Dinucleotide polymorphisms present in the 5'-flanking region of the human H2 relaxin gene, but not in the corresponding region of the H1 gene.

Relaxin is a peptide hormone that, in humans, is encoded by two genes referred to as H1 and H2, both located into chromosome 9p24.1. We have searched for polymorphisms in the 5'-flanking sequence of these genes. Both genes possess a CT repeat followed by a GT repeat. CT and GT repeats of the H2 gene are longer than those of the H1 gene. Moreover, CT and GT repeats of the H2 gene, but not those of the H1 gene, show length polymorphism. Protein-DNA interaction experiments suggest that difference between the H1 and H2 GT repeats may have arisen because the requirements of the transcriptional regulation of the two genes are different.

Missense mutations of human homeoboxes: A review.

The homeodomain (encoded by the homeobox) is the DNA-binding domain of a large variety of transcriptional regulators involved in controlling cell fate decisions and development. Mutations of homeobox-containing genes cause several diseases in humans. A variety of missense mutations giving rise to human diseases have been described. These mutations are an excellent model to better understand homeodomain molecular functions. To this end, homeobox missense mutations giving rise to human diseases are reviewed. Seventy-four independent homeobox mutations have been observed in 17 different genes. In the same genes, 30 missense mutations outside the homeobox have been observed, indicating that the homeodomain is more easily affected by single amino acids changes than the rest of the protein. Most missense mutations have dominant effects. Several data indicate that dominance is mostly due to haploinsufficiency. Among proteins having the homeodomain as the only DNA-binding domain, three "hot spot" regions can be delineated: 1) at codon encoding for Arg5; 2) at codon encoding for Arg31; and 3) at codons encoding for amino acids of recognition helix. In the latter, mutations at codons encoding for Arg residues at positions 52 and 53 are prevalent. In the recognition helix, Arg residues at positions 52 and 53 establish contacts with phosphates in the DNA backbone. Missense mutations of amino acids that contribute to sequence discrimination (such as those at positions 50 and 54) are present only in a minority of cases. Similar data have been obtained when missense mutations of proteins possessing an additional DNA-binding domain have been analyzed. The only exception is observed in the POU1F1 (PIT1) homeodomain, in which Arg58 is a "hot spot" for mutations, but is not involved in DNA recognition.

ApeI/Ref-I expression and cellular localization in human thyroid carcinoma cell lines.

For its DNA repair, transcription factor regulation and anti-apoptotic activity, the apurinic/apirimidinic ApeI/Ref-I endonuclease is thought to play a relevant role in human tumorigenesis. In human thyroid tumors, we demonstrated an altered nuclear/cytoplasmic ratio in all the carcinomas examined but not in follicular adenomas. In this study, Ref-I expression and cellular localization were analyzed in a series of human thyroid carcinoma cell lines. We found a reduced nuclear/cytoplasmic ratio in BCPAP, TPC I and ARO cells and not in WRO cells. Such a pattern of expression corresponds to that observed in thyroid tumoral tissues except for the WRO cells which behave as the follicular adenomas rather than carcinomas. Thus, these cell lines represent an excellent in vitro model to analyze the molecular mechanisms involved in Ref-I regulation and activity and clarify its role in thyroid tumorigenesis.

TSH controls Ref-1 nuclear translocation in thyroid cells.

Ref-1 (called also APE) is a bifunctional protein playing a role in a large variety of cell functions. It is a major member of the DNA base excision repair system. Moreover, through reduction of cysteine residues, Ref-1 controls the activity of several transcription factors. It has been previously demonstrated that TSH up-regulates Ref-1 gene expression in thyroid cells. By using the rat FRTL-5 cell line, we demonstrate that TSH controls Ref-1 intracellular localization. Western blot experiments indicate that addition of TSH to the culture medium increases the Ref-1 cytoplasm-to-nucleus translocation. This phenomenon occurs at early times of TSH stimulation and is not dependent on protein neosynthesis. The Ref-1 cellular compartmentalization was also investigated in human thyroid tumors. A Ref-1 nuclear/cytoplasmic ratio difference between normal and cancerous thyroid tissues was observed. These results suggest that Ref-1 localization may have a critical role in the control of thyroid cell functions.

Expression and function of the homeodomain-containing protein Hex in thyroid cells.

