169 Oral - Patterning and Morphogenesis II
Saturday April 09, 10:45 AM - 11:00 AM

Authors:
Bailey Warder; Kara Nelson; Justin Sui; Lauren Anllo; Stephen DiNardo

Affiliation: University of Pennsylvania

Keywords:
l. gonads; f. niche and other local signaling

Stem cells often rely on signals from a niche, which in many tissues adopts a precise morphology. What remains elusive is how niches are formed, and how niche morphology impacts function. I use the gonadal niche to study mechanisms of niche formation, combining genetic tractability with powerful live-imaging techniques pioneered in our lab. This niche adopts a distinct morphology, with a smoothened boundary between itself and adherent germline stem cells (GSCs). The niche plays key roles in regulating GSC behavior and it is thus vital to identify mechanisms of niche formation. We have found that the niche-GSC boundary is enriched for F-actin and Myosin II (MyoII). I therefore hypothesize that actomyosin contractility (AMC) shapes the niche, and makes it more efficient in guiding GSC behavior. Through transgenic and pharmacological manipulations, I show that precise levels of AMC are required for niche shape. Further, live-imaging shows that proper niche shape is crucial for function. Current work addresses mechanisms that robustly polarize F-actin and MyoII in the niche. Interestingly, AMC can be regulated by mechanical forces exerted on a cell. I have evidence that GSC divisions are required for niche morphogenesis, and I suspect that AMC in the niche is induced by forces inherent to GSC divisions. Our work suggests a unique feedback mechanism where stem cells shape the niche that guides their behavior. T32 GM007229 (BW), F32 GM125123 (LA), R35 GM136270 (SD)