Angela Valentina D'Elia

A proteomic approach to identify early molecular targets of oxidative stress in human epithelial lens cells

Oxidative stress is one of the most relevant contributors of cataractogenesis. To identify early protein targets of oxidative stress in lens cells, we used a differential proteomics approach to CD5A human epithelial lens cells treated with 500 microM H2O2 for 30 min. This dose of H2O2 was assayed to induce efficiently a block of cellular proliferation and to activate the oxidative stress-early inducible transcription factor EGR-1 (early growth response gene product 1), previously reported as stimulated factor in a model of cataractogenesis [Nakajima, Nakajima, Fukiage, Azuma and Shearer (2002) Exp. Eye Res. 74, 231-236]. We identified nine proteins, which sensitively reacted to H2O2 treatment by using two-dimensional gel electrophoresis and matrix-assisted laserdesorption ionization-time-of-flight-MS. In addition to cytoskeletal proteins (tubulin 1alpha and vimentin) and enzymes (phosphoglycerate kinase 1, ATP synthase beta, enolase alpha, nucleophosmin and heat-shock cognate 54 kDa protein), which presented quantitative differences in expression profiles, peroxiredoxin and glyceraldehyde 3-phosphate dehydrogenase showed changes in pI as a result of overoxidation. Mass-mapping experiments demonstrated the specific modification of peroxiredoxin I active-site cysteine into cysteic acid, thus providing an explanation for the increase in negative charge measured for this protein. With respect to other global differential approaches based on gene expression analysis, our results allowed us to identify novel molecular targets of oxidative stress in lens cells. These results indicate that a combination of different approaches is required for a complete functional understanding of the biological events triggered by oxidative stress.

Association between plasminogen activator inhibitor 1 gene polymorphisms and preeclampsia.

It is known that the plasminogen activator inhibitor 1 (PAI-1) protein levels are increased in placentas of preeclamptic subjects. Therefore, we assessed whether polymorphisms related to the transcriptional control of the PAI-1 gene (–675 4G/5G and –844G/A) are associated with mild preeclampsia. We compared 52 women with preeclampsia to 80 women with a normal pregnancy. None of the preeclamptic women suffered from the severe form of preeclampsia. DNA was extracted from blood, and –675 4G/5G and –844G/A genotypes of the PAI-1 gene were determined. Since it has been shown that the presence of factor V Leiden, prothrombin G20210A, and MTHFR C677T gene variants may be associated with preeclampsia, their frequency was also evaluated in our study groups. The factor V Leiden, PT G20210A, and MTHFR C677T gene variants were not associated with preeclampsia. In the case of the –675 4G/5G polymorphism, genotypes 4G/4G and 5G/5G were more prevalent in the preeclamptic and in the control group, respectively. In the case of –844 G/A polymorphism, genotypes A/A and G/G were more prevalent in the preeclamptic and in the control group, respectively. By using the χ2 test for trend, differences for both genotypes were significant (p = 0.0141 for the –675 genotypes and p = 0.0492 for the –844 genotypes). The frequency of the 4G and 5G alleles of the –675 gene polymorphism was significantly different between preeclamptic and normal women (p = 0.032). Differently, the allelic frequency of the –844 gene polymorphism did not show significant differences between preeclamptic and normal women (p = 0.083). In conclusion, the hypofibrinolytic genotypes 4G/4G and A/A at positions –675 and –844 of the PAI-1 gene are associated with the occurrence of mild preeclampsia independently of thrombophilic mutations of the factor V, prothrombin, and MTHFR genes.

Thyroid Transcription Factor-1 Facilitates Cerebrospinal Fluid Formation by Regulating Aquaporin-1 Synthesis in the Brain

In the brain, aquaporin-1 (AQP-1), a water channel for high osmotic water permeability, is mainly expressed in the apical membrane of the ventricular choroid plexus and regulates formation of cerebrospinal fluid (CSF). Although the physiology of AQP-1 has been the subject of several publications, much less is known about the trans-acting factors involved in the control of AQP-1 gene expression. Here we report that TTF-1, a homeodomain-containing transcriptional regulator, is coexpressed with AQP-1 in the rat brain choroid plexus and enhances AQP-1 gene transcription by binding to conserved core TTF-1-binding motifs in the 5′-flanking region of the AQP-1 gene. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased AQP-1 synthesis and reduced CSF formation. In addition, blockade of TTF-1 synthesis increased survival of the animals following acute water intoxication-induced brain edema. These results suggest that TTF-1 is physiologically involved in the transcriptional control of AQP-1, which is required for CSF formation.

A de novo nonsense mutation of PAX6 gene in a patient with aniridia, ataxia, and mental retardation

Claudio Graziano, Angela V. D’Elia, Laura Mazzanti, Filomena Moscano, Simonetta Guidelli Guidi, Emanuela Scarano, Daniela Turchetti, Emilio Franzoni, Giovanni Romeo, Giuseppe Damante, and Marco Seri* U.O. di Genetica Medica, Dipartimento di Medicina Interna, Cardioangiologia ed Epatologia, Università degli Studi di Bologna, Bologna, Italy Dipartimento di Scienze e Tecnologie Biomediche, Università degli Studi di Udine, Udine, Italy Clinica Pediatrica, Dipartimento di Pediatria, Università degli Studi di Bologna, Bologna, Italy U.O. di Neuropsichiatria Infantile, Dipartimento di Pediatria, Università degli Studi di Bologna, Bologna, Italy Ottica Fisiopatologica, Policlinico S. Orsola-Malpighi, Bologna, Italy

