The balance between stem cell proliferation and differentiation is important for growth and development in many organisms. This balance is highly regulated, and requires an interaction between the niche and the stem cell pool in order to be maintained. In C. elegans, the somatic distal tip cell (DTC) acts as the germline stem cell niche by providing cues to the stem cell pool via GLP-1/Notch signalling. We have identified the Derlin protein DER-1 (CUP-2) as having a role in regulating the DTC. The DTC is normally located at the distal most end of the gonad. It can move several cells away from the distal most end as the worms age (Kocsisova et al., 2019). As
cup-2 mutant worms age, the DTC moves further proximally down the gonad arm than what is seen with wild type. In some more extreme cases, the stem cell pool moves along with the DTC, which suggests the DTC remains functional at the new location. We are characterizing
cup-2's expression along with its displacement phenotype to determine where
cup-2 is required such that the DTC will remain in place. Additionally, we are exploring
cup-2's known functions, endoplasmic reticulum associated degradation (ERAD) and endocytosis, to determine if they play a role in the placement of the DTC. Finally, we are looking at the surrounding basement membrane to determine if it may play a novel role in holding the DTC in place. This investigation of CUP-2 may help us understand how the DTC and potentially other niches are held in place, and how this displacement affects germline stem cells and the balance between stem cell proliferation and differentiation. References Kocsisova, Z., Kornfeld, K. & Schedl, T. Rapid population-wide declines in stem cell number and activity during reproductive aging in C. elegans. Development 146, (2019).