Medical Sciences Commons^™

Ccpa Regulates Arginine Biosynthesis In Staphylococcus Aureus Through Repression Of Proline Catabolism., Austin S. Nuxoll, Steven M. Halouska, Marat Sadykov, Mark L. Hanke, Kenneth W. Bayles, Tammy Kielian, Robert Powers, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus is a leading cause of community-associated and nosocomial infections. Imperative to the success of S. aureus is the ability to adapt and utilize nutrients that are readily available. Genomic sequencing suggests that S. aureus has the genes required for synthesis of all twenty amino acids. However, in vitro experimentation demonstrates that staphylococci have multiple amino acid auxotrophies, including arginine. Although S. aureus possesses the highly conserved anabolic pathway that synthesizes arginine via glutamate, we demonstrate here that inactivation of ccpA facilitates the synthesis of arginine via the urea cycle utilizing proline as a substrate. Mutations within putA, rocD, …

Mucin (Muc) Expression During Pancreatic Cancer Progression In Spontaneous Mouse Model: Potential Implications For Diagnosis And Therapy., Satyanarayana Rachagani, María P Torres, Sushil Kumar, Dhanya Haridas, Michael J. Baine, Muzafar A. Macha, Sukhwinder Kaur, Moorthy P. Ponnusamy, Parama Dey, Parthasarathy Seshacharyulu, Sonny L. Johansson, Maneesh Jain, Kay-Uwe Wagner, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: Pancreatic cancer (PC) is a lethal malignancy primarily driven by activated Kras mutations and characterized by the deregulation of several genes including mucins. Previous studies on mucins have identified their significant role in both benign and malignant human diseases including PC progression and metastasis. However, the initiation of MUC expression during PC remains unknown because of lack of early stage tumor tissues from PC patients.

METHODS: In the present study, we have evaluated stage specific expression patterns of mucins during mouse PC progression in (Kras(G12D);Pdx1-Cre (KC)) murine PC model from pancreatic intraepithelial neoplasia (PanIN) to pancreatic ductal adenocarcinoma (PDAC) …

Exosome-Mediated Shuttling Of Microrna-29 Regulates Hiv Tat And Morphine-Mediated Neuronal Dysfunction., Guoku Hu, H Yao, A D. Chaudhuri, Sowmya V. Yelamanchili, H Wen, P D. Cheney, Howard S. Fox, Shilpa J. Buch

Journal Articles: Pharmacology & Experimental Neuroscience

Neuronal damage is a hallmark feature of HIV-associated neurological disorders (HANDs). Opiate drug abuse accelerates the incidence and progression of HAND; however, the mechanisms underlying the potentiation of neuropathogenesis by these drugs remain elusive. Opiates such as morphine have been shown to enhance HIV transactivation protein Tat-mediated toxicity in both human neurons and neuroblastoma cells. In the present study, we demonstrate reduced expression of the tropic factor platelet-derived growth factor (PDGF)-B with a concomitant increase in miR-29b in the basal ganglia region of the brains of morphine-dependent simian immunodeficiency virus (SIV)-infected macaques compared with the SIV-infected controls. In vitro relevance …

Mammalian Alteration/Deficiency In Activation 3 (Ada3) Is Essential For Embryonic Development And Cell Cycle Progression., Shakur Mohibi, Channabasavaiah B. Gurumurthy, Alo Nag, Jun Wang, Sameer Mirza, Yousaf Mian, Meghan Quinn, Bryan J. Katafiasz, James D. Eudy, Sanjit Pandey, Chittibabu Guda, Mayumi Naramura, Hamid Band, Vimla Band

Journal Articles: Genetics, Cell Biology & Anatomy

Ada3 protein is an essential component of histone acetyl transferase containing coactivator complexes conserved from yeast to human. We show here that germline deletion of Ada3 in mouse is embryonic lethal, and adenovirus-Cre mediated conditional deletion of Ada3 in Ada3(FL/FL) mouse embryonic fibroblasts leads to a severe proliferation defect which was rescued by ectopic expression of human Ada3. A delay in G(1) to S phase of cell cycle was also seen that was due to accumulation of Cdk inhibitor p27 which was an indirect effect of c-myc gene transcription control by Ada3. We further showed that this defect could be …

