Ketamine affects the integration of developmentally generated granule neurons in the adult stage

BACKGROUND

Ketamine has been reported to cause neonatal neurotoxicity in a variety of developing animal models. Various studies have been conducted to study the mechanism of neurotoxicity for general anesthetic use during the neonatal period. Previous experiments have suggested that developmentally generated granule neurons in the hippocampus dentate gyrus (DG) supported hippocampus-dependent memory. Therefore, this study aimed to investigate whether ketamine affects the functional integration of developmentally generated granule neurons in the DG. For this purpose,the postnatal day 7 (PND-7) Sprague-Dawley (SD) rats were divided into the control group and the ketamine group (rats who received 4 injections of 40 mg/kg ketamine at 1 h intervals). To label dividing cells, BrdU was administered for three consecutive days after the ketamine exposure; NeuN+/BrdU+cells were observed by using immunofluorescence. To evaluate the developmentally generated granule neurons that support hippocampus-dependent memory, spatial reference memory was tested by using Morris Water Maze at 3 months old, after which the immunofluorescence was used to detect c-Fos expression in the NeuN+/BrdU+ cells. The expression of caspase-3 was measured by western blot to detect the apoptosis in the hippocampal DG.

RESULTS

The present results showed that the neonatal ketamine exposure did not influence the survival rate of developmentally generated granule neurons at 2 and 3 months old, but ketamine interfered with the integration of these neurons into the hippocampal DG neural circuits and caused a deficit in hippocampal-dependent spatial reference memory tasks.

CONCLUSIONS

In summary, these findings may promote more studies to investigate the neurotoxicity of ketamine in the developing brain.

S100P regulates the collective invasion of pancreatic cancer cells into the lymphatic endothelial monolayer

Lymph node metastasis is an independent prognostic factor in pancreatic cancer. However, the mechanisms of lymph node colonization are unknown. As a mechanism of lymphatic metastasis, it has been reported for other types of cancer that spheroids from tumor cells cause circular chemorepellent‑induced defects (CCIDs) in lymphatic endothelial monolayers. In pancreatic cancer, such mechanisms of metastasis have not been elucidated. The present study evaluated the involvement of this new mechanism of metastasis in pancreatic cancer and investigated the associated factors. In human pancreatic cancer tissue, it was observed that clusters of cancer cells penetrated the wall of lymphatic ducts around the primary tumor. An in vitro co‑culture system was then used to analyze the mechanisms of tumor cell‑mediated disruption of lymphatic vessels. Time‑lapse microscopic imaging revealed that spheroids from pancreatic cancer cells caused circular defects in lymphatic endothelial monolayers. CCID formation ability differed depending on the cell line. Neither aggregation of spheroids nor adhesion to lymphatic endothelial cells (LECs) exhibited a significant correlation with this phenomenon. The addition of supernatant from cultured cancer cells enhanced CCID formation. Microarray analysis revealed that the expression of S100 calcium binding protein P (S100P) was significantly increased when LECs were treated with supernatant from cultured cancer cells. Addition of a S100P antagonist significantly suppressed the migration of LECs and CCID formation. The present findings demonstrated that spheroids from pancreatic cancer cells caused circular defects in lymphatic endothelial monolayers. These CCIDs in pancreatic cancer were partly regulated by S100P, suggesting that S100P may be a promising target to inhibit lymph node metastasis.

Antibodies against specific extractable nuclear antigens (ENAs) as diagnostic and prognostic tools and inducers of a profibrotic phenotype in cultured human skin fibroblasts: are they functional?

BACKGROUND

The importance of systemic sclerosis (SSc) autoantibodies for diagnosis has become recognized by their incorporation into the 2013 ACR/EULAR classification criteria. Clear prognostic and phenotypic associations with cutaneous subtype and internal organ involvement have been also described. However, little is known about the potential of autoantibodies to exert a direct pathogenic role in SSc. The aim of the study is to assess the pathogenic capacity of anti-DNA-topoisomerase I (anti-Topo-I) and anti-centromeric protein B (anti-Cenp-B) autoantibodies to induce pro-fibrotic markers in dermal fibroblasts.

METHODS

Dermal fibroblasts were isolated from unaffected and affected skin samples of (n = 10) limited cutaneous SSc (LcSSc) patients, from affected skin samples of diffuse cutaneous (DcSSc) patients (n = 10) and from healthy subjects (n = 20). Fibroblasts were stimulated with anti-Topo-I, anti-Cenp-B IgGs, and control IgGs in ratios 1:100 and 1:200 for 24 h. Cells were also incubated with 10% SSc anti-Topo-I+ and anti-Cenp-B+ whole serum and with 10% control serum for 24 h. Viability was assessed by MTT test, while apoptosis was assessed by flow cytometry. Activation of pro-fibrotic genes ACTA2, COL1A1, and TAGLN was evaluated by quantitative real-time PCR (qPCR), while the respective protein levels alpha-smooth-muscle actin (α-SMA), type-I-collagen (Col-I), and transgelin (SM22) were assessed by immunocytochemistry (ICC).

