Biology subjects

Aguilar, K.

Publications and source records attributed to Aguilar, K..

4 recordsLinked to original sources

bioRxiv2025

Daple-FLT3 (CCDC88C-FLT3) gene fusion requires the coiled-coil domain for maximal activation and pericentrosomal localization

Gene fusions are stable protein products often occurring from chromosomal rearrangements. These chimeric proteins typically contain distinct molecular entities from each parent gene, and thus, create a product with altered or aberrant function. Gene fusions are frequently found in cancers, including Leukemia. Here, we characterize the kinase activity and subcellular distribution of the Daple-FLT3 (CCDC88C-FLT3) fusion oncoprotein--a rare, but recurrent gene fusion found in patients with hematological malignancies. The protein contains the FLT3 kinase domain and is activated without ligand stimulation. This leads to activation in STAT5a, AKT, and MAPK signaling, which can be modulated by the tyrosine kinase inhibitors (TKIs) sorafenib, quizartinib, and to a lesser degree, imatinib. Moreover, fusion of this kinase domain to Daple facilitates its localization to the pericentrosomal space and enhances kinase activation. These findings provide evidence that targeting Daple-FLT3 outside of its kinase domain may be a complementary approach with TKI therapy. Key PointsO_LIDaple-FLT3 fusion proteins contain a constitutively active kinase domain, activating distinct signaling molecules in cells C_LIO_LICoiled-coil domain on Daple is dispensable for kinase activation, but necessary for maximal activation C_LI

cancer biology↗

bioRxiv2025

Endothelin Signaling via EDNRB receptor Reduces Proliferation and Promotes Proneural-to-Mesenchymal Transition in Gliomas

Diffuse gliomas are incurable primary brain tumors encompassing three histo-molecular subtypes: glioblastomas (GB), astrocytomas, and oligodendrogliomas. The latter two harbor IDH1 mutations and exhibit slower progression than glioblastomas. Diffuse gliomas are composed of highly plastic tumor cells capable of transitioning between astrocyte-like, oligodendrocyte-like, progenitor-like, and mesenchymal-like states, driven by genetic alterations and microenvironmental cues. The proneural-to-mesenchymal transition (PMT), associated with increased malignancy, is notably influenced by cytokines in the tumor microenvironment. Endothelin cytokines (ET-1, ET-2, ET-3), primarily secreted by vascular cells, regulate not only vascular tone but also astrocyte and neural stem cell proliferation via the G-protein-coupled receptors EDNRA and EDNRB. Prior studies using serum-cultured glioma lines suggested pro-proliferative effects of endothelins; however, such models poorly recapitulate the in vivo glioma context. In this study, we comprehensively revisited endothelin signaling - covering receptor expression, regulation, downstream pathways, and cellular responses-using eleven serum-free, patient-derived glioma lines (glioblastomas, IDH-wt and IDH-mutant oligodendrogliomas and astrocytomas), along with primary tumor samples. Multi-omics and electrophysiological analyses revealed EDNRB as the predominant receptor, enriched in astrocyte-like cells, upregulated by BMPs or growth factor withdrawal, and downregulated by interferons, IL-6 cytokines, endothelins, and Hippo/YAP activation. In contrast, EDNRA was expressed by a perivascular tumor subpopulation and induced by Notch signaling in glioblastomas but not in IDH1-mutant cells. Functionally, endothelins reduced proliferation across all models while promoting migration and PMT. Mechanistically, EDNRB activation increased intracellular Ca{superscript 2} and activated ERK, STAT3, and apamin-sensitive SK2/SK3 potassium channels. These findings identify endothelin signaling as an important regulator of glioma cell plasticity and behavior. HighlightsO_LIEDNRB is the predominant endothelin receptor expressed in glioma cells, with a small subset of tumor cells expressing EDNRA in close proximity to blood vessels C_LIO_LIEndothelin signaling reduces proliferation while promoting cell migration and Proneural-to-Mesenchymal transition C_LIO_LIEndothelin activates downstream Ca2+, K+, ERK, and STAT3 signaling pathways C_LIO_LIEDNRB expression is both positively and negatively regulated by inflammatory cytokines and the Hippo/YAP1 pathway, whereas EDNRA is upregulated by Notch signaling and hypoxia C_LI

cancer biology↗

bioRxiv2025

Effects of Interleukin-6 dysregulation in a mouse model of Alzheimer's disease: unraveling the complexity beyond amyloidosis