The homeodomain-containing protein Hex (also named Prh) is expressed in primitive endoderm (during the early phases of development), in some endoderm-derived tissues and in endothelial and hematopoietic precursors. Hex expression is exting-uished during terminal differentiation of endothelial and hematopoietic cells as well as in adult lung. Previous investigations have demonstrated that Hex is expressed during early thyroid gland development. No information has been reported on Hex expression in adult thyroid gland or on the function of this protein in follicular thyroid cells. These issues represent the focus of the present study. We demonstrate that Hex mRNA is present in rat and human adult thyroid gland as well as in differentiated follicular thyroid cell lines. In FRTL-5 cells TSH reduces Hex expression. In thyroid cell lines transformed by several oncogenes Hex expression is completely abolished. By using co-transfection assays we demonstrate that Hex is a repressor of the thyroglobulin promoter and that it is able to abolish the activating effects of both TTF-1 and Pax8. These data would suggest that Hex may play an important role in thyroid cell differentiation. Protein-DNA interaction experiments indicate that Hex is able to bind sites of the thyroglobulin promoter containing either the core sequence 5'-TAAT-3' or 5'-CAAG-3'. The DNA binding specificity of the Hex homeodomain, therefore, is more 'relaxed' than that observed in the majority of other homeo-domains.

Expression of Pax-8, p53 and bcl-2 in human benign and malignant thyroid diseases.

BACKGROUND: Immunohistochemical expression of the transcription factor Pax-8 in human thyroid diseases has never been investigated. The relationship between Pax-8, bcl-2 and p53 in thyroid neoplasms is also matter of interest. MATERIALS AND METHODS: Seventy-three thyroid tissue samples were evaluated for the expression of Pax-8, p53 and bcl-2 using the immunoperoxidase technique. The series included 11 follicular adenomas, 11 goitres, 23 papillary carcinomas, 16 follicular carcinomas, 6 undifferentiated carcinomas and 6 medullary carcinomas. RESULTS: The percentage of Pax-8 positive cells ranged from 14.9 to 27.1% and 10.1 to 39% in goitres and follicular adenomas, respectively. Among differentiated carcinomas, follicular histotype showed a Pax-8 immunoreactivity ranging from 0 to 26.5% of the neoplastic cells whereas in papillary carcinomas the percentage of positive cells ranged from 0 to 16.8%. None out of the six undifferentiated carcinomas showed Pax-8 immunoreactivity. The same negative pattern was noticed in medullary carcinomas. A statistically significant difference in Pax-8 expression was observed between non-malignant and malignant diseases (p < 0.0001). A different reactivity for Pax-8 was also noticed between differentiated carcinomas and undifferentiated carcinomas (p = 0.07). None of the benign tissues stained for p53 whereas among malignant specimens different percentages of p53 expression were observed with all undifferentiated carcinomas expressing the highest positivity (range 24.1-88.6%). Finally, when a combined analysis of bcl-2 and Pax-8 reactivity was carried out, some carcinomas proved to be Pax-8 negative and bcl-2 positive whereas others showed a similar immunoreactive pattern for both Pax-8 and bcl-2. CONCLUSIONS: Pax-8 is mainly expressed in benign rather than in malignant thyroid diseases and, among neoplasms, differentiated carcinomas express Pax-8 more frequently than undifferentiated carcinomas. An inverse pattern was observed for p53. Bcl-2 seems to be partially related to Pax-8 expression. However, a Pax-8 independent bcl-2 expression is also evident.

Correlations between individual clinical manifestations and CTG repeat amplification in myotonic dystrophy.

Myotonic dystrophy (DM) is a multisystemic disease caused by the expansion of a CTG repeat, located in the 3'-untranslated region of the DMPK gene. The number of CTG repeats broadly correlates with the overall severity of the disease. However, correlations between CTG repeat number and presence/absence or severity of individual clinical manifestations in the same patients are yet scarce. In this study the number of CTG repeats detected in blood cells of 24 DM subjects was correlated with the severity of single clinical manifestations. The presence/absence of muscular atrophy, respiratory insufficiency, cardiac abnormalities, diabetes, cataract, sleep disorders, sterility or hypogonadism is not related to the number of CTG repeats. Muscular atrophy and respiratory insufficiency are present with the highest frequency, occurring in 96 and 92% of the cases, respectively. A significant correlation was found with age of onset (r = -0.57, p<0.01), muscular disability (r = 0.46, p<0.05), intellective quotient (r = -0.58, p<0.01) and short-term memory (r= -0.59, p<0.01). Therefore, the CTG repeat number has a predictive value only in the case of some clinical manifestations, this suggesting that pathogenetic mechanisms of DM may differ depending on the tissue.

