A novel patient with White–Sutton syndrome refines the mutational and clinical repertoire of the POGZ‐related phenotype and suggests further observations

A rare developmental delay (DD)/intellectual disability (ID) syndrome with craniofacial dysmorphisms and autistic features, termed White–Sutton syndrome (WHSUS, MIM#614787), has been recently described, identifying truncating mutations in the chromatin regulator POGZ (KIAA0461, MIM#614787). We describe a further WHSUS patient harboring a novel nonsense de novo POGZ variant, which afflicts a protein domain with transposase activity less frequently impacted by mutational events (DDE domain). This patient displays additional physical and behavioral features, these latter mimicking Smith–Magenis syndrome (SMS, MIM#182290). Considering sleep–wake cycle anomalies and abnormal behavior manifested by this boy, we reinforced the clinical resemblance between WHSUS and SMS, being both chromatinopathies. In addition, using the DeepGestalt technology, we identified a different facial overlap between WHSUS patients with mutations in the DDE domain (Group 1) and individuals harboring variants in other protein domains/regions (Group 2). This report further delineates the clinical and molecular repertoire of the POGZ‐related phenotype, adding a novel patient with uncommon clinical and behavioral features and provides the first computer‐aided facial study of WHSUS patients.     

MRE11 mutations and impaired ATM-dependent responses in an Italian family with ataxia-telangiectasia-like disorder

Hypomorphic mutations of the MRE11 gene are the hallmark of the radiosensitive ataxia-telangiectasia-like disorder (ATLD). Here, we describe a new family with two affected siblings, ATLD5 and ATLD6, now aged 37 and 36, respectively. They presented with late onset cerebellar degeneration slowly progressing until puberty and absence of telangiectasias, and were cancer-free. Both patients were wild-type for ATM and NBS1, but compound heterozygotes for MRE11 gene mutations [1422C-->A, T481K; 1714C-->T, R571X]. The 1422C-->A allele was inherited from the mother, whereas the 1714C-->T, allele paternally inherited, was apparently null as a result of nonsense-mediated mRNA decay (NMD). Interestingly, the 1714C-->T mutation is the same as previously identified in an unrelated English ATLD family (probands ATLD3 and ATLD4), suggesting an important role for NMD in saving potentially lethal mutations. Lymphoblastoid cell lines (LCLs) derived from ATLD5 and ATLD6 were normal for ATM, but defective for Mre11, Rad50 and Nbs1 (the MRN complex) protein expression. Their response to gamma-radiation was abnormal, as evidenced by the enhanced radiosensitivity, attenuated autophosphorylation of ATM-S1981 and phosphorylation of the ATM targets p53-S15 and Smc1-S966, failure to form Mre11 nuclear foci and defective G1 checkpoint arrest. The fibroblasts, but not LCLs, from ATLD5 and ATLD6 showed an impaired ATM-dependent Chk2 phosphorylation. These findings further underscore the interconnection between ATM activity and MRN function, which rationalizes the clinical similarity between ataxia-telangiectasia (A-T) and ATLD.     

Protein kinase A activity in platelets from patients with bipolar disorder

BACKGROUND: Abnormal levels of protein kinase A (PKA) were found in patients with bipolar disorder (BD). Since altered levels are generally accompanied by functional modifications, the purpose of this study was to investigate PKA activity in patients with BD. METHODS: PKA activity was assessed in platelets from 20 drug-free bipolar patients and 19 controls. RESULTS: The cAMP-stimulated PKA activity was significantly increased in bipolar patients compared with controls. LIMITATIONS: This study made use of platelets, which may not fully represent changes occurring in specific brain regions. CONCLUSION: This study adds to the growing evidence suggesting that abnormalities of PKA are associated with BD.     

