Seiji Fujisaki

Dimerization of the Polycomb-group protein Mel-18 is regulated by PKC phosphorylation.

The Polycomb-group (Pc-G) gene products form complexes via protein-protein interactions and maintain the transcriptional repression of genes involved in embryogenesis, cell cycle, and tumorigenesis. Previously, we have shown that mouse Mel-18, a Pc-G protein, has tumor suppressor gene-like activity and negatively regulates transcription. Here, we show in vitro by pull-down assays and in vivo in transiently transfected COS-7 cells that Mel-18 forms homodimers. Deletion analysis revealed that the N-terminal RING-finger and alpha-helix domains are required for homodimer formation. In addition, we demonstrated that Mel-18 homo-dimerization is regulated by protein kinase C (PKC) and protein phosphatases, such that dephosphorylated Mel-18 is able to homo-dimerize. These results suggest that the stoichiometry and/or equilibrium of subunits of the class II Polycomb complex containing Mel-18 might be regulated by changes in phosphorylation status via the PKC signaling pathway.

A case of pancreatic schwannoma showing increased FDG uptake on PET/CT

Highlights • Pancreatic schwannoma is rare and preoperative diagnosis is difficult due to the lack of specific symptoms, radiological characteristics and tumor markers.• Incidental detection of pancreatic schwannoma is predicted to increase due to the widespread use of CT and MRI. It is important to take into account this tumor in the differential diagnosis of pancreatic tumors.• We should be aware that FDG-PET/CT shows abnormal accumulation in a benign pancreatic schwannoma.

A colovesical fistula with a persistent descending mesocolon due to partial situs inversus: A case report

Highlights • Colovesical fistula was occered in the extremely rare condition: partial situs inversus with persistent descending mesocolon (PDM).• Distinctive features of PDM were shortening adhesions noted at the dorsal aspect of the descending and sigmoid mesocolon without marginal vessel.• In this case, these congenital abnormalities might help the suture failure during the operation of sigmoid colectomy.

Appendicitis complicated by appendiceal metastasis via peritoneal dissemination from lung cancer.

Peritoneal disseminations from lung cancer are difficult to detect during the patients clinical course. Therefore, complications of this condition are unclear. We report a case in which peritoneal dissemination from lung cancer complicated appendicitis.

Acute diffuse peritonitis due to spontaneous rupture of a primary gastrointestinal stromal tumor of the jejunum: A case report

Highlights • Completely different types of GIST rupture have been reported as same perforation type.• We classified retrieved cases of GIST rupture to three types: abscess type, hemoperitoneum type, bowel perforation type.• Each type demonstrates a specific mechanism of perforation causing characteristic complaints.