Biology subjects

Kollipara, R.

Publications and source records attributed to Kollipara, R..

4 recordsLinked to original sources

bioRxiv2023

Glioblastoma initiation, migration, and cell types are regulated by core bHLH transcription factors ASCL1 and OLIG2

Glioblastomas (GBMs) are highly aggressive, infiltrative, and heterogeneous brain tumors driven by complex driver mutations and glioma stem cells (GSCs). The neurodevelopmental transcription factors ASCL1 and OLIG2 are co-expressed in GBMs, but their role in regulating the heterogeneity and hierarchy of GBM tumor cells is unclear. Here, we show that oncogenic driver mutations lead to dysregulation of ASCL1 and OLIG2, which function redundantly to initiate brain tumor formation in a mouse model of GBM. Subsequently, the dynamic levels and reciprocal binding of ASCL1 and OLIG2 to each other and to downstream target genes then determine the cell types and degree of migration of tumor cells. Single-cell RNA sequencing (scRNA-seq) reveals that a high level of ASCL1 is key in defining GSCs by upregulating a collection of ribosomal protein, mitochondrial, neural stem cell (NSC), and cancer metastasis genes - all essential for sustaining the high proliferation, migration, and therapeutic resistance of GSCs.

neuroscience↗

bioRxiv2023

CBD can be combined with additional cannabinoids for optimal seizure reduction and requires GPR55 for its anticonvulsant effects

BackgroundCannabis has demonstrated anticonvulsant properties, and cannabis-based medicines are approved to treat pediatric patients with severe pediatric epilepsies that are particularly refractive to approved anti-epileptic drugs (AEDs). About thirty percent of epileptic patients do not have satisfactory seizure management with AEDs and could potentially benefit from cannabis-based intervention. Here we report the use of single and combined cannabinoids to treat Pentylenetetrazol (PTZ) induced convulsions in a zebrafish model, their effect on gene expression, and a simple assay for assessing their uptake in zebrafish tissues. These data provide novel insights as to the potential of treating epilepsy with cannabinoids. MethodsZebrafish larvae were treated with cannabinoids and their seizures measured through an optimized behaviour tracking method. Cannabinoid uptake was measured with a novel HPLC-UV method. Gene expression changes were assessed using quantitative PCR (qPCR), and chemical inhibitors of potential cannabinoid receptors were used to block activity. ResultsTreatment with cannabinol (CBN), cannabichromene (CBC) and cannabigerol (CBG) decreased seizure intensity at lower doses than CBD when accounting for the amount of cannabinoid recovered from exposed larvae. {Delta}9-tetrahydrocannabinol ({Delta}9-THC), {Delta}8-tetrahydrocannabinol ({Delta}8-THC) were effective at higher doses. Synergistic effects were observed between CBD and other cannabinoids such as {Delta}9-THC, {Delta}8-THC, and CBG. The reduction of PTZ induced seizures via CBD is partially mediated by the G-protein coupled receptor GPR55, as pharmacological inhibition of the receptor reduced the therapeutic action of CBD. Changes in expression of endocannabinoid system (napepld, gde1, faah, ptgs2a) and neural (fosab, pyya) genes in response to phytocannabinoid treatment were observed and highlight novel mechanisms of phytocannabinoid action. ConclusionsCBD can be combined with additional cannabinoids for optimal reduction of seizure activity and requires the activity of GPR55. Changes in fosab regulation of gene expression and endocannabinoid signalling may influence the anticonvulsant effects of cannabis, however further investigation is required.

pharmacology and toxicology↗

bioRxiv2020

ASCL1 regulates neurodevelopmental transcription factors and cell cycle genes in glioblastoma

Glioblastomas (GBMs) are incurable brain tumors with a high degree of cellular heterogeneity and genetic mutations. Transcription factors that normally regulate neural progenitors and glial development are aberrantly co-expressed in GBM, conferring cancer stem-like properties to drive tumor progression and therapeutic resistance. However, the functional role of individual transcription factors in GBMs in vivo remains elusive. Here, we demonstrate that the basic-helix-loop-helix (bHLH) transcription factor ASCL1 regulates transcriptional targets that are central to GBM development, including neural stem cell and glial transcription factors, oncogenic signaling molecules, chromatin modifying genes, and cell cycle and mitotic genes. We also show that the loss of ASCL1 significantly reduces the proliferation of GBMs induced in the brain of a genetically relevant glioma mouse model, resulting in extended survival times. RNA-seq analysis of mouse GBM tumors reveal that the loss of ASCL1 is associated with downregulation of cell cycle genes, illustrating an important role for ASCL1 in controlling the proliferation of GBM. TABLE OF CONTENTSO_ST_ABSMain PointsC_ST_ABSO_LIASCL1 is co-expressed with neural stem cell/glial transcription factors in GBM C_LIO_LIASCL1 binds to genes that are important for cell proliferation and cancer in the brain. C_LIO_LILoss of ASCL1 downregulates cell cycle genes and increase survival of glioma mouse model. C_LI Table of Content Image O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/958132v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@8aa2d7org.highwire.dtl.DTLVardef@1c908edorg.highwire.dtl.DTLVardef@1690085org.highwire.dtl.DTLVardef@a13728_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2019

GCNA preserves genome integrity and fertility across species

The propagation of species depends on the ability of germ cells to protect their genome in the face of numerous exogenous and endogenous threats. While these cells employ a number of known repair pathways, specialized mechanisms that ensure high-fidelity replication, chromosome segregation, and repair of germ cell genomes remain incompletely understood. Here, we identify Germ Cell Nuclear Acidic Peptidase (GCNA) as a highly conserved regulator of genome stability in flies, worms, zebrafish, and humans. GCNA contains a long acidic intrinsically disordered region (IDR) and a protease-like SprT domain. In addition to chromosomal instability and replication stress, GCNA mutants accumulate DNA-protein crosslinks (DPCs). GCNA acts in parallel with a second SprT domain protein Spartan. Structural analysis reveals that while the SprT domain is needed to limit meiotic and replicative damage, most of GCNAs function maps to its IDR. This work shows GCNA protects germ cells from various sources of damage, providing novel insights into conserved mechanisms that promote genome integrity across generations.\n\nHighlightsGCNA ensures genomic stability in germ cells and early embryos across species\n\nGCNA limits replication stress and DNA double stranded breaks\n\nGCNA restricts DNA-Protein Crosslinks within germ cells and early embryos\n\nThe IDR and SprT domains of GCNA govern distinct aspects of genome integrity\n\nGraphic Abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=189 SRC=\"FIGDIR/small/570804_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (54K):\norg.highwire.dtl.DTLVardef@1928d82org.highwire.dtl.DTLVardef@885ff2org.highwire.dtl.DTLVardef@15322c9org.highwire.dtl.DTLVardef@110c615_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