Venkatadri Kolla - Academia.edu (original) (raw)

Papers by Venkatadri Kolla

Virus Genes, Mar 31, 2000

Bacteriophage MB78, a virulent phage of Salmonella typhimurium isolated in our laboratory. It is ... more Bacteriophage MB78, a virulent phage of Salmonella typhimurium isolated in our laboratory. It is different from the well-known temperate phage P22 and 9NA. A detailed physical map has been constructed. To understand more about the physiology and genetics of this interesting phage it has become necessary to fragment the phage genome, clone the fragments and analyze in depth. A number of promoters of bacteriophage MB78 have been cloned and characterized recently. As a part of this program, in this investigation, we report cloning, sequencing and expression and promoter analysis of the ClaI G fragment. We identi®ed the expressed protein as phage structural. Phage structural proteins play a vital role in forming the core head of the phage particle.

Journal of Biological Chemistry, May 2, 1996

Mol Cell Biochem, 2000

The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the stero... more The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the steroid/thyroid hormone receptor superfamily of ligand inducible transcription factors and have been shown to bind the glucocorticoid response element (GRE). Sodium-potassium ATPase (Na/K ATPase) is a major target of mineralocorticoids. Both aldosterone and glucocorticoids activate the human Na/K ATPase α1 subunit and β1 subunit genes transcriptionally. However, the mechanisms of corticosteroid regulation of mammalian Na/K ATPase subunit gene expression are not known. In this investigation, we report for the first time that cell lines (T-84 and 293) express endogenous MR by RT-PCR message expression. However, the protein product was not expressed as determined by western blot analyses. In transactivation studies of MR with GRE31, we detected MR expression at low concentrations of aldosterone. We also performed Northern blot and nuclear run-off transcription assays to further confirm that the regulation is transcriptional. We conclude that the transcriptional regulation of the human Na/K ATPase α1 and β1 subunits by aldosterone occurs via the involvement of the MR. (Mol Cell Biochem 204: [35][36][37][38][39][40] 2000)

Oncotarget, 2016

Neuroblastoma (NB), a tumor of the sympathetic nervous system, is the most common extracranial so... more Neuroblastoma (NB), a tumor of the sympathetic nervous system, is the most common extracranial solid tumor of childhood. We and others have identified distinct patterns of genomic change that underlie diverse clinical behaviors, from spontaneous regression to relentless progression. We first identified CHD5 as a tumor suppressor gene that is frequently deleted in NBs. Mutation of the remaining CHD5 allele is rare in these tumors, yet expression is very low or absent, so expression is likely regulated by epigenetic mechanisms. In order to understand the potential role of miRNA regulation of CHD5 protein expression in NBs, we examined all miRNAs that are predicted to target the 3&amp;#39;-UTR using miRanda, TargetScan and other algorithms. We identified 18 miRNAs that were predicted by 2 or more programs: miR-204, -211, -216b, -17, -19ab, -20ab, -93, -106ab, -130ab, -301ab, -454, -519d, -3666. We then performed transient transfections in two NB cell lines, NLF (MYCN amplified) and SY5Y (MYCN non-amplified), with the reporter plasmid and miRNA mimic, as well as appropriate controls. We found seven miRNAs that significantly downregulated CHD5 expression in NB: miR-211, 17, -93, -20b, -106b, -204, and -3666. Interestingly, MYCN upregulates several of the candidates we identified: miR-17, -93, -106b &amp;amp; -20b. This suggests that miRNAs driven by MYCN and other genes represent a potential epigenetic mechanism to regulate CHD5 expression.

Journal of Biological Chemistry, May 1, 1997

We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (R... more We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (RA) in interferon (IFN)-unresponsive cells permits growth inhibition by IFNs. Here, we show that the promoter of STAT1 directly responds to retinoic acid treatment. Sequence and functional analysis of the murine STAT1 promoter have identified a direct repeat motif that serves as a retinoic acid response element. Mutagenesis of this element resulted in a loss of response to RA. This element is activated by RA receptors ␣, ␤, and ␥. In vivo, RA receptor ␤ and retinoid X receptor ␣ preferentially interacted with this element. Thus, these data define a molecular basis for the synergy between IFNs and retinoids in tumor growth inhibition.

