IU Indianapolis ScholarWorks :: Browsing by Author "Hartley, Antja-Voy"

Browsing by Author "Hartley, Antja-Voy"

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A complex signature network that controls the upregulation of PRMT5 in colorectal cancer
(Elsevier, 2022-03) Wei, Han; Hartley, Antja-Voy; Motolani, Aishat; Jiang, Guanglong; Safa, Ahmad; Prabhu, Lakshmi; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
Aging: Cancer – an unlikely couple
(Impact Journals, 2017-09-20) Hartley, Antja-Voy; Martin, Matthew; Lu, Tao; Pharmacology and Toxicology, School of Medicine
Critical role of phosphorylation of serine 165 of YBX1 on the activation of NF- B in colon cancer
(Office of the Vice Chancellor for Research, 2015-04-17) Prabhu, Lakshmi; Mundade, Rasika; Wang, Benlian; Wei, Han; Hartley, Antja-Voy; McElyea, Kyle; Temm, Constance J.; Sandusky, George; Liu, Yunlong; Lu, Tao
Y-box binding protein 1 (YBX1) is a multifunctional protein known to facilitate many of the hallmarks of cancer. Elevated levels of YBX1 protein are highly correlated with cancer progression, making it an excellent marker in cancer. The connection between YBX1 and the important nuclear factor B (NF-B), has never been previously reported. Here, we show that overexpression of wild type YBX1 (wtYBX1) activates NF-B, suggesting that YBX1 is a potential NF-B activator. Furthermore, using mass spectrometry analysis, we identified novel phosphorylation of serine 165 (S165) on YBX1. Overexpression of the S165A-YBX1 mutant in either 293 cells or colon cancer HT29 cells showed dramatically reduced NF-B activating ability as compared to that of wtYBX1, confirming that S165 phosphorylation is critical for the activation of NF-B by YBX1. We further show that expression of the S165A-YBX1 mutant dramatically decreased the expression of NF-B-inducible genes, reduced cell growth, and compromised tumorigenic ability as compared to wtYBX1. Taken together, we provide the first evidence that YBX1 functions as a tumor promoter via NF-B activation, and phosphorylation of S165 of YBX1 is critical for this function. Therefore, our important discovery may lead to blocking S165 phosphorylation as a potential therapeutic strategy to treat colon cancer.
Critical role of phosphorylation of serine 165 of YBX1 on the activation of NF-κB in colon cancer.
(Impact Journals, 2015-10-06) Prabhu, Lakshmi; Mundade, Rasika; Wang, Benlian; Wei, Han; Hartley, Antja-Voy; Martin, Matthew; McElyea, Kyle; Temm, Constance J.; Sandusky, George; Liu, Yunlong; Lu, Tao; Department of Pharmacology and Toxicology, IU School of Medicine
Y-box binding protein 1 [YBX1] is a multifunctional protein known to facilitate many of the hallmarks of cancer. Elevated levels of YBX1 protein are highly correlated with cancer progression, making it an excellent marker in cancer. The connection between YBX1 and the important nuclear factor κB [NF-κB] has never been reported. Here, we show that overexpression of wild type YBX1 [WT-YBX1] activates NF-κB, suggesting that YBX1 is a potential NF-κB activator. Furthermore, using mass spectrometry analysis we identified novel phosphorylation of serine 165 [S165] on YBX1. Overexpression of the S165A-YBX1 mutant in either HEK293 cells or colon cancer HT29 cells showed dramatically reduced NF-κB activating ability as compared with that of WT-YBX1, confirming that S165 phosphorylation is critical for the activation of NF-κB by YBX1. We also show that expression of the S165A-YBX1 mutant dramatically decreased the expression of
Modulating the modulators: regulation of protein arginine methyltransferases by post-translational modifications
(Elsevier, 2020-09) Hartley, Antja-Voy; Lu, Tao; Pharmacology and Toxicology, School of Medicine
The therapeutic potential of targeting protein arginine methyltransferases (PRMTs) is inextricably linked to their key roles in various cellular functions, including splicing, proliferation, cell cycle regulation, differentiation, and DNA damage signaling. Unsurprisingly, the development of inhibitors against these enzymes has become a rapidly expanding research area. However, effective targeting of PRMTs requires a deeper understanding of the mechanistic details behind their regulation at multiple levels, involving those mechanisms that alter their activity, interactions, and localization. Recently, post-translational modifications (PTMs) of PRMTs have emerged as another crucial aspect of this regulation. Here, we review the regulatory role of PTMs in the activity and function of PRMTs, with emphasis on the contribution of these PTMs to pathological states, such as cancer.
