Catalytic Subunit 1 of Protein Phosphatase 2A Is a Subunit of the STRIPAK Complex and Governs Fungal Sexual Development.

UNLABELLED: The generation of complex three-dimensional structures is a key developmental step for most eukaryotic organisms. The details of the molecular machinery controlling this step remain to be determined. An excellent model system to study this general process is the generation of three-dimensional fruiting bodies in filamentous fungi like Sordaria macrospora Fruiting body development is controlled by subunits of the highly conserved striatin-interacting phosphatase and kinase (STRIPAK) complex, which has been described in organisms ranging from yeasts to humans. The highly conserved heterotrimeric protein phosphatase PP2A is a subunit of STRIPAK. Here, catalytic subunit 1 of PP2A was functionally characterized. The Δpp2Ac1 strain is sterile, unable to undergo hyphal fusion, and devoid of ascogonial septation. Further, PP2Ac1, together with STRIPAK subunit PRO22, governs vegetative and stress-related growth. We revealed in vitro catalytic activity of wild-type PP2Ac1, and our in vivo analysis showed that inactive PP2Ac1 blocks the complementation of the sterile deletion strain. Tandem affinity purification, followed by mass spectrometry and yeast two-hybrid analysis, verified that PP2Ac1 is a subunit of STRIPAK. Further, these data indicate links between the STRIPAK complex and other developmental signaling pathways, implying the presence of a large interconnected signaling network that controls eukaryotic developmental processes. The insights gained in our study can be transferred to higher eukaryotes and will be important for understanding eukaryotic cellular development in general. IMPORTANCE: The striatin-interacting phosphatase and kinase (STRIPAK) complex is highly conserved from yeasts to humans and is an important regulator of numerous eukaryotic developmental processes, such as cellular signaling and cell development. Although functional insights into the STRIPAK complex are accumulating, the detailed molecular mechanisms of single subunits are only partially understood. The first fungal STRIPAK was described in Sordaria macrospora, which is a well-established model organism used to study the formation of fungal fruiting bodies, three-dimensional organ-like structures. We analyzed STRIPAK subunit PP2Ac1, catalytic subunit 1 of protein phosphatase PP2A, to study the importance of the catalytic activity of this protein during sexual development. The results of our yeast two-hybrid analysis and tandem affinity purification, followed by mass spectrometry, indicate that PP2Ac1 activity connects STRIPAK with other signaling pathways and thus forms a large interconnected signaling network.

The composition and function of the striatin-interacting phosphatases and kinases (STRIPAK) complex in fungi.

The striatin-interacting phosphatases and kinases (STRIPAK) complex is a highly conserved eukaryotic protein complex that was recently described for diverse animal and fungal species. Here, we summarize our current knowledge about the composition and function of the STRIPAK complex from the ascomycete Sordaria macrospora, which we discovered by investigating sexually sterile mutants (pro), having a defect in fruiting body development. Mass spectrometry and yeast two-hybrid analysis defined core subunits of the STRIPAK complex, which have structural homologs in animal and other fungal organisms. These subunits (and their mammalian homologs) are PRO11 (striatin), PRO22 (STRIP1/2), SmMOB3 (Mob3), PRO45 (SLMAP), and PP2AA, the structural, and PP2Ac, the catalytic subunits of protein phosphatase 2A (PP2A). Beside fruiting body formation, the STRIPAK complex controls vegetative growth and hyphal fusion in S. macrospora. Although the contribution of single subunits to diverse cellular and developmental processes is not yet fully understood, functional analysis has already shown that mammalian homologs are able to substitute the function of distinct fungal STRIPAK subunits. This underscores the view that fungal model organisms serve as useful tools to get a molecular insight into cellular and developmental processes of eukaryotes in general. Future work will unravel the precise localization of single subunits within the cell and decipher their STRIPAK-related and STRIPAK-independent functions. Finally, evidence is accumulating that there is a crosstalk between STRIPAK and various signaling pathways, suggesting that eukaryotic development is dependent on STRIPAK signaling.

Symptomatic Lymphocele Formation After Sentinel Lymph Node Biopsy for Early Stage Cervical Cancer.

In early stage cervical cancer, nodal status is the most important prognostic factor, and execution of retroperitoneal lymphadenectomy is currently an integral part of surgical therapy. Sentinel lymph node biopsy has been progressively incorporated with surgical therapy and could reduce morbidity. However, the current incidence of complications exclusively related to the procedure is unknown. We report on a 29-year-old woman affected by cervical cancer (Fédération Internationale de Gynécologie et d'Obstétrique Stage 1b1), who underwent sentinel lymph node biopsy in combination with radical vaginal trachelectomy, and who later developed a symptomatic pelvic lymphocele that required surgical therapy. Conservative procedures in the pelvic lymph nodes are not free of complications, especially with regard to the formation of symptomatic lymphoceles. This report brings to light an important discussion about the exact magnitude of the complications associated with the procedure.

Laparoscopic Fertility-preserving Treatment of a Pure Nongestational Choriocarcinoma of the Ovary: Case Report and Review of Current Literature.

This case report demonstrates the feasibility of laparoscopic and fertility-preserving approach in nongestational choriocarcinoma of the ovary (NGCO). Pure NGCO is a rare malignant condition. In the last decade, only 14 cases have been reported in the literature. The use of laparoscopy and fertility-preserving procedures in nonepithelial ovarian malignancies is extremely controversial. A 23-year-old woman underwent emergency laparoscopy due to acute abdominal pain associated with an 8-cm large adnexal mass. The initial procedure consisted only of a left oophoroplasty, and histology revealed a tumor of high malignant potential compatible with a primary NGCO. Approximately 3 weeks after initial surgery, she was submitted to a laparoscopic staging surgery, including left adnexectomy, omentectomy, peritoneal biopsies, and retroperitoneal lymphadenectomy. Final pathology confirmed an International Federation of Gynecology and Obstetrics stage IIB NGCO. Before initiation of adjuvant chemotherapy based on 3 courses of bleomycin, etoposide, and cisplatin, the patient received goserelin for ovarian suppression. Nine months after therapy, the patient presented no signs of recurrence and reassumed normal menstruation cycles with normal levels of gonadotropins and tumor markers. The current report brings new insights into the possibility of using use minimally invasive surgery and a combination of fertility-preserving methods for the treatment of NGCO.