Cancer letters, Jan 18, 2016

Neuroblastoma (NB) is one of the most common and deadly childhood solid tumors. These tumors are ... more Neuroblastoma (NB) is one of the most common and deadly childhood solid tumors. These tumors are characterized by clinical heterogeneity, from spontaneous regression to relentless progression, and the Trk family of neurotrophin receptors plays an important role in this heterogeneous behavior. We wanted to determine if entrectinib (RXDX-101, Ignyta, Inc.), an oral Pan-Trk, Alk and Ros1 inhibitor, was effective in our NB model. In vitro effects of entrectinib, either as a single agent or in combination with the chemotherapeutic agents Irinotecan (Irino) and Temozolomide (TMZ), were studied on an SH-SY5Y cell line stably transfected with TrkB. In vivo growth inhibition activity was studied in NB xenografts, again as a single agent or in combination with Irino-TMZ. Entrectinib significantly inhibited the growth of TrkB-expressing NB cells in vitro, and it significantly enhanced the growth inhibition of Irino-TMZ when used in combination. Single agent therapy resulted in significant tumo...

Proceedings of the National Academy of Sciences of the United States of America, Jan 6, 1997

In this investigation, we show that the gene encoding p48, a subunit of transcription factor ISGF... more In this investigation, we show that the gene encoding p48, a subunit of transcription factor ISGF3, is transcriptionally induced by interferon γ (IFN-γ). We have identified a novel IFN-γ-activated response element in the p48 gene promoter. This motif, notated as gamma-activated transcriptional element (GATE), has no significant resemblance to either pIRE (palindromic IFN-response element) or GAS (the IFN-γ-activated sequence) but has partial homology to ISRE (IFN-stimulated response element). When fused to a neutral promoter, GATE, a 24-bp element, induced the expression of reporter genes following IFN-γ treatment. In murine RAW cells, two IFN-gamma-inducible factors (GIF) bind to GATE. Binding of these factors to GATE is inhibited by cycloheximide and staurosporine. Although p48 gene induction is dependent on STAT1 and JAK1, activated STAT1 does not bind to GATE. Thus, GIFs appear to be novel trans-acting factors in the IFN-signaling pathway.

Journal of Plant Physiology, Jun 1, 2004

The present study reports quick and significant changes induced by plant hormones in the volume o... more The present study reports quick and significant changes induced by plant hormones in the volume of mesophyll protoplasts of pea (Pisum sativum). Four plant hormones: gibberellic acid (GA 3 ), indole 3-acetic acid (IAA), abscisic acid (ABA)( ± ) and methyl jasmonate (MJ), caused marked changes in the volume of mesophyll protoplasts. GA 3 and IAA increased the volume of the protoplasts (up to 90 %) whereas the ABA and MJ decreased (by about 40 %) the volume. Aquaporins or water channels appear to play an important role in swelling/shrinkage of the protoplasts as indicated by the suppression of volume changes by HgCl 2 and reversal by mercaptoethanol. The possible role of secondary messengers in volume changes induced by GA 3 was investigated by using selected pharmacological reagents. The GA 3 induced swelling was restricted by GDP-β-S (G-protein antagonist), U73122 (phospholipase C inhibitor), and TFP (calmodulin antagonist), but was not affected by 1-butanol (phospholipase D inhibitor), GTP-γ-S (G-protein agonist), or verapamil (calcium channel blocker). The results suggest that the mesophyll protoplasts can be a simple and useful system for further studies on volume changes in plant tissues. Key words: abscisic acid -gibberellic acid -indole 3-acetic acid -methyl jasmonate -plant hormones -shrinkage -swelling Abbreviations: GDP-β-S = Guanosine 5′-O-(2-thiodiphosphate). -GTP-γ-S = Guanosine 5′-O-(3thiotriphosphate). -PLC = phospholipase C. -PLD = phospholipase D. -TFP = Trifluoperazine. -U73122 = 1-(6-[([17β]-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl)-1H-pyrrole-2,5-dione

