Protein tyrosine phosphatase-? regulates hematopoietic stem cell-repopulating capacity.

ABSTRACT: Hematopoietic stem cell (HSC) function is regulated by activation of receptor tyrosine kinases (RTKs). Receptor protein tyrosine phosphatases (PTPs) counterbalance RTK signaling; however, the functions of receptor PTPs in HSCs remain incompletely understood. We found that a receptor PTP, PTP?, was substantially overexpressed in mouse and human HSCs compared with more mature hematopoietic cells. Competitive transplantation of bone marrow cells from PTP?-deficient mice revealed that the loss of PTP? substantially increased long-term HSC-repopulating capacity compared with BM cells from control mice. While HSCs from PTP?-deficient mice had no apparent alterations in cell-cycle status, apoptosis, or homing capacity, these HSCs exhibited increased levels of activated RAC1, a RhoGTPase that regulates HSC engraftment capacity. shRNA-mediated silencing of PTP? also increased activated RAC1 levels in wild-type HSCs. Functionally, PTP?-deficient BM cells displayed increased cobblestone area-forming cell (CAFC) capacity and augmented transendothelial migration capacity, which was abrogated by RAC inhibition. Specific selection of human cord blood CD34?CD38?CD45RA?lin? PTP?? cells substantially increased the repopulating capacity of human HSCs compared with CD34?CD38?CD45RA?lin? cells and CD34?CD38?CD45RA?lin?PTP?? cells. Our results demonstrate that PTP? regulates HSC functional capacity via RAC1 inhibition and suggest that selecting for PTP?-negative human HSCs may be an effective strategy for enriching human HSCs for transplantation.

SUBMITTER: Quarmyne M 

PROVIDER: S-EPMC4382260 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature