Papers by Shekhar Mayanil
Journal of Biological Chemistry, 2001
Pax3 is a transcription factor that is required for the development of embryonic neural tube, neu... more Pax3 is a transcription factor that is required for the development of embryonic neural tube, neural crest, and somatic derivatives. Our previous study (Mayanil,
Journal of Biological Chemistry, 2000
Polysialic acid (PSA) is a developmentally regulated carbohydrate found primarily on neural cell ... more Polysialic acid (PSA) is a developmentally regulated carbohydrate found primarily on neural cell adhesion molecules (NCAM) in embryonic tissues. The majority of NCAM in adult tissues lacks this unique carbohydrate, but polysialylated NCAM (PSA-NCAM) is present in adult brain regions where neural regeneration persists and in some pediatric brain tumors such as medulloblastoma, which show greater propensity for leptomeningeal spread. Pax3, a developmentally regulated paired homeodomain transcription factor, is thought to be involved in the regulation of neural cell adhesion molecules. Overexpression of murine Pax3 into a human medulloblastoma cell line (DAOY) resulted in an increase in NCAM polysialylation and a 2-4-fold increase in ␣2,8-polysialyltransferase type II mRNA levels. No difference was observed in ␣2,8-polysialyltransferase type IV message. The addition of PSA to NCAM changed the adhesive behavior of these Pax3 transfectants. Transfectants expressing high PSA-NCAM show much less NCAM-dependent aggregation than those with less PSA-NCAM. In addition, Pax3 transfectants having high PSA-NCAM show heterophilic adhesion involving polysialic acid to heparan sulfate proteoglycan and agrin. These observations suggest that a developmentally regulated transcription factor, Pax3, could affect NCAM polysialylation and subsequently cell-cell and cell-substratum interaction.
Molecular biology of the cell, Jan 15, 2011
Pax3 plays a role in regulating Hes1 and Neurog2 activity and thereby stem cell maintenance and n... more Pax3 plays a role in regulating Hes1 and Neurog2 activity and thereby stem cell maintenance and neurogenesis. A mechanism for Pax3 regulation of these two opposing events, during caudal neural tube development, is examined in this study. Pax3 acetylation on C-terminal lysine residues K437 and K475 may be critical for proper regulation of Hes1 and Neurog2. Removal of these lysine residues increased Hes1 but decreased Neurog2 promoter activity. SIRT1 deacetylase may be a key component in regulating Pax3 acetylation. Chromatin immunoprecipitation assays showed that SIRT1 is associated with Hes1 and Neurog2 promoters during murine embryonic caudal neural tube development at E9.5, but not at E12.5. Overexpression of SIRT1 decreased Pax3 acetylation, Neurog2 and Brn3a positive staining. Conversely, siRNA-mediated silencing of SIRT1 increased these factors. These studies suggest that Pax3 acetylation results in decreased Hes1 and increased Neurog2 activity, thereby promoting sensory neuron...
Nanomedicine: Nanotechnology, Biology and Medicine, 2014
This study examined a novel drug delivery system for treatment of malignant brain gliomas: DOX co... more This study examined a novel drug delivery system for treatment of malignant brain gliomas: DOX complexed with nanodiamonds (ND-Dox), and administered via convection-enhanced delivery (CED). Drug retention and toxicity were examined in glioma cell lines, and distribution, retention and toxicity were examined in normal rat parenchyma. Efficacy was assessed in a bioluminescence rodent tumor model. NDs markedly enhanced DOX uptake and retention in glioma cells. ND-Dox delivered via CED extended DOX retention and localized DOX toxicity in normal rodent parenchyma, and was significantly more efficient at killing tumor cells than uncomplexed DOX. Outcomes from this work suggest that CED of ND-Dox is a promising approach for brain tumor treatment.
Developmental Biology, 2008
Corrigendum to "Key basic helix-loop-helix transcription factor genes Hes1 and Ngn2 are regulated... more Corrigendum to "Key basic helix-loop-helix transcription factor genes Hes1 and Ngn2 are regulated by Pax3 during mouse embryonic development" [Dev.