Molecular Cancer, 2015

Background: Chromodomain-helicase DNA binding protein 5 (CHD5) is an important tumor suppressor g... more Background: Chromodomain-helicase DNA binding protein 5 (CHD5) is an important tumor suppressor gene deleted from 1p36.31 in neuroblastomas (NBs). High CHD5 expression is associated with a favorable prognosis, but deletion or low expression is frequent in high-risk tumors. We explored the role of CHD5 expression in the neuronal differentiation of NB cell lines. Methods: NB cell lines SH-SY5Y (SY5Y), NGP, SK-N-DZ, IMR5, LAN5, SK-N-FI, NB69 and SH-EP were treated with 1-10 μM 13-cis-retinoic acid (13cRA) for 3-12 days. qRT-PCR and Western blot analyses were performed to measure mRNA and protein expression levels, respectively. Morphological differences were examined by both phase contrast and immunofluorescence studies.

Molecular and Cellular Biochemistry

The molecular basis for the enhanced growth inhibition of MCF-7 human breast cancer xenografts by... more The molecular basis for the enhanced growth inhibition of MCF-7 human breast cancer xenografts by a combination of human interferon-beta (IFN-beta) and tamoxifen was investigated. Treatment of MCF-7, MDA-MB-231, and BT-20 cells with the combination of IFN-beta and tamoxifen resulted in enhanced antiproliferative effects in vitro. Treatment with the combination of IFN-beta and tamoxifen enhanced the expression of several IFN-beta-inducible genes in human breast carcinoma cell lines relative to levels induced by IFN-beta alone. Tamoxifen alone did not induce transcription of IFN-stimulated genes (ISGs). Augmentation of ISG expression by the combination of IFN-beta and tamoxifen was noted in breast tumor cell lines irrespective of their functional estrogen receptor (ER) status or their dependence on estradiol for growth, suggesting that upregulation of ISGs was independent of ER status. Enhancement of IFN-stimulated gene expression by tamoxifen occurred at the transcriptional level. Ex...

Journal of Biological Chemistry

We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (R... more We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (RA) in interferon (IFN)-unresponsive cells permits growth inhibition by IFNs. Here, we show that the promoter of STAT1 directly responds to retinoic acid treatment. Sequence and functional analysis of the murine STAT1 promoter have identified a direct repeat motif that serves as a retinoic acid response element. Mutagenesis of this element resulted in a loss of response to RA. This element is activated by RA receptors α, β, and γ. In vivo, RA receptor β and retinoid X receptor α preferentially interacted with this element. Thus, these data define a molecular basis for the synergy between IFNs and retinoids in tumor growth inhibition.

Molecular and cellular biochemistry, 2000

The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the stero... more The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the steroid/thyroid hormone receptor superfamily of ligand inducible transcription factors and have been shown to bind the glucocorticoid response element (GRE). Sodium-potassium ATPase (Na/KATPase) is a major target of mineralocorticoids. Both aldosterone and glucocorticoids activate the human Na/K ATPase alpha1 subunit and beta1 subunit genes transcriptionally. However, the mechanisms of corticosteroid regulation of mammalian Na/K ATPase subunit gene expression are not known. In this investigation, we report for the first time that cell lines (T-84 and 293) express endogenous MR by RT-PCR message expression. However, the protein product was not expressed as determined by western blot analyses. In transactivation studies of MR with GRE31, we detected MR expression at low concentrations of aldosterone. We also performed Northern blot and nuclear run-off transcription assays to further confirm tha...