RESULTS

MTT showed that anti-Cenp-B/anti-Topo-I IgGs and anti-Cenp-B+/anti-Topo-I+ sera reduced viability (in a dilution-dependent manner for IgGs) for all the fibroblast populations. Apoptosis is induced in unaffected LcSSc and control fibroblasts, while affected LcSSc/DcSSc fibroblasts showed apoptosis resistance. Basal mRNA (ACTA2, COL1A1, and TAGLN) and protein (α-SMA, Col-1, and SM22) levels were higher in affected LcSSc/DcSSc fibroblasts compared to LcSSc unaffected and to control ones. Stimulation with anti-Cenp-B/anti-Topo-I IgGs and with anti-Cenp-B+/anti-Topo-I+ sera showed a better induction in unaffected LcSSc and control fibroblasts. However, a statistically significant increase of all pro-fibrotic markers is reported also in affected LcSSc/DcSSc fibroblasts upon stimulation with both IgGs and sera.

CONCLUSIONS

This study suggests a pathogenic role of SSc-specific autoantibodies to directly induce pro-fibrotic activation in human dermal fibroblasts. Therefore, besides the diagnostic and prognostic use of those autoantibodies, these data might further justify the importance of immunosuppressive drugs in the early stages of the autoimmune disease, including SSc.

Compound C620-0696, a new potent inhibitor targeting BPTF, the chromatin-remodeling factor in non-small-cell lung cancer

Bromodomain PHD-finger transcription factor (BPTF) is the largest subunit of the nucleosome remodeling factor and plays an important role in chromatin remodeling for gene activation through its association with histone acetylation or methylation. BPTF is also involved in oncogene transcription in diverse progressions of cancers. Despite clinical trials for inhibitors of bromodomain and extra-terminal family proteins in human cancers, no potent and selective inhibitor targeting the BPTF bromodomain has been discovered. In this study, we identified a potential inhibitor, namely, C620-0696, by computational docking modeling to target bromodomain. Results of biolayer interferometry revealed that compound C620-0696 exhibited high binding affinity to the BPTF bromodomain. Moreover, C620-0696 was cytotoxic in BPTF with a high expression of non-small-cell lung cancer (NSCLC) cells. It suppressed the expression of the BPTF target gene c-MYC, which is known as an oncogenic transcriptional regulator in various cancers. C620-0696 also partially inhibited the migration and colony formation of NSCLC cells owing to apoptosis induction and cell cycle blockage. Thus, our study presents an effective strategy to target a bromodomain factor-mediated tumorigenesis in cancers with small molecules, supporting further exploration of the use of these inhibitors in oncology.

Precise Tubular Braid Structures of Ultrafine Microwires as Neural Probes: Significantly Reduced Chronic Immune Response and Greater Local Neural Survival in Rat Cortex

Braided multi-electrode probes (BMEPs) for neural interfaces comprise ultrafine microwire bundles interwoven into tubular braids. BMEPs provide highly flexible probes and tethers, and an open lattice structure with up to 24 recording/stimulating channels in precise geometries, currently all within a [Formula: see text] diameter footprint. This paper compares the long-term tissue effects of BMEPs ( [Formula: see text] wires) versus single conventional 50- [Formula: see text] wires, by testing nearby chronic immune response and neural survival in rat cortex. Four different types of electrodes were implanted in cortex in each of eight rats: 1) BMEP with tether; 2) tethered 50- [Formula: see text] wire; 3) BMEP without a tether; and 4) untethered 50- [Formula: see text] wire. Quantitative immunohistological statistical comparisons after eight weeks using GFAP, ED1, and NeuN staining clearly showed that both BMEP implants had significantly less tissue immune response and more neuronal survival than either of the 50- [Formula: see text] wires ( ) in each of the eight rats. Data strongly indicate that BMEP tissue responses are superior, and that BMEP designs partly alleviate chronic tissue inflammatory responses and neural losses. The flexible body, tether and open braid lattice, and finer wire diameters of BMEP designs may all contribute to reducing the biological long-term response.

