Dr Fani Papagiannouli

Dr Fani Papagiannouli completed her undergraduate studies in Biology (University of Patras, Greece) in 1998 with honors by the State Scholarships Foundation IKY. She started her Ph.D. at the University of Heidelberg (Germany) and the German Cancer Research Center (DKFZ, Heidelberg), working on the role of the highly conserved polarity and tumor suppressor genes dlg, scrib and lgl in the Drosophila male gonads and testis architecture. 

After completing her PhD in 2003, she continued her research analysing the development and morphogenetic events of the early Drosophila embryo at Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH). In 2009 she joined the Centre for Organismal Studies (COS, Heidelberg) to study the role of the Hox transcription factors abdA and AbdB in the Drosophila testis. Her work uncovered that abdA controls fate transition within the somatic lineage, while AbdB emerged as a key regulator of stem cell niche positioning and architecture. Genome-wide studies revealed that AbdB in pre-meiotic germ cells provides positional cues for integrin localization by directly controlling Boss/Sev signaling between adjacent cell types.

 In 2016 Fani moved to Stanford University (USA), with an awarded Fellowship from the German Research Foundation (DFG), to study soma-germline communication and signaling regulation in the Drosophila testis, together with Prof. Margaret Fuller. She returned to Germany in 2018 to continue her studies on the mechanisms and factors that regulate germ cell control during spermatogenesis in Drosophila, hosted by Prof. Maria Leptin at the Institute of Genetics in Cologne. Her latest work revealed that cortical polarity and cellular trafficking regulate EGFR in the somatic epithelial-type cyst cells that encapsulate the germ cells and promote germ cell survival and animal fertility.

Dr Fani Papagiannouli joined the Medway School of Pharmacy in September 2019 as a Lecturer in Biological Sciences with speciality in Genetics, Stem Cell and Developmental Biology. Her scientific focus is on the mechanisms and factors that regulate stem cell maintenance and how stem cells interact with their neighbouring cells to shape the niche and local tissue microenvironment. Elucidating the role of transcription factors such as the Hox gene AbdB, as well as that of the cortical polarity proteins Dlg, Scrib and Lgl, and nucleoporins in soma-germline coordination, within the complex gene network underlying testis homeostasis, are some of her main research interests.

Specialist areas

Genetics, Stem Cell & Developmental Biology, Cell Biology, Molecular Biology, Cell Signalling, Drosophila, Spermatogenesis, Gene Regulation, Genomics, Proteomics, High-resolution microscopy, Electron microscopy, Image Analysis Histology.

Watch our “Pint of Science” lab presentation “Fruit flies and the power of curiosity-driven research”: https://www.youtube.com/watch?v=nDUHkwPXRrM&ab_channel=PintofScienceUK

Follow our publications on PubMed: https://www.ncbi.nlm.nih.gov/pubmed/?term=Papagiannouli+F

Orchid URL: https://orcid.org/0000-0003-4094-6688

Research in Papagiannouli’s lab aims to understand the principles underlying cell-cell communication and stem cell-related processes in the Drosophila testis. In this system, germline stem cells and their daughter germ cells proliferate and progressively differentiate enclosed in squamous epithelial-type somatic cyst cells, forming a small organoid-like “cyst”, the unit of differentiation. We are particularly interested in how communication between the germline and the somatic cyst cells is established and maintained, in particular how the somatic cyst cells support the developmental decision of the germline during spermatogenesis. The microenvironment of those cysts provides an ideal model system to investigate how key cellular mechanisms such as endocytosis, polarity cues and nucleocytoplasmic transport cooperate with signaling and transcriptional control to maintain cyst cell-germline communication and achieve a coordinated cellular output.

The lab focuses on how cortical polarity components regulate signaling in the male germline system. Fani Papagiannouli has shown that Dlg, Scrib and Lgl are critically required in the somatic lineage to encapsulate the germ cells and preserve the architecture and homeostasis of the male gonads and larval testes (Marhold§, Papagiannouli§ et al., 2003; Papagiannouli, 2013; Papagiannouli and Mechler, 2009, 2010). Latest findings identified Dlg, Scrib, Lgl and clathrin-mediated endocytosis (CME) as key regulators of EGFR signaling, since knockdown of their function leads to increased EGFR signaling levels, apoptotic death of the neighbouring germ cells and infertility of the male flies (Papagiannouli et. al., 2019). Lowering the EGFR signaling levels in cyst cells can rescue the observed defects, restore germ cell survival and the function of the testis-barrier, while the membrane phospholipid PtdIns(4,5)P2 (PIP2) contributes to EGFR/Ras-mediated activation of the MAPK dpERK downstream of the pathway. Future work aims to dissect the precise mechanistic features underlying the Dlg- and CME- mediated regulation of EGFR signaling, by employing highly innovative proteomic approaches and advanced electron microscopy.
This project is funded by a Medway School of Pharmacy Post Graduate Research Scholarship.

Other aspects of on-going research in the lab are to decipher the landscape of nucleoporin function in nucleocytoplasmic transport and cyst cell-germline coordination (Papagiannouli et. al., bioRxiv Oct. 24; doi: 10.1101/452466) and build up on the previously identified role of the Hox transcription factor AbdB in stem cell niche positioning and architecture (Papagiannouli et. al., 2014; Schardt et. al., 2015; Papagiannouli et. al., 2015).

The high degree of conservation of the components we study, at gene and cellular level across species, will allow us to drive qualitative conclusions on how stem cells communicate with their neighbours to replenish differentiated tissues. Given the role of squamous epithelial cells in the development of prevalent human cancers, the outcome of our research will eventually formulate general rules underlying the function of squamous epithelial cells of broader importance. The regulatory strategies uncovered in our studies could collectively aid the identification of new approaches in regenerative medicine and infertility.