Biology subjects

Kelly, G. M.

Publications and source records attributed to Kelly, G. M..

6 recordsLinked to original sources

bioRxiv2025

Gastric epithelium from BRCA1 and BRCA2 carriers harbors increased double-stranded DNA damage and augmented growth.

An accumulating body of evidence suggests carriers of a pathogenic germline variant (PGV) in BRCA1 or BRCA2 have increased gastric cancer (GC) risk. BRCA1 and BRCA2 are tumor suppressor genes involved in promoting homologous recombination to repair double-stranded DNA breaks. The aim of this investigation was to identify differences within the gastric epithelium and in patient-derived gastric organoids (PDGOs) between BRCA1 and BRCA2 carriers and non-carriers to determine if evidence of early gastric carcinogenesis exists amongst these carriers. First, using gastric epithelial biopsies, BRCA2 carriers were found to harbor higher expression of the proliferative marker Ki-67 within the antral gastric epithelium and strikingly, biopsies from both BRCA1 and BRCA2 carriers displayed a marked increase in double-stranded DNA damage. These results were further explored using PDGOs, where a growth advantage was observed for both BRCA1 and BRCA2 PDGOs compared to non-carrier PDGOs. Furthermore, both BRCA1 and BRCA2 PDGOs displayed a more pronounced enhancement of Ki-67 expression as well as increased double stranded DNA damage compared to non-carrier PDGOs. Importantly, none of the PDGOs showed signs of BRCA1 or BRCA2 loss of heterozygosity, potentially indicating a haploinsufficient phenotype. Taken together, these novel findings suggest that haploinsufficiency in BRCA1 and BRCA2 carriers may lead to DNA damage in the gastric epithelium, which may serve as an early event contributing to GC development.

cancer biology↗

bioRxiv2024

Bone Mineralization Regulation: Using Zebrafish as a Model to Study ANKH-associated Mineralization Disorders

Craniometaphyseal Dysplasia (CMD) is a rare skeletal disorder that can result from mutations in the ANKH gene. This gene encodes progressive ankylosis (ANK), which is responsible for transporting inorganic pyrophosphate (PPi) and ATP from the intracellular to the extracellular environment, where PPi inhibits bone mineralization. When ANK is dysfunctional, as in patients with CMD, the passage of PPi to the extracellular environment is reduced, leading to excess mineralization, particularly in bones of the skull. Zebrafish may serve as a promising model to study the mechanistic basis of CMD. Here we provide a detailed analysis of the zebrafish ankh paralogs, ankha and ankhb, in terms of their phylogenic relationship with ANKH in other vertebrates as well as their spatiotemporal expression patterns during zebrafish development. We found a closer evolutionary relationship exists between the zebrafish ankhb protein and its human and other "higher" vertebrate counterparts. Furthermore, we noted distinct temporal expression patterns with ankha more prominently expressed in early development stages, and ankhb expression at larval growth stages. Whole mount in situ hybridization was used to compare spatial expression patterns of each paralog during bone development. Both paralogs showed strong expression in the craniofacial region as well as the notochord and somites, with only subtle patterning differences. Given the substantial overlap in spatiotemporal expression of ankha and ankhb, the exact roles of these genes remain speculative. However, this study lays the groundwork for functional analyses of each ankh paralog and the potential of using zebrafish to find possible targeted therapies for CMD.

developmental biology↗

bioRxiv2022

Never in Mitosis Kinase 2 regulation of metabolism is required for neural differentiation

1.Wnt and Hh are known signalling pathways involved in neural differentiation and recent work has shown the cell cycle regulator, Never in Mitosis Kinase 2 (Nek2) is able to regulate both pathways. Despite its known function in pathway regulation, few studies have explored Nek2 within embryonic development. The P19 embryonal carcinoma cell model was used to investigate Nek2 and neural differentiation through CRISPR knockout and overexpression studies. Loss of Nek2 reduced cell proliferation in the undifferentiated state and during directed differentiation, while overexpression increased cell proliferation. Despite these changes in proliferation rates, Nek2 deficient cells maintained pluripotency markers after neural induction while Nek2 overexpressing cells lost these markers in the undifferentiated state. Nek2 deficient cells lost the ability to differentiate into both neurons and astrocytes, although Nek2 overexpressing cells enhanced neuron differentiation at the expense of astrocytes. Hh and Wnt signaling were explored, however there was no clear connection between Nek2 and these pathways causing the observed changes to differentiation phenotypes. Mass spectrometry was also used during wildtype and Nek2 knockout cell differentiation and we identified reduced electron transport chain components in the knockout population. Immunoblotting confirmed the loss of these components and additional studies showed cells lacking Nek2 were exclusively glycolytic. Interestingly, hypoxia inducible factor 1 was stabilized in these Nek2 knockout cells despite culturing them under normoxic conditions. Since neural differentiation requires a metabolic switch from glycolysis to oxidative phosphorylation, we propose a mechanism where Nek2 prevents HIF1 stabilization, thereby allowing cells to use oxidative phosphorylation to facilitate neuron and astrocyte differentiation.

