Neuronal Transcription Factor Research Articles

HMX3 is a critical vulnerability in MECOM-negative KMT2A::MLLT3 acute myelomonocytic leukemia.

KMT2A::MLLT3 acute myelomonocytic leukemia (AML) comes in two clinically and biologically different subtypes. One is characterized by inferior outcome, older age, and MECOM oncogene expression. The other is mainly observed in children and young adults, associates with better clinical outcome, but lacks MECOM. To identify cell fate determining transcription factors downstream of KMT2A::MLLT3, we applied a bioinformatic algorithm that integrates gene and enhancer expression from primary MECOM-positive and -negative KMT2A::MLLT3 AML samples. This identified MECOM to be most influential in the MECOM-positive group, while neuronal transcription factor HMX3 was most influential in the MECOM-negative group. In large AML cohorts, HMX3 expression associated with a unique gene expression profile, younger age (p < 0.002) and KMT2A-rearranged and KAT6A-CREBBP leukemia (p < 0.00001). HMX3 was not expressed in other major genetic risk groups and healthy blood cells. RNA-sequencing analyses following forced HMX3 expression in healthy CD34+ cells and its silencing in KMT2A::MLT3 cells showed that HMX3 drives cancer-associated E2F and MYC gene programs (p < 0.001). HMX3 expression in healthy CD34+ cells blocked monocytic but not granulocytic colony formation. Strikingly, HMX3 silencing in KMT2A::MLLT3 patient cells resulted in cell cycle arrest, monocytic differentiation and apoptosis. Thus, the neuronal transcription factor HMX3 is a leukemia-specific vulnerability in KMT2A::MLLT3 AML.

BCL2 expression is enriched in advanced prostate cancer with features of lineage plasticity.

The widespread use of potent androgen receptor signaling inhibitors (ARSIs) has led to an increasing emergence of AR-independent castration-resistant prostate cancer (CRPC), typically driven by loss of AR expression, lineage plasticity, and transformation to prostate cancers (PCs) that exhibit phenotypes of neuroendocrine or basal-like cells. The anti-apoptotic protein BCL2 is upregulated in neuroendocrine cancers and may be a therapeutic target for this aggressive PC disease subset. There is an unmet clinical need, therefore, to clinically characterize BCL2 expression in metastatic CRPC (mCRPC), determine its association with AR expression, uncover its mechanisms of regulation, and evaluate BCL2 as a therapeutic target and/or biomarker with clinical utility. Here, using multiple PC biopsy cohorts and models, we demonstrate that BCL2 expression is enriched in AR-negative mCRPC, associating with shorter overall survival and resistance to ARSIs. Moreover, high BCL2 expression associates with lineage plasticity features and neuroendocrine marker positivity. We provide evidence that BCL2 expression is regulated by DNA methylation, associated with epithelial-mesenchymal transition, and increased by the neuronal transcription factor ASCL1. Finally, BCL2 inhibition had antitumor activity in some, but not all, BCL2-positive PC models, highlighting the need for combination strategies to enhance tumor cell apoptosis and enrich response.

Generation of three isogenic gene-edited Huntington’s disease human embryonic stem cell lines with DOX-inducible NGN2 expression cassette in the AAVS1 safe locus

Neurogenin 2 (NGN2), a neuronal transcription factor, can expedite differentiation of stem cells into mature glutamatergic neurons. We have utilized an allelic series of previously published and characterized isogenic Huntington's disease (IsoHD) human embryonic stem cell lines (Ooi et al., 2019), carrying different CAG repeat lengths in the first exon of the huntingtin gene. These IsoHDs were modified using CRISPR/Cas9 to insert NGN2 under the TET-ON doxycycline inducible promoter. The resulting IsoHD-NGN2 cell lines retained pluripotency in the absence of doxycycline (DOX), and via addition of DOX to the culturing media differentiation to neurons was achieved within 14 days.

