER proteins in specific cell types, providing a valuable resource for secretome mapping and profiling,” said Meyer, who is a McMahon Lab doctoral student at the Eli and Edythe Broad Center for Regenerative Medicine. and research on stem cells at the USC.

Yang, postdoctoral researcher at McMahon Lab, added: “Our mouse model will facilitate a better understanding of the critical role of the secretory in development, as well as in healthy and diseased adult states.”

The mice are now in a community repository, so that other scientists can benefit from this new technology.

“Given the central role of key secreted proteins such as insulin, there is great interest in The identification of new secreted proteins, ”said McMahon. “Genome studies suggest that there are many new proteins to characterize. We look forward to a deep dive into this area now that we have validated the technology.

Additional co-authors include: Jinjin Guo and Jill A. McMahon of USC Namrata D. Udeshi, Dominique K. Carey, Charles Xu and Steven A. Carr of the Wide Institute of Harvard and Mit Yanhui Hu and David Rocco of the Harvard Healthcare School Norbert Perrimon of the Harvard Health-Related School and Howalth Care Hughes Health Care Qiao Fang Institute of University of Toronto Jihui Sha and James Wohlschlegel of UCLA Shishang Qin of Peking University and Alice Y. Ting of Chan Zuckerberg Biohub and Stanford University.

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