Early stage of diffusional kurtosis imaging and dynamic contrast-enhanced magnetic resonance imaging correlated with long-term neurocognitive function after experimental traumatic brain injury

Development of a reliable biomarker for prognostic monitoring of cognitive impairment after traumatic brain injury (TBI) is of great importance. The aim of the study was to explore the value of early diffusional kurtosis imaging (DKI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in evaluation of chronic cognitive function after TBI. MRI was performed on TBI and control rats at 7 days post-injury. MRI parameters were measured in bilateral cortex, hippocampus, thalamus and corpus callosum (CC). All the rats underwent Morris water maze (MWM) at 6 months after injury. Immunohistochemistry (IHC) analysis of neuron [NeuN], astroglia [GFAP], microglia [Iba-1], and myelin [MBP] was performed after the MWM test. Our study revealed that, TBI group showed higher volume transfer coefficient (K^trans) value in ipsilateral cortex (P < 0.0001) and no detectable changes in other regions-of-interest (ROIs), compared with control group. DKI showed higher MK in all ipsilateral ROIs (P < 0.05), higher MD in ipsilateral cortex, hippocampus and CC (P < 0.05 for all) in TBI group. TBI group had worse performance in MWM test at 6 months post-injury(P < 0.05). IHC analysis showed lower NeuN, and higher GFAP and Iba-1 in all ipsilateral ROIs (P < 0.05) in TBI rats. NeuN, and GFAP and Iba-1 correlated significantly with MK value in ipsilateral regions of cortex. The MK value of ipsilateral cortex and CC and K^trans value of ipsilateral cortex also correlated significantly with time in the target quadrant. Therefore, our study indicated that early DKI and DCE-MRI could be used to assess the microstructural changes associated with long-term cognitive outcome following TBI.

A requirement for STAG2 in replication fork progression creates a targetable synthetic lethality in cohesin-mutant cancers

Cohesin is a multiprotein ring that is responsible for cohesion of sister chromatids and formation of DNA loops to regulate gene expression. Genomic analyses have identified that the cohesin subunit STAG2 is frequently inactivated by mutations in cancer. However, the reason STAG2 mutations are selected during tumorigenesis and strategies for therapeutically targeting mutant cancer cells are largely unknown. Here we show that STAG2 is essential for DNA replication fork progression, whereby STAG2 inactivation in non-transformed cells leads to replication fork stalling and collapse with disruption of interaction between the cohesin ring and the replication machinery as well as failure to establish SMC3 acetylation. As a consequence, STAG2 mutation confers synthetic lethality with DNA double-strand break repair genes and increased sensitivity to select cytotoxic chemotherapeutic agents and PARP or ATR inhibitors. These studies identify a critical role for STAG2 in replication fork procession and elucidate a potential therapeutic strategy for cohesin-mutant cancers.

PML-like subnuclear bodies, containing XRCC1, juxtaposed to DNA replication-based single-strand breaks

DNA lesions induce recruitment and accumulation of various repair factors, resulting in formation of discrete nuclear foci. Using superresolution fluorescence microscopy as well as live cell and quantitative imaging, we demonstrate that X-ray repair cross-complementing protein 1 (XRCC1), a key factor in single-strand break and base excision repair, is recruited into nuclear bodies formed in response to replication-related single-strand breaks. Intriguingly, these bodies are assembled immediately in the vicinity of these breaks and never fully colocalize with replication foci. They are structurally organized, containing canonical promyelocytic leukemia (PML) nuclear body protein SP100 concentrated in a peripheral layer, and XRCC1 in the center. They also contain other factors, including PML, poly(ADP-ribose) polymerase 1 (PARP1), ligase IIIα, and origin recognition complex subunit 5. The breast cancer 1 and -2 C terminus domains of XRCC1 are essential for formation of these repair foci. These results reveal that XRCC1-contaning foci constitute newly recognized PML-like nuclear bodies that accrete and locally deliver essential factors for repair of single-strand DNA breaks in replication regions.-Kordon, M. M., Szczurek, A., Berniak, K., Szelest, O., Solarczyk, K., Tworzydło, M., Wachsmann-Hogiu, S., Vaahtokari, A., Cremer, C., Pederson, T., Dobrucki, J. W. PML-like subnuclear bodies, containing XRCC1, juxtaposed to DNA replication-based single-strand breaks.

PML nuclear body-residing proteins sequentially associate with HPV genome after infectious nuclear delivery

