Notch-Directed Germ Cell Proliferation Is Mediated by Proteoglycan-Dependent Transcription

Abstract

Notch receptors are essential membrane-bound regulators of cell proliferation and differentiation in metazoa. In the nematode Caenorhabditis elegans, correct expression of GLP-1 (germline proliferation-1), a germline-expressed Notch receptor, is important for germ cell maintenance. However, mechanisms that regulate GLP-1 expression are undefined. Here, we demonstrate that an AP-2 transcription factor (APTF-2) regulates GLP-1 expression through calcium-dependent binding to a conserved motif in the glp-1 promoter. Our data reveals that SDN-1 (syndecan-1), a transmembrane proteoglycan, regulates a TRP calcium channel in the soma to modulate the interaction between APTF-2 and glp-1 promoter - thus providing a potential communication nexus between the germline and its somatic environment to control germ cell fate decisions.

The C. elegans gonadal sheath Sh1 cells extend asymmetrically over a differentiating germ cell population in the proliferative zone

“…Therefore, we consider the results presented here to be confirmatory of the foundational finding of (Gordon et al, 2020), which is that almost all mitotic germ cells in the adult hermaphrodite contact the DTC or Sh1, with a noteworthy population in contact with both. Other recent work suggests a role for the sheath cells in promoting adult germ cell proliferation, specifically through modulation of Notch receptor glp-1 expression (Gopal et al, 2020). We focus especially on young adults in these studies (less than 24 hours post mid-L4, see Methods).…”

The C. elegans gonadal sheath Sh1 cells extend asymmetrically over a differentiating germ cell population in the proliferative zone

“…Therefore, we consider the results presented here to be confirmatory of the foundational finding of (Gordon et al, 2020), which is that almost all mitotic germ cells in the adult hermaphrodite contact the DTC or Sh1, with a noteworthy population in contact with both. Other recent work suggests a role for the sheath cells in promoting adult germ cell proliferation, specifically through modulation of Notch receptor glp-1 expression (Gopal et al, 2020).…”