The detection of the cytomegalovirus DNA in the colonic mucosa of patients with ulcerative colitis is associated with increased long-term risk of proctocolectomy: results from an outpatient IBD clinic.

PURPOSE: Cytomegalovirus (CMV) infection has been found to be associated with a reactivation of ulcerative colitis (UC) and with an impaired response to medical therapy. In the past, only limited data were available on the long-term outcome for UC patients with positive tissue CMV-PCR in the colonic mucosa. METHODS: Between January 2010 and April 2015, we performed a qualitative PCR screening for CMV DNA in one biopsy from most actively inflamed rectal mucosa (tCMV-PCR). All tCMV-PCR-positive patients received 900 mg of valganciclovir b.i.d. for at least 15 days. We analyzed the association of the tCMV-PCR status with the time to steroid-free remission (SFR) and with the risk of proctocolectomy during the further course. RESULTS: One hundred eight consecutive patients (50 women, 58 men, median age 41 years, median UC duration 6 years) with active UC not responding to anti-inflammatory medication were analyzed. Eight of the 24 tCMV-PCR-positive patients (33.3%) compared to ten of the 84 tCMV-PCR-negative patients (11.9%) underwent proctocolectomy during a median follow-up of 52 months (p < 0.005). The median time from CMV diagnosis to colectomy was 501 days (median, interquartile range (IQR): 170, 902 days) in tCMV-PCR-positive and 958 days (IQR: 287, 1328 days) in tCMV-PCR-negative patients (p < 0.01). The median time to SFR was 126 days in tCMV-PCR-positive patients vs. 63 days in tCMV-PCR-negative patients (p < 0.01). CONCLUSIONS: The detection of the CMV DNA in the colonic mucosa of patients with active UC is associated with a longer time to steroid-free UC remission and with an increased rate and earlier need of proctocolectomy.

The retinal dehydrogenase/reductase retSDR1/DHRS3 gene is activated by p53 and p63 but not by mutants derived from tumors or EEC/ADULT malformation syndromes.

Retinol and its metabolites have important roles in many processes including embryonic development, cellular differentiation, apoptosis and maintenance of epithelia. Retinal short-chain dehydrogenase/reductase retSDR1, also known as dehydrogenase/reductase member 3 (DHRS3), is involved in maintaining the cellular supply of retinol metabolites. We observe that retSDR1 expression is activated by members of the p53 family. Particularly p53 and TAp63γ regulate transcription through two separate response elements in the retSDR1 promoter. Both proteins bind the promoter in vitro and in vivo. Induction of DNA damage leads to recruitment of p53 and p63 to the retSDR1 promoter. A tumor-derived p53 mutant is unable to activate retSDR1 transcription. As mutants of p63 in humans exhibit phenotypes that cause several autosomal dominantly inherited syndromes leading to developmental malformations, we tested the transcriptional response of TAp63γ mutants derived from the EEC, SHFM and ADULT syndromes. EEC syndrome-specific mutations of TAp63γ fail to transactivate retSDR1 and an ADULT syndrome-derived mutant stimulates retSDR1 transcription significantly less than the wild-type variant of p63. Taken together, the results suggest a potential role of the p53/p63-mediated retSDR1 activation in tumor suppression as well as in developmental processes.

Identification of two regulatory binding sites which confer myotube specific expression of the mono-ADP-ribosyltransferase ART1 gene.

BACKGROUND: Mono-ADP-ribosyltransferase (ART) 1 belongs to a family of mammalian ectoenzymes that catalyze the transfer of ADP-ribose from NAD+ to a target protein. ART1 is predominantly expressed in skeletal and cardiac muscle. It ADP-ribosylates alpha7-integrin which together with beta1-integrin forms a dimer and binds to laminin, a protein of the extracellular matrix involved in cell adhesion. This posttranslational modification leads to an increased laminin binding affinity. RESULTS: Using C2C12 and C3H-10T 1/2 cells as models of myogenesis, we found that ART1 expression was restricted to myotube formation. We identified a fragment spanning the gene 1.3 kb upstream of the transcriptional start site as the functional promoter of the ART1 gene. This region contains an E box and an A/T-rich element, two conserved binding sites for transcription factors found in the promoters of most skeletal muscle specific genes. Mutating the DNA consensus sequence of either the E box or the A/T-rich element resulted in a nearly complete loss of ART1 promoter inducibility, indicating a cooperative role of the transcription factors binding to those sites. Gel mobility shift analyses carried out with nuclear extracts from C2C12 and C3H-10T 1/2 cells revealed binding of myogenin to the E box and MEF-2 to the A/T-rich element, the binding being restricted to C2C12 and C3H-10T 1/2 myotubes. CONCLUSION: Here we describe the molecular mechanism underlying the regulation of the ART1 gene expression in skeletal muscle cells. The differentiation-dependent upregulation of ART1 mRNA is induced by the binding of myogenin to an E box and of MEF-2 to an A/T-rich element in the proximal promoter region of the ART1 gene. Thus the transcriptional regulation involves molecular mechanisms similar to those used to activate muscle-specific genes.