Subnuclear promyelocytic leukemia (PML) nuclear bodies (NBs) are targeted by many DNA viruses after nuclear delivery. PML protein is essential for formation of PML NBs. Sp100 and Small Ubiquitin-Like Modifier (SUMO) are also permanently residing within PML NBs. Often, large DNA viruses disassemble and reorganize PML NBs to counteract their intrinsic antiviral activity and support establishment of infection. However, human papillomavirus (HPV) requires PML protein to retain incoming viral DNA in the nucleus for subsequent efficient transcription. In contrast, Sp100 was identified as a restriction factor for HPV. These findings suggested that PML NBs are important regulators of early stages of the HPV life cycle. Nuclear delivery of incoming HPV DNA requires mitosis. Viral particles are retained within membrane-bound transport vesicles throughout mitosis. The viral genome is released from transport vesicles by an unknown mechanism several hours after nuclear envelope reformation. The minor capsid protein L2 mediates intracellular transport by becoming transmembranous in the endocytic compartment. Herein, we tested our hypothesis that PML protein is recruited to incoming viral genome prior to egress from transport vesicles. High-resolution microscopy revealed that PML protein, SUMO-1, and Sp100 are recruited to incoming viral genomes, rather than viral genomes being targeted to preformed PML NBs. Differential immunofluorescent staining suggested that PML protein and SUMO-1 associated with transport vesicles containing viral particles prior to egress, implying that recruitment is likely mediated by L2 protein. In contrast, Sp100 recruitment to HPV-harboring PML NBs occurred after release of viral genomes from transport vesicles. The delayed recruitment of Sp100 is specific for HPV-associated PML NBs. These data suggest that the virus continuously resides within a protective environment until the transport vesicle breaks down in late G1 phase and imply that HPV might modulate PML NB assembly to achieve establishment of infection and the shift to viral maintenance.

Repression of Transcription at DNA Breaks Requires Cohesin throughout Interphase and Prevents Genome Instability

Cohesin subunits are frequently mutated in cancer, but how they function as tumor suppressors is unknown. Cohesin mediates sister chromatid cohesion, but this is not always perturbed in cancer cells. Here, we identify a previously unknown role for cohesin. We find that cohesin is required to repress transcription at DNA double-strand breaks (DSBs). Notably, cohesin represses transcription at DSBs throughout interphase, indicating that this is distinct from its known role in mediating DNA repair through sister chromatid cohesion. We identified a cancer-associated SA2 mutation that supports sister chromatid cohesion but is unable to repress transcription at DSBs. We further show that failure to repress transcription at DSBs leads to large-scale genome rearrangements. Cancer samples lacking SA2 display mutational patterns consistent with loss of this pathway. These findings uncover a new function for cohesin that provides insights into its frequent loss in cancer.

Differential ACPA Binding to Nuclear Antigens Reveals a PAD-Independent Pathway and a Distinct Subset of Acetylation Cross-Reactive Autoantibodies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) associated anti-citrullinated protein autoantibodies (ACPA) target a wide range of modified proteins. Citrullination occurs during physiological processes such as apoptosis, yet little is known about the interaction of ACPA with nuclear antigens or apoptotic cells. Since uncleared apoptotic cells and neutrophil extracellular trap (NET) products have been postulated to be central sources of autoantigen and immunostimulation in autoimmune disease, we sought to characterize the anti-nuclear and anti-neutrophil reactivities of ACPA. Serology showed that a subset of anti-CCP2 seropositive RA patients had high reactivity to full-length citrullinated histones. In contrast, seronegative RA patients displayed elevated IgG reactivity to native histone compared to controls, but no citrulline-specific reactivity. Screening of 10 single B-cell derived monoclonal ACPA from RA patients revealed that four ACPA exhibited strong binding to apoptotic cells and three of these had anti-nuclear (ANA) autoantibody reactivity. Modified histones were confirmed to be the primary targets of this anti-nuclear ACPA subset following immunoprecipitation from apoptotic cell lysates. Monoclonal ACPA were also screened for reactivities against stimulated murine and human neutrophils, and all the nuclear-reactive monoclonal ACPA bound to NETs. Intriguingly, one ACPA mAb displayed a contrasting cytoplasmic perinuclear neutrophil binding and may represent a different NET-reactive ACPA subset. Notably, studies of CRISPR-Cas9 PAD4 KO cells and cells from PAD KO mice showed that the cytoplasmic NET-binding was fully dependent on PAD4, whilst nuclear- and histone-mediated NET reactivity was largely PAD-independent. Our further analysis revealed that the nuclear binding could be explained by consensus-motif driven ACPA cross-reactivity to acetylated histones. Specific acetylated histone peptides targeted by the monoclonal antibodies were identified and the anti-modified protein autoantibody (AMPA) profile of the ACPA was found to correlate with the functional activity of the antibodies. In conclusion, when investigating monoclonal ACPA, we could group ACPA into distinct subsets based on their nuclear binding-patterns and acetylation-mediated binding to apoptotic cells, neutrophils, and NETs. Differential anti-modified protein reactivities of RA-autoantibody subsets could have an important functional impact and provide insights in RA pathogenesis.

