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Biomedical subjects

T Oehler

Publications and source records attributed to T Oehler.

9 recordsLinked to original sources
PubMed2002

Fatal sepsis in an AIDS patient during therapy for Pneumocystis carinii pneumonia.

The case of a patient with a newly diagnosed HIV infection and Pneumocystis carinii pneumonia is presented. Despite treatment with high-dose trimethoprim/sulfamethoxazole (TMP/SMX) and prednisone with initial improvement, the patient acutely deteriorated with severe acidosis and died on the 4th day of hospitalization. Cryptococcus neoformans grew the next day in broncheoalveolar lavage (BAL) and blood culture. As simultaneous presence of more than one opportunistic infection can occur in these patients, systematic workup for other common opportunistic infections must be performed.

AIDS-Related Opportunistic Infections↗
PubMed2000

[Advice to HIV infected persons travelling to tropical or subtropical destinations].

Many HIV-infected persons travel from temperate zones to (sub)tropical destinations. HIV-specific immigration issues, medical resources abroad and problems regarding travel with multiple medication need to be anticipated. When prescribing immunisations and specific chemoprophylaxis, the stage of immunodeficiency as well as drug interactions with antiretrovirals must be taken into account. Live vaccines may be contraindicated. With good pretravel advice the risk of severe health problems is low for most HIV-infected travellers.

Anti-HIV Agents↗
PubMed1995

Stimulation of c-Jun activity by CBP: c-Jun residues Ser63/73 are required for CBP induced stimulation in vivo and CBP binding in vitro.

The CBP protein mediates PKA induced transcription by binding to the PKA phosphorylated activation domain of CREB. Here we show that CBP also stimulates the activity of both c-Jun and v-Jun in vivo. The CREB binding domain of CBP is sufficient to contact to c-Jun in vitro. When this domain of CBP is linked to the activation domain of VP16 and expressed in vivo it stimulates c-Jun dependent transcription. Deletion analysis of c-Jun indicate that the CBP binding site is within the N-terminal activation domain. Loss of binding to CBP in vitro correlates with severely reduced transactivation capacity in vivo. Mutation of Ser63/73 in c-Jun, or the corresponding position in v-Jun (Ser36/46) leads to reduced binding to CBP in vitro and abolishes augmentation of transcription in vivo. These data are consistent with a mechanism by which CBP acts as a co-activator protein for Jun dependent transcription by interacting with the Jun N-terminal activation domain.

Binding Sites↗
PubMed1995

A switch region determines the cell type-specific positive or negative action of YY1 on the activity of the human papillomavirus type 18 promoter.

YY1 is a zinc finger transcription factor which acts as either a repressor or an activator dependent on the promoter context. YY1 is a potent activator of the genuine human papillomavirus type 18 (HPV-18) upstream regulatory region (URR) in HeLa cells, which are known for high-level expression of the HPV-18 early genes. The activating activity of YY1 is dependent on the presence of a newly identified switch region located upstream of the YY1 binding site. Deletion of this region causes YY1 to act as a repressor of HPV-18 promoter activity. In vivo footprinting of the HPV-18 URR and an in vitro electrophoretic mobility shift assay identified proteins binding to the switch region. Site-directed mutagenesis of the switch region and YY1 binding sites suggests that these two regions work in concert to yield high-level HPV-18 URR activity in HeLa cells but not in HepG2 cells, where HPV-18 is almost inactive. These data identified a novel mode of cell type-specific regulation of HPV-18 promoter activity by positive or negative action of YY1, determined by the switch region binding factor(s).

Base Sequence↗
PubMed1993

Mutation of a phosphorylation site in the DNA-binding domain is required for redox-independent transactivation of AP1-dependent genes by v-Jun.

The ability of the nuclear oncoprotein Jun to activate transcription is controlled both by level of DNA binding and by the activity of its transactivation domain. Control of DNA binding is achieved by two mechanisms: phosphorylation and redox regulation. Mutation of Ser-226 inhibits phosphorylation of the DNA binding, resulting in enhanced DNA-binding and transactivation activity of Jun. In contrast, mutation of Cys-252, which is the target for repression of DNA-binding activity under oxidative conditions, results in a strong decrease of Jun-specific activation of transcription. However, transactivation by c-Jun-Cys-252 is fully restored upon mutation of Ser-226. Both mutations are also found in the oncogenic counterpart of c-Jun, v-Jun, and are the only differences between these proteins in the DNA-binding domain, suggesting that v-Jun escapes down-modulation of DNA binding by both mechanisms. However, inhibition of phosphorylation of Ser-226 is absolutely required for the ability of v-Jun to activate transcription of AP-1-dependent genes in a redox-independent manner.

Animals↗
PubMed1992

A common intermediary factor (p52/54) recognizing "acidic blob"-type domains is required for transcriptional activation by the Jun proteins.

The ability of the c-Jun protein, the main component of the transcription factor AP1, to interact directly or indirectly with the RNA polymerase II-initiation complex to activate transcription was investigated by in vivo transcription interference ("squelching") experiments. Coexpression of a Jun mutant lacking its DNA binding domain strongly represses the activity of wild-type c-Jun. Repression depends on the presence of the transactivation domains (TADs), suggesting that a limiting factor interacting with the TADs is essential to link Jun and the components of the transcriptional machinery. The activity of this intermediary factor(s) is restricted to TADs characterized by an abundance of negatively charged amino acids, as demonstrated by the abilities of the TADs of JunB, GAL4, and VP16 to repress c-Jun activity. Depending on the presence of the TADs of Jun, we found physical interaction between Jun and a cluster of three proteins with molecular masses of 52, 53, and 54 kDa (p52/54). Association between Jun and p52/54 is strongly reduced in the presence of VP16, suggesting that the two proteins compete for binding to p52/54. Transcription factors containing a different type of TAD (e.g., GHF1, estrogen receptor, or serum response factor) fail to inhibit Jun activity, suggesting that these proteins act through a different mechanism. We consider the requirement of Jun to interact with p52/54 utilized by other transcription factors a new mechanism in the regulation of transcription of Jun-dependent target genes.

Base Sequence↗
PubMed1990

Characterization of the v-myb DNA binding domain.

The transforming protein encoded by the v-myb oncogene is a sequence-specific DNA-binding protein that is thought to be involved in the regulation of gene expression. The N-terminal region of the v-myb protein is composed of two highly conserved tandem repeat sequences of unknown function. It has been speculated that the N-terminal v-myb repeats might be crucial for DNA-binding, since N-terminal deletions destroy the DNA-binding activity of the v-myb protein. Here, we have studied the v-myb DNA-binding domain in more detail. Our results show that the N-terminal region of the v-myb protein is sufficient for specific DNA-binding. Dissection of this region suggests that both repeats are required for DNA-binding, but that both repeats play different roles in v-myb protein DNA interaction. We also show that the myb repeats of a drosophila melanogaster homolog of c-myb function as sequence-specific DNA-binding domain. Our results support the view that specific sequence-recognition, mediated by the conserved myb repeats, is a general feature of myb-related proteins.

Animals↗