Biology subjects

McGlynn, K.

Publications and source records attributed to McGlynn, K..

8 recordsLinked to original sources

bioRxiv2024

The Cancer Testis Antigen Testis Specific Serine Kinase 6 (TSSK6) is abnormally expressed in colorectal cancer and is essential for oncogenic behaviors

Cancer testis antigens (CTAs) are a collection of proteins whose expression is normally restricted to the gamete, but abnormally activated in a wide variety of tumors. The CTA, Testis specific serine kinase 6 (TSSK6), is essential for male fertility in mice. Functional relevance of TSSK6 to cancer, if any, has not previously been investigated. Here we find that TSSK6 is frequently anomalously expressed in colorectal cancer and patients with elevated TSSK6 expression have reduced relapse free survival. Depletion of TSSK6 from colorectal cancer cells attenuates anchorage independent growth, invasion and growth in vivo. Conversely, overexpression of TSSK6 enhances anchorage independence and invasion in vitro as well as in vivo tumor growth. Notably, ectopic expression of TSSK6 in semi-transformed human colonic epithelial cells is sufficient to confer anchorage independence and enhance invasion. In somatic cells, TSSK6 co-localizes with and enhances the formation of paxillin and tensin positive foci at the cell periphery, suggesting a function in focal adhesion formation. Importantly, TSSK6 kinase activity is essential to induce these tumorigenic behaviors. Our findings establish that TSSK6 exhibits oncogenic activity when abnormally expressed in colorectal cancer cells. Thus, TSSK6 is a previously unrecognized intervention target for therapy, which could exhibit an exceptionally broad therapeutic window.

cancer biology↗

bioRxiv2023

The Cancer Testes Antigen, HORMAD1, is a Tumor-Specific Replication Fork Protection Factor

Tumors frequently activate the expression of genes that are only otherwise required for meiosis. HORMAD1, which is essential for meiotic recombination in multiple species, is expressed in over 50% of human lung adenocarcinoma cells (LUAD). We previously found that HORMAD1 promotes DNA double strand break (DSB) repair in LUAD. Here, we report that HORMAD1 takes on an additional role in protecting genomic integrity. Specifically, we find HORMAD1 is critical for protecting stalled DNA replication forks in LUAD. Loss of HORMAD1 leads to nascent DNA degradation, an event which is mediated by the MRE11-DNA2-BLM pathway. Moreover, following exogenous induction of DNA replication stress, HORMAD1 deleted cells accumulate single stranded DNA (ssDNA). We find that these phenotypes are the result of a lack of RAD51 and BRCA2 loading onto stalled replication forks. Ultimately, loss of HORMAD1 leads to increased DSBs and chromosomal aberrations in response to replication stress. Collectively, our data support a model where HORMAD1 expression is selected to mitigate DNA replication stress, which would otherwise induce deleterious genomic instability.

cancer biology↗

bioRxiv2020

Sperm-specific COX6B2 Enhances Oxidative Phosphorylation, Proliferation, and Survival in Lung Adenocarcinoma

Cancer testis antigens (CTAs) are genes whose expression is normally restricted to the testis but anomalously activated in cancer. In sperm, a number of CTAs promote energy generation, however whether these proteins contribute to tumor cell metabolism is not understood. Here we describe COX6B2, a sperm-specific component of cytochrome c oxidase (complex IV). COX6B2 is frequently expressed in human lung adenocarcinoma (LUAD) and expression correlates with reduced survival time in patients. COX6B2, but not its somatic isoform COX6B1, enhances activity of complex IV, increasing mitochondrial oxidative phosphorylation (OXPHOS) and NAD+ generation. Consequently, COX6B2-expressing cells display a proliferative advantage, particularly in low oxygen conditions. Conversely, depletion of COX6B2 attenuates OXPHOS and collapses mitochondrial membrane potential leading to cell death or senescence. Furthermore, COX6B2 is both necessary and sufficient for growth of tumors in vivo. Our findings reveal a previously unappreciated, tumor specific metabolic pathway hijacked from one of the most ATP-intensive processes in the animal kingdom: sperm motility.

cancer biology↗

bioRxiv2020

The testis protein ZNF165 is a SMAD3 cofactor that coordinates oncogenic TGFβ signaling in triple-negative breast cancer

Cancer/testis (CT) antigens are proteins whose expression is normally restricted to germ cells yet aberrantly activated in tumors, where their functions remain relatively cryptic. Here we report that ZNF165, a CT antigen frequently expressed in triple-negative breast cancer (TNBC), associates with SMAD3 to modulate transcription of transforming growth factor {beta} (TGF{beta})-dependent genes and thereby promote growth and survival. In addition, we identify the KRAB zinc finger protein, ZNF446, and its associated tripartite motif protein, TRIM27, as obligate components of the ZNF165-SMAD3 complex that also support tumor cell viability. Importantly, we find that TRIM27 alone is necessary for ZNF165 transcriptional activity and is required for orthotopic tumor growth in vivo. Our findings indicate that aberrant expression of a testis-specific transcription factor is sufficient to co-opt somatic transcriptional machinery to drive a pro-tumorigenic gene expression program.

cancer biology↗

bioRxiv2019

ERK2 phosphorylates the epigenetic regulator CXXC-finger protein 1 (Cfp1)