Identification of the first deletion in the LRP5 gene in a patient with Autosomal Dominant Osteopetrosis type I

In the last decade, the low-density lipoprotein receptor-related protein 5 (LRP5) gene, coding for a coreceptor in the canonical Wnt signalling pathway, has been shown to play an important role in regulating bone mass and to be involved in the pathogenesis of several bone disorders. Here we describe a patient who presented with a clinical picture of Autosomal Dominant Osteopetrosis type I (ADO I), in whom we could identify the first deletion in the LRP5 gene causing increased bone mass. This mutation caused the in-frame deletion of two amino acids in the fourth blade of the first propeller of the protein, namely the highly conserved glycine at position 171 and the following glutamate residue. In vitro studies suggested that the pathogenic effect of this novel mutation could be due to a decreased inhibition of Wnt signalling by the antagonistic proteins sclerostin and Dickkopf-1, encoded respectively by the SOST and DKK1 genes, in the presence of mutated LRP5. Our results highlight an increasing molecular heterogeneity in LRP5-related bone diseases.

Functional interaction among thyroid-specific transcription factors: Pax8 regulates the activity of Hex promoter

The transcription factor Hex is expressed in the thyroid follicular cells (TFC) and in several other cell types. In TFC, Hex contributes to the control of the tissue-specific gene expression. By means of RT-PCR assays we found a correlation between the Hex and Pax8 (a different tissue-specific transcription factor, expressed in TFC) mRNA levels in normal and neoplastic thyroid tissues. This finding suggested the presence of a functional correlation between the two transcription factors. Therefore, we tested whether Pax8 regulates the transcriptional activity of Hex promoter. Indeed, by using cotransfection experiments in non-thyroidal cells, we show that increasing doses of Pax8 expression vector elicited a dose-dependent increase of the transcriptional activity of Hex promoter. Accordingly, gel-retardation assays indicated that in the Hex promoter are present several Pax8 binding sites. The Pax8 activating effect on Hex promoter was further increased by the contemporary presence of Hex protein. In fact, cotransfection of both Hex and Pax8 expression vectors doubled the transcriptional activity of Hex promoter with respect to the condition in which the Pax8 expression vector only was transfected. In addition, we show that also the transcriptional cofactor APE/Ref-1 cooperated with Pax8 for upregulation of Hex promoter activity. These findings, together with other published data, suggest that a network of functional interactions between transcriptional regulators is present in TFC.

Genetic thrombophilias and uterine artery Doppler velocimetry and preeclampsia

The aim of this study was to evaluate the correlation between genetic thrombophilic mutations, uterine artery Doppler at 24 weeks of gestation and preeclampsia.

Plasminogen activator inhibitor-1 gene polymorphisms in pre-eclampsia.

Pre-eclampsia (P-EC) is a multisystem disorder of pregnancy, characterized by new-onset hypertension and proteinuria. Deregulation of the coagulation cascade and hypofibrinolysis appear to play a central role in the development of this disease. After a brief review of the genetic basis of P-EC and the role of genes encoding proteins involved in coagulation, we focus on polymorphisms of the plasminogen activator inhibitor (PAI-1) gene. The most relevant association studies between PAI-1 gene polymorphisms and P-EC are reviewed. Results indicate that the 4G/4G genotype of the -675 4G/5G polymorphism represents a weak risk factor for P-EC.

Molecular analysis of a human PAX6 homeobox mutant

Pax6 controls eye, pancreas and brain morphogenesis. In humans, heterozygous PAX6 mutations cause aniridia and various other congenital eye abnormalities. Most frequent PAX6 missense mutations are located in the paired domain (PD), while very few missense mutations have been identified in the homeodomain (HD). In the present report, we describe a molecular analysis of the human PAX6 R242T missense mutation, which is located in the second helix of the HD. It was identified in a male child with partial aniridia in the left eye, presenting as a pseudo-coloboma. Gel-retardation assays revealed that the mutant HD binds DNA as well as the wild-type HD. In addition, the mutation does not modify the DNA-binding properties of the PD. Cell transfection assays indicated that the steady-state levels of the full length mutant protein are higher than those of the wild-type one. In cotransfection assays a PAX6 responsive promoter is activated to a higher extent by the mutant protein than by the wild-type protein. In vitro limited proteolysis assays indicated that the presence of the mutation reduces the sensitivity to trypsin digestion. Thus, we suggest that the R242T human phenotype could be due to abnormal increase of PAX6 protein, in keeping with the reported sensitivity of the eye phenotype to increased PAX6 dosage.

CASR gene activating mutations in two families with autosomal dominant hypocalcemia.

BACKGROUND Autosomal dominant hypocalcemia (ADH) is an endocrine disorder caused by activating mutations of the calcium-sensing receptor (CASR) gene which plays a major role in maintaining calcium homeostasis. Biochemical features of ADH are hypocalcemia and hypercalciuria with inappropriately low levels of parathyroid hormone (PTH). We report on two four-generation families affected by ADH. AIM To identify mutations of CASR gene in subjects affected by familial idiopathic hypoparathyroidism. To perform functional assays of identified CASR variants by transient transfection on HEK293 cells. RESULTS We identified two CASR variants (Q681R and P221L): the Q681R variant was novel while the P221L had been previously published. Functional assays on the Q681R variant showed that it did not alter the whole expression nor the correct plasmamembrane localization, but enhanced the signaling function, increasing the sensitivity of the receptor as compared to the WT. CONCLUSIONS We report two activating CASR mutations in two families affected by ADH and the functional assays performed on the novel variant Q681R. Our work enlarged the spectrum of mutations of the CASR and contributed to a better elucidation of the protein function.