An 'environment to nucleus' signaling system operates in B lymphocytes: redox status modulates BSAP/Pax-5 activation through Ref-1 nuclear translocation.

The Ref-1 (also called APE or HAP1) protein is a bifunctional enzyme impacting on a wide variety of important cellular functions. It acts as a major member of the DNA base excision repair pathway. Moreover, Ref-1 stimulates the DNA-binding activity of several transcription factors (TFs) through the reduction of highly reactive cysteine residues. Therefore, it represents a mechanism that regulates eukaryotic gene expression in a fast way. However, it has been demonstrated that external stimuli directly act on Ref-1 by increasing its expression levels, a time-consuming mechanism representing a paradox in terms of rapidity of TF regulation. In this paper we demonstrate that this is only an apparent paradox. Exposure of B lymphocytes to H(2)O(2)induced a rapid and sustained increase in Ref-1 protein levels in the nucleus as evaluated by both western blot analysis and by pulse-chase experiments. A time course, two color in situ immunocytochemistry indicated that the up-regulation of Ref-1 in the nucleus at <30 min was primarily the consequence of translocation of its cytoplasmic form. This early nuclear accumulation is effective in modulating the DNA-binding activity of the B cell-specific activator protein BSAP/Pax-5. In fact, EMSA experiments demonstrate that a transient interaction with Ref-1 up-regulates the DNA-binding activity of BSAP/Pax-5. Moreover, in a co-transfection experiment, Ref-1 increased the BSAP/Pax-5 activating effect on an oligomerized BSAP/Pax-5 binding site of the CD19 promoter by 5- to 8-fold. Thus, Ref-1 mediates its effect by up-regulating the DNA-binding activity of BSAP/Pax-5, accounting for a new and fast outside/inside pathway of signaling in B cells.

[The T index in the elderly with altered values of free thyroxine and/or thyrotropin. A new thyroid diagnostic-therapeutic index]. / L'indice T in anziani con valore alterato di tiroxina libera e/o di tireotropina. Un nuovo indice diagnostico-terapeutico tiroideo.

BACKGROUND: Routinary evaluation of FT4 and TSH, in elderly in-patients without thyroid disease shows frequent, isolated and, often unclear, changes from normal values of plasma TSH and FT4 concentrations. A new parameter called "T index" derived from the product of FT4 and TSH values has been used by the authors. In a previous work they studied "T index" variations in 1257 elderly subjects with normal FT4 and TSH levels. They have determined the "T index" theoretic model of distribution and identified a normality range (values from 5.78 to 50.76), a suspect range (values from 2.92 to 5.78 and from 50.76 to 68.6) and a pathologic range (values less than 2.92 and more than 68.6). Aim of this study was to investigate "T index" variations in a group of 357 elderly subjects with altered FT4 and/or TSH levels. METHODS: Patients were divided into eight groups according to different concentrations of FT4 and/or TSH levels. "T index" results were expressed as mean, standard deviation, maximum and minimum values. Patients were therefore divided into three groups (normality range, suspect range, pathologic range) according to "T index" distribution as previously described. RESULTS: In 20% of elderly people hospitalized, we found alterations of thyroid hormones levels represented mostly by: a) FT4 normal; TSH low. b) FT4 normal; TSH high, c) FT4 low; TSH normal. In case of hypothalamus-hypophysis hypothyroidism and in case of hyperthyroidism, "T index" score is, usually, less than 2.92, whereas in case of hypothalamus-hypophysis hypothyroidism and hypothyroidism "T index" score is, nearly always, more than 68.6. When TSH levels are into the range of normality "T index" score has always normality levels. The "T index" helps us to divide patients with subclinical hyperthyroidism into two groups: one with values from 5.78 to 2.92 (suspect range), and the other, with values less than 2.92 pathologic range). In patients with subclinical hypothyroidism, some patients have values from 50.76 to 68.6 (suspect range), other patients have values more than 68.6 (pathologic range). CONCLUSIONS: In case of subclinical hypothyroidism or subclinical hyperthyroidism the use of "T index" seems to be a good way to select the cases in which it is better to start pharmacological treatment (hormonal replacement or thyroid inhibition) from those which is better to follow-up.

Screening of Bcr-Abl transcripts in Philadelphia negative essential thrombocythemia.

