TY  - JOUR
A1  - Hesbacher, Sonja
A1  - Pfitzer, Lisa
A1  - Wiedorfer, Katharina
A1  - Angermeyer, Sabrina
A1  - Borst, Andreas
A1  - Haferkamp, Sebastian
A1  - Scholz, Claus-Jürgen
A1  - Wobser, Marion
A1  - Schrama, David
A1  - Houben, Roland
T1  - RB1 is the crucial target of the Merkel cell polyomavirus Large T antigen in Merkel cell carcinoma cells
JF  - Oncotarget
N2  - The pocket protein (PP) family consists of the three members RB1, p107 and p130 all possessing tumor suppressive properties. Indeed, the PPs jointly control the G1/S transition mainly by inhibiting E2F transcription factors. Notably, several viral oncoproteins are capable of binding and inhibiting PPs. Merkel cell polyomavirus (MCPyV) is considered as etiological factor for Merkel cell carcinoma (MCC) with expression of the viral Large T antigen (LT) harboring an intact PP binding domain being required for proliferation of most MCC cells. Therefore, we analyzed the interaction of MCPyV-LT with the PPs. Co-IP experiments indicate that MCPyV-LT binds potently only to RB1. Moreover, MCPyV-LT knockdown-induced growth arrest in MCC cells can be rescued by knockdown of RB1, but not by p107 or p130 knockdown. Accordingly, cell cycle arrest and E2F target gene repression mediated by the single PPs can only in the case of RB1 be significantly reverted by MCPyV-LT expression. Moreover, data from an MCC patient indicate that loss of RB1 rendered the MCPyV-positive MCC cells LT independent. Thus, our results suggest that RB1 is the dominant tumor suppressor PP in MCC, and that inactivation of RB1 by MCPyV-LT is largely sufficient for its growth supporting function in established MCPyV-positive MCC cells.
KW  - Merkel cell carcinoma
KW  - polyomavirus
KW  - Large T antigen
KW  - retinoblastoma protein
KW  - viral carcinogenesis
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177858
VL  - 7
IS  - 22
ER  - 
TY  - JOUR
A1  - Thomas, Anna C.
A1  - Zeng, Zhiqiang
A1  - Rivière, Jean-Baptiste
A1  - O'Shaughnessy, Ryan
A1  - Al-Olabi, Lara
A1  - St.-Onge, Judith
A1  - Atherton, David J.
A1  - Aubert, Hélène
A1  - Bagazgoitia, Lorea
A1  - Barbarot, Sébastien
A1  - Bourrat, Emmanuelle
A1  - Chiaverini, Christine
A1  - Chong, W. Kling
A1  - Duffourd, Yannis
A1  - Glover, Mary
A1  - Groesser, Leopold
A1  - Hadj-Rabia, Smail
A1  - Hamm, Henning
A1  - Happle, Rudolf
A1  - Mushtaq, Imran
A1  - Lacour, Jean-Philippe
A1  - Waelchli, Regula
A1  - Wobser, Marion
A1  - Vabres, Pierre
A1  - Patton, E. Elizabeth
A1  - Kinsler, Veronica A.
T1  - Mosaic activating mutations in GNA11 and GNAQ are associated with phakomatosis pigmentovascularis and extensive dermal melanocytosis
JF  - Journal of Investigative Dermatology
N2  - Common birthmarks can be an indicator of underlying genetic disease but are often overlooked. Mongolian blue spots (dermal melanocytosis) are usually localized and transient, but they can be extensive, permanent, and associated with extracutaneous abnormalities. Co-occurrence with vascular birthmarks defines a subtype of phakomatosis pigmentovascularis, a group of syndromes associated with neurovascular, ophthalmological, overgrowth, and malignant complications. Here, we discover that extensive dermal melanocytosis and phakomatosis pigmentovascularis are associated with activating mutations in GNA11 and GNAQ, genes that encode Ga subunits of heterotrimeric G proteins. The mutations were detected at very low levels in affected tissues but were undetectable in the blood, indicating that these conditions are postzygotic mosaic disorders. In vitro expression of mutant GNA11\(^R183C\) and GNA11\(^Q209L\) in human cell lines demonstrated activation of the downstream p38 MAPK signaling pathway and the p38, JNK, and ERK pathways, respectively. Transgenic mosaic zebrafish models expressing mutant GNA11\(^R183C\) under promoter mitfa developed extensive dermal melanocytosis recapitulating the human phenotype. Phakomatosis pigmentovascularis and extensive dermal melanocytosis are therefore diagnoses in the group of mosaic heterotrimeric G-protein disorders, joining McCune-Albright and Sturge-Weber syndromes. These findings will allow accurate clinical and molecular diagnosis of this subset of common birthmarks, thereby identifying infants at risk for serious complications, and provide novel therapeutic opportunities.
KW  - uveal melanoma
KW  - G Protein
KW  - dermal melanocytosis
KW  - Sturge-Weber syndrom
KW  - cesioflammea
KW  - germline
KW  - phakomatosis pigmentovascularis
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189689
VL  - 136
IS  - 4
ER  -