The retinoic acid-inducible transcription factor AP-2 is expressed in epithelial and neural crest cell lineages during murine development. AP-2 can regulate neural and epithelial gene transcription, and is associated with overexpression of c-erbB-2 in human breast-cancer cell lines. To ascertain the importance of AP-2 for normal development, we have derived mice containing a homozygous disruption of the AP-2 gene. These AP-2-null mice have multiple congenital defects and die at birth. In particular, the AP-2 knockout mice exhibit anencephaly, craniofacial defects and thoraco-abdominoschisis. Skeletal defects occur in the head and trunk region, where many bones are deformed or absent. Analysis of these mice earlier in embryogenesis indicates a failure of cranial neural-tube closure and defects in cranial ganglia development. We have shown that AP-2 is a fundamental regulator of mammalian craniofacial development.

[Key Words: Enhancer factor; in vitro and in vivo transcription; DNA binding; teratocarcinoma differentiation; Drosophila expression system]

[Key Words: Enhancer factor~ DNA binding~ dimerization; mammalian expression~ proline-rich activator~ palindromic binding site]

Morphogenesis of mammalian facial processes requires coordination of cellular proliferation, migration, and apoptosis to develop intricate features. Cleft lip and/or palate (CL/P), the most frequent human craniofacial birth defect, can be caused by perturbation of any of these programs. Mutations of WNT, P63, and IRF6 yield CL/P in humans and mice; however, how these genes are regulated remains elusive. We generated mouse lines lacking Pbx genes in cephalic ectoderm and demonstrated that they exhibit fully penetrant CL/P and perturbed Wnt signalling. We also characterized a midfacial regulatory element that Pbx proteins bind in order to control the expression of Wnt9b-Wnt3, which in turn regulate p63. Altogether, we establish a Pbx-dependent Wnt-p63-Irf6 regulatory module in midfacial ectoderm that is conserved within mammals. Dysregulation of this network leads to localized suppression of midfacial apoptosis and CL/P. Ectopic Wnt ectodermal expression in Pbx mutants rescues the clefting, opening avenues for tissue repair.

Measurement of exercise capacity is an integral element in assessment of patients with cardiopulmonary disease. The 6-min walk test (6MWT) provides information regarding functional capacity, response to therapy and prognosis across a range of chronic cardiopulmonary conditions. A distance less than 350 m is associated with increased mortality in chronic obstructive pulmonary disease, chronic heart failure and pulmonary arterial hypertension. Desaturation during a 6MWT is an important prognostic indicator for patients with interstitial lung disease. The 6MWT is sensitive to commonly used therapies in chronic obstructive pulmonary disease such as pulmonary rehabilitation, oxygen, long-term use of inhaled corticosteroids and lung volume reduction surgery. However, it appears less reliable to detect changes in clinical status associated with medical therapies for heart failure. A change in walking distance of more than 50 m is clinically significant in most disease states. When interpreting the results of a 6MWT, consideration should be given to choice of predictive values and the methods by which the test was carried out.

No abstract

The treatment of Epstein-Barr virus (EBV)-associated lymphoproliferative disease (PTLD) in EBV seronegative solid organ transplant recipients who acquire their EBV infection after engraftment poses a considerable challenge because of underlying immunosuppression that inhibits the virus-specific cytotoxic T cell (CTL) response in vivo. We have developed a protocol for activating autologous EBVspecific CTL lines from these patients and show their potential use for immunotherapy against PTLD in solid organ transplant patients. Peripheral blood mononuclear cells from a panel of solid organ transplant recipients with and without active PTLD were used to assess EBV-specific memory CTL responses. The activation protocol involved cocultivation of peripheral blood mononuclear cells with an autologous lymphoblastoid cell line under conditions that favored expansion of virus-specific CTL and hindered the proliferation of allospecific T cells. These CTL consistently showed (i) strong EBV-specificity, including reactivity through defined epitopes in spite of concurrent immunosuppressive therapy, and (ii) no alloreactivity toward donor alloantigens. More importantly, adoptive transfer of these autologous CTLs into a single patient with active PTLD was coincident with a very significant regression of the PTLD. These results demonstrate that a potent EBV-specific memory response can be expanded from solid organ recipients who have acquired their primary EBV infection under high levels of immunosuppressive therapy and that these T cells may have therapeutic potential against PTLD.

The simian virus 40 (SV40) transcriptional enhancer is composed of multiple cis-acting DNA sequence motifs, each individually having a two- to fourfold effect on the efficiency of transcription. When various distinct cis-elements act in combination, however, a dramatic enhancement of transcription initiation often results. SV40-enhancer A-domain sequences were previously shown to be important for early and late transcription in vivo. Here we report the isolation of the enhancer binding factor AP-4, which recognizes a motif in this domain. Purified AP-4 activates SV40 late transcription in vitro, and this stimulation is augmented by the addition of transcription factor AP-1 which binds to adjacent sequences in the A-domain, suggesting coordinate action of the two factors for transcriptional enhancement. AP-1 also represses late transcription from a major in vitro start site which is poorly used in vivo, indicating that AP-1 can act as both a positive and negative regulator of SV40 late transcription. Thus by manipulating the levels of different trans-acting factors in vitro, we can recreate the pattern of SV40 late initiation observed during the viral lytic cycle in vivo.