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder characterised by the absence of the Philadelphia (Ph+) chromosome. Recent studies have reported controversial results relating to BCR-ABL rearrangements in ET patients. We studied 44 Ph-negative ET patients with the RT-PCR technique at diagnosis or during the follow-up. None of them showed any of the BCR-ABL transcript actually described by others in ET; neither the "classical" P210 nor the P190 or P230 variants. Our results confirm the absence of BCR-ABL abnormalities in Ph-negative ET patients.

[Thyroid function in elderly with neoplasms]. / Funzionalità tiroidea nei neoplastici anziani.

BACKGROUND: A variety of severe illnesses can induce changes in thyroid hormone metabolism, leading to findings referred to as "sick euthyroid syndrome" (ESS). These thyroid hormone changes may be mediated in part by cytokines or other inflammatory mediators, acting at the level of the hypothalamus and pituitary gland, the thyroid gland, and the hepatic deiodinase system. The degree of thyroid function disturbance correlates with disease severity and low levels of thyroid hormones predict a poor prognosis in several illnesses. It remains unresolved whether the hormone responses in the ESS represent part of an adaptative response, which lowers tissue energy requirements in the face of systemic illness, or a maladaptive response, which induces damaging tissue hypothyroidism. METHODS: This study examines the incidence of ESS among 220 elderly subjects hospitalized with cancer. In each subjects some individual variables were studied: age, sex, type of cancer, presence of metastasis, rapid shortage of corporeal weight, general clinic condition. The following laboratory parameters were studied: serum glucose, sodium, potassium, calcium, cholesterol, lipids, proteins, leukocytes, serum, lipids haemoglobin, plateletes, VES and the end free triiodothyronine, free tiroxine and thyrotropin. RESULTS: The research points out that ESS is more frequent in the elderly subjects with cancer (incidence 58%). ESS type 1, with FT3 low and FT4 and TSH normal, is the most frequent form. The incidence of ESS is higher in elderly subjects with cancer, with recent and marked lose of corporeal weight (incidence 86%) and in subjects with worst clinical conditions. Finally, a significant direct correlation between FT3/serum cholesterol, FT3/serum proteins, FT3/serum sodium, FT3/FT4 is observed. CONCLUSIONS: The results obtained point out the not yet solved problem of hormone replacement therapy in elderly patients with cancer in bad clinical conditions.

Typing of hepatitis C virus by a new method based on restriction fragment length polymorphism.

A new restriction fragment length polymorphism (RFLP) analysis has been developed for hepatitis C virus (HCV) typing in the viral 5' non-coding region and contiguous core region. These genomic sequences were chosen for the relative nucleotide homology among different genotypes and for the presence of polymorphic sites. By employing two endonucleases (AccI and MboI) and, in some instances, a third one (EcoRII), we can unambiguously and reproducibly distinguish between genotypes and subtypes 1a, 1b, 1c, 2a, 2c, 2b, 3a, 3b, 4a, 5a and 6a. The method was applied for diagnosing two Italian groups of HCV-infected individuals reflecting a randomly collected population and a group of intravenous drug users. The accuracy of this method has been validated by comparison with INNOLiPA and by sequencing. Our approach represents an improvement over previous RFLP methods, since typing is accurate and simpler.

Structural defects of a Pax8 mutant that give rise to congenital hypothyroidism.

Pax proteins are transcriptional regulators that play important roles during embryogenesis. These proteins recognize specific DNA sequences via a conserved element: the paired domain (Prd domain). The low level of organized secondary structure, in the free state, is a general feature of Prd domains; however, these proteins undergo a dramatic gain in alpha-helical content upon interaction with DNA ('induced fit'). Pax8 is expressed in the developing thyroid, kidney and several areas of the central nervous system. In humans, mutations of the Pax8 gene, which are mapped to the coding region of the Prd domain, give rise to congenital hypothyroidism. Here, we have investigated the molecular defects caused by a mutation in which leucine at position 62 is substituted for an arginine. Leu62 is conserved among Prd domains, and contributes towards the packing together of helices 1 and 3. The binding affinity of the Leu62Arg mutant for a specific DNA sequence (the C sequence of thyroglobulin promoter) is decreased 60-fold with respect to the wild-type Pax8 Prd domain. However, the affinities with which the wild-type and the mutant proteins bind to a non-specific DNA sequence are very similar. CD spectra demonstrate that, in the absence of DNA, both wild-type Pax8 and the Leu62Arg mutant possess a low alpha-helical content; however, in the Leu62Arg mutant, the gain in alpha-helical content upon interaction with DNA is greatly reduced with respect to the wild-type protein. Thus the molecular defect of the Leu62Arg mutant causes a reduced capability for induced fit upon DNA interaction.