BackgroundThe Ras-Raf-MEK-ERK signaling pathway is essential for proper development and homeostatic regulation in eukaryotic cells and underlies progression of several types of cancer. Many pathway functions are performed by extracellular signal-regulated kinase (ERK)1 and 2 (ERK1/2), serine/threonine protein kinases of the mitogen-activated protein kinase (MAPK) family that interact with a large number of substrates and are highly active in the nucleus.\n\nResultsWe identified the epigenetic regulator CXXC-finger protein 1 (CFP1) as a protein that interacts with ERK2 on chromatin. CFP1 is involved in multiple aspects of chromatin regulation, including histone methylation and DNA methylation. Here, we demonstrate the overlapping roles for ERK1/2 and CFP1 in regulation of immediate early gene (IEG) induction. Our work suggests multiple modes of co-regulation and demonstrates that CFP1 is required for an optimal signal-dependent response. We also show that CFP1 is an ERK2 substrate in vitro and identify several phosphorylation sites. Furthermore, we provide evidence that Su(var)3-9, Enhancer-of-zeste and Trithorax (Set)1b, a CFP1-interacting histone methylase, is phosphorylated by ERK2 and is regulated by CFP1.\n\nConclusionOur work highlights ERK1/2 interactions with chromatin regulators that contribute to MAPK signaling diversity in the nucleus.

cell biology↗

bioRxiv2018

Next-generation sequencing based hospital outbreak investigation yields insight into Klebsiella aerogenes population structure and determinants of carbapenem resistance and virulence

Klebsiella aerogenes is a nosocomial pathogen associated with drug resistance and outbreaks in intensive care units. In a 5-month period in 2017, we experienced an increased incidence of cultures for carbapenem-resistant K. aerogenes (CR-KA) from an adult cardiothoracic intensive care unit (CICU) involving 15 patients. Phylogenomic analysis following whole-genome sequencing (WGS) identified the outbreak CR-KA isolates to group together as a tight clonal cluster (<7 SNPs apart), suggestive of a protracted intra-ward transmission event. No clonal relationships were identified between the CICU CR-KA strains and additional hospital CR-KA patient isolates from different wards and/or previous years. Genes encoding carbapenemases or drug-resistant plasmids were absent in the outbreak strains, and carbapenem resistance was attributed to mutations impacting AmpD activity and membrane permeability. The CICU outbreak strains harbored an integrative conjugative element (ICEKp10), which has been associated with pathogenicity in hypervirulent Klebsiella pneumoniae lineages. Comparative genomics with global K. aerogenes genomes showed our outbreak strains to group closely with global ST4 strains, which along with ST93 likely represent dominant K. aerogenes lineages associated with human infections. WGS is a powerful tool that goes beyond high-resolution tracking of transmission events into identifying the genetic basis of drug-resistance and virulence, which are not part of conventional diagnostic workflows. With an increasing availability of sequenced genomes from across the globe, population structure analysis offers opportunities to identify emerging trends and dominant clones associated with specific syndromes and geographical locations for poorly characterized pathogens.

genomics↗

bioRxiv2018

BDNF/TrkB signaling in pancreatic islet beta cells

Adrenergic signaling is a well-known input into pancreatic islet function. Specifically, the insulin-secreting islet {beta} cell expresses the Gi/o-linked 2-adrenergic receptor, which upon activation suppresses insulin secretion. The use of adrenergic agonist epinephrine at micromolar doses may have supraphysiological effects. We found that pretreating {beta} cells with micromolar concentrations of epinephrine differentially inhibited activation of receptor tyrosine kinases. We chose TrkB as an example because of its relative sensitivity to the effects of epinephrine and due to its potential regulatory role in the {beta} cell. Our characterization of brain-derived neurotrophic factor (BDNF)-TrkB signaling in MIN6 {beta} cells showed that TrkB is activated by BDNF as expected, leading to canonical TrkB autophosphorylation and subsequent downstream signaling, as well as chronic effects on {beta} cell growth. Micromolar, but not nanomolar, concentrations of epinephrine blocked BDNF-induced TrkB autophosphorylation and downstream mitogen-activated protein kinase pathway activation, suggesting an inhibitory phenomenon at the receptor level. We determined epinephrine-mediated inhibition of TrkB activation to be Gi/o-dependent using pertussis toxin, arguing against an off-target effect of high dose epinephrine. Published data suggested that inhibition of potassium channels or phosphoinositide-3-kinase signaling may abrogate the negative effects of epinephrine, however these did not rescue TrkB signaling in our experiments. Taken together, these results show that 1) TrkB kinase signaling occurs in {beta} cells and 2) use of epinephrine in studies of insulin secretion requires careful consideration of concentration-dependent effects. BDNF-TrkB signaling in {beta} cells may underlie pro-survival or growth signaling and warrants further study.

cell biology↗

bioRxiv2018

Chromomycin A2 potently inhibits glucose-stimulated insulin secretion from pancreatic beta cells.

Enhancers or inhibitors of insulin secretion could become therapeutics as well as lead to the identification of requisite {beta}-cell regulatory pathways and increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is co-secreted with insulin in MIN6 {beta}-cells to perform a high-throughput natural product screen for chronic effects on glucose-stimulated insulin secretion. Using multiple phenotypic analyses, we identified that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion through at least three mechanisms: disruption of Wnt signaling, interfering with {beta}-cell gene expression, and suppression of triggering calcium (Ca2+) influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even post-washout, but did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel-opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx which may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. The FUSION bioinformatic database indicated that the phenotypic effects of CMA2 clustered with a number of Wnt/GSK3 pathway-related genes. Consistently, CMA2 decreased GSK3 phosphorylation and suppressed activation of a {beta}-catenin activity reporter. CMA2 and a related compound mithramycin are described to have DNA-interaction properties, possibly abrogating transcription factor binding to critical {beta}-cell gene promoters. We observed that CMA2, but not mithramycin, suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt {beta}-cell function through both non-cytotoxic and cytotoxic mechanisms. Future applications of CMA2 and similar aureolic acid analogs for disease therapies should consider the potential impacts on pancreatic islet function.

cell biology↗