Experimentally-induced maternal hypothyroidism alters enzyme activities and the sensorimotor cortex of the offspring rats

In this study, we used an experimental model of congenital hypothyroidism to show that deficient thyroid hormones (TH) disrupt different neurochemical, morphological and functional aspects in the cerebral cortex of 15-day-old offspring. Our results showing decreased glutamine synthetase (GS) activity and Ca²⁺ overload in the cerebral cortex of hypothyroid pups suggest misregulated glutamate metabolism associated with developmentally induced TH deficiency. The ¹⁴C-MeAIB accumulation indicates upregulated System A activity and glutamine uptake by neurons. Energy metabolism in hypothyroid cortical slices was preserved, as demonstrated by unaltered glucose metabolism. We also found upregulated acetylcholinesterase activity, depleting acetylcholine from the synaptic cleft, pointing to disrupted cholinergic system. Increased reactive oxygen species (ROS) generation, lipid peroxidation, glutathione (GSH) depletion, which were associated with glutathione peroxidase, superoxide dismutase and gamma-glutamyltransferase downregulation suggest redox imbalance. Disrupted astrocyte cytoskeleton was evidenced by downregulated and hyperphosphorylated glial fibrillary acidic protein (GFAP). Morphological and structural characterization of the sensorimotor cerebral cortex (SCC) showed unaltered thickness of the SCC. However, decreased size of neurons on the layers II & III and IV in the right SCC and increased NeuN positive neurons in specific SCC layers, suggest that they are differently affected by the low TH levels during neurodevelopment. Hypothyroid pups presented increased number of foot-faults in the gridwalk test indicating affected motor functions. Taken together, our results show that congenital hypothyroidism disrupts glutamatergic and cholinergic neurotransmission, Ca²⁺ equilibrium, redox balance, cytoskeleton integrity, morphological and functional aspects in the cerebral cortex of young rats.

NeuN-Specific Fluorescent Probe Revealing Neuronal Nuclei Protein and Nuclear Acids Association in Living Neurons under STED Nanoscopy

Neuronal nuclei (NeuN) protein is a key RNA-associated protein to guide the transcription of RNA and regulate mRNA splicing in neurons. However, the lack of effective labeling and tracking method has hindered the elucidation of the biological mechanism of NeuN operation in living neurons to understand correlated central nervous system disorders. Here, we report a molecular probe that can be inserted into a neighboring hydrophobic-hydrophilic region in NeuN, which upon binding becomes capable of emitting light in red region. The NeuN specificity enables the probe imaging neuronal cells in primary brain regions including hippocampus, cerebellum, midbrain, and cingulate gyrus. The probes' optical properties are such to enable stimulated emission depletion imaging showing for the first time the 3D structure of RNA tangling into NeuN in a living neuron with tens of nanometer resolution.

Dual-specificity phosphatase 18 modulates the SUMOylation and aggregation of Ataxin-1

We previously reported that SUMOylation promotes the aggregation of ataxin-1 and JNK is involved in the process. Here we show that dual-specificity phosphatase 18 (DUSP18), a member of protein tyrosine phosphatases, exerts the opposite effects on ataxin-1. DUSP18 associated with ataxin-1 and suppressed JNK activated by ataxin-1. Interestingly DUSP18, but not the other DUSPs interacting with ataxin-1, caused the mobility shift of ataxin-1. De-phosphorylation by DUSP18 was initially suspected as a cause for such an effect; however, the phosphorylation of ataxin-1 was unchanged. Instead DUSP18 inhibited SUMOylation and reduced ataxin-1 aggregation. The catalytic mutant of DUSP18 failed to reduce the SUMOylation and aggregation of ataxin-1 indicating that the phosphatase activity is indispensable for the effects. Moreover, DUSP18 disrupted the co-localization of ataxin-1 with the PML component Sp100. These results together implicate that JNK and DUSP18 reciprocally modulate the SUMOylation, which plays a regulatory role in the aggregation of ataxin-1.

