Shaping the niche: Lessons from the Drosophila testis and other model systems

Abstract

Stem cells are fascinating, as they supply the cells that construct our adult bodies and replenish, as we age, worn out, damaged, and diseased tissues. Stem cell regulation relies on intrinsic signals but also on inputs emanating from the neighbouring niche. The Drosophila testis provides an excellent system for studying such processes. Although recent advances have uncovered several signalling, cytoskeletal and other factors affecting niche homeostasis and testis differentiation, many aspects of niche regulation and maintenance remain unsolved. In this review, we discuss aspects of niche establishment and integrity not yet fully understood and we compare it to the current knowledge in other model systems such as vertebrates and plants. We also address specific questions on stem cell maintenance and niche regulation in the Drosophila testis under the control of Hox genes. Finally, we provide insights on the striking functional conservation of homologous genes in plants and animals and their respective stem cell niches. Elucidating conserved mechanisms of stem cell control in both lineages could reveal the importance underlying this conservation and justify the evolutionary pressure to adapt homologous molecules for performing the same task.

The Male Stem Cell Niche: Insights from Drosophila and Mammalian Model Systems

“…All these studies on the role of septate junction components in the Drosophila testis, underline the importance of the CySCs and SCCs to encapsulate the germline and establish the cyst integrity, which is necessary for germline differentiation and normal testis function to finally produce healthy sperm and ensure fertility [10,89,93]. Interestingly, the Drosophila testis cyst cells show striking similarities with the Sertoli cells, the supportive cells of the mammalian germline, in terms of cytoskeletal and scaffolding components [10].…”

“…Interestingly, the Drosophila testis cyst cells show striking similarities with the Sertoli cells, the supportive cells of the mammalian germline, in terms of cytoskeletal and scaffolding components [10]. Since several of these genes show high degree of conservation to their vertebrate homologues [28,89], what we learn about cyst cell function, soma-germline coordination and the underlying regulatory logic in the Drosophila testis can be directly tested in other organisms and stem cell systems in other tissues.…”

“…The advantages of each model system, combined with the development of new tools and methodologies, open up the possibility to test concepts and transfer knowledge from one model system to the other. Finally, understanding the basic mechanisms regulating germline stem cells and their niches can ultimately be used in regenerative medicine to repair aging and damaged stem cells, treat male infertility and improve applications in agricultural species [2,10,130,163,174].…”

“…In mammalian systems, the location of the niche is defined largely based on its proximity to the stem cells. The niche or stem cell regulatory microenvironment is defined by the cellular components and extracellular matrix (ECM) in proximity to the stem cells, and the signals emanating from the support cells [9,10]. Significant progress regarding stem cells and their surrounding microenvironment has been made in different mammalian tissue types like the nervous system, the endothelial cells and hematopoietic system, the skin and hair follicles as well as the intestine [11][12][13][14][15][16][17][18].…”

New insights into the normal and leukemic stem cell niche: A timely review

“…The concept that tissue stem cells develop within specialized microenvironments or niches originated from genetic studies of germ cell development in Drosophila (1), but much of what we know about stem cell niche biology has emerged from studies of the hematopoietic stem cell (HSC) niche, first conceptualized over 30 years ago by Schofield (2). In this issue of Clinical Cytometry, Krause et al provide a comprehensive update on this rapidly moving field (3).…”