Abstract 4751: The antiviral, Daclatasvir, downregulates Tribbles 2 pseudokinase and reverses enzalutamide resistance in prostate cancer

Abstract Background: FDA-approved enzalutamide is commonly prescribed for advanced prostate cancer. However, enzalutamide-resistant prostate cancer (ERPC) invariably develops, which leads to aggressive, lethal disease. Recently, we found that the Tribbles 2 (TRIB2) pseudokinase is overexpressed in ERPC cells and confers resistance to enzalutamide by promoting lineage plasticity to neuroendocrine differentiation. Though TRIB2 emerged as an excellent molecular target for ERPC, suitable inhibitors are not commercially available for effective targeting. Methods: Compounds were tested using a luciferase-tagged TRIB2 fusion protein-based assay system. Binding of drugs with TRIB2 protein was analyzed by thermal shift assays and by advanced computer-based homology modeling. Degradation of TRIB2 protein was measured by Western blot. Drug effects on re-sensitization of ERPC cells and synergy with enzalutamide were determined through cell viability and apoptosis assays. To gauge the in vivo effects of Daclatasvir (DCV), ERPC tumor xenograft-bearing mice were treated with varying doses of DCV via oral gavage. Tumor growth was calculated by measuring volumes and molecular markers in tumors were analyzed by immunohistochemistry. Results: By designing a luciferase-tagged TRIB2 fusion protein-based assay system, we screened a library of about 1,600 FDA-approved compounds and found that DCV, effectively inhibits the TRIB2-luciferase activity (more than 70% inhibition in 24 hours at 10 micromolar) but does not inhibit the activity of free luciferase. Notably, DCV directly binds to pure TRIB2 protein, leading to its destabilization and a reduction in the half-maximal melting temperature (Tm) from 41oC to 37oC, as confirmed by thermal shift assays. Interestingly, we found that DCV degrades TRIB2 proteins via activation of proteasomes and re-sensitizes ERPC cells to enzalutamide. DCV downregulates the master neuronal transcription factor, BRN2, and the stemness factor, SOX2, and synergizes with enzalutamide at lower, sub-lethal doses to decrease the viability of prostate cancer cells by inducing apoptosis. Finally, DCV was found to effectively inhibit the growth of ERPC tumors and decrease the protein level of TRIB2 in mice when delivered via oral gavage. Conclusion: These findings indicate that DCV effectively downregulates TRIB2 both in vitro and in vivo and suggest that further testing of DCV may help design an innovative therapeutic approach for management of enzalutamide-resistant, aggressive, lethal prostate cancer. Citation Format: Jitender Monga, Rohith Guddeti, Craig Rogers, Shirish Gadgeel, Dhananjay Chitale, Jagadananda Ghosh. The antiviral, Daclatasvir, downregulates Tribbles 2 pseudokinase and reverses enzalutamide resistance in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4751.

Specific transcription factors Ascl1 and Lhx6 attenuate diabetic neuropathic pain by modulating spinal neuroinflammation and microglial activation in mice

Gamma-aminobutyric acid (GABA) neuronal system-related transcription factors (TFs) play a critical role in GABA production, and GABA modulates diabetic neuropathic pain (DNP). The present study investigated the therapeutic effects of intrathecal delivery of two TFs achaete-scute homolog 1 (Ascl1) and LIM homeobox protein 6 (Lhx6) in a mouse model of DNP and elucidated their underlying mechanisms. GABA-related specific TFs, including Ascl1, Lhx6, distal-less homeobox 1, distal-less homeobox 5, the Nkx2.1 homeobox gene, and the Nkx2.2 homeobox gene, were investigated under normal and diabetic conditions. Among these, the expression of Ascl1 and Lhx6 was significantly downregulated in mice with diabetes. Therefore, a single intrathecal injection of combined lenti-Ascl1/Lhx6 was performed. Intrathecal delivery of lenti-Ascl1/Lhx6 significantly relieved mechanical allodynia and heat hyperalgesia in mice with DNP. Ascl1/Lhx6 delivery also reduced microglial activation, decreased the levels of pro-inflammatory cytokines including tumor necrosis factor-α and interleukin (IL)-1β, increased the levels of anti-inflammatory cytokines including IL-4, IL-10, and IL-13, and reduced the activation of p38, c-Jun N-terminal kinase, and NF-κB in the spinal cord of mice with DNP, thereby reducing DNP. The results of this study suggest that intrathecal Ascl1/Lhx6 delivery attenuates DNP via upregulating spinal GABA neuronal function and inducing anti-inflammatory effects.

First person – Tanja Müller

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Tanja Müller is first author on ‘ The neuronal transcription factor MEIS2 is a calpain-2 protease target’, published in JCS. Tanja conducted the research described in this article while a PhD student in Prof. Dr Dorothea Schulte's lab at the Institute of Neurology (Edinger Institute), University Hospital Frankfurt, Germany. She is now a postdoc and co-lead of the Translational Neurooncology Junior Group in the lab of Dr Ann-Christin Hau at the Translational Neurooncology Group at the University Hospital Frankfurt, Germany. Her current research focuses on the identification of invasion-promoting genes in high-grade glial tumors.

