Critical residues of the homeodomain involved in contacting DNA bases also specify the nuclear accumulation of thyroid transcription factor-1

The N-terminal end of thyroid transcription factor-1 (TTF-1) homeodomain is composed of a stretch of five basic amino-acids that is conserved in both POU- and NK2-class homeodomains and constitutes a functional nuclear localization signal. By analyzing the cellular distribution of fusion proteins, composed of a jellyfish green fluorescent variant and different parts of TTF-1, we show here that the presence of this basic sequence is not sufficient by itself to confer complete nuclear accumulation. By mutagenesis, we identified a second region located in the center of the DNA recognition helix of the homeodomain that is also able to specify a predominantly nuclear localization of the chimeric proteins, independently of the presence of the basic NLS. The destruction, by mutagenesis, of both the basic stretch and the motif in the DNA recognition helix led to the total loss of nuclear accumulation, indicating that complete nuclear accumulation of TTF-1 results from the concerted action of these two proteic signals. Both of the regions of the homeodomain that are involved in nuclear targeting also encompass critical amino-acids responsible for DNA binding site recognition, as evidenced by the loss of DNA binding activity in vitro upon mutagenesis. Specifically, residues in the central part of the DNA recognition helix are involved in contacting bases in the major groove of DNA and are the most conserved in homeodomain proteins, suggesting that this part of the homeodomain could play a general role in the nuclear localization of members of this family of proteins.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Subfertility guidelines in Europe: the quantity and quality of intrauterine insemination guidelines.

Contains fulltext : 50449.pdf (publisher's version ) (Closed access)BACKGROUND: International collaboration could facilitate systematic development of guidelines to regulate and improve clinical practice. To promote European collaboration in guideline development in reproductive medicine, insight into existing subfertility guidelines in Europe is essential. The study aim was to explore the number and quality of clinical practice guidelines on homologous intrauterine insemination (IUI) in Europe. METHODS: To identify IUI guidelines in Europe, electronic databases and Internet were systematically searched and key experts on assisted reproduction in 25 European countries were questioned. The quality of IUI guidelines was systematically assessed with the internationally validated Appraisal of Guidelines for Research and Evaluation (AGREE) Instrument. Qualitative methods were used to appraise IUI guideline recommendations and references. RESULTS: National guidelines on IUI are available in four of 25 European countries. The quality of IUI guidelines in Europe is moderate to high, but the recommendations and references differ considerably. CONCLUSIONS: The number of IUI guidelines in Europe is surprisingly small, and differences in their recommendations and references are considerable. To overcome these deficiencies in clinical guidance on IUI care in Europe, a central body with expertise in up-to-date guideline development methodology and sufficient resources could be established in Europe for central selection and international exchange of evidence to support guideline recommendations