developmental biology↗

bioRxiv2021

Sufu regulation of Hedgehog signaling in P19 cells is required for proper glial cell differentiation

Hedgehog signaling is essential for vertebrate development, however, less is known about the negative regulators that influence this pathway. Using the mouse P19 embryonal carcinoma cell model, Suppressor of Fused (SUFU), a negative regulator of the Hedgehog pathway, was investigated during retinoic acid-induced neural differentiation. We found Hedgehog signaling was activated in the early phase of differentiation but was inactive during terminal differentiation of neurons and astrocytes. Early activation was required for neural differentiation however, it alone was not sufficient to induce neural lineages. SUFU, which regulates signaling at the level of GLI, remained relatively unchanged during differentiation, but its loss through CRISPR-Cas9 gene editing resulted in ectopic expression of Hedgehog target genes. Interestingly, these SUFU-deficient cells were unable to differentiate without retinoic acid, and when used they showed delayed and decreased astrocyte differentiation; neuron differentiation was unaffected. Ectopic activation of Hh target genes in SUFU-deficient cells remained throughout retinoic acid-induced differentiation and this was accompanied by the loss of GLI3, despite the presence of the Gli3 message. Thus, the study indicates the proper timing and proportion of astrocyte differentiation requires SUFU, and its normal regulation of GLI3 to maintain Hh signaling in an inactive state.

developmental biology↗

bioRxiv2020

Lactate Accelerates Mouse ES Cell Differentiation Towards the XEN Lineage

Metabolism plays a crucial role for cell survival and function; however, recent evidence has implicated it in regulating embryonic development. The inner cell mass undergoes orchestrated cellular divisions resulting in the formation of embryonic stem cells and extraembryonic endoderm (XEN) cells. Concomitantly, changes in the metabolic profile occurs during development and are well-documented in the embryonic lineages. However, a comprehensive multi-omics analysis of these features in XEN cells remains lacking. We observed that feeder-free XEN cells exhibited high sensitivity to glycolytic inhibition in addition to maintaining elevated intra- and extracellular lactate levels. XEN cells maintain high lactate levels by increased LDHA activity and re-routing pyruvate away from the mitochondria. Importantly, exogenous lactate supplementation or promoting intracellular lactate accumulation enhances XEN differentiation in vitro. Our results highlight how lactate contributes to XEN differentiation in the mammalian embryo and may serve to enhance reprogramming efficiency of cells used for regenerative medicine. HighlightsO_LIFeeder-free XEN cells exhibit high sensitivity to glycolytic inhibition C_LIO_LIDistinct transcriptomic, proteomic and metabolomic profile exists between feeder-free ES and XEN cells C_LIO_LIElevated intracellular and extracellular lactate is observed in feeder-free XEN cells C_LIO_LILactate enhances feeder-free XEN differentiation in vitro C_LI

developmental biology↗

bioRxiv2018

Serum-dependent and independent regulation of PARP2

PARP2 belongs to a family of proteins involved in cell differentiation, DNA damage repair, cellular energy expenditure, chromatin modeling and cell differentiation. In addition to these overlapping functions with PARP1, PARP2 participates in spermatogenesis, T-cell maturation, extraembryonic endoderm formation and adipogenesis. The function(s) of PARP2 is far from complete, and the mechanism(s) by which the gene and protein are regulated are unknown. In this study, we found that two different mechanisms are used in vitro to regulate PARP2 levels. In the presence of serum, PARP2 is degraded through the ubiquitin-proteasome pathway, however, when serum is removed, PARP2 is rapidly sequestered into an SDS- and urea-insoluble fraction. This sequestration is relieved by serum in a dose-dependent manner, and again PARP2 is detected by immunoblotting. Furthermore, and despite the presence of a putative serum response element in the PARP2 gene, transcription is not affected by serum deprivation. These observations that PARP2 is tightly regulated by distinct pathways highlights the critical roles PARP2 plays under different physiological conditions.

cell biology↗