Neurogenin-2 induced neuronal differentiation in co-cultured bone marrow stromal and neonatal cortical cells.

To explore a novel and dynamic role for neurogenin-2 in promoting cortical neurogenesis in cells produced from co-culturing neonatal cortical neural progenitor cells with bone marrow stromal cells. The experimental study was conducted from June 2016 to January 2019 at the neuropharmacology laboratory of the Hussein Ebrahim Jamal Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, Karachi. The growth of cells at different stages in harvested cells was determined by 3-(4, 5- dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay. Immunocytochemistry was used to evaluate the protein expressions of neuronal markers and transcription factors. Data was analysed using SPSS 20. Data showed significant generation of neuronal cells and this was also verified by increased expression of nesting in cortical co-cultures with bone marrow stromal cells. Immunoreactive outcomes showed over expressions in co-cultured chlorotoxin cells. Subsequently, neurogenin-2 was found intermixed with induced expressions of transcriptional factor NeuroD1 and reduced glial fibrillary acidic protein-labelled cells. Better understanding of the mechanisms underlying transcriptional modulation of neurogenic events hold the key for emerging treatment approaches towards neurodegeneration.

Thyroid hormones mediate the impact of early-life stress on ventral tegmental area gene expression and behavior

Proper thyroid function is essential to the developing brain, including dopamine neuron differentiation, growth, and maintenance. Stress across the lifespan impacts thyroid hormone signaling and anxiety disorders and depression have been associated with thyroid dysfunction (both hypo- and hyper-active). However, less is known about how stress during postnatal development impacts thyroid function and related brain development. Our previous work in mice demonstrated that early-life stress (ELS) transiently impinged on expression of a transcription factor in dopamine neurons, Otx2, shown to be regulated by thyroid hormones. We hypothesized that thyroid hormone signaling may link experience of ELS with transcriptional dysregulation within the dopaminergic midbrain, and ultimately behavior. Here, we find that ELS transiently increases thyroid-stimulating hormone levels (inversely related to thyroid signaling) in both male and female mice at P21, an effect which recovers by adolescence. We next tested whether transient treatment of ELS mice with synthetic thyroid hormone (levothyroxine, LT4) could ameliorate the impact of ELS on sensitivity to future stress, and on expression of genes related to dopamine neuron development and maintenance, thyroid signaling, and plasticity within the ventral tegmental area. Among male mice, but not females, juvenile LT4 treatment prevented hypersensitivity to adult stress. We also found that rescuing developmental deficits in thyroid hormone signaling after ELS restored levels of some genes altered directly by ELS, and prevented alterations in expression of other genes sensitive to the second hit of adult stress. These findings suggest that thyroid signaling mediates the deleterious impact of ELS on VTA development, and that temporary treatment of hypothyroidism after ELS may be sufficient to prevent future stress hypersensitivity.

Deletion of the Neuronal Transcription Factor Satb1 Induced Disturbance of the Kinome and Mechanisms of Hypoxic Preconditioning.

Genetic disorders affecting the functioning of the brain lead not only to the development of numerous hereditary diseases but also to the development of neurodegenerative and cognitive disorders. The result of this may be the disability of part of the able-bodied population. Almost all pathological states of the brain are characterized by serious defects in the intracellular and intercellular signaling of neurons and glial cells. At the same time, the mechanisms of disruption of these signaling cascades are not well understood due to the large number of molecules, including transcription factors that, when mutated, cause brain malformations. The transcription factor Satb1 is one of the least studied factors in the cerebral cortex, and the effects of its deletion in the postnatal brain are practically not studied. Hyperexcitability of neurons is observed in many genetic diseases of the nervous system (Hirschsprung's disease, Martin-Bell syndrome, Huntington's disease, Alzheimer's, etc.), as well as in ischemic brain phenomena and convulsive and epileptic conditions of the brain. In turn, all these disorders of brain physiology are associated with defects in intracellular and intercellular signaling and are often the result of genetic disorders. Using Satb1 mutant mice and calcium neuroimaging, we show that Satb1 deletion in projection neurons of the neocortex causes downregulation of protein kinases PKC, CaMKII, and AKT/PKB, while a partial deletion does not cause a dramatic disruption of kinome and Ca2+ signaling. As a result, Satb1-null neurons are characterized by increased spontaneous Ca2+ activity and hyperexcitability when modeling epileptiform activity. As a result of the deletion of Satb1, preconditioning mechanisms are disrupted in neurons during episodes of hypoxia. This occurs against the background of increased sensitivity of neurons to a decrease in the partial pressure of oxygen, which may indicate the vulnerability of neuronal networks and be accompanied by impaired expression of the Satb1 transcription factor. Here, we show that Satb1 deletion impaired the expression of a number of key kinases and neuronal hyperexcitation in models of epileptiform activity and hypoxia.

