Biology subjects

Delaney, K.

Publications and source records attributed to Delaney, K..

7 recordsLinked to original sources

bioRxiv2026

SLBP-independent control of maternal histone mRNA

Replication-dependent (RD) histones are crucial for packaging newly replicated DNA into chromatin, ensuring genome stability. In metazoans, the mRNA of RD histones is uniquely regulated through a conserved 3' stem-loop bound by stem-loop binding protein (SLBP). This allows cell cycle-coupled regulation of these important transcripts. However, oocytes must stabilise histone mRNAs independently of the cell cycle to ensure maternal loading to support the first embryonic divisions. Using Caenorhabditis elegans as a model system, we discovered an SLBP-independent mechanism that ensures RD histone transcript stability during oogenesis. This is mediated by the protein complex PETISCO, bound to the effector protein TOST-1, which directly binds the histone stem-loop region and maintains maternal histone mRNA levels during oogenesis and early embryogenesis. Loss of this mechanism disrupts histone homeostasis, leading to premature genome activation, mitotic defects, and embryonic lethality. Interestingly, the same complex, PETISCO, acts in piRNA biogenesis when bound to the effector PID-1, revealing an intriguing co-option of this histone mRNA homeostasis mechanism by the piRNA pathway. Our findings reveal a unique SLBP-independent mechanism of histone mRNA regulation, that served as a basis for the evolution of a novel piRNA biogenesis mechanism.

molecular biology↗

bioRxiv2025

Transgenerational maintenance of H3K27me3 heterochromatin is balanced by chromodomain proteins in Caenorhabditis elegans

The ability to replicate and pass information to descendants is a fundamental requirement for life. In addition to the DNA-based genetic information, modifications of the DNA or DNA-associated proteins can create patterns of heritable gene regulation. Such epigenetic inheritance allows for adaptation without mutation, but its limits and regulation are incompletely understood. Here we developed a C. elegans system to study the transgenerational epigenetic inheritance of H3K27me3, a conserved histone posttranslational modification associated with gene repression. We find that induced alterations of the genome-wide H3K27me3 landscape and the associated fertility defects persist for many generations in genetically wildtype descendants under selective pressure. We uncover that the inheritance of the altered H3K27me3 landscape is regulated by two chromodomain proteins with antagonizing functions, and provide mechanistic insight into how this molecular memory is initiated and maintained. Our results demonstrate that epigenetic inheritance can act as a mutation-independent, heritable mechanism of adaptation. In BriefOzdemir et al. demonstrate that an altered genomic distribution of the histone modification H3K27me3 can be epigenetically inherited across many generations through the activity of HERI-1/SET-32/MES-4, which is antagonized by CEC-6/PRC2 in C. elegans. HighlightsO_LIAltered H3K27me3 landscapes can be inherited for at least 15 generations in C. elegans. C_LIO_LIThe chromodomain proteins CEC-6 and HERI-1 have opposite roles in antagonizing or promoting the maintenance of the altered H3K27me3 landscape. C_LIO_LIH3K23me3 and H3K36me3 replace H3K27me3 to promote the intergenerational and transgenerational inheritance of the altered epigenome. C_LI

genetics↗

bioRxiv2020

Evaluation of the Abbott ARCHITECT HIV Ag/Ab Combo Assay for Determining Recent HIV-1 Infection

BackgroundGiven the challenges and costs associated with implementing HIV-1 incidence assay testing, there is great interest in evaluating the use of commercial HIV diagnostic tests for determining recent HIV infection. A diagnostic test with the capability of providing reliable data for the determination of recent HIV infection without substantial modifications to the test protocol would have a significant impact on HIV surveillance. The Abbott ARCHITECT HIV Ag/Ab Combo Assay is an antigen/antibody immunoassay, which meets the criteria as the first screening test in the recommended HIV laboratory diagnostic algorithm for the United States. MethodsIn this study, we evaluated the performance characteristics of the ARCHITECT HIV Ag/Ab Combo signal-to-cutoff ratio (S/Co) for determining recent infection, including estimation of the mean duration of recent infection (MDRI) and false recent rate (FRR), and selection of recency cutoffs. ResultsThe MDRI estimates for the S/Co recency cutoff of 400 is within the 4 to 12 months range recommended for HIV incidence assays, and the FRR rate for this cutoff was 1.5%. Additionally, ARCHITECT Combo S/Co values were compared relative to diagnostic test results from two prior prospective HIV-1 diagnostic studies in order to validate the use of the S/Co for both diagnostic and recency determination. ConclusionDual-use of the ARCHITECT Combo assay data for diagnostic and incidence purposes would reduce the need for separate HIV incidence testing and allow for monitoring of recent infection for incidence estimation and other public health applications.