Multiple pathways of cell invasion are regulated by multiple families of serine proteases

The complex process of tumor invasion requires the coordinated expression and activity of cell-substratum adhesive interactions and of cell-associated protease systems, which destroy the extracellular matrix (ECM), in order to enable the invading cells to simultaneously grip and destroy the anatomical barriers that control cell spreading. A number of data indicate that such a `grip and go' process may be performed by an enlarging series of cell membrane-associated serine proteases and serine protease receptors, which provide the invasive cells with a functional unit (the protease and its receptor), able to mediate cell-substratum adhesion through specific receptor domains, to proteolytically degrade ECM and to deliver into the cell signals that up-regulate the expression either of the protease/receptor complex, or of other adhesion molecules, such as integrins. There is evidence that some proteases and protease receptor expression are under the control of tumor hypoxia, which is the result of an imbalance in oxygen supply and demand. The urokinase-type plasminogen activator (u-PA) receptor (u-PAR) is under hypoxic control and cooperates with other serine proteases of the blood coagulation pathways that may extravasate in the tumor milieu as a result of hypoxia-simulated increase of vessel permeability. Other serine proteases and their receptors cooperate with the cell-associated fibrinolytic system to promote cell invasion. Among these, tissue factor and its ligand coagulation factor VII, thrombin and its protease-activated receptors, and type II trans-membrane serine proteases seem to play a crucial role. This Review takes into consideration the complex scenario of the single serine proteases and related receptors that are involved in cell invasion, as well as the protease receptor/adhesion molecule interplay which is necessary to focus the cell surface-driven proteolysis where adhesion provides a grip to the invading cell. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hirschsprung associated GDNF mutations do not prevent RET activation

Hirschsprung disease (HSCR) is a complex disorder characterised by aganglia of distal gastrointestinal tracts. The highest proportion of both familial and sporadic cases is due to mutations of the RET proto-oncogene. Five germline mutations in the glial cell-line-derived neurotrophic factor (GDNF) gene, one of the RET ligands, have been detected in HSCR patients. Pedigrees analysis and the observed association between these GDNF alterations and RET variants in the same patients raised the question of whether the GDNF gene plays any causative/predisposing role in HSCR pathogenesis. In the present work, we have studied the ability of GDNF proteins, each bearing one of the reported mutations, to activate RET by performing a functional test in cultured neuroblastoma cells. Consistently with the lack of genotype/phenotype correlation in human subjects, our results indicate absence of detectable alterations of mutant GDNF induced RET activation.     

Drosophila dSAP18 is a nuclear protein that associates with chromosomes and the nuclear matrix, and interacts with pinin, a protein factor involved in RNA splicing

SAP18 is a highly conserved protein that was proposed to be involved in multiple cellular processes from autophagy to gene regulation and mRNA processing. In this paper we show that, in Drosophila, dSAP18 is a predominantly nuclear protein that associates to both chromosomes and the nuclear matrix. dSAP18 becomes nuclear early during development, at the onset of cellularization, and remains so all through embryo development. dSAP18 is also nuclear in salivary glands, ovaries and cultured S2 cells. Here we also show that dSAP18 forms a complex with the Drosophila homolog of pinin (dPnn), a protein factor involved in mRNA splicing. dSAP18-dPnn interaction was confirmed in vivo, through co-immunoprecipitation experiments, as well as in vitro, through GST pull-down assays. These results are discussed in the context of the possible functions played by SAP18.     

Cytogenetics of a new cytotype of African Mus (subgenus Nannomys) minutoides (Rodentia, Muridae) from Kenya: C- and G- banding and distribution of (TTAGGG) n telomeric sequences

We present the results of a cytogenetic study on Mus (Nannomys) minutoides from Kenya by means of C- and G- banding and in-situ fluorescence hybridization (FISH) to localize the telomeric sequences. The karyotype is characterized by the occurrence of several Rb chromosomes Rb(1.X), Rb(1.Y). Rb(2.17), Rb(3.13), Rb(4.10), Rb(5.11), Rb(6.7), Rb(8.12), not previously described for this species. This finding suggests a high level of chromosomal diversification, which means it is possible to consider this cytotype as a new, well-differentiated, chromosomal lineage within the subgenus. The C-banding of the metaphases illustrated conspicuous blocks of centromeric heterochromatin at the paracentromeric regions of all telocentric chromosomes. Centromeric heterochromatin is not visible on all biarmed chromosomes. Following hybridization with telomeric probes, bright interstitial telomeric sequence (ITS) fluorescence signals are evident at the pericentromeric area of all Rb chromosomes, with the exception of Rb(2.17). Considering the localization of the C-positive heterochromatin and of the telomeric sequences, the events leading to the Kenyan cytotype from an all-telocentric condition probably included two steps: first, fusion without loss of heterochromatin and pericentromeric telomeric sequences; second, the reduction of the C-positive satellite DNA followed by the amplification of telomeric sequences in the C-negative paracentromeric region of Rb chromosomes. The presence of a single Rb(2.17) without ITS indicates possible variations of this mechanism.     