Combined yolk sac tumor and adenocarcinoma in a gastric stump: molecular evidence of clonality.

BACKGROUND: Extragonadal yolk sac tumors of the gastrointestinal tract are extremely rare neoplasms. Their greater rarity compared with other extragonadal yolk sac tumors suggests that different pathogenetic mechanisms could be involved according to the site of origin. This report describes a case of a combined yolk sac tumor and adenocarcinoma that arose in a gastric stump in a man age 61 years 43 years after he underwent distal gastric resection and gastrojejunostomy (Billroth II operation) for a benign duodenal ulcer. The coexistence of an adenocarcinomatous component with the yolk sac component suggests that the two histologic patterns may represent distinct phenotypes arising from a common mucosal epithelial cell. METHODS: Immunohistochemical and molecular techniques were used to define the mutation pattern of p53 in both components of the tumor. RESULTS: Single-strand conformation polymorphism and sequencing analyses demonstrated the same pattern of p53 mutation in the adenocarcinomatous and yolk sac tumor components. CONCLUSIONS: This finding suggests that the two tumors could have been derived from the same cellular clone and supports the hypothesis that the two components represented a heterogeneous differentiation of the same tumor.

Co-operation between the PAI and RED subdomains of Pax-8 in the interaction with the thyroglobulin promoter.

Pax proteins are transcription factors that play an important role in the differentiation of several cell types. These proteins bind to specific DNA sequences through the paired domain. This evolutionarily conserved element is composed of two subdomains (PAI and RED), located at the N- and C-terminals, respectively. Due to the presence of these two subdomains, Pax proteins may recognize DNA in different modes, a possibility that has not been exhaustively explored yet. The C site of the thyroglobulin promoter is bound by the thyroid-specific transcription factor Pax-8. In this study we have characterized the mode by which the Pax-8 paired domain interacts with the C site. Results allow the identification of the respective positions of the PAI and RED subdomains when the full-length protein is bound to the C site. The binding of the isolated PAI and RED subdomains to the C site and to several related mutants was also evaluated. Both subdomains interact with DNA as a monomer and display a lower binding affinity than the full-length protein. Therefore, the Pax-8 paired domain-C site interaction occurs through a co-operation between the two subdomains. The binding properties of the PAI subdomain suggest that the co-operation between PAI and RED subdomains does not merely consist of the sum of contacts established by the single subdomain: the presence of the RED subdomain is necessary for correct DNA recognition by the PAI subdomain, thus accounting for a sort of chronology of events during DNA binding. Since the RED subdomain is much more variable than the PAI subdomain among Pax proteins, these results could explain how distinct Pax proteins may select different target genes.

Pax-8 protein levels regulate thyroglobulin gene expression.

Pax proteins are transcription factors that control differentiation of several cell types. In adult organisms Pax-8 is expressed in the follicular thyroid cell where it interacts with sequences of thyroglobulin and thyroperoxidase promoters. In this study, we provide evidence indicating that Pax-8 protein levels regulate thyroglobulin gene transcription. The most critical approach consisted in increasing Pax-8 protein levels by transfecting thyroid cells with a Pax-8 expression vector. In this situation the thyroglobulin promoter transcriptional activity was significantly increased with respect to untransfected cells. In contrast, the transfection of thyroid transcription factor-1 (TTF-1) expression vector causes a modest decrease of thyroglobulin promoter activity, rather than an increase. Northern blots of human papillary cancers reveal a significant correlation between Pax-8 and thyroglobulin mRNAs. Gel-retardation assays suggest that the mechanism by which the Pax-8 protein levels modulate thyroglobulin promoter activity may occur through competition with TTF-1 for a common binding site. Since we also demonstrate that Pax-8 expression is subjected to TSH control, our data strongly suggest that Pax-8 protein levels could represent an important determinant for the regulation of thyroid cells.

Ref-1 controls pax-8 DNA-binding activity.