microbiology↗

bioRxiv2020

Trans-generational inheritance of centromere identity requires the CENP-A N-terminal tail in the C. elegans maternal germ line

Centromere protein A (CENP-A) is a histone H3 variant that defines centromeric chromatin and is essential for centromere function. In most eukaryotes CENP-A-containing chromatin is epigenetically maintained, and centromere identity is inherited from one cell cycle to the next. In the germ line of the holocentric nematode Caenorhabditis elegans, this inheritance cycle is disrupted. CENP-A is removed at the mitosis-to-meiosis transition and is established de novo on chromatin during diplotene of meiosis I. Here we show that the N-terminal tail of CENP-A is required for the de novo establishment of centromeres, but dispensable for centromere maintenance during embryogenesis. Worms homozygous for a CENP-A tail deletion maintain a functional centromere during development, but give rise to inviable offspring because they fail to re-establish centromeres in the maternal germ line. We identify the N-terminal tail of CENP-A as a critical domain for the interaction with the conserved kinetochore protein KNL-2, and argue that this interaction plays an important role in setting centromere identity in the germ line. We conclude that centromere establishment and maintenance are functionally distinct in C. elegans.

genetics↗

bioRxiv2020

A Pumpless Microfluidic Neonatal Lung Assist Device for Support of Preterm Neonates in Respiratory Distress

Premature neonates suffer from respiratory morbidity as their lungs are immature and current supportive treatment such as mechanical ventilation or extracorporeal membrane oxygenation (ECMO) cause iatrogenic injuries. A non-invasive and biomimetic concept known as the "artificial placenta" would be beneficial to overcome complications associated with the current respiratory support of preterm infants. Here, a pumpless oxygenator connected to the systemic circulation supports the lung function to relieve respiratory distress. In this paper, we demonstrate the first successful operation of a microfluidic, artificial placenta type neonatal lung assist device (LAD) on a newborn piglet model which is the closest representation of preterm human infants. This LAD has high oxygenation capability in both pure oxygen and room air as the sweep gas. It was able to relieve the respiratory distress that the newborn piglet was put under during experimentation, repeatedly and over significant duration of time. These findings indicate that this LAD has potential application as a biomimetic artificial placenta to support respiratory needs of preterm neonates.

bioengineering↗

bioRxiv2019

Precise subcellular functional organization of excitation and inhibition in the direction-selective ganglion cell circuit

Recent studies indicate that the precise timing and location of excitation and inhibition (E/I) within active dendritic trees can significantly impact neuronal function. How excitatory and inhibitory inputs are functionally organized at the subcellular level in intact circuits remains unclear. To address this issue, we took advantage of the retinal direction-selective ganglion cell circuit, in which directionally tuned inhibitory GABAergic input arising from starburst amacrine cells shape direction-selective dendritic responses. We combined two-photon Ca2+ imaging with genetic, pharmacological, and single-cell ablation methods to examine local E/I. We demonstrate that when active dendritic conductances are blocked, direction selectivity emerges semi-independently within unusually small dendritic segments (<10 {micro}m). Impressively, the direction encoded by each segment is relatively homogenous throughout the ganglion cells dendritic tree. Together the results demonstrate a precise subcellular functional organization of excitatory and inhibitory input, which suggests that the parallel processing scheme proposed for direction encoding could be more fine-grained than previously envisioned.

neuroscience↗

bioRxiv2019

Local inhibition of PRC2 activity by H3.3K27M drives DNA replication defects through misregulation of the JNK pathway

Substitution of lysine 27 with methionine in histone H3.3 is a recently discovered driver mutation of pediatric high-grade gliomas. Mutant tumor cells show decreased levels and altered distribution of H3K27me3. How these chromatin changes are established genome-wide and lead to tumorigenesis only in specific tissues remains unclear. Here we show that H3.3K27M-mediated alterations in H3K27me3 distribution result in ectopic DNA replication and cell cycle progression of germ cells in Caenorhabditis elegans. By genetically inducing changes in the H3.3 distribution, we demonstrate that both H3.3K27M oncohistone incorporation and pre-existing H3K27me3 act locally and antagonistically on Polycomb Repressive Complex 2 (PRC2) in a concentration-dependent manner, explaining the observed H3K27me3 distribution in mutant cells. The altered heterochromatin patterns lead to extensive misregulation of gene expression. Through unbiased genetic screening, we found that inhibiting JNK pathway components, which are overexpressed in H3.3K27M cells, suppresses the ectopic DNA replication and cell cycle progression without rescuing the altered H3K27me3 distribution. Moreover, we show that JNK inhibition suppresses the replicative fate in human tumor-derived H3.3K27M cells, thus establishing C. elegans as a powerful model for the identification of potential drug targets for treatment of H3.3K27M tumors.

molecular biology↗