Biology subjects

Osburn, K. L.

Publications and source records attributed to Osburn, K. L..

2 recordsLinked to original sources

bioRxiv2025

Exogenous expression of a histone H3.3 isoform causes extranuclear divisions in the C. elegans intestine

Histone proteins condense DNA into chromatin and play significant roles in gene regulation. Mutations that alter histone function can disrupt critical gene expression programs and are implicated in driving cancer and other human diseases. Most mechanistic research on histones has been conducted in cell culture, mitotic tissues, or animal disease models rather than in normal tissue. Caenorhabditis elegans is a model organism with a well-established developmental program and conserved histone mechanisms shared with other metazoans. Prior work generated several single-copy histone reporters expressing exogenous histone protein in the intestine. Surprisingly, the histone H3.3 reporter worms possessed extra nuclei in the anterior intestine. This phenotype was incompletely penetrant and arose early during larval development. Mutations predicted to perturb histone H3.3 reporter expression or deposition into chromatin ameliorated the phenotype. DNA Fluorescence In situ Hybridization (FISH) was used to measure chromosome copy number and revealed approximately half the DNA content in the extra nuclei versus undivided controls, suggesting aberrant nuclear division during normal rounds of intestinal endoreduplication. Thus, these reporters serendipitously identified a distinct function of histone H3.3 in triggering aberrant nuclear division during animal development. Other histone isoforms may have previously unrecognized biological functions in terminally differentiated tissue alongside their roles in mitotic tissue.

developmental biology↗

bioRxiv2025

In vivo pulse-chase in C. elegans reveals intestinal histone turnover changes upon starvation

The ability to study protein dynamics and function in the authentic context of a multicellular organism is paramount to better understand biological phenomena in animal health and disease. Pulse-chase of self-labeling fusion protein tags provide the opportunity to label proteins of interest and track those proteins over time. There are currently several challenges associated with performing in vivo protein pulse-chase in animals, such as cost, reproducibility, and accurate detection methods. The C. elegans model organism has attributes that alleviate many of these challenges. This work tests the feasibility of applying the Halo modified enzyme (HaloTag) for in vivo protein pulse-chase in C. elegans. HaloTag intestinal histone reporters were created in the worm and used to demonstrate that reporter protein could be efficiently pulse-labeled by soaking animals in ligand. Labeled protein stability could be monitored over time by fluorescent confocal microscopy. Further investigation revealed reporter protein stability was dependent on the animals nutritional state. Chromatin Immunoprecipitation and sequencing (ChIP-seq) of the reporters showed incorporation in chromatin with little change hours into starvation, implying a lack of chromatin regulation at the time point tested. Collectively, this work presents a straightforward method to label and track proteins of interest in C. elegans that can address a multitude of biological questions surrounding protein stability and dynamics in this animal model.

biochemistry↗