Hypoxia-Inducible Factor 1α Stabilization Restores Epigenetic Control of Nitric Oxide Synthase 1 Expression and Reverses Gastroparesis in Female Diabetic Mice

Although depletion of neuronal nitric oxide synthase (NOS1)-expressing neurons contributes to gastroparesis, stimulating nitrergic signaling is not an effective therapy. We investigated whether hypoxia-inducible factor 1α (HIF1A), which is activated by high O2 consumption in central neurons, is a Nos1 transcription factor in enteric neurons and whether stabilizing HIF1A reverses gastroparesis. Mice with streptozotocin-induced diabetes, human and mouse tissues, NOS1+ mouse neuroblastoma cells, and isolated nitrergic neurons were studied. Gastric emptying of solids and volumes were determined by breath test and single-photon emission computed tomography, respectively. Gene expression was analyzed by RNA-sequencing, microarrays, immunoblotting, and immunofluorescence. Epigenetic assays included chromatin immunoprecipitation sequencing (13 targets), chromosome conformation capture sequencing, and reporter assays. Mechanistic studies used Cre-mediated recombination, RNA interference, and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-mediated epigenome editing. HIF1A signaling from physiological intracellular hypoxia was active in mouse and human NOS1+ myenteric neurons but reduced in diabetes. Deleting Hif1a in Nos1-expressing neurons reduced NOS1 protein by 50% to 92% and delayed gastric emptying of solids in female but not male mice. Stabilizing HIF1A with roxadustat (FG-4592), which is approved for human use, restored NOS1 and reversed gastroparesis in female diabetic mice. In nitrergic neurons, HIF1A up-regulated Nos1 transcription by binding and activating proximal and distal cis-regulatory elements, including newly discovered super-enhancers, facilitating RNA polymerase loading and pause-release, and by recruiting cohesin to loop anchors to alter chromosome topology. Pharmacologic HIF1A stabilization is a novel, translatable approach to restoring nitrergic signaling and treating diabetic gastroparesis. The newly recognized effects of HIF1A on chromosome topology may provide insights into physioxia- and ischemia-related organ function.

SRF deletion results in earlier disease onset in a mouse model of amyotrophic lateral sclerosis.

Changes in neuronal activity modulate the vulnerability of motoneurons (MNs) in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). So far, the molecular basis of neuronal activity's impact in ALS is poorly understood. Herein, we investigated the impact of deleting the neuronal activity-stimulated transcription factor (TF) serum response factor (SRF) in MNs of SOD1G93A mice. SRF was present in vulnerable MMP9+ MNs. Ablation of SRF in MNs induced an earlier disease onset starting around 7-8 weeks after birth, as revealed by enhanced weight loss and decreased motor ability. This earlier disease onset in SRF-depleted MNs was accompanied by a mild elevation of neuroinflammation and neuromuscular synapse degeneration, whereas overall MN numbers and mortality were unaffected. In SRF-deficient mice, MNs showed impaired induction of autophagy-encoding genes, suggesting a potentially new SRF function in transcriptional regulation of autophagy. Complementary, constitutively active SRF-VP16 enhanced autophagy-encoding gene transcription and autophagy progression in cells. Furthermore, SRF-VP16 decreased ALS-associated aggregate induction. Chemogenetic modulation of neuronal activity uncovered SRF as having important TF-mediating activity-dependent effects, which might be beneficial to reduce ALS disease burden. Thus, our data identify SRF as a gene regulator connecting neuronal activity with the cellular autophagy program initiated in degenerating MNs.

