Biology subjects

Papagiannouli, F.

Publications and source records attributed to Papagiannouli, F..

3 recordsLinked to original sources

bioRxiv2018

Nuclear export in somatic cyst cells controls cyst cell-germline coordination and germline differentiation in the Drosophila testis

Nucleocytoplasmic communication is crucial for proper cell function and coordination of intrinsic cues with signaling responses emanating from the neighboring cells and the local tissue microenvironment. In the Drosophila male germline system, germ cells proliferate and progressively differentiate enclosed in supportive somatic cyst cells, forming a small cyst, the functional unit of differentiation. Here we show that the peripheral nucleoporins Nup62, Nup214 and Nup88, and the exportin Emb are critically required in cyst cells to maintain cyst cell survival and germline encapsulation in order to protect cyst cell-germline communication and promote germ cell differentiation. Knockdown of nup62, emb, nup214 or nup88 in cyst cells leads to cell-autonomous defects in mRNA export, and cell non-autonomous overproliferation of early germ cells in the absence of cyst cell-derived differentiation signals. Suppression of apoptosis can reverse cyst cell elimination and partially restored those defects. Interestingly, overexpression of the Drosophila Profilin gene chickadee can rescue cyst cell survival and restore germline encapsulation and differentiation, by counteracting Ntf-2 mediated export, suggesting that the function of Profilin in cyst cells is linked to nuclear export.

developmental biology↗

bioRxiv2018

The Dlg-module and clathrin-mediated endocytosis regulate EGFR signaling and cyst cell-germline coordination in the Drosophila testis

Tissue homeostasis and repair relies on proper communication of stem cells and their differentiating daughters with the local tissue microenvironment. In the Drosophila male germline adult stem cell lineage, germ cells proliferate and progressively differentiate enclosed in supportive somatic cyst cells, forming a small organoid, the functional unit of differentiation. Here we show that cell polarity and vesicle trafficking influence signal transduction in cyst cells, with profound effects on the germ cells they enclose. Our data suggest that both the cortical components Dlg, Scrib, Lgl and the clathrin-mediated endocytic (CME) machinery downregulate EGFR signaling. Knockdown of dlg, scrib, lgl or CME components in cyst cells resulted in germ cell death, similar to increased signal transduction via the EGFR, while lowering EGFR or downstream signaling components rescued the defects. This work provides new insights on how cell polarity and endocytosis cooperate to regulate signal transduction and sculpt developing tissues.

developmental biology↗

bioRxiv2017

Decoding the regulatory logic of the Drosophila male stem cell system

In the past decade, the importance of the niche to provide regulatory inputs to balance stem cell self-renewal and differentiation has become clear. However, the regulatory interplay between stem cells and their niche at the whole genome level is still poorly understood. To elucidate the mechanisms controlling stem cells and their progenies as they progress through their developmental program at the transcriptional level, we recorded the regulatory program of two independent cell lineages in the Drosophila testis stem cell model. To this end, we identified genes active in the soma or germline as well as genome-wide binding profiles of two essential transcription factors, Zfh-1 and Abd-A, expressed in somatic support cells and crucial for fate acquisition of both cell lineages. Our data identified key roles for TOR signalling, signal processing V-ATPase proton pumps and the nuclear transport engaged nucleoporins and we demonstrate their importance in controlling germline maintenance, proliferation and differentiation from the support side. To make our dataset publicly available and support quick and intuitive data mining, we generated an interactive online analysis tool. Applying our tool for comparative analysis, we uncovered conserved core gene sets of adult stem cells across species boundaries. We have tested the functional relevance of these genes in the Drosophila testis and intestine and find a striking overrepresentation of stem cell defects when the corresponding genes were depleted. In summary, our dataset and interactive platform represents a versatile tool for identifying novel gene networks active in diverse stem cell types and provides a valuable resource for elucidating the multifaceted regulatory inputs required to guide proper stem cell behaviour.

developmental biology↗