Child's Nervous System, 2013
This study investigated epigenetic modifications in human central nervous system atypical teratoi... more This study investigated epigenetic modifications in human central nervous system atypical teratoid rhabdoid tumors (AT/RTs), in response to inhibition of insulin-like growth factor receptor 1 (IGF-1R). Tumor tissue was obtained from two pediatric patients, tissue was dissociated, and primary cultures were established. Cultured cells were treated with picropodophyllin (PPP; 0, 1, and 2 μM for 48 h), a selective IGF-1R inhibitor. Histone acetylation and methylation patterns (H3K9ac, H3K18ac, H3K4me3, H3K27me3) and levels of histone deacetylases (HDACs; HDAC1, HDAC3, and SirT1) and histone acetyl transferases (GCN5 and p300) were examined. H3K9ac and H3K18ac decreased in response to treatment with PPP. HDAC levels showed a biphasic response, increasing with 1 μM PPP, but then decreasing with 2 μM PPP. Inhibition of IGF-1R modified epigenetic status in AT/RT. Determining the mechanisms behind these modifications will guide the development of novel therapeutic targets for this malignant embryonal cancer.
Biochimica et Biophysica Acta (BBA) - General Subjects, 1983
Increasing concentrations of dopamine fail to give a biphasic response to (Na+ + K+)-ATPase activ... more Increasing concentrations of dopamine fail to give a biphasic response to (Na+ + K+)-ATPase activity in various subcellular fractions of rat brain preincubated with monoamine oxidase inhibitors, viz. 1 X 10(-4) M clorgyline and 1 X 10(-4) M deprenyl. The product of the monoamine-oxidase-catalysed reaction with dopamine as substrate is 3-methoxy-4-hydroxyphenylacetaldehyde. An analogue of this product is 3-methoxy-4-hydroxybenzaldehyde. This analogue, when incubated with the subcellular fractions which had been preincubated with monoamine oxidase inhibitors and dopamine, gave a more pronounced biphasic response to (Na+ + K+)-ATPase activity than that observed in the fractions incubated with dopamine alone.
… International journal of …, 2009
Résumé/Abstract Pax3 regulates neural crest cell migration and is critical during neural crest de... more Résumé/Abstract Pax3 regulates neural crest cell migration and is critical during neural crest development. TGFβs modify neural crest cell migration and differentiation. TGFβ2 nullizygous embryos (TGFβ2-/-Pax3+/+) display open neural tube and bifid spine, ...
Developmental Biology, 2008
Pax3 is expressed early during embryonic development in spatially restricted domains including li... more Pax3 is expressed early during embryonic development in spatially restricted domains including limb muscle, neural crest, and neural tube. Pax3 functions at the nodal point in melanocyte stem cell differentiation, cardiogenesis and neurogenesis. Additionally Pax3 has been implicated in migration and differentiation of precursor cell populations. Currently there are questions about how Pax3 regulates these diverse functions. In this study we found that in the absence of functional Pax3, as in Splotch embryos, the neural crest cells undergo premature neurogenesis, as evidenced by increased Brn3a positive staining in neural tube explants, in comparison with wild-type. Premature neurogenesis in the absence of functional Pax3 may be due to a change in the regulation of basic helix-loop-helix transcription factors implicated in proliferation and differentiation. Using promoter-luciferase activity measurements in transient co-transfection experiments and electro-mobility shift assays, we show that Pax3 regulates Hairy and enhancer of split homolog-1 (Hes1) and Neurogenin2 (Ngn2) by directly binding to their promoters. Chromatin immunoprecipitation assays confirmed that Pax3 bound to cis-regulatory elements within Hes1 and Ngn2 promoters. These observations suggest that Pax3 regulates Hes1 and Ngn2 and imply that it may couple migration with neural stem cell maintenance and neurogenesis.
In Vitro Cellular & Developmental Biology - Animal, 1998
Three sources of fetal bovine serum (FBS) were fractionated by amlnonium sulfate precipitation an... more Three sources of fetal bovine serum (FBS) were fractionated by amlnonium sulfate precipitation and by sodium dodecyl suli'ate-polyacrylamide gel electrophoresis (SDS-PAGE), transferred to lmmobilon-P membranes, immunoblotted with a panel of transcription factor antibodies, and detected by enhanced chemiluminescence. Nine transcription factors were detected-ATF-2, SRE-ZBP, GATA-2, TFIID, Ets-1/Ets-2, E2F-1, Oct-2, p53, and AP-2; four transcription factors were not detected-Myo D, CREB, Sp2, and Wilms' tumor. The results indicated the presence of varying amounts of several transcription factors in three commercial sources and may represent heretoh)re unrecognized factors influencing cell culture.