Secreted Semaphorin 5a Suppressed Pancreatic Tumour Burden But Increased Metastasis And Endothelial Cell Proliferation., A Sadanandam, S S. Sidhu, S Wullschleger, S Singh, M L. Varney, C-S Yang, A E. Ashour, Surinder K. Batra, Rakesh Singh

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: Our earlier reports demonstrated that membrane-bound semaphorin 5A (SEMA5A) is expressed in aggressive pancreatic cancer cells and tumours, and promotes tumour growth and metastasis. In this study, we examine whether (1) pancreatic cancer cells secrete SEMA5A and (2) that secreted SEMA5A modulates certain phenotypes associated with tumour progression, angiogenesis and metastasis through various other molecular factors and signalling proteins.

METHODS AND RESULTS: In this study, we show that human pancreatic cancer cell lines secrete the extracellular domain (ECD) of SEMA5A (SEMA5A-ECD) and overexpression of mouse Sema5A-ECD in Panc1 cells (not expressing SEMA5A; Panc1-Sema5A-ECD; control cells - Panc1-control) significantly increases …

Differential Effects Of Interleukin-17 Receptor Signaling On Innate And Adaptive Immunity During Central Nervous System Bacterial Infection., Debbie Vidlak, Tammy Kielian

Journal Articles: Pathology and Microbiology

Although IL-17A (commonly referred to as IL-17) has been implicated in the pathogenesis of central nervous system (CNS) autoimmune disease, its role during CNS bacterial infections remains unclear. To evaluate the broader impact of IL-17 family members in the context of CNS infection, we utilized IL-17 receptor (IL-17R) knockout (KO) mice that lack the ability to respond to IL-17, IL-17F and IL-17E (IL-25). In this article, we demonstrate that IL-17R signaling regulates bacterial clearance as well as natural killer T (NKT) cell and gamma-delta (γδ) T cell infiltrates during Staphylococcus aureus-induced brain abscess formation. Specifically, when compared with wild-type (WT) …

Perk-Dependent Repression Of Mir-106b-25 Cluster Is Required For Er Stress-Induced Apoptosis., S. Gupta, D. E. Read, A. Deepti, K. Cawley, A. Gupta, D. Oommen, T. Verfaillie, S. Matus, Mary A. Smith, Justin L. Mott, P. Agostinis, C. Hetz, A. Samali

Journal Articles: Biochemistry & Molecular Biology

Activation of the unfolded protein response sensor PKR-like endoplasmic reticulum kinase (Perk) attenuates endoplasmic reticulum (ER) stress levels. Conversantly, if the damage is too severe and ER function cannot be restored, this signaling branch triggers apoptosis. Bcl-2 homology 3-only family member Bim is essential for ER stress-induced apoptosis. However, the regulatory mechanisms controlling Bim activation under ER stress conditions are not well understood. Here, we show that downregulation of the miR-106b-25 cluster contributes to ER stress-induced apoptosis and the upregulation of Bim. Hypericin-mediated photo-oxidative ER damage induced Perk-dependent cell death and led to a significant decrease in the levels of …

Deciphering Mechanisms Of Staphylococcal Biofilm Evasion Of Host Immunity., Mark L. Hanke, Tammy Kielian

Journal Articles: Pathology and Microbiology

Biofilms are adherent communities of bacteria contained within a complex matrix. Although host immune responses to planktonic staphylococcal species have been relatively well-characterized, less is known regarding immunity to staphylococcal biofilms and how they modulate anti-bacterial effector mechanisms when organized in this protective milieu. Previously, staphylococcal biofilms were thought to escape immune recognition on the basis of their chronic and indolent nature. Instead, we have proposed that staphylococcal biofilms skew the host immune response away from a proinflammatory bactericidal phenotype toward an anti-inflammatory, pro-fibrotic response that favors bacterial persistence. This possibility is supported by recent studies from our laboratory using …

Il-1ri (Interleukin-1 Receptor Type I) Signalling Is Essential For Host Defence And Hemichannel Activity During Acute Central Nervous System Bacterial Infection., Juan Xiong, Maria Burkovetskaya, Nikolay Karpuk, Tammy Kielian

