Biology subjects

Moss, E. G.

Publications and source records attributed to Moss, E. G..

3 recordsLinked to original sources

bioRxiv2024

A temporal sequence of heterochronic gene activities promotes stage-specific developmental events in C. elegans

The heterochronic genes of the nematode Caenorhabditis elegans control the succession of postembryonic developmental events. The four core heterochronic genes lin-14, lin-28, hbl-1, and lin-41 act in a sequence to specify cell fates specific to each of the four larval stages. It was previously shown that lin-14 has two activities separated in time that promote L1 and L2 developmental events, respectively. Using the auxin-inducible degron system, we find that lin-28 and hbl-1 each have two activities that control L2 and L3 events which are also separated in time. Relative to events they control, both lin-28 and hbl-1 appear to act just prior to or concurrently with events of the L2. Relative to each other, lin-28 and hbl-1 appear to act simultaneously. By contrast, the lin-14 activity controlling L2 events precedes those of lin-28 and hbl-1 controlling the same events, suggesting lin-14s regulation of lin-28 is responsible for the delay. Likewise, the activities of lin-28 and hbl-1 controlling L3 fates act well in advance of those fates, suggesting a similar regulatory gap. lin-41 acts early in the L3 to affect fates of the L4, although it was not possible to determine whether it too has two temporally separated activities. We also uncovered a feedback phenomenon that prevents the reactivation of heterochronic gene activity late in development after it has been down-regulated. This study places the heterochronic gene activities into a timeline of postembryonic development relative to one another and to the developmental events whose timing they control.

genetics↗

bioRxiv2023

Orthologs of the C. elegans heterochronic genes have divergent functions in C. briggsae

The heterochronic genes of C. elegans comprise the best-studied pathway controlling the timing of tissue and organ formation in an animal. To begin to understand the evolution of this pathway and the significance of the relationships among its components, we characterized 11 C. briggsae orthologs of C. elegans heterochronic genes. Using CRISPR/Cas9, we made a variety of alleles and found that several mutant phenotypes differ in significant ways from those of C. elegans. Although most mutant orthologs displayed defects in developmental timing, their phenotypes could differ in which stages were affected, the penetrance and expressivity of the phenotypes, or by having additional pleiotropies that were not obviously connected to developmental timing. However, when examining pairwise epistasis and synergistic relationships, we found those paralleled the known relationships between their C. elegans orthologs, suggesting that the arrangements of these genes in functional modules is conserved, but the modules relationships to each other and/or to their targets has drifted since the time of the species last common ancestor. Furthermore, our investigation has revealed a relationship to this pathway to other aspects of the animals growth and development, including gonad development, that is relevant to both species.

developmental biology↗

bioRxiv2021

An engineered, orthogonal auxin analog/AtTIR1(F79G) pairing improves both specificity and efficacy of the auxin degradation system in Caenorhabditis elegans

The auxin-inducible degradation system in C. elegans allows for spatial and temporal control of protein degradation via heterologous expression of a single Arabidopsis thaliana F-box protein, transport inhibitor response 1 (AtTIR1). In this system, exogenous auxin (Indole-3-acetic acid; IAA) enhances the ability of AtTIR1 to function as a substrate recognition component that adapts engineered degron-tagged proteins to the endogenous C. elegans E3 ubiquitin ligases complex (SKR-1/2-CUL-1-F-box (SCF)), targeting them for degradation by the proteosome. While this system has been employed to dissect the developmental functions of many C. elegans proteins, we have found that several auxin-inducible degron (AID)-tagged proteins are constitutively degraded by AtTIR1 in the absence of auxin, leading to undesired loss-of-function phenotypes. In this manuscript, we adapt an orthogonal auxin-derivative/mutant AtTIR1 pair (C. elegans AID version 2 (C.e.AIDv2)) that transforms the specificity of allosteric regulation of TIR1 from IAA to one that is dependent on an auxin derivative harboring a bulky aryl group (5-Ph-IAA). We find that a mutant AtTIR1(F79G) allele that alters the ligand binding interface of TIR1 dramatically reduces ligand-independent degradation of multiple AID*-tagged proteins. In addition to solving the ectopic degradation problem for some AID targets, addition of 5-Ph-IAA to culture media of animals expressing AtTIR1(F79G) leads to more penetrant loss-of-function phenotypes for AID*-tagged proteins than those elicited by the AtTIR1-IAA pairing at similar auxin analog concentrations. The improved specificity and efficacy afforded by the mutant AtTIR1(F79G) allele expands the utility of the AID system and broadens the number of proteins that can be effectively targeted with it. ARITCLE SUMMARYImplementation of the auxin induced degradation (AID) system has increased the power if the C. elegans model through its ability to rapidly degrade target proteins in the presence of the plant hormone auxin (IAA). The current C.e.AID system is limited in that a substantial level of target degradation occurs in the absence of ligand and full levels of target protein degradation require high levels of auxin inducer. In this manuscript, we modify the AID system to solve these problems.

molecular biology↗