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Anna Starzinski-Powitz

Publications and source records attributed to Anna Starzinski-Powitz.

10 recordsLinked to original sources
PubMed2006

Targeting of transmembrane protein shrew-1 to adherens junctions is controlled by cytoplasmic sorting motifs.

We recently identified transmembrane protein shrew-1 and showed that it is able to target to adherens junctions in polarized epithelial cells. This suggested shrew-1 possesses specific basolateral sorting motifs, which we analyzed by mutational analysis. Systematic mutation of amino acids in putative sorting signals in the cytoplasmic domain of shrew-1 revealed three tyrosines and a dileucine motif necessary for basolateral sorting. Substitution of these amino acids leads to apical localization of shrew-1. By applying tannic acid to either the apical or basolateral part of polarized epithelial cells, thereby blocking vesicle fusion with the plasma membrane, we obtained evidence that the apically localized mutants were primarily targeted to the basolateral membrane and were then redistributed to the apical domain. Further support for a postendocytic sorting mechanism of shrew-1 was obtained by demonstrating that mu1B, a subunit of the epithelial cell-specific adaptor complex AP-1B, interacts with shrew-1. In conclusion, our data provide evidence for a scenario where shrew-1 is primarily delivered to the basolateral membrane by a so far unknown mechanism. Once there, adaptor protein complex AP-1B is involved in retaining shrew-1 at the basolateral membrane by postendocytic sorting mechanisms.

Adherens Junctions↗
PubMed2006

The SHREW1 gene, frequently deleted in oligodendrogliomas, functions to inhibit cell adhesion and migration.

Allelic loss of the short arm of chromosome 1 has been observed frequently in oligodendroglioma (60-80%). We evaluated 177 oligodendroglial tumor samples and defined a consensus region of deletion of approximately 630 kb. This region contains a single gene, SHREW1, which encodes a novel transmembrane protein in adherens junctions. Whereas a mutation was not detected in the coding region of the SHREW1 gene in oligodendrogliomas, restoration of SHREW1 expression resulted in suppression of cell adhesion and migration. Thus, SHREW1 inactivation may play a role in the development of oligodendroglial tumors.

Cell Adhesion↗
PubMed2005

Differentiation of circulating endothelial progenitor cells to a cardiomyogenic phenotype depends on E-cadherin.

Progenitor cells may contribute to cardiac regeneration. Here, we investigated the role of cadherins and integrins for differentiation of human adult circulating endothelial progenitor cells (EPCs) into cardiomyocytes (CM) in a co-culture system. N- and E-cadherin were expressed in EPCs and were localized at the interface between EPCs and CM. Incubation of a blocking antibody against E-cadherin reduced the expression of CM marker protein in EPCs. Blocking antibodies against N- or P-cadherin or the beta1- and beta2-integrins were not effective. These data suggested that cell-to-cell communication mediated by E-cadherin contributes to the acquirement of a cardiomyogenic phenotype of human endothelial progenitor cells.

Antibodies, Blocking↗
PubMed2005

Oxytocin receptor expression in smooth muscle cells of peritoneal endometriotic lesions and ovarian endometriotic cysts.

OBJECTIVE: To investigate the expression of oxytocin receptor (OTR) in peritoneal and ovarian endometriotic lesions. DESIGN: Retrospective nonrandomized study. SETTING: University hospital endometriosis research center. PATIENT(S): Premenopausal women with histologically confirmed endometriosis were selected. Peritoneal endometriotic lesions (n = 120); ovarian endometriotic cysts (n = 40); peritoneal biopsies, distant from the endometriotic lesion (n = 55); and unaffected peritoneal biopsies from patients without endometriosis (n = 11) were obtained. Hysterectomy specimens from patients without endometriosis and/or adenomyosis were used for controls (n = 10). INTERVENTION(S): Histopathological examination of peritoneal and ovarian specimens for OTR expression and identification of smooth muscle cells by immunohistochemistry staining with antibodies against OTR and smooth muscle actin. In addition, Western blot analysis, double-immunofluorescence, and in vitro studies with primary cell cultures have been performed. MAIN OUTCOME MEASURE(S): Comparison of the immunoreactive score of the OTR and smooth muscle actin expression with the smooth muscle content in peritoneum with and without endometriosis. RESULT(S): In the epithelial cells of endometriotic lesions, we could demonstrate a high OTR expression. The stromal cells were OTR negative with the exception of some single cells. By using a monoclonal anti-smooth muscle actin antibody, these cells could be identified as intrastromal OTR-positive smooth muscle cells. The peritoneum of women with endometriosis shows a significantly higher smooth muscle content than the peritoneum of women without endometriosis. There were no significant differences between the smooth muscle content of active or inactive lesions and the stage of disease. CONCLUSION(S): Oxytocin receptor is expressed in smooth muscle cells and epithelial cells of peritoneal endometriotic lesions and ovarian endometriotic cysts. The inhibition of OTR by specific inhibitors might be a useful approach for the treatment of endometriosis-associated pain.

