A Possible Role for FRM-1, a C. elegans FERM Family Protein, in Embryonic Development

Abstract

FRM-1 is a member of the FERM protein superfamily containing a FERM domain, which is a highly conserved protein-protein interaction module found in most eukaryotes. Although FRM-1 is thought to be involved in linking intracellular proteins to membrane proteins, the specific role for FRM-1 remains to be elucidated. In an effort to explore the biological function of FRM-1, we examined the phenotype of frm-1(tm4168) mutant worms. We observed that frm-1(tm4168) worms have a delayed hatching phenotype. Twelve hours after being laid, when virtually all wild-type eggs had hatched, only 64% of frm-1(tm4168) eggs had hatched. About 3% of frm-1(tm4168) eggs failed to hatch, even 3 days after they had been laid. We also found that frm-1(tm4168) mutants displayed a temperature-sensitive sterility phenotype. About 13% of frm-1(tm4168) worms were unable to produce eggs or produced nonviable eggs at 25°C. In contrast, less than 1% of wild-type animals were sterile at this temperature. At 20°C, neither the mutant nor wild type appeared to be sterile. Western blot analysis indicates that FRM-1 is expressed throughout the developmental stages with the strongest expression at the egg stage. Immunostaining experiments revealed that FRM-1 is mainly localized to the plasma membrane of most if not all cells at an early embryonic stage and to the plasma membrane of P cells during the late embryonic stages. GFP fusion experiments showed that FRM-1 can be expressed in the pharynx and intestine at the larval and adult stages. Our data suggest that FRM-1 may participate in diverse biological processes, including embryonic development.

Plastin and spectrin cooperate to stabilize the actomyosin cortex during cytokinesis

“…The efficiency of the triple RNAi was validated by confirming: signal disappearance in a strain that expresses ERM-1::GFP, delayed hatching due to FRM-1 depletion, and decreased brood size due to UNC-44 depletion. [35][36][37] Cytokinesis successfully completed in 96% of triple-depleted plst-1(prt89);sma-1DPH embryos (Figure 4D). We conclude that neither the SH3 nor the PH domain of SMA-1 is required for the synergistic action between SMA-1 and PLST-1 during cytokinesis, which completes even when 3 additional membrane anchoring proteins are co-depleted in sma-1DPH embryos.…”

An interphase contractile ring reshapes primordial germ cells to allow bulk cytoplasmic remodeling

“…Embryos were dissected on poly-L-lysine-coated slides, freeze cracked, and fixed in −20°C MeOH (20 min) and 3.7% formaldehyde in salts (50 mM Pipes, 25 mM Hepes, 10 mM EGTA, and 2 mM MgCl 2 ; 5 min) before washing in PBS-Tween and immunostaining directly on slides in PBS-Tween containing 1% IgG-free BSA (001-000-162; Jackson ImmunoResearch). The following primary antibodies were used: chicken anti-GFP 1:10 (GFP-1010; Aves Labs), rabbit anti-UNC-59 1:100 (Maddox et al, 2005; a gift from Karen Oegema), rabbit anti-ANI-1 1:100 (Maddox et al, 2005; a gift from Karen Oegema), and mouse anti-FRM-1 1:1,000 (Choi et al, 2011; a gift from Nam Jeong Cho). The following secondary antibodies were used: AlexaFluor 488 goat anti-chicken IgY (H+L) (A-11039; Thermo Fisher Scientific), Cy3 donkey anti-rabbit IgG (H+L) (711-165-152, lot 86701; Jackson ImmunoResearch), and Cy5 donkey anti-mouse IgG (H+L) (715-175-151, lot 76920; Jackson ImmunoResearch).…”

Niche Cell Wrapping Ensures Primordial Germ Cell Quiescence and Protection from Intercellular Cannibalism

“…Embryos were collected from rinsed gravid hermaphrodites that were incubated in water for 4 hours to allow eggs to age. Fixation and immunostaining were performed as described [36] using the following primary and secondary antibodies: chicken anti-EPI-1 (1:8) [5], chicken anti-LAM-3 (1:8) [5], mouse anti-FRM-1 (1:1000) [26], Alexa Fluor 647 donkey anti-chicken IgY (1:500, Jackson Im-munoResearch), and Alexa Fluor 488 goat anti-mouse IgG (1:1000, Invitrogen).…”