House keeping genes and gene expression analysis in transplant recipients: a note of caution.
BACKGROUND
House keeping genes are often used as a means of standardising results obtained in gene expression investigations. This study was performed to investigate whether beta-actin, beta2-microglobulin (two genes frequently quoted as house keeping genes) and/or transferrin receptor would be suitable house keeping genes for use in gene expression analysis of renal transplant recipients.


METHODS
Sequential expression of all three genes was measured in the peripheral blood mononuclear cells of 13 living donors and 45 renal transplant recipients, pre-operatively and then daily for up to 2 weeks. Fifteen of the recipients experienced an episode of biopsy proven acute rejection. Gene expression measurement was performed using quantitative real time 'TaqMan' PCR technology.


RESULTS
Gene expression of all three genes was unchanged in the living donor cohort. However, in the transplant recipients there were significant increases in expression following transplantation in the non-rejectors, and preceding the diagnosis of acute rejection. In the latter group, levels returned to pre-transplant values after the commencement of anti-rejection therapy.


CONCLUSIONS
Beta-actin, beta2-microglobulin and transferrin receptor gene expression, although not influenced by surgery, is influenced by transplantation, acute rejection and anti-rejection therapy making these genes unsuitable as house keeping genes following renal transplantation. These findings may cast doubt on the results of some studies that used these genes for the purposes of standardisation when looking at cDNA measurement. We suggest that any group wishing to use a house keeping gene ensure that its expression is independent of study parameters prior to the start of the study.
Gibbs
Paul J
PJ
Wessex Renal and Transplant Unit, St. Mary's Hospital, Milton Road, Portsmouth, PO3 6AD, UK. paulgibbs@torre.demon.co.uk
Cameron
Colin
C
Tan
Lam Chin
LC
Sadek
Sami A
SA
Howell
W Martin
WM
D000199:Actins / Q000235:genetics; D000328:Adult; D005260:Female; D015870:Gene Expression / Q000235:genetics*; D006084:Graft Rejection / Q000235:genetics; D006085:Graft Survival / Q000235:genetics; D006801:Humans; D016030:Kidney Transplantation; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D012313:RNA / Q000032:analysis / Q000235:genetics; D011990:Receptors, Transferrin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D001613:beta 2-Microglobulin / Q000235:genetics
D000199:Actins; D011990:Receptors, Transferrin; D001613:beta 2-Microglobulin; D012313:RNA