title: The role of dipeptidyl peptidase 4 in hematopoiesis and transplantation.
abstract: OBJECTIVE
  Dipeptidyl peptidase 4 (DPP4, CD26) is a protease that cleaves selected amino acids at the N-terminal penultimate position and has the potential to alter the protein function. The regulation and roles of DPP4 activity are not well understood; therefore, the purpose of this review is to discuss the recent literature regarding DPP4 regulation, as well as the variety of molecules it may affect, and their potential clinical applications.
  
  
  RESULTS
  Recent insight into the number of proteins that have DPP4 sites, and how DPP4 truncation may alter hematopoiesis based on the protein full length vs. truncated state, has shown that DPP4 truncation of colony-stimulating factors (CSFs) alters their function and that the activity of these CSFs can be enhanced when DPP4 activity is inhibited. DPP4 inhibition has recently been used in a clinical trial to attempt to enhance the engraftment of cord blood cells, and an endogenous DPP4 inhibitor tissue factor pathway inhibitor has been discovered, increasing our understanding of the potential importance of DPP4.
  
  
  CONCLUSIONS
  DPP4 plays a role in regulating the activity of CSFs and other cytokines involved in hematopoiesis. This information may be useful for enhancing hematopoietic cell transplantation, blood cell recovery after stress, and for understanding the physiology and pathophysiology of blood and other cell systems.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5181, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: O'Leary
authors.forename: Xuan
authors.initials: X
authors.lastname: Ou
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D003115:Colony-Stimulating Factors / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000502:physiology*; D054873:Dipeptidyl-Peptidase IV Inhibitors; D006410:Hematopoiesis / Q000502:physiology*; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans
chemical_list: D003115:Colony-Stimulating Factors; D054873:Dipeptidyl-Peptidase IV Inhibitors; D018819:Dipeptidyl Peptidase 4