Molecular and cellular biochemistry, 1997

Other names: bHLHe37, N-myc, MODED, ODED HGNC (Hugo): MYCN Location: 2p24.3 Local order: Centrome... more Other names: bHLHe37, N-myc, MODED, ODED HGNC (Hugo): MYCN Location: 2p24.3 Local order: Centromeric to DDX1. DNA/RNA Description 3 exons.

Virus Genes, Mar 31, 2000

Journal of Biological Chemistry, May 2, 1996

Mol Cell Biochem, 2000

Oncotarget, 2016

Journal of Biological Chemistry, May 1, 1997

Cancer letters, Jan 18, 2016

Proceedings of the National Academy of Sciences of the United States of America, Jan 6, 1997

Journal of Plant Physiology, Jun 1, 2004

Molecular Cancer, 2015

Molecular and Cellular Biochemistry

Journal of Biological Chemistry

We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (R... more We have previously demonstrated that up-regulation of STAT1 protein by all-trans-retinoic acid (RA) in interferon (IFN)-unresponsive cells permits growth inhibition by IFNs. Here, we show that the promoter of STAT1 directly responds to retinoic acid treatment. Sequence and functional analysis of the murine STAT1 promoter have identified a direct repeat motif that serves as a retinoic acid response element. Mutagenesis of this element resulted in a loss of response to RA. This element is activated by RA receptors α, β, and γ. In vivo, RA receptor β and retinoid X receptor α preferentially interacted with this element. Thus, these data define a molecular basis for the synergy between IFNs and retinoids in tumor growth inhibition.

Molecular and cellular biochemistry, 2000

The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the stero... more The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) are members of the steroid/thyroid hormone receptor superfamily of ligand inducible transcription factors and have been shown to bind the glucocorticoid response element (GRE). Sodium-potassium ATPase (Na/KATPase) is a major target of mineralocorticoids. Both aldosterone and glucocorticoids activate the human Na/K ATPase alpha1 subunit and beta1 subunit genes transcriptionally. However, the mechanisms of corticosteroid regulation of mammalian Na/K ATPase subunit gene expression are not known. In this investigation, we report for the first time that cell lines (T-84 and 293) express endogenous MR by RT-PCR message expression. However, the protein product was not expressed as determined by western blot analyses. In transactivation studies of MR with GRE31, we detected MR expression at low concentrations of aldosterone. We also performed Northern blot and nuclear run-off transcription assays to further confirm tha...

Molecular and cellular biochemistry, 1997

A B S T R A C T Haploid spermatids undergo extensive cellular, molecular and morphological change... more A B S T R A C T Haploid spermatids undergo extensive cellular, molecular and morphological changes to form spermatozoa during spermiogenesis. Abnormalities in these steps can lead to serious male fertility problems, from oligospermia to complete azoospermia. CHD5 is a chromatin-remodeling nuclear protein expressed almost exclusively in the brain and testis. Male Chd5 knockout (KO) mice have deregulated spermatogenesis, characterized by immature slough-ing of spermatids, spermiation failure, disorganization of the spermatogenic cycle and abnormal head morphology in elongating spermatids. This results in the inappropriate placement and juxtaposition of germ cell types within the epithelium. Sperm that did enter the epididymis displayed irregular shaped sperm heads, and retained cytoplasmic components. These sperm also stained positively for acidic aniline, indicating improper removal of histones and lack of proper chromatin condensation. Electron microscopy showed that spermatids in the seminiferous tubules of Chd5 KO mice have extensive nuclear deformation , with irregular shaped heads of elongated spermatids, and lack the progression of chromatin condensation in an anterior-to-posterior direction. However, the mRNA expression levels of other important genes controlling spermatogenesis were not affected. Chd5 KO mice also showed decreased H4 hyperacetylation beginning at stage IX, step 9, which is vital for the histone-transition protein replacement in spermiogenesis. Our data indicate that CHD5 is required for normal spermiogenesis, especially for spermatid chromatin condensation.