title: Altered regulation of CXCR4 expression during aging contributes to increased CXCL12-dependent chemotactic migration of CD4(+)  T cells.
abstract: Chemokine-dependent migration of T lymphocytes assures recirculation of naïve T cells to secondary lymphoid organs and tissue-specific trafficking of memory-effector T cells. Previous studies carried out in rodents have demonstrated age-associated modulation of the expression of chemokine receptors such as CXCR4 and CCR5; however, little is known about the molecular mechanisms that regulate receptor expression and turnover in T cells, during advancing age in humans. Our recent results demonstrating increased chemotactic migration in response to CXCL12 in CD4(+)  T cells obtained from the elderly, as compared to those from young donors, led us to hypothesize that increase in surface expression, because of altered endocytic regulation of CXCR4 on T cells during aging, might be directly responsible for increased migration toward CXCL12. Studies presented here demonstrate a significant increase in the surface expression of CXCR4 in CD4(+)  T cells from elderly human donors, relative to those from the young. Additionally, CXCL12-mediated endocytosis of CXCR4 was differentially regulated during aging, which could be attributed to alterations in the ubiquitination of CXCR4. Thus, altered ubiquitination of CXCR4 may contribute to the increased surface expression and enhanced T-cell migration to chemotactic stimuli in the elderly.
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Stefania
authors.initials: S
authors.lastname: Cané
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Ponnappan
authors.forename: Usha
authors.initials: U
authors.lastname: Ponnappan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D054377:Chemokine CXCL12 / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D008213:Lymphocyte Activation; D019713:Receptors, CCR5 / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors; D054875:Ubiquitination; D055815:Young Adult
chemical_list: C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D008024:Ligands; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; C509299:USP14 protein, human; D043222:Ubiquitin Thiolesterase