Biology subjects

Casey, M.

Publications and source records attributed to Casey, M..

3 recordsLinked to original sources

bioRxiv2026

Pharmacologic inhibition of OLIG2 by CT-179 disrupts mitotic progression and enhances standard-of-care chemoradiotherapy in glioblastoma

Background: Glioblastoma (GBM) remains uniformly fatal. The basic helix-loop-helix transcription factor OLIG2 is universally expressed in diffuse glioma, sustains the tumor-propagating stem-like fraction, and opposes p53-mediated genotoxic responses, but has historically been considered undruggable. We characterized CT-179, a brain-penetrant small-molecule OLIG2 inhibitor, as a candidate therapeutic for GBM. Methods: Target engagement was assessed by cellular thermal shift assay, differential scanning fluorimetry, crosslinking, and electrophoretic mobility shift assay. Anti-tumor activity was evaluated across eleven patient-derived GBM cell lines, in zebrafish oligodendrocyte precursor cell (OPC)-derived tumors, and orthotopic and subcutaneous GBM models, including combinations with radiotherapy plus temozolomide and with selective Bcl-2 family inhibitors. Results: CT-179 engaged OLIG2 and altered the conformation of dimerized OLIG2 on chromatin without preventing dimerization or fully displacing OLIG2 from DNA. CT-179 reduced OLIG2-positive OPCs and OPC-derived tumors in zebrafish and inhibited proliferation across all eleven GBM lines (IC50 < 360 nM), depleting the stem-like fraction and inducing apoptosis through mitotic catastrophe, mitotic slippage, or a hybrid response. RNA-seq across three patient-derived glioma stem cell lines identified {beta}-tubulin gene isoforms as the most strongly CT-179-down-regulated transcripts at the early time point and showed correlated {beta}-tubulin and OLIG2 expression in TCGA glioblastoma specimens. Combination with the Mcl-1 inhibitor S63845 or the Bcl-2/Bcl-xL/Bcl-w inhibitor ABT-737 produced greater-than-additive cytotoxicity. Oral CT-179 crossed the blood-brain barrier and extended median survival as a single agent across two independent adult orthotopic patient-derived backgrounds (GBM8 and G06); intraperitoneal CT-179 was associated with reduced intratumoral OLIG2 and Ki-67 staining in GBM8 orthotopic xenografts. Combination of CT-179 with radiotherapy and temozolomide eliminated all GBM8 and 7 of 8 GBM4 subcutaneous xenografts without weight loss and significantly extended survival when combined with radiotherapy in MGMT-unmethylated GBM6 orthotopic xenografts (CT-179 administered intraperitoneally). Conclusions: CT-179 is a brain-penetrant inhibitor of an established GBM driver with single-agent and combination activity across several orthotopic models, supporting clinical development for GBM and translational evaluation in other OLIG2-dependent CNS malignancies.

cancer biology↗

bioRxiv2023

Alpha-synuclein null mutation exacerbates the phenotype of a model of Menkes disease in female mice

Genetic modifier screens provide a useful tool, in diverse organisms from Drosophila to C. elegans and mice, for recovering new genes of interest that may reduce or enhance a phenotype of interest. This study reports a modifier screen, based on N-ethyl-N-nitrosourea (ENU) mutagenesis and outcrossing, designed to increase understanding of the normal function of murine -synuclein (Snca). Human SNCA was the first gene linked to familial Parkinsons disease. Since the discovery of the genetic link of SNCA to Parkinsons nearly three decades ago, numerous studies have investigated the normal function of SNCA protein with divergent roles associated with different cellular compartments. Understanding of the normal function of murine Snca is complicated by the fact that mice with homozygous null mutations live a normal lifespan and have only subtle synaptic deficits. Here, we report that the first genetic modifier (a sensitized mutation) that was identified in our screen was the X-linked gene, ATPase copper transporting alpha (Atp7a). In humans, mutations in Atp7a are linked to to Menkes disease, a disease with pleiotropic phenotypes that include a severe neurological component. Atp7a encodes a trans-Golgi copper transporter that supplies the copper co-factor to enzymes that pass through the ER-Golgi network. Male mice that carry a mutation in Atp7a die within 3 weeks of age regardless of Snca genotype. In contrast, here we show that Snca disruption modifies the phenotype of Atp7a in female mice. Female mice that carry the Atp7a mutation, on an Snca null background, die earlier (prior to 35 days) at a significantly higher rate than those that carry the Atp7a mutation on a wildtype Snca background ATPase copper transporting alpha. Thus, Snca null mutations sensitize female mice to mutations in Atp7a, suggesting that Snca protein may have a protective effect in females, perhaps in neurons, given the co-expression patterns. Although data has suggested diverse functions for human and mouse -synuclein proteins in multiple cell compartments, this is the first demonstration via use of genetic screening to demonstrate that Snca protein may function in the ER-Golgi system in the mammalian brain in a sex-dependent manner. Author summaryThis study sought to probe the normal function(s) of a protein associated with Parkinsons disease, the second most common neurodegenerative disease in humans. We used a genetic modifier approach to uncover aspects of normal protein function, via mutagenesis of mice and screening for neurological problems that are decreased or enhanced in mice that are null for -synuclein (Snca). Through these studies, we identified the X-linked gene that is mutated in Menkes disease in humans as a modifier of the null Snca phenotype, specifically in female mice. The gene mutated in Menkes disease, ATP7a, encodes a copper transporter that is known to act in the trans-Golgi sub-cellular compartment. Genetic modifier effects suggest that Snca may also play a role in that compartment, potentially in the mammalian brain.

neuroscience↗

bioRxiv2021

A NET4-RabG3 couple mediate the link between actin and the tonoplast and is essential for normal actin cytoskeletal remodelling in stomatal closure to flg22

Members of the NETWORKED (NET) family are involved in actin-membrane interactions. They tether the cells plasma membrane (PM) to the actin network. Moreover, in a similar manner, they are also involved in the tethering of membrane bound organelles to the actin cytoskeleton; the endoplasmic reticulum (ER) and the ER to the PM. This raises the question as to whether NET proteins are involved in actin cytoskeletal remodelling. Here we show that two members of the NET family, NET4A and NET4B, are essential for normal guard cell actin reorganization, which is a process critical for stomatal closure in plant immunity. NET4 proteins interact with F-actin and with members of the Rab7 GTPase RABG3 family through two distinct domains, allowing for simultaneous localization to actin filaments and the tonoplast. NET4 proteins interact with GTP-bound, active RABG3 members, suggesting their function as downstream effectors. We also show that RABG3b is critical for stomatal closure induced by microbial patterns. Taken together, we conclude that the actin cytoskeletal remodelling during stomatal closure depends on a molecular link between actin filaments and the tonoplast, which is mediated by the NET4-RABG3b interaction. We propose that stomatal closure to microbial patterns involves the coordinated action of immune signalling events and proper actin cytoskeletal remodelling.

plant biology↗