Developmental dynamics of prepiriform cortex in prenatal human ontogenesis

The prepiriform cortex is a part of the phylogenetically oldest pallial division (paleocortex) representing the primary olfactory cortex. While olfactory centers in laboratory animals have been extensively investigated, the developmental timetable of the human prepiriform area is poorly understood. Thus, in the present study we aim to examine the prepiriform cortex in human fetuses from eight postconceptional weeks to birth. Based on cytoarchitecture and immunohistochemistry analysis (NeuN-, SYP-, NSE-, TH-, GFAP-, MBP-) four main periods of the prepiriform cortex fetal development are suggested: the beginning of prefetal stage (the eighth week from conception), the period from the ending of prefetal stage (9-12 postconceptional weeks) to 17 weeks of gestation, 18-27 weeks of gestation and the late fetal period (29-40 gestational weeks). We found that the initial layer differentiation took place before the ninthtenth weeks from conception and by ten weeks the paleocortical plate of the prepiriform cortex was shaped. Both total cell density and NeuN-immunoreactive cell density peaked in the early fetuses and started to decrease after 17 gestational weeks, attaining intermediate values at 18-27 weeks and becoming significantly lower in the late fetuses. In contrast, the NeuN-immunoreactive cell ratio gradually increased over the whole examined period. The prepiriform cortex was defined as approaches the state at birth at 30 gestational weeks. The same developmental periods were observed with SYP- and NSE-assays. No significant distribution of TH immunoreactivity was described in the prepiriform cortex of human fetuses. The prior paleocortex development was demonstrated using glial markers: GFAPimmunoreactivity appeared in the prepiriform cortex at the middle of the early fetal period, ahead of the neocortex and insular cortex. The earlier rates of GFAP-immunoreactivity expansion in the prepiriform cortex, as compared to other pallial regions, persisted in the later fetuses. The first MBP-immunoreactive fibres within pallium were detected in the lateral olfactory tract at 30 weeks. Therefore, the prepiriform cortex approaches a level of maturation similar to that at birth already at the beginning of the late fetal period and matures prior to other pallial regions.

Fixation and Spread of Somatic Mutations in Adult Human Colonic Epithelium

We investigated the means and timing by which mutations become fixed in the human colonic epithelium by visualizing somatic clones and mathematical inference. Fixation requires two sequential steps. First, one of approximately seven active stem cells residing within each colonic crypt has to be mutated. Second, the mutated stem cell has to replace neighbors to populate the entire crypt in a process that takes several years. Subsequent clonal expansion due to crypt fission is infrequent for neutral mutations (around 0.7% of all crypts undergo fission in a single year). Pro-oncogenic mutations subvert both stem cell replacement to accelerate fixation and clonal expansion by crypt fission to achieve high mutant allele frequencies with age. The benchmarking of these behaviors allows the advantage associated with different gene-specific mutations to be compared irrespective of the cellular mechanisms by which they are conferred.

Novel long noncoding RNA NMR promotes tumor progression via NSUN2 and BPTF in esophageal squamous cell carcinoma

Long noncoding RNAs (lncRNA) have been implicated in cancer but most of them remain largely unstudied. Here, we identified a novel NSUN2 methylated lncRNA (NMR), which was significantly upregulated in esophageal squamous cell carcinoma (ESCC), functioned as a key regulator of ESCC tumor metastasis and drug resistance. Upregulation of NMR correlated with tumor metastasis and indicated poor overall survival in ESCC patients. Functionally, NMR could promote tumor cell migration and invasion, inhibit cisplatin-induced apoptosis and increase drug resistance in ESCC cells. Mechanistically, transcription of NMR could be upregulated by NF-κB activation after IL-1β and TNF-α treatment. NMR was methylated by NSUN2 and might competitively inhibit methylation of potential mRNAs. NMR could directly bind to chromatin regulator BPTF, and potentially promote MMP3 and MMP10 expression by ERK1/2 pathway through recruiting BPTF to chromatin. Taken together, NMR functions as an oncogenic gene and may serve as new biomarker and therapeutic target in ESCC.

Cohesin mutations in myeloid malignancies made simple

PURPOSE OF REVIEW

Recurrent loss of function mutations within genes of the cohesin complex have been identified in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). STAG2 is the most commonly mutated cohesin member in AML as well as solid tumors. STAG2 is recurrently, mutated in Ewing's Sarcoma, bladder cancer, and glioblastoma, and is one of only ten genes known to be recurrently mutated in over four distinct tissue types of human cancer RECENT FINDINGS: The cohesin complex, a multiprotein ring, is canonically known to align and stabilize replicated chromosomes prior to cell division. Although initially thought to lead to unequal chromosomal separation in dividing cells, data in myeloid malignancies show this is not observed in cohesin mutant MDS/AML, either in large patient cohorts or mouse models. Mounting evidence supports a potential alternate mechanism whereby drivers of cell-type specific gene expression and hematopoietic development are impaired through alteration in three-dimensional nuclear organization and gene structure.

SUMMARY

Understanding the functional consequences of cohesin mutations in regulating lineage-specific and signal-dependent defects and in myeloid transformation will identify novel pathophysiologic mechanisms of disease and inform the development of novel therapeutic targets.