Transcriptional activation of the tumor suppressor and differentiation gene S100A2 by a novel p63-binding site.

S100A2 is generally found expressed in the epidermis and was recently shown to play a crucial role in the differentiation of keratinocytes. Also known as CaN19, S100A2 was identified as a potential tumor suppressor. Expression of S100A2 is upregulated by p53. The proteins p63 and p73 are related to p53 and are expressed as several splice variants with partially overlapping tasks but also functions different from p53. It had been shown that p63 proteins with mutations in their DNA-binding domain cause severe phenotypes in man as autosomal dominantly inherited disease including EEC, AEC, SHFM, LMS and ADULT syndromes. Here we show that S100A2 is a transcriptional target of p63/p73 family members, particularly the p63 splice variant TAp63gamma. The regulation is mediated by a novel transcriptional element in the S100A2 promoter which is bound by TAp63gamma but not by p53. Mutant p63 proteins derived from EEC and ADULT syndrome patients cannot activate S100A2 transcription whereas SHFM-related mutants still can stimulate the S100A2 promoter. Consistent with a function in tumor suppression S100A2 expression is stimulated upon DNA damage. After doxorubicin treatment p63gamma proteins are recruited to the S100A2 promoter in vivo. This may indicate a function of the p63-dependent S100A2 regulation in tumor suppression.

Gene expression of cyclin-dependent kinase subunit Cks2 is repressed by the tumor suppressor p53 but not by the related proteins p63 or p73.

Cks2 proteins are essential components of cyclin/cyclin-dependent kinase complexes and contribute to cell cycle control. We identify Cks2 as a transcriptional target downregulated by the tumor suppressor p53. Cks2 expression was found to be repressed by p53 both at the mRNA and the protein levels. p53 downregulates transcription from the Cks2 promoter in a dose-dependent manner and in all cell types tested. This repression appears to be independent of p53 binding to the Cks2 promoter. In contrast to p53, neither p63 nor p73 proteins can repress Cks2 transcription. Thus p53, rather than its homologues p63 and p73, may contribute to control of the first metaphase/anaphase transition of mammalian meiosis by downregulation of Cks2 expression.

Expression of cyclin-dependent kinase subunit 1 (Cks1) is regulated during the cell cycle by a CDE/CHR tandem element and is downregulated by p53 but not by p63 or p73.

Cks1 is a member of the cyclin-dependent kinase subunit family. These proteins are essential components of cyclin/cyclin-dependent kinase (cdk) complexes contributing to cell cycle control in all eukaryotes. Cks1 protein is found overexpressed in a number of tumors. Expression of Cks1 mRNA starts in late G1 reaching a peak in S/G2-phases of the cell cycle. We find that this expression pattern depends on transcriptional regulation and is controlled by a combination of a cell cycle-dependent element (CDE) together with a cell cycle genes homology region (CHR) in the Cks1 promoter. Furthermore, we observe Cks1 mRNA and protein to be downregulated after induced expression of the tumor suppressor p53. This repression is due to p53 downregulating transcription from the Cks1 promoter. p53-dependent repression is seen in a dose-dependent manner and in several cell types of different origin. In contrast to p53, its homologues p63 and p73 do not significantly repress transcription from the Cks1 promoter. The Cks1 promoter does not contain a p53 binding site. For some promoters the CCAAT box-binding transcription factor NF-Y had been implicated in p53-dependent repression. NF-Y is the main activator for Cks1 transcription but does not influence p53-dependent repression from the Cks1 promoter. Generally, the observation that the potential oncogene Cks1 is downregulated by the tumor suppressor p53 corresponds well with the idea that p53 employs multiple ways in order to halt the cell cycle.