title: Impaired telomerase activity in uninfected haematopoietic progenitors in HIV-1-infected patients.
abstract: BACKGROUND
  Haematopoietic progenitor cells (HPC) of HIV-1-infected patients are severely compromised in their replication and clonogenic capacities, and show an enhanced propensity to apoptosis, despite the lack of productive or latent HIV-1 infection.
  
  
  OBJECTIVE
  To investigate telomerase enzyme levels in CD34+ HPC isolated from HIV-1-infected patients, because the absence of telomerase activity has been found to be correlated with a diminished replication potential.
  
  
  METHODS
  Telomerase levels were measured by a PCR-based telomeric repeat amplification protocol. CD34+ HPC isolated from the peripheral blood of 11 HIV-1-infected patients were compared with CD34+ HPC isolated from peripheral blood (nine subjects) or bone marrow (six subjects) from 15 healthy donors. Telomerase levels were also studied in normal HPC after exposure to either gp120 or transforming growth factor (TGF)-beta1.
  
  
  RESULTS
  CD34+ HPC isolated from either peripheral blood or bone marrow from healthy donors expressed a high level of telomerase activity. On the contrary, CD34+ HPC isolated from HIV-1-seropositive patients did not express any detectable telomerase activity in nine patients, and a clearly reduced enzymatic activity in two patients. Furthermore, telomerase activity in normal CD34+ HPC exposed to recombinant gp120 was significantly reduced, and to a higher extent than in CD34+ HPC exposed to recombinant TGF-beta1.
  
  
  CONCLUSIONS
  This is the first study to demonstrate severely impaired telomerase activity in uninfected CD34+ HPC isolated from HIV-1-infected patients. The mechanism underlying this impairment probably involves the interaction of HIV-1 envelope glycoprotein gp120 with the cell membrane. These results may add to our understanding of the pathogenesis of the lesion of the HPC compartment.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Vignoli
authors.forename: B
authors.initials: B
authors.lastname: Stecca
authors.forename: G
authors.initials: G
authors.lastname: Furlini
authors.forename: M C
authors.initials: MC
authors.lastname: Re
authors.forename: V
authors.initials: V
authors.lastname: Mantovani
authors.forename: G
authors.initials: G
authors.lastname: Zauli
authors.forename: G
authors.initials: G
authors.lastname: Visani
authors.forename: V
authors.initials: V
authors.lastname: Colangeli
authors.forename: M
authors.initials: M
authors.lastname: La Placa
mesh_terms: D000328:Adult; D018952:Antigens, CD34; D005260:Female; D015699:HIV Envelope Protein gp120 / Q000378:metabolism / Q000494:pharmacology; D006679:HIV Seropositivity / Q000097:blood / Q000201:enzymology* / Q000235:genetics; D015497:HIV-1; D006367:HeLa Cells; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018952:Antigens, CD34; D015699:HIV Envelope Protein gp120; D016212:Transforming Growth Factor beta; D019098:Telomerase