Incorporation of new neurons in the olfactory bulb after paced mating in the female rat

One of the regions that constantly produces neurogenesis in the adult brain is the subventricular zone (SVZ), whose new cells migrate to the olfactory bulbs (OB). When the females regulate the copulatory events (paced mating) the number of new cells in the SVZ increases, as well as those observed in the OB 15 days later. However, no changes were observed in the number of cells 45 days after the females paced the sexual interaction. Constant sensory stimulation is an important promoter of cell survival in the OB circuit. Hence, we increased the number of mating sessions in this study to cover the period where stimulation of the new cells is critical for their incorporation into pre-existing circuits in the OB. Ovariectomized female Wistar rats, were injected with the mitotic marker 5-bromo-2'-deoxyuridine (BrdU, 100 mg/kg, per injection) before, at the end and one hour after mating. Sexual behavior was recorded for 1 h in 10 weekly sessions. After the last mating session, brain sections were processed to determine BrdU immunoreactivity. Our results indicate that females that paced the sexual interaction for 10 sessions had a higher number of cells in the glomerular layer (GL) of the accessory olfactory bulb (AOB) and a higher number of neurons in the granular layer (GrL) of the main olfactory bulb (MOB) in comparison to the control group. These results indicate that continued sexual interaction contributes to the integration of new cells and neurons, induced in the first sexual experience, into pre-exiting circuits of the OB.

Ventral Midline Thalamus Is Necessary for Hippocampal Place Field Stability and Cell Firing Modulation

The reuniens (Re) and rhomboid (Rh) nuclei of the ventral midline thalamus are reciprocally connected with the hippocampus (Hip) and the medial prefrontal cortex (mPFC). Growing evidence suggests that these nuclei might play a crucial role in cognitive processes requiring Hip-mPFC interactions, including spatial navigation. Here, we tested the effect of ReRh lesions on the firing properties and spatial activity of dorsal hippocampal CA1 place cells as male rats explored a familiar or a novel environment. We found no change in the spatial characteristics of CA1 place cells in the familiar environment following ReRh lesions. Contrariwise, spatial coherence was decreased during the first session in a novel environment. We then investigated field stability of place cells recorded across 5 d both in the familiar and in a novel environment presented in a predefined sequence. While the remapping capacity of the place cells was not affected by the lesion, our results clearly demonstrated a disruption of the CA1 cellular representation of both environments in ReRh rats. More specifically, we found ReRh lesions to produce (1) a pronounced and long-lasting decrease of place field stability and (2) a strong alteration of overdispersion (i.e., firing variability). Thus, in ReRh rats, exploration of a novel environment appears to interfere with the representation of the familiar one, leading to decreased field stability in both environments. The present study shows the involvement of ReRh nuclei in the long-term spatial stability of CA1 place fields.SIGNIFICANCE STATEMENT Growing evidence suggest that the ventral midline thalamic nuclei (reuniens and rhomboid) might play a substantial role in various cognitive tasks including spatial memory. In the present article, we show that the lesions of these nuclei impair the spatial representations encoded by CA1 place cells of both familiar and novel environments. First, reduced variability of place cell firing appears to indicate an impairment of attentional processes. Second, impaired stability of place cell representations could explain the long-term memory deficits observed in previous behavioral studies.

Polysialylated Neural Cell Adhesion Molecule Supports Regeneration of Neurons in the Nucleus Ambiguus After Unilateral Recurrent Laryngeal Nerve Avulsion in Adult Rats

OBJECTIVES

A correlation appears to exist between the expression of the polysialic acid neural cell adhesion molecule (PSA-NCAM) and repair in central nervous system (CNS) diseases. However, the expression of PSA-NCAM in the CNS after peripheral nerve injury remains unclear. This study aimed to evaluate the expression of PSA-NCAM in the ipsilateral nucleus ambiguus (NA) after unilateral recurrent laryngeal nerve (RLN) avulsion.

MATERIALS AND METHODS

The left RLN of adult Sprague Dawley rats were avulsed. The expression of PSA-NCAM, PSA-NCAM/NeuN, and PSA-NCAM/Tuj1 in the brain stem was investigated using immunohistochemistry. The results were subjected to one-way analysis of variance followed by the Tukey post hoc test for statistical analyses.

RESULTS

PSA-NCAM-positive and PSA-NCAM/NeuN and PSA-NCAM/Tuj1 double-labeled positive cells were observed 7 days post injury in the ipsilateral NA. PSA-NCAM/NeuN and PSA-NCAM/Tuj1 double-labeled cells were observed at 21 and 7 days post injury, respectively. PSA-NCAM/NeuN double-labeled cells were also found in the contralateral NA.

CONCLUSIONS

After unilateral avulsion of the RLN, the expression of PSA-NCAM in the ipsilateral NA was correlated with the proliferation and the differentiation of neural cells. PSA-NCAM expression may be used as a predictor of the initiation of repair in neural cells.