Synergistic Enhancement of Adeno‐Associated Virus‐Mediated In Vivo Direct Neuronal Reprogramming by Spatially Aligned Fibrous Matrices in Spinal Cord Injury Models

AbstractIn vivo direct neuronal reprogramming approaches, which convert host glial cells into neurons without using exogenous cellular supplies, have become a powerful strategy for neuronal regeneration. However, their effectiveness in severe spinal cord injury (SCI) models with a physical gap between the injured sites is unclear. This study highlights the important role of physical guidance in increasing the therapeutic efficacy of in vivo reprogramming technologies in SCI hemisection models. Reactive astrocytes are selected as host targets for conversion into neurons. An astrocyte‐tropic adeno‐associated viral (AAV) vector, AAVShH19, is used to deliver the neuronal transcription factor NeuroD1 to reactive astrocytes. The infusion of AAVShH19‐NeuroD1 induces astrocyte‐to‐neuron conversion, but improvement of locomotive function is not observed due to the physical distance between the rostral and caudal sides, which impedes axonal extension. To address this issue, electrospun fibrous matrices with adhesive and aligned structural features are implanted into the hemisection cavity and designed to release AAVShH19‐NeuroD1. The combination of the AAV‐mediated reprogramming approach and the matrices promoted astrocyte‐to‐neuron conversion and coordinated the elongation of neuronal axons along the fibers, leading to improved synaptic connections and motor function. This study demonstrates the potential of physical support to enhance the efficacy of direct neuronal reprogramming.

Lineage tracing identifies in vitro microglia-to-neuron conversion by NeuroD1 expression.

Neuronal regeneration to replenish lost neurons after injury is critical for brain repair. Microglia, brain-resident macrophages that have the propensity to accumulate at the site of injury, can be a potential source for replenishing lost neurons through fate conversion into neurons, induced by forced expression of neuronal lineage-specific transcription factors. However, it has not been strictly demonstrated that microglia, rather than central nervous system-associated macrophages, such as meningeal macrophages, convert into neurons. Here, we show that NeuroD1-transduced microglia can be successfully converted into neurons in vitro using lineage-mapping strategies. We also found that a chemical cocktail treatment further promoted NeuroD1-induced microglia-to-neuron conversion. NeuroD1 with loss-of-function mutation, on the other hand, failed to induce the neuronal conversion. Our results indicate that microglia are indeed reprogrammed into neurons by NeuroD1 with neurogenic transcriptional activity.

Abstract 1698: Novel role of Tribbles 2 driving treatment-emergent neuroendocrine differentiation in prostate cancer

Abstract Background: Prostate cancer initially responds to androgen receptor (AR) targeted therapies, such as enzalutamide. However, therapy-resistant, incurable disease invariably develops which remains as the major cause for mortality among prostate cancer patients. Molecular mechanism underlying emergence of resistant prostate cancer is yet to be fully characterized. Methods: We developed an in vitro cell culture model to mimic the clinical conditions in enzalutamide-resistant prostate cancer. These cells were transcriptionally profiled for gene expression analysis by Illumina Hi-Seq whole genome gene-expression array. Hits were validated by RT-qPCR and Western blot. For clinical correlation, enzalutamide treated prostate PDX models and surgical tumors (warm autopsy) from prostate cancer patients were comprehensively analyzed. Regulation and role of new hits were determined by treating cells and xenograft tumors with lentiviral-based shRNAs followed by analysis of cell viability, apoptosis, and effects on downstream targets. Pro-cancer effects were analyzed by cell proliferation, invasion, and soft-agar colony formation assays. Results: We identified that the Tribbles 2 (TRIB2) pseudokinase is overexpressed in enzalutamide-resistant prostate cancer (ERPC) cells. Elevated level of TRIB2 was also observed in enzalutamide treated PDX tumors, and in prostate tumors from patients who developed enzalutamide resistant metastatic disease. Interestingly, TRIB2 protein level is especially higher in prostate cancer cells and tumors, where the AR activity is low or absent due to genetic changes. Transfection and overexpression of TRIB2 results in aggressive prostate cancer cell growth and resistance to enzalutamide, apalutamide, darolutamide, and abiraterone. Furthermore, TRIB2 overexpression results in trans-differentiation in prostate cancer cells including neurite outgrowth and adeno-to-neuroendocrine lineage transition. Curiously, we found that TRIB2 downregulates luminal markers (AR, CK8), but upregulates the neuroendocrine markers (CHGA, NSE, SYP). Knockdown of TRIB2 triggers loss of neuroendocrine features, reduces viability of ERPC cells, and sensitize them back to enzalutamide, suggesting that TRIB2 plays a direct role in neuroendocrine differentiation and therapeutic resistance. We also found that TRIB2 upregulates the master neuronal transcription factor, BRN2, and the stemness factor, SOX2, and inhibition of either BRN2 or SOX2 re-sensitizes ERPC cells to enzalutamide. Conclusion: These findings reveal that TRIB2 is a novel driver for lineage plasticity and neuroendocrine differentiation in prostate cancer cells and greatly contributes to enzalutamide resistance. Citation Format: Jitender Monga, Craig Rogers, Shirish Gadgeel, Dhananjay Chitale, Jagadananda Ghosh. Novel role of Tribbles 2 driving treatment-emergent neuroendocrine differentiation in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1698.