Redox potential controls the DNA-binding activity of several transcription factors. In some cases, the regulation of DNA-binding activity by the redox state is mediated by the Ref-1 nuclear protein. In this study, we demonstrate that Ref-1 is able to induce "in vitro" the DNA-binding activity of the Pax-8 paired domain. In co-transfection experiments, Ref-1 increases the Pax-8 activating effect on thyroglobulin promoter. Moreover, immunoreactivity data suggest that, in nuclear extracts of thyroid cells, the levels of Ref-1 correlate with the amounts of reduced Pax-8. Therefore, the regulation of the Pax-8 DNA-binding activity by redox potential, that we have demonstrated occurring "in vitro", could represent a means to control "in vivo" the function of Pax proteins. Alignment of the Paired domains sequences present in the Protein Data Bank demonstrates a strong conservation of Cys residues, suggesting that the redox regulation of the Paired domain DNA-binding activity is widely conserved along phylogenesis.

Redox potential controls the structure and DNA binding activity of the paired domain.

Pax proteins are transcriptional regulators controlling a variety of cell fates during animal development. This role depends on the intact function of the paired (Prd) domain that is able to recognize specific DNA sequences. The Prd domain is composed of two distinct helix-turn-helix subdomains, PAI and RED. Molecular functions of Pax proteins are subjected to different levels of regulation involving both pre-translational and post-translational mechanisms. By using Pax-5 and Pax-8 recombinant proteins, we demonstrate that the binding activity of the Prd domain is regulated through the oxidation/reduction of conserved cysteine residues. Mass spectrometry analysis and mutagenesis experiments demonstrate that the redox regulation is accomplished through the reversible formation of an intramolecular disulfide bridge involving the cysteines present in the PAI subdomain, whereas the RED subdomain appears quite insensitive to redox potential. Circular dichroism experiments indicate that only the reduced form of the Prd domain is able to undergo the proper conformational change necessary for sequence-specific DNA binding. Nuclear extracts from different cell lines contain an activity that is able to reduce the Paired domain and, therefore, to control the DNA binding activity of this protein. Immunodepletion of nuclear extracts demonstrate that the protein Ref-1 contributes to the redox regulation of the Prd DNA binding activity. Given the modular nature of the Prd domain and the independent DNA binding specificity of the PAI and RED subdomains, we propose that this control mechanism should be involved in "switching" among different DNA sequences and therefore different target genes.

Structural and functional properties of the N transcriptional activation domain of thyroid transcription factor-1: similarities with the acidic activation domains.

The thyroid transcription factor 1 (TTF-1) is a tissue-specific transcription factor involved in the development of thyroid and lung. TTF-1 contains two transcriptional activation domains (N and C domain). The primary amino acid sequence of the N domain does not show any typical characteristic of known transcriptional activation domains. In aqueous solution the N domain exists in a random-coil conformation. The increase of the milieu hydrophobicity, by the addition of trifluoroethanol, induces a considerable gain of alpha-helical structure. Acidic transcriptional activation domains are largely unstructured in solution, but, under hydrophobic conditions, folding into alpha-helices or beta-strands can be induced. Therefore our data indicate that the inducibility of alpha-helix by hydrophobic conditions is a property not restricted to acidic domains. Co-transfections experiments indicate that the acidic domain of herpes simplex virus protein VP16 (VP16) and the TTF-1 N domain are interchangeable and that a chimaeric protein, which combines VP16 linked to the DNA-binding domain of TTF-1, undergoes the same regulatory constraints that operate for the wild-type TTF-1. In addition, we demonstrate that the TTF-1 N domain possesses two typical properties of acidic activation domains: TBP (TATA-binding protein) binding and ability to activate transcription in yeast. Accordingly, the TTF-1 N domain is able to squelch the activity of the p65 acidic domain. Altogether, these structural and functional data suggest that a non-acidic transcriptional activation domain (TTF-1 N domain) activates transcription by using molecular mechanisms similar to those used by acidic domains. TTF-1 N domain and acidic domains define a family of proteins whose common property is to activate transcription through the use of mechanisms largely conserved during evolutionary development.

Glyceraldehyde 3-phosphate-induced DNA or protein modifications severely inhibit the protein/DNA interaction.

In this study, the effect of the reducing sugar glyceraldehyde 3-phosphate on protein/DNA interaction has been investigated. Treatment with glyceraldehyde 3-phosphate of oligonucleotides recognized by various transcription factors severely inhibits protein binding. The inhibitory effect is time and dose-dependent. Treatment with glyceraldehyde 3-phosphate of the homeodomain protein TTF-1 HD has also an inhibitory effect on the interaction with DNA, again in a time and dose-dependent manner. These "in vitro" effects could have "in vivo" counterparts and therefore contribute to molecular alterations observed either when intracellular protein are exposed to high doses of reducing sugars (i.e. in diabetes) or after a long time exposure (i.e. in Gzero-arrested cells during aging).