UCLA researchers unlock protein key to harnessing regenerative power of blood stem cells

In this study, the authors showed that a cell surface protein called protein tyrosine phosphatase-sigma (PTP-sigma) regulates the critical process called engraftment, which is how HSCs start to grow and make healthy blood cells after transplantation. Mamle Quarmyne, a graduate student Chute’s lab and first author of the study, demonstrated that PTP-sigma is produced (expressed) on a high percentage of mouse and human HSCs. She showed further that genetic deletion of PTP-sigma in mice markedly increased the ability of HSCs to engraft in transplanted mice.  In a complementary study, Quarmyne demonstrated that selection of human blood HSCs which did not express PTP-sigma led to a 15-fold increase in HSC engraftment in transplanted immune-deficient mice. Taken together, these studies showed that PTP-sigma suppresses normal HSC engraftment capacity and targeted blocking of PTP-sigma can substantially improve mouse and human HSC engraftment after transplantation. Chute and colleagues showed further that PTP-sigma regulates HSC function by suppressing a protein, RAC1, which is known to promote HSC engraftment after transplantation.    “These findings have tremendous therapeutic potential since we have identified a new receptor on HSCs, PTP-sigma, which can be specifically targeted as a means to potently increase the engraftment of transplanted HSCs in patients,” said Chute, senior author of the study and professor of hematology/oncology and radiation oncology at UCLA. “...
Source: UCLA Newsroom: Health Sciences - Category: Universities & Medical Training Source Type: news