NPAS4 in the medial prefrontal cortex mediates chronic social defeat stress-induced anhedonia-like behavior and reductions in excitatory synapses.

Chronic stress can produce reward system deficits (i.e., anhedonia) and other common symptoms associated with depressive disorders, as well as neural circuit hypofunction in the medial prefrontal cortex (mPFC). However, the molecular mechanisms by which chronic stress promotes depressive-like behavior and hypofrontality remain unclear. We show here that the neuronal activity-regulated transcription factor, NPAS4, in the mPFC is regulated by chronic social defeat stress (CSDS), and it is required in this brain region for CSDS-induced changes in sucrose preference and natural reward motivation in the mice. Interestingly, NPAS4 is not required for CSDS-induced social avoidance or anxiety-like behavior. We also find that mPFC NPAS4 is required for CSDS-induced reductions in pyramidal neuron dendritic spine density, excitatory synaptic transmission, and presynaptic function, revealing a relationship between perturbation in excitatory synaptic transmission and the expression of anhedonia-like behavior in the mice. Finally, analysis of the mice mPFC tissues revealed that NPAS4 regulates the expression of numerous genes linked to glutamatergic synapses and ribosomal function, the expression of upregulated genes in CSDS-susceptible animals, and differentially expressed genes in postmortem human brains of patients with common neuropsychiatric disorders, including depression. Together, our findings position NPAS4 as a key mediator of chronic stress-induced hypofrontal states and anhedonia-like behavior.

Metadichol® Induced the Expression of Neuronal Transcription Factors in Human Fibroblast Dermal Cells.

Metadichol® Induced the Expression of Neuronal Transcription Factors in Human Fibroblast Dermal Cells.

Evidence that direct inhibition of transcription factor binding is the prevailing mode of gene and repeat repression by DNA methylation

Cytosine methylation efficiently silences CpG-rich regulatory regions of genes and repeats in mammalian genomes. To what extent this entails direct inhibition of transcription factor (TF) binding versus indirect inhibition via recruitment of methyl-CpG-binding domain (MBD) proteins is unclear. Here we show that combinatorial genetic deletions of all four proteins with functional MBDs in mouse embryonic stem cells, derived neurons or a human cell line do not reactivate genes or repeats with methylated promoters. These do, however, become activated by methylation-restricted TFs if DNA methylation is removed. We identify several causal TFs in neurons, including ONECUT1, which is methylation sensitive only at a motif variant. Rampantly upregulated retrotransposons in methylation-free neurons feature a CRE motif, which activates them in the absence of DNA methylation via methylation-sensitive binding of CREB1. Our study reveals methylation-sensitive TFs in vivo and argues that direct inhibition, rather than indirect repression by the tested MBD proteins, is the prevailing mechanism of methylation-mediated repression at regulatory regions and repeats.

Neurovascular responses to neuronal activity during sensory development.

Understanding the development of intercellular communication in sensory regions is relevant to elucidate mechanisms of physiological and pathological responses to oxygen shortage in the newborn brain. Decades of studies in laboratory rodents show that neuronal activity impacts sensory maturation during two periods of postnatal development distinguished by the maturation of accessory structures at the sensory periphery. During the first of these developmental periods, angiogenesis is modulated by neuronal activity, and physiological levels of neuronal activity cause local tissue hypoxic events. This correlation suggests that neuronal activity is upstream of the production of angiogenic factors, a process that is mediated by intermittent hypoxia caused by neuronal oxygen consumption. In this perspective article we address three theoretical implications based on this hypothesis: first, that spontaneous activity of sensory neurons has properties that favor the generation of intermittent tissue hypoxia in neonate rodents; second, that intermittent hypoxia promotes the expression of hypoxia inducible transcription factors (HIFs) in sensory neurons and astrocytes; and third, that activity-dependent production of angiogenic factors is involved in pathological oxygen contexts.