Identification, characterization and biological activity of oxytocin receptor in the developing human penis

Although abnormalities of the male external genitalia (MEG) are a relatively common problem, little is known concerning the molecular mechanisms that finely regulate penile development. We report here the expression of the oxytocin receptor (OTR) gene by real-time RT-PCR in human fetal tissues (11th-12th week of gestation), including the MEG. The developing penis expressed a very high level of OTR mRNA, only a half log(10) unit lower than fetal central nervous system, used as a positive control. The OTR protein is also highly expressed (western, immunohistochemistry and binding studies) and immunolocalized both in the mesenchymal body and in the surrounding blood capillaries, which will later constitute penile trabeculae and sinusoids. Binding studies using [125I]oxytocin antagonist ([125I]OTA) in cultured human fetal penile smooth muscle cells (hfPSMC) revealed the presence of specific OTR with a high capacity and affinity for oxytocin (OT) and for OTA. Increasing concentrations of OT dose-dependently induced intracellular Ca2+ mobilization. Furthermore, OTR mediated an increase in the proliferation and the migration of hfPSMC. In conclusion, we demonstrate that in the developing human MEG, OTR is highly expressed and might be involved in coordinating timely and appropriate proliferation and migration of the penile cells. Thus, OTR might represent an additional target for investigating human fetal MEG organogenesis.     

Differential Effects of Thalidomide on Angiogenesis and Tumor Growth in Mice

Thalidomide, clinically used as an antiinflammatory and antitumoral drug, inhibited sponge-induced angiogenesis when administered systemically (100 mg/kg^–1) in mice. However, it failed to inhibit solid Ehrlich tumor in the same mouse strain. We have used functional, biochemical and histological parameters to assess neovascularization and fibrovascular tissue infiltration of the mice sponge granuloma. The neovascularization growth as detected by development of blood flow and hemoglobin content extracted from the implants showed that thalidomide inhibited fibrovascular tissue formation by 40%. The functional and biochemical parameters correlated well with the histological study. Thalidomide had no inhibitory effect in the development of Ehrlich tumor. The detection of this selective action using the same animal strain bearing two different processes, supports the hypothesis that rather than species specificity, thalidomide is tissue specific. This approach may be used to identify the specificity of other therapeutic agents against distinct angiogenesis-dependent diseases.     

Malignancy-associated allelic losses on the X-chromosome in foregut but not in midgut endocrine tumours

Information on genetic changes involved in the progression of gastroenteropancreatic (GEP) endocrine tumours is scanty. On the other hand, the identification of molecular markers of malignancy could be crucial for the prognostic evaluation of these neoplasms, which is hardly predictable on the basis of conventional histological criteria. An association of X-chromosome deletions with malignancy has already been found in gastric endocrine tumours. To investigate this further, a comparative loss of heterozygosity (LOH) analysis was performed on 17 pancreatic endocrine tumours (PETs) and 17 intestinal (ten ileal, six appendiceal, and one rectal) carcinoids from female patients. The relationship of X-chromosome LOH with the ploidy status of the neoplasms was also investigated. LOH was found in six of eight malignant PETs (60% of the informative markers), but was infrequent in the nine benign ones (4.5%). In contrast, although retention of heterozygosity was consistently observed in benign midgut tumours, LOH was infrequent in malignant carcinoids (15%). No correlation was found between LOH and the ploidy status. These results indicate an association between X-chromosome LOH and malignancy in foregut endocrine tumours. The lack of such an association in midgut carcinoids suggests that different molecular mechanisms are involved in the progression of these two categories of endocrine neoplasms, which are otherwise considered to be closely related. These findings emphasize the need for further molecular studies on GEP endocrine tumours, carefully subdivided according to their anatomical site of origin.