scholarly journals Stem cell niche exit in C. elegans via orientation and segregation of daughter cells by a cryptic cell outside the niche

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Kacy L Gordon ◽  
Jay W Zussman ◽  
Xin Li ◽  
Camille Miller ◽  
David R Sherwood
Keyword(s):  
Stem Cell ◽  
Germ Cell ◽  
Stem Cell Niche ◽  
Cell Pair ◽  
C Elegans ◽  
Daughter Cells ◽  
Somatic Gonad ◽  
Cell Niche ◽  
Disproportionate Number ◽  
Gonad Cell

Stem cells reside in and rely upon their niche to maintain stemness but must balance self-renewal with the production of daughters that leave the niche to differentiate. We discovered a mechanism of stem cell niche exit in the canonical C. elegans distal tip cell (DTC) germ stem cell niche mediated by previously unobserved, thin, membranous protrusions of the adjacent somatic gonad cell pair (Sh1). A disproportionate number of germ cell divisions were observed at the DTC-Sh1 interface. Stem-like and differentiating cell fates segregated across this boundary. Spindles polarized, pairs of daughter cells oriented between the DTC and Sh1, and Sh1 grew over the Sh1-facing daughter. Impeding Sh1 growth by RNAi to cofilin and Arp2/3 perturbed the DTC-Sh1 interface, reduced germ cell proliferation, and shifted a differentiation marker. Because Sh1 membrane protrusions eluded detection for decades, it is possible that similar structures actively regulate niche exit in other systems.

scholarly journals The creation of sexual dimorphism in Drosophila gonad stem cell niches

2018 ◽  
Author(s):  
Nicole Camara ◽  
Cale Whitworth ◽  
Mark Van Doren
Keyword(s):  
Stem Cell ◽  
Sexual Dimorphism ◽  
Stem Cell Niche ◽  
Group Decision ◽  
Female Gonad ◽  
Male And Female ◽  
Somatic Gonad ◽  
Niche Formation ◽  
Cell Niche ◽  
Stem Cell Niches

SUMMARYSex-specific development of the gonads is a key aspect of sexual dimorphism that is regulated by Doublesex/Mab3 Related Transcription Factors (DMRTs) in diverse animals species. We find that in mutants for Drosophila dsx, important components of the male and female gonad stem cell niches (hubs and terminal filaments/cap cells, respectively) still form. Initially, gonads in all dsx mutants (both XX and XY) initiate the male program of development, but later half of these gonads switch to form female stem cell niche structures. One individual can have both male-type and female-type gonad niches, however male and female niches are usually not observed in the same gonad, indicating that cells make a “group decision” about which program to follow. We conclude that dsx does not act in an instructive manner to regulate male vs. female niche formation, as these structures form in the absence of dsx function. Instead, dsx acts to “tip the balance” between the male or female programs, which are then executed independent of dsx. We show that bric a brac acts downstream of dsx to control the male vs. female niche decision. These results indicate that, in both flies and mammals, the sexual fate of the somatic gonad is remarkably plastic and is controlled by a combination of autonomous and non-autonomous cues.

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