Adult↗
PubMed2003

Novel membrane protein shrew-1 targets to cadherin-mediated junctions in polarized epithelial cells.

While searching for potential candidate molecules relevant for the pathogenesis of endometriosis, we discovered a 2910-base pair cDNA encoding a novel putative 411-amino acid integral membrane protein that we called shrew-1. The putative open-reading frame was confirmed with antibodies against shrew-1 peptides that labeled a protein of approximately 48 kDa in extracts of shrew-1 mRNA-positive tissue and also detected ectopically expressed shrew-1. Expression of epitope-tagged shrew-1 in epithelial cells and analysis by surface biotinylation and immunoblots demonstrated that shrew-1 is indeed a transmembrane protein. Shrew-1 is able to target to E-cadherin-mediated adherens junctions and interact with the E-cadherin-catenin complex in polarized MCF7 and Madin-Darby canine kidney cells, but not with the N-cadherin-catenin complex in nonpolarized epithelial cells. Direct interaction of shrew-1 with beta-catenin in in vitro pull-down assay suggests that beta-catenin might be one of the proteins that targets and/or retains shrew-1 in the adherens junctions. Interestingly, shrew-1 was partially translocated in response to scatter factor (ligand of receptor tyrosine kinase c-met) from the plasma membrane to the cytoplasm where it still colocalized with endogenous E-cadherin. In summary, we introduce shrew-1 as a novel component of adherens junctions, interacting with E-cadherin-beta-catenin complexes in polarized epithelial cells.

Adherens Junctions↗
PubMed2003

Noninvasive diagnosis of endometriosis: the role of imaging and markers.

Endometriosis is defined by the presence of endometrial tissue outside the uterus. Clinical and basic research in endometriosis has been hampered severely by the lack of accurate noninvasive diagnostic techniques. Transvaginal ultrasonography, MRI, and endometrial and serum markers have the potential to facilitate the diagnosis and can be useful in the follow-up of patients. Endometriosis research has entered the postgenomic era, and powerful genomic and proteomic technology is being applied in the search for novel diagnostic and therapeutic approaches. This article explores the recent advances in imaging techniques and the development of diagnostic molecular markers of endometriosis.

Biomarkers↗
PubMed2002

The LIM-only protein FHL2 interacts with beta-catenin and promotes differentiation of mouse myoblasts.

FHL2 is a LIM-domain protein expressed in myoblasts but down-regulated in malignant rhabdomyosarcoma cells, suggesting an important role of FHL2 in muscle development. To investigate the importance of FHL2 during myoblast differentiation, we performed a yeast two-hybrid screen using a cDNA library derived from myoblasts induced for differentiation. We identified beta-catenin as a novel interaction partner of FHL2 and confirmed the specificity of association by direct in vitro binding tests and coimmunoprecipitation assays from cell lysates. Deletion analysis of both proteins revealed that the NH2-terminal part of beta-catenin is sufficient for binding in yeast, but addition of the first armadillo repeat is necessary for binding FHL2 in mammalian cells, whereas the presence of all four LIM domains of FHL2 is needed for the interaction. Expression of FHL2 counteracts beta-catenin-mediated activation of a TCF/LEF-dependent reporter gene in a dose-dependent and muscle cell-specific manner. After injection into Xenopus embryos, FHL2 inhibited the beta-catenin-induced axis duplication. C2C12 mouse myoblasts stably expressing FHL2 show increased myogenic differentiation reflected by accelerated myotube formation and expression of muscle-specific proteins. These data imply that FHL2 is a muscle-specific repressor of LEF/TCF target genes and promotes myogenic differentiation by interacting with beta-catenin.

Animals↗