Identification of vitamin D receptor as a target of p63

p63, a p53 homolog has been shown to play a role in development and cancer. p63 is essential for both commitment of ectoderm to stratified epithelia and for the proliferative potential of epithelial stem cells. p63 knockout mice are born with severe development defects and lack organs of epithelial origin. In addition, p63 has also been shown to play a role in cancer development through the differential regulation of genes with tumor suppressor function and genes involved in metastasis. In order to understand the role of p63 in cancer and development, genes that are specifically regulated by p63 but not p53 were identified. In this study, we provide evidence that p63gamma specifically upregulates vitamin D Receptor (VDR). In contrast, p53 does not appear to be involved in upregulation of VDR expression. Additionally, we demonstrate that a naturally occurring p63 missense mutant, p63gamma (R279H) and p14(ARF), both act in a dominant negative manner to inhibit p63gamma-mediated upregulation of VDR. Furthermore, using chromatin immunoprecipitation assays, we demonstrated that p63 directly binds to the VDR promoter in vivo. Our findings clearly demonstrate that VDR is a direct target of p63 and suggests that p63 may play a role in cancer and differentiation through modulation of the VDR pathway.

Human herpesvirus 6 infection and associated pathogenesis following bone marrow transplantation

Human herpesvirus 6 (HHV-6) infections following bone marrow transplantation (BMT) have been shown to be associated with fever, skin rash, graft versus host disease, encephalitis, delay in engraftment, marrow suppression, and pneumonia. Unfortunately several of these studies were case reports and although the results were suggestive they prompted us to study these pathological events systematically. These associations were primarily based on either HHV-6 isolation, HHV-6 DNA detection, antigen detection or increases in HHV-6 specific antibodies. HHV-6 activity was more frequent during the post- rather than the pre-transplantation period. All HHV-6 isolates from BMT patients have been shown to be variant B. A better understanding of HHV-6 associated pathogenesis gained by larger prospective trials is needed to facilitate proper treatment of cases of idiopathic illnesses or those associated with symptoms (fever, skin rash) similar to those caused by HHV-6.

Human herpesvirus 6: infection and disease following autologous and allogeneic bone marrow transplantation

Human herpesvirus 6 activity (HHV-6) was studied in 15 allogeneic and 11 autologous marrow transplantation patients. After transplantation, HHV-6 was isolated from the peripheral blood mononuclear cells of 12 of 26 patients (6 allogeneic and 6 autologous). All isolates were variant B. Eleven of 26 and 12 of 19 patients showed salivary shedding of HHV-6 DNA before and after transplantation, respectively. The antibody titer increased in 7 of 26 patients. Thus, 23 of 26 patients showed evidence of active HHV-6 infection either by virus isolation, salivary shedding, or increases in antibody titers. The fraction of saliva specimens positive in 19 patients was negatively associated with their antibody titers (P= .005). The proportion of cultures positive increased after transplantation (P = .007). Sinusitis was associated with HHV-6 isolation in autologous recipients (P= .002). In allogeneic patients, active human cytomegalovirus infection was associated with HHV-6 isolation (P = .04). No association was observed between HHV-6 infection and GVHD, pneumonia, delay in engraftment, or marrow suppression. Of the 120 clinical events analyzed in 26 patients, HHV-6 was defined as a probable cause of 16 events in 9 patients based on the propinquity of HHV-6 activity and the clinical event plus the absence of other identified causes of the event.