Functionalizing Ascl1 with Novel Intracellular Protein Delivery Technology for Promoting Neuronal Differentiation of Human Induced Pluripotent Stem Cells

Pluripotent stem cells can become any cell type found in the body. Accordingly, one of the major challenges when working with pluripotent stem cells is producing a highly homogenous population of differentiated cells, which can then be used for downstream applications such as cell therapies or drug screening. The transcription factor Ascl1 plays a key role in neural development and previous work has shown that Ascl1 overexpression using viral vectors can reprogram fibroblasts directly into neurons. Here we report on how a recombinant version of the Ascl1 protein functionalized with intracellular protein delivery technology (Ascl1-IPTD) can be used to rapidly differentiate human induced pluripotent stem cells (hiPSCs) into neurons. We first evaluated a range of Ascl1-IPTD concentrations to determine the most effective amount for generating neurons from hiPSCs cultured in serum free media. Next, we looked at the frequency of Ascl1-IPTD supplementation in the media on differentiation and found that one time supplementation is sufficient enough to trigger the neural differentiation process. Ascl1-IPTD was efficiently taken up by the hiPSCs and enabled rapid differentiation into TUJ1-positive and NeuN-positive populations with neuronal morphology after 8 days. After 12 days of culture, hiPSC-derived neurons produced by Ascl1-IPTD treatment exhibited greater neurite length and higher numbers of branch points compared to neurons derived using a standard neural progenitor differentiation protocol. This work validates Ascl1-IPTD as a powerful tool for engineering neural tissue from pluripotent stem cells.

Sp100 colocalizes with HPV replication foci and restricts the productive stage of the infectious cycle

We have shown previously that Sp100 (a component of the ND10 nuclear body) represses transcription, replication and establishment of incoming human papillomavirus (HPV) DNA in the early stages of infection. In this follow up study, we show that Sp100 does not substantially regulate viral infection in the maintenance phase, however at late stages of infection Sp100 interacts with amplifying viral genomes to repress viral processes. We find that Sp100 localizes to HPV16 replication foci generated in primary keratinocytes, to HPV31 replication foci that form in differentiated cells, and to HPV16 replication foci in CIN 1 cervical biopsies. To analyze this further, Sp100 was down regulated by siRNA treatment of differentiating HPV31 containing cells and levels of viral transcription and replication were assessed. This revealed that Sp100 represses viral transcription and replication in differentiated cells. Analysis of Sp100 binding to viral chromatin showed that Sp100 bound across the viral genome, and that binding increased at late stages of infection. Therefore, Sp100 represses the HPV life cycle at both early and late stages of infection.

Developmental changes in Notch1 and NLE1 expression in a genetic model of absence epilepsy

Childhood absence epilepsy (CAE) is an epilepsy syndrome with seizures occurring in the early childhood, highlighting that seizures susceptibility in CAE is dependent on brain development. The Notch 1 signalling pathway is important in brain development, yet the role of the Notch1 signalling pathway in CAE remains elusive. We here explored Notch1 and its modulator notchless homologue 1 (NLE1) expression in WAG/Rij and control rats using immunohistochemistry. Functional Notch 1 effects were assessed in WAG/Rij rats in vivo. WAG/Rij rats lack the developmental increase in cortical Notch1 and NLE 1 mRNA expression seen in controls, and Notch 1 and NLE1 mRNA and protein expression were lower in somatosensory cortices of WAG/Rij rats when compared to controls. This coincided with an overall decreased cortical GFAP expression in the early development in WAG/Rij rats. These effects were region-specific as they were not observed in thalamic tissues. Neuron-to-glia ratio as a marker of the impact of Notch signalling on differentiation was higher in layer 4 of somatosensory cortex of WAG/Rij rats. Acute application of Notch 1 agonist Jagged 1 suppressed, whereas DAPT, a Notch antagonist, facilitated spike and wave discharges (SWDs) in WAG/Rij rats. These findings point to Notch1 as an important signalling pathway in CAE which likely shapes architectural organization of the somatosensory cortex, a region critically involved in developmental epileptogenesis in CAE. More immediate effects of Notch 1 signalling are seen on in vivo SWDs in CAE, pointing to the Notch 1 pathway as a possible treatment target in CAE.

BPTF Maintains Chromatin Accessibility and the Self-Renewal Capacity of Mammary Gland Stem Cells

Chromatin remodeling is a key requirement for transcriptional control of cellular differentiation. However, the factors that alter chromatin architecture in mammary stem cells (MaSCs) are poorly understood. Here, we show that BPTF, the largest subunit of the NURF chromatin remodeling complex, is essential for MaSC self-renewal and differentiation of mammary epithelial cells (MECs). BPTF depletion arrests cells at a previously undefined stage of epithelial differentiation that is associated with an incapacity to achieve the luminal cell fate. Moreover, genome-wide analysis of DNA accessibility following genetic or chemical inhibition, suggests a role for BPTF in maintaining the open chromatin landscape at enhancers regions in MECs. Collectively, our study implicates BPTF in maintaining the unique epigenetic state of MaSCs.