Interleukin-6 (IL-6) is a cytokine detected in the brains and peripheral fluids of both Alzheimers disease (AD) patients and mouse models, where it colocalizes with amyloid-beta (A{beta}) levels and amyloid plaques. Interestingly, IL-6 deficiency ameliorates cognitive deficits and attenuates hippocampal neuroinflammation, whereas astrocyte-targeted IL-6 signaling via its soluble receptor accentuates pathological features in AD mouse models. This finding suggests that central IL-6 overexpression may actively drive disease manifestations. However, because IL-6 also signals through its classical membrane-bound receptor pathway, the overall impact of central IL-6 on Alzheimers disease pathophysiology is still not fully elucidated. To explore the contribution of central IL-6 overexpression in modulating AD-related mortality, metabolic, behavioral and neuroinflammatory changes in the hippocampus and cortex, we crossed a transgenic mouse model (Tg2576) of A{beta}-driven amyloidosis with mice expressing IL-6 under the Glial Fibrillary Acidic Protein (GFAP) promoter, which predominantly targets astrocytes. Chronic IL-6 overexpression reduced inguinal white adiposity in both males and females and decreased body weight in females. Early behavioral alterations were also observed, along with increased cortical and hippocampal A{beta}42/A{beta}40 ratios and gliosis in aged Tg2576 female and male mice. Interestingly, chronic IL-6 overexpression also decreased cortical and hippocampal periplaque astrocytosis and microgliosis, suggesting a heterogeneous response of astrocytes and microglia to IL-6 overexpression within the primary regions affected by this pathology. Finally, cortical transcriptomic profiling in Tg2576 mice revealed widespread changes in immune, synaptic, and stress response pathways in response to chronic IL-6 overexpression, with cortical neuroinflammatory and neurotransmission-associated gene networks showing sex-dependent differences. Our findings emphasize that chronic central-targeted IL-6 overexpression shapes the cortical and hippocampal molecular landscape underlying amyloidosis in both male and female Tg2576 mice. Thereby, we propose IL-6 as a potential target for future AD therapeutic strategies.

neuroscience↗

bioRxiv2024

Tissue-specific and endogenous protein labeling with split fluorescent proteins

The ability to label proteins by fusion with genetically encoded fluorescent proteins is a powerful tool for understanding dynamic biological processes. However, current approaches for expressing fluorescent protein fusions possess drawbacks, especially at the whole organism level. Expression by transgenesis risks potential overexpression artifacts while fluorescent protein insertion at endogenous loci is technically difficult and, more importantly, does not allow for tissue-specific study of broadly expressed proteins. To overcome these limitations, we have adopted the split fluorescent protein system mNeonGreen21-10/11 (split-mNG2) to achieve tissue-specific and endogenous protein labeling in zebrafish. In our approach, mNG21-10 is expressed under a tissue-specific promoter using standard transgenesis while mNG211 is inserted into protein-coding genes of interest using CRISPR/Cas-directed gene editing. Each mNG2 fragment on its own is not fluorescent, but when co-expressed the fragments self-assemble into a fluorescent complex. Here, we report successful use of split-mNG2 to achieve differential labeling of the cytoskeleton genes tubb4b and krt8 in various tissues. We also demonstrate that by anchoring the mNG21-10 component to specific cellular compartments, the split-mNG2 system can be used to manipulate protein function. Our approach should be broadly useful for a wide range of applications.

developmental biology↗