The International Journal of Developmental Biology, 2009
Pax3 regulates neural crest cell migration and is critical during neural crest development. TGFβs... more Pax3 regulates neural crest cell migration and is critical during neural crest development. TGFβs modify neural crest cell migration and differentiation. TGFβ2 nullizygous embryos (TGFβ2-/-Pax3 +/+) display open neural tube and bifid spine, whereas in wild type embryos the neural tube is closed. In previous work, we have demonstrated that Pax3 regulates TGFβ2 by directly binding to cis-regulatory elements on its promoter. In this study, we found that the TGFβ2 nullizygous phenotype can be reversed to the wild type phenotype by down-regulating one allele of Pax3, as in TGFβ2-/-Pax3 +/embryos obtained through breeding TGFβ2 +/-Pax3 +/mice. The data in this paper suggest that Pax3 and TGFβ2 interact in a coordinated gene regulatory network, linked by common downstream effector genes, to bring about this phenotypic reversal. Downstream effectors may include Hes1, Ngn2 and Sox9, as well as other genes involved in neuronal differentiation.
Neurogenesis (Austin, Tex.), 2017
Until recently folate receptor alpha (FRα) has only been considered as a folate transporter. Howe... more Until recently folate receptor alpha (FRα) has only been considered as a folate transporter. However, a novel role of FRα as a transcription factor was reported by our lab. More recently our lab showed a novel pleiotropic role of FRα: (a) direct transcriptional activation of Oct4, Sox2, and Klf4 genes; and (b) repression of biogenesis of miRNAs that target these genes or their effector molecules. These observations beg a question: "Can a simple molecule such as folate be used to manipulate the production and/or differentiation of endogenous neural stem cells (NSCs), which may hold promise for future therapies?" Conditions such as spinal cord injury, motor neuron diseases, Alzheimer's disease and multiple sclerosis may benefit from increasing stem cell pool and promoting specific pathways of differentiation. On the flip-side, these NSCs may also contribute to some CNS tumors therefore promoting differentiation could prove more beneficial. FRα may hold promises for both ...
MicroRNA in Regenerative Medicine, 2015
The Journal of Nutrition, Mar 1, 2017
The work by Antony and colleagues in this issue of the Journal (1) truly exemplifies the dictum '... more The work by Antony and colleagues in this issue of the Journal (1) truly exemplifies the dictum ''that which is bad can trigger good in the human body.'' Elevated homocysteine that is a direct result of folate deficiency can result in poor immune function; chronic low energy (including chronic fatigue syndrome); poor digestion; issues such as constipation, bloating, and irritable bowel syndrome; stunted growth; anemia; canker sores in the mouth and a tender, swollen tongue; mood swings; and irritability. Folate deficiency, accompanied by increased concentrations of homocysteine (hyperhomocysteinemia) in the blood, causes endothelial cell injury, inflammation leading to atherogenesis, and ischemic injury (2). Hyperhomocysteinemia has also been associated with early pregnancy loss (3) and with neural tube defects (4). In addition, some evidence suggests that people with elevated homocysteine concentrations have twice the normal risk of developing neurodegenerative disorders (5). Despite the fact that elevated homocysteine is not good for the human body, cells have homocysteine sensors that allow them to take appropriate actions against it. AntonyÕs laboratory has been pioneering the study of characterizing the folate deficiency sensor inside the cell, which senses the rise in homocysteine concentrations and increases the expression of folate receptor a (FRa) (6-8). Homocysteine binds to heterogeneous nuclear ribonucleoprotein (hnRNP) E1 and opens its high-affinity mRNA binding site to accommodate FRa mRNA; therefore, it acts like a folate deficiency sensor inside the cell. This triggers the upregulation of high-affinity FRa to sequester as much folate as possible in the extracellular matrix for the maintenance of cellular functions. The question now is, if all of the hnRNP-E1 gets used up in binding the FRa operon to make more FRa protein, then what is the mechanism for the ongoing generation of hnRNP-E1 to replenish the homocysteinylated hnRNP-E1 that is degraded? The article in this issue of the Journal from AntonyÕs laboratory outlines in detail how, in addition to upregulating the FRa operon, hnRNP-E1 also auto-upregulates itself through a novel positive feedback loop during prolonged folate deficiency, thereby maximizing the
Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery, Jan 8, 2018
In this study, we investigate a neuroprotective agent, erythropoietin (EPO), in animal hydrocepha... more In this study, we investigate a neuroprotective agent, erythropoietin (EPO), in animal hydrocephalus model and its potential reversal effects on hydrocephalus by altering the expression of aquaporin-4 (AQP4). Obstructive hydrocephalus was induced in 2-week-old rat pups by injecting kaolin (50 μl, 10 mg/ml in saline) into the cisterna magna, while the control pups received only saline. Kaolin-injected pups were divided into two groups on the fifth day after kaolin injection; one group received intra-peritoneal (i.p.) EPO (1 μg/pup) for 5 consecutive days, while other group received i.p. saline for 5 days. The effects of EPO on hydrocephalus were investigated by studying cerebral ventricle size and structural ependymal changes. We examined also the EPO effects on AQP4 expression and microRNA expression. EPO treatment significantly reduced dilation of the cerebral ventricle and denudation of ependymal line in hydrocephalic pups comparing with the control group. Increased expression of ...
Stem cells (Dayton, Ohio), Nov 14, 2016
Prenatal folic acid (FA) supplementation prevents neural tube defects. Folate receptor alpha (FRα... more Prenatal folic acid (FA) supplementation prevents neural tube defects. Folate receptor alpha (FRα) is critical for embryonic development, including neural crest (NC) development. Previously we showed that FRα translocates to the nucleus in response to FA, where it acts as a transcription factor. In this study, we examined if FA through interaction with FRα regulates stem cell characteristics of cranial neural crest cells (CNCCs)-critical for normal development. We hypothesized that FRα upregulates coding genes and simultaneously downregulates non-coding miRNA which targets coding genes in CNCCs. Quantitative RT-PCR and chromatin immunoprecipitation showed that FRα upregulates Oct4, Sox2, and Klf4 by binding to their cis-regulator elements-5' enhancer/promoters defined by H3K27Ac and p300 occupancy. FA via FRα downregulates miRNAs, miR-138 and miR-let-7, which target Oct4 and Trim71 (an Oct4 downstream effector), respectively. Co-immunoprecipitation data suggests that FRα interac...
Neuroscience Discovery, 2014
(Folate receptor alpha), a GPI-anchored protein is critical for embryonic development. Disruption... more (Folate receptor alpha), a GPI-anchored protein is critical for embryonic development. Disruption of both FRα alleles in mice results in pups with a range of malformations and is lethal to the embryos at the time of neural tube closure. Recent body of evidences emphasizes its role in neural tube defects, cerebral folate deficiency, autism and autism spectrum disorders. Circulating autoantibodies against FRα and cerebral folate deficiency appear to play a crucial role in the cause and pathogenesis of a particular subgroup of autism spectrum disorders with co-existing neurological deficits. Since FRα is known to be over-expressed in cancer cells, it has found a novel theranostic role in cancer diagnosis and treatment by using FA-conjugated imaging agents as diagnostic tools and FA-conjugated nanotherapeutics and immunotherapy for cancer. This review highlights some recent advances and novel roles of FRα other than it being just a folate transporter.
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1989
1. Monoamine oxidase (amine: oxygen oxidoreductase [deaminating], EC 1.4.3.4) (MAO) and Na+/K+ AT... more 1. Monoamine oxidase (amine: oxygen oxidoreductase [deaminating], EC 1.4.3.4) (MAO) and Na+/K+ ATPase (Na+/K+-ATPase, Mg2+-dependent ATP phosphohydrolase, EC 3,1,6,3) showed reciprocal relationship in their activity patterns during experimentally perturbed situations in vivo as well as in vitro. 2. M-signal hypothesis is proposed, which attempts at explaining the regulation of plasma membrane function by the intermediate of metabolic processes in the cell. This metabolic intermediate referred to as M-signal exercise its influence on the plasma membrane Na+/K+ ATPase which is responsible for the uptake process.
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Papers by Shekhar Mayanil