Novel Serine 176 Phosphorylation of YBX1 Activates NF-κB in Colon Cancer
(American Society for Biochemistry and Molecular Biology, 2017-02-24) Martin, Matthew; Hua, Laiqing; Wang, Benlian; Wei, Han; Prabhu, Lakshmi; Hartley, Antja-Voy; Jiang, Guanglong; Liu, Yunlong; Lu, Tao; Medical and Molecular Genetics, School of Medicine
Y box protein 1 (YBX1) is a well known oncoprotein that has tumor-promoting functions. YBX1 is widely considered to be an attractive therapeutic target in cancer. To develop novel therapeutics to target YBX1, it is of great importance to understand how YBX1 is finely regulated in cancer. Previously, we have shown that YBX1 could function as a tumor promoter through phosphorylation of its Ser-165 residue, leading to the activation of the NF-κB signaling pathway (1). In this study, using mass spectrometry analysis, we discovered a distinct phosphorylation site, Ser-176, on YBX1. Overexpression of the YBX1-S176A (serine-to-alanine) mutant in either HEK293 cells or colon cancer HT29 cells showed dramatically reduced NF-κB-activating ability compared with that of WT-YBX1, confirming that Ser-176 phosphorylation is critical for the activation of NF-κB by YBX1. Importantly, the mutant of Ser-176 and the previously reported Ser-165 sites regulate distinct groups of NF-κB target genes, suggesting the unique and irreplaceable function of each of these two phosphorylated serine residues. Our important findings could provide a novel cancer therapy strategy by blocking either Ser-176 or Ser-165 phosphorylation or both of YBX1 in colon cancer.
PRMT5-mediated methylation of YBX1 regulates NF-κB activity in colorectal cancer
(Nature Publishing Group, 2020-09-28) Hartley, Antja-Voy; Wang, Benlian; Mundade, Rasika; Jiang, Guanglong; Sun, Mengyao; Wei, Han; Sun, Steven; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
The multifunctional protein Y-box binding protein 1 (YBX1), is a critical regulator of transcription and translation, and is widely recognized as an oncogenic driver in several solid tumors, including colorectal cancer (CRC). However, very little is known about the upstream or downstream factors that underlie YBX1′s regulation and involvement in CRC. Previously, we demonstrated that YBX1 overexpression correlated with potent activation of nuclear factor κB (NF-κB), a well-known transcription factor believed to be crucial in CRC progression. Here, we report a novel interaction between NF-κB, YBX1 and protein arginine methyltransferase 5 (PRMT5). Our findings reveal for the first time that PRMT5 catalyzes methylation of YBX1 at arginine 205 (YBX1-R205me2), an event that is critical for YBX1-mediated NF-κB activation and its downstream target gene expression. Importantly, when WT-YBX1 is overexpressed, this methylation exists under basal (unstimulated) conditions and is further augmented upon interleukin-1β (IL-1β) stimulation. Mechanistically, co-immunoprecipitation studies reveal that the R205 to alanine (A) mutant of YBX1 (YBX1-R205A) interacted less well with the p65 subunit of NF-κB and attenuated the DNA binding ability of p65. Importantly, overexpression of YBX1-R205A significantly reduced cell growth, migration and anchorage-independent growth of CRC cells. Collectively, our findings shed important light on the regulation of a novel PRMT5/YBX1/NF-κB axis through PRMT5-mediated YBX1-R205 methylation. Given the fact that PRMT5, YBX1 and NF-κB are all among top crucial factors in cancer progression, pharmacological disruption of this pivotal axis could serve as the basis for new therapeutics for CRC and other PRMT5/YBX1/NF-κB-associated cancers.
PRMTs and miRNAs: functional cooperation in cancer and beyond
(Taylor & Francis, 2019-06-24) Jin, Jiamin; Martin, Matthew; Hartley, Antja-Voy; Lu, Tao; Pharmacology and Toxicology, School of Medicine
Epigenetic modulators play pivotal roles in directing gene expression for the maintenance of normal cellular functions. However, when these modulators are aberrantly regulated, this can result in a variety of disease states, including cancer. One class of epigenetic regulators, protein arginine methyltransferases (PRMTs), have been shown to play critical roles in disease through methylation of arginine residues (R) on histone or non-histone proteins. Quite different from PRMTs, microRNAs (miRNAs) belong to the family of modulators known as noncoding RNAs (ncRNA) that act to regulate gene expression via RNA-mediated gene silencing. Importantly, miRNAs are frequently dysregulated and contribute to the progression of cancer and other conditions, including neurological and cardiovascular diseases. Recently, numerous studies have shown that miRNAs and other epigenetic enzymes can co-regulate each other. This review highlights multiple nodes of interaction between miRNAs and PRMTs and also discusses how this interplay might open up promising opportunities for drug development for the treatment of cancer and other diseases.