Journal Articles: Pathology and Microbiology

Staphylococcus aureus is a common aetiological agent of bacterial brain abscesses. We have previously established that a considerable IL-1 (interleukin-1) response is elicited immediately following S. aureus infection, where the cytokine can exert pleiotropic effects on glial activation and blood-brain barrier permeability. To assess the combined actions of IL-1α and IL-1β during CNS (central nervous system) infection, host defence responses were evaluated in IL-1RI (IL-1 receptor type I) KO (knockout) animals. IL-1RI KO mice were exquisitely sensitive to intracerebral S. aureus infection, as demonstrated by enhanced mortality rates and bacterial burdens within the first 24 h following pathogen exposure compared …

Identification Of Bovine Leukemia Virus Tax Function Associated With Host Cell Transcription, Signaling, Stress Response And Immune Response Pathway By Microarray-Based Gene Expression Analysis., Mariluz Araínga, Eri Takeda, Yoko Aida

Journal Articles: Pharmacology & Experimental Neuroscience

BACKGROUND: Bovine leukemia virus (BLV) is associated with enzootic bovine leukosis and is closely related to human T-cell leukemia virus type I. The Tax protein of BLV is a transcriptional activator of viral replication and a key contributor to oncogenic potential. We previously identified interesting mutant forms of Tax with elevated (TaxD247G) or reduced (TaxS240P) transactivation effects on BLV replication and propagation. However, the effects of these mutations on functions other than transcriptional activation are unknown. In this study, to identify genes that play a role in the cascade of signal events regulated by wild-type and mutant Tax proteins, we …

Limitations Of The Rhesus Macaque Draft Genome Assembly And Annotation, Xiongfei Zhang, Joel Goodsell, Robert B. Norgren

Journal Articles: Genetics, Cell Biology & Anatomy

Finished genome sequences and assemblies are available for only a few vertebrates. Thus, investigators studying many species must rely on draft genomes. Using the rhesus macaque as an example, we document the effects of sequencing errors, gaps in sequence and misassemblies on one automated gene model pipeline, Gnomon. The combination of draft genome with automated gene finding software can result in spurious sequences. We estimate that approximately 50% of the rhesus gene models are missing, incomplete or incorrect. The problems identified in this work likely apply to all draft vertebrate genomes annotated with any automated gene model pipeline and thus …

Interferon-Α Regulates Glutaminase 1 Promoter Through Stat1 Phosphorylation: Relevance To Hiv-1 Associated Neurocognitive Disorders., Lixia Zhao, Yunlong Huang, Changhai Tian, Lynn Taylor, Norman Curthoys, Yi Wang, Hamilton Vernon, Jialin C. Zheng

Journal Articles: Pharmacology & Experimental Neuroscience

HIV-1 associated neurocognitive disorders (HAND) develop during progressive HIV-1 infection and affect up to 50% of infected individuals. Activated microglia and macrophages are critical cell populations that are involved in the pathogenesis of HAND, which is specifically related to the production and release of various soluble neurotoxic factors including glutamate. In the central nervous system (CNS), glutamate is typically derived from glutamine by mitochondrial enzyme glutaminase. Our previous study has shown that glutaminase is upregulated in HIV-1 infected monocyte-derived-macrophages (MDM) and microglia. However, how HIV-1 leads to glutaminase upregulation, or how glutaminase expression is regulated in general, remains unclear. In …

Myd88-Dependent Signaling Influences Fibrosis And Alternative Macrophage Activation During Staphylococcus Aureus Biofilm Infection., Mark L. Hanke, Amanda Angle, Tammy Kielian

Journal Articles: Pathology and Microbiology

Bacterial biofilms represent a significant therapeutic challenge based on their ability to evade host immune and antibiotic-mediated clearance. Recent studies have implicated IL-1β in biofilm containment, whereas Toll-like receptors (TLRs) had no effect. This is intriguing, since both the IL-1 receptor (IL-1R) and most TLRs impinge on MyD88-dependent signaling pathways, yet the role of this key adaptor in modulating the host response to biofilm growth is unknown. Therefore, we examined the course of S. aureus catheter-associated biofilm infection in MyD88 knockout (KO) mice. MyD88 KO animals displayed significantly increased bacterial burdens on catheters and surrounding tissues during early infection, which …