PDE3 inhibition by cilostazol attenuated developmental hyperserotonemia induced behavioural and biochemical deficits in a rat model of autism spectrum disorder

BackgroundHyperserotonemia, in the early developmental phase generates behavioural and biochemical phenotypes associated with autism spectrum disorder (ASD) in rats. Phosphodiesterase-3 (PDE3) inhibition by cilostazol has been shown to provide benefits in various brain conditions. We investigated the role of a selective PDE3 inhibitor cilostazol on ASD related behavioural phenotypes. MethodAdministration of 5-Methoxytryptamine (5-MT) to rats perinatally (GD12-Parturition) and in early developmental stages (PND0-PND20), resulted into developmental hyperserotonemia (DHS). DHS associated behavioural changes (social behaviour deficits, repetitive behaviour, anxiety and hyperlocomotion) were assessed using a battery of behavioural examinations. Also, effect on biochemical markers related with neuronal function (BDNF – neuronal survival and pCREB – neuronal transcription factor), inflammation (IL-6, IL-10 and TNF-α) and oxidative stress (TBARS and GSH) were studied in important brain areas (frontal cortex, cerebellum, hippocampus, and striatum). Cilostazol was administered in two doses 30 & 60 mg.kg-1 p.o. each day to male rats from PND21 to PND48. ResultAdministration of cilostazol to 5-MT rats resulted in improvement of behavioural deficits. Also, cilostazol administration significantly increased the levels of BDNF, pCREB, IL-10, GSH and significantly decreased TNF-α, IL-6 and TBARS levels in different brain areas. ConclusionDHS during prenatal and early postnatal developmental stages leads to pervasive harm to the serotonergic system, leading to prolonged effects as observed via behavioural and biochemical outcomes of the study. Serotonin regulates early brain neurogenesis, synaptogenesis, and neuronal differentiation probably via the CREB/BDNF pathway and DHS is known to reduce the activity of CREB/BDNF pathway. Cilostazol administration to pups exposed to DHS perinatally has resulted in increase of neurotrophic factors, reduced inflammation and reduced oxidative stress, probably via increased cAMP/CREB/BDNF signalling. Also, improvement in behavioural profile of animals subjected to DHS. Thus, PDE3 and its inhibitors could be considered as molecules of interest for research in developmental disorders.

Abstract 787: RE1-silencing transcription factor (REST) controls neuroendocrine gene programs in pancreatic ductal adenocarcinoma

Abstract Neuroendocrine (NE) differentiation features contribute to intratumoral heterogeneity and aggressive biology in a subset of pancreatic ductal adenocarcinoma (PDAC) tumors associated with poor disease outcome. We recently showed that treating pancreatic cancer cells with gemcitabine, a standard-of-care chemotherapy for PDAC, increases expression of NE markers, suggesting that ductal to neuroendocrine lineage plasticity could play a role in drug resistance. NE features in prostate cancer have been previously associated with loss of the neuronal gene repressor RE1-Silencing Transcription Factor (REST); in the present study, we explore a potential role of REST in regulating NE differentiation in PDAC. Our experiments show that loss of REST in PDAC cells increases NE gene expression, gemcitabine resistance, and colony formation. RNA sequencing data from gemcitabine-treated PDAC cells were enriched for REST target genes, suggesting gemcitabine relieves REST-mediated repression. Chromatin immunoprecipitation experiments corroborated this by demonstrating that gemcitabine reduces REST binding to the NE genes SYP and SNAP25. In addition, single cell ATAC sequencing also uncovered a heterogeneous response to gemcitabine treatment, revealing two gemcitabine-driven cell states with differing REST motif accessibility. Our study indicates that REST controls NE gene programs in PDAC and that loss of REST promotes gemcitabine resistance and oncogenic growth. Mirroring the heterogeneity of PDAC tumors, a subset of PDAC cells treated with gemcitabine have reduced REST motif accessibility, which may reflect a therapy resistant NE-like subpopulation. Citation Format: Kevin Alexander MacPherson, Meghan M. Joly, Brittany Allen-Petersen, Carl Pelz, Mary C. Thoma, Kristof Torkenczy, Andrew Adey, Daniel Liefwalker, Patrick J. Worth, Rosalie C. Sears. RE1-silencing transcription factor (REST) controls neuroendocrine gene programs in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 787.