Regulation of a PRMT5/NF-κB Axis by Phosphorylation of PRMT5 at Serine 15 in Colorectal Cancer
(MDPI, 2020-05-23) Hartley, Antja-Voy; Wang, Benlian; Jiang, Guanglong; Wei, Han; Sun, Mengyao; Prabhu, Lakshmi; Martin, Matthew; Safa, Ahmad; Sun, Steven; Liu, Yunlong; Lu, Tao; Pharmacology and Toxicology, School of Medicine
patients. Importantly, our previous work demonstrated that PRMT5 overexpression could substantially augment activation of the nuclear factor kappa B (NF-κB) via methylation of arginine 30 (R30) on its p65 subunit, while knockdown of PRMT5 showed the opposite effect. However, the precise mechanisms governing this PRMT5/NF-κB axis are still largely unknown. Here, we report a novel finding that PRMT5 is phosphorylated on serine 15 (S15) in response to interleukin-1β (IL-1β) stimulation. Interestingly, we identified for the first time that the oncogenic kinase, PKCι could catalyze this phosphorylation event. Overexpression of the serine-to-alanine mutant of PRMT5 (S15A), in either HEK293 cells or CRC cells HT29, DLD1, and HCT116 attenuated NF-κB transactivation compared to WT-PRMT5, confirming that S15 phosphorylation is critical for the activation of NF-κB by PRMT5. Furthermore, the S15A mutant when compared to WT-PRMT5, could downregulate a subset of IL-1β-inducible NF-κB-target genes which correlated with attenuated promoter occupancy of p65 at its target genes. Additionally, the S15A mutant reduced IL-1β-induced methyltransferase activity of PRMT5 and disrupted the interaction of PRMT5 with p65. Furthermore, our data indicate that blockade of PKCι-regulated PRMT5-mediated activation of NF-κB was likely through phosphorylation of PRMT5 at S15. Finally, inhibition of PKCι or overexpression of the S15A mutant attenuated the growth, migratory, and colony-forming abilities of CRC cells compared to the WT-PRMT5. Collectively, we have identified a novel PKCι/PRMT5/NF-κB signaling axis, suggesting that pharmacological disruption of this pivotal axis could serve as the basis for new anti-cancer therapeutics.
Role of Novel Serine 316 Phosphorylation of the p65 Subunit of NF-κB in Differential Gene Regulation
(American Society for Biochemistry & Molecular Biology, 2015-06-16) Wang, Benlian; Prabhu, Lakshmi; Zhao, Wei; Martin, Matthew; Hartley, Antja-Voy; Lu, Tao; Wei, Han; Department of Pharmacology and Toxicology, IU School of Medicine
Nuclear factor κB (NF-κB) is a central coordinator in immune and inflammatory responses. Constitutive NF-κB is often found in some types of cancers, contributing to oncogenesis and tumor progression. Therefore, knowing how NF-κB is regulated is important for its therapeutic control. Post-translational modification of the p65 subunit of NF-κB is a well known approach for its regulation. Here, we reported that in response to interleukin 1β, the p65 subunit of NF-κB is phosphorylated on the novel serine 316. Overexpression of S316A (serine 316 → alanine) mutant exhibited significantly reduced ability to activate NF-κB and decreased cell growth as compared with wtp65 (wild type p65). Moreover, conditioned media from cells expressing the S316A-p65 mutant had a considerably lower ability to induce NF-κB than that of wtp65. Our data suggested that phosphorylation of p65 on Ser-316 controls the activity and function of NF-κB. Importantly, we found that phosphorylation at the novel Ser-316 site and other two known phosphorylation sites, Ser-529 and Ser-536, either individually or cooperatively, regulated distinct groups of NF-κB-dependent genes, suggesting the unique role of each individual phosphorylation site on NF-κB-dependent gene regulation. Our novel findings provide an important piece of evidence regarding differential regulation of NF-κB-dependent genes through phosphorylation of different p65 serine residues, thus shedding light on novel mechanisms for the pathway-specific control of NF-κB. This knowledge is key to develop strategies for prevention and treatment of constitutive NF-κB-driven inflammatory diseases and cancers.

Browsing by Author "Hartley, Antja-Voy"

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