scholarly journals Activation of Innate Defense against a Paramyxovirus Is Mediated by RIG-I and TLR7 and TLR8 in a Cell-Type-Specific Manner

2005 ◽  
Vol 79 (20) ◽  
pp. 12944-12951 ◽  
Author(s):  
Jesper Melchjorsen ◽  
Søren B. Jensen ◽  
Lene Malmgaard ◽  
Simon B. Rasmussen ◽  
Friedemann Weber ◽  
...  
Keyword(s):  
Sendai Virus ◽  
Large Degree ◽  
Molecular Structures ◽  
Dependent Manner ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Protein Kinase R ◽  
Innate Defense ◽  
Expression Of Genes ◽  
A Cell

ABSTRACT Recognition of pathogens by the innate immune system is mediated by pattern recognition receptors (PRRs), which recognize specific molecular structures of the infectious agents and subsequently trigger expression of genes involved in host defense. Toll-like receptors (TLRs) represent a well-characterized class of membrane-bound PRRs, and the RNA helicase retinoic acid inducible gene I (RIG-I) has recently been described as a novel cytoplasmic PRR recognizing double-stranded RNA (dsRNA). Here we show that activation of signal transduction and induction of cytokine expression by the paramyxovirus Sendai virus is dependent on virus replication and involves PRRs in a cell-type-dependent manner. While nonimmune cells relied entirely on recognition of dsRNA through RIG-I for activation of an antiviral response, myeloid cells utilized both the single-stranded RNA sensing TLR7 and TLR8 and dsRNA-dependent mechanisms independent of RIG-I, TLR3, and dsRNA-activated protein kinase R to trigger this response. Therefore, there appears to be a large degree of cell-type specificity in the mechanisms used by the host to recognize infecting viruses.

scholarly journals Sendai virus trailer RNA simultaneously blocks two apoptosis-inducing mechanisms in a cell type-dependent manner

2005 ◽  
Vol 86 (8) ◽  
pp. 2305-2314 ◽  
Author(s):  
Marian Wiegand ◽  
Sascha Bossow ◽  
Wolfgang J. Neubert
Keyword(s):  
Cell Lines ◽  
Cytopathic Effect ◽  
Sendai Virus ◽  
Cellular Protein ◽  
Dependent Manner ◽  
Cell Type ◽  
Initiator Caspases ◽  
A Cell ◽  
Cell Type Specific ◽  
Intracellular Antigen

Induction of apoptosis during Sendai virus (SeV) infection has previously been documented to be triggered by initiator caspases (for strain F) or by a contribution of the cellular protein TIAR (T-cell-activated intracellular antigen-related) (for strain Z). Here, evidence was provided that both TIAR and caspases are simultaneously involved in apoptosis induction as a result of infection with SeV strain F. SeV F infection induced death in all tested cell lines, which could only be partially prevented through the pan-caspase inhibitor z-VAD-fmk. However, infection of seven different cell lines with the SeV mutant Fctr48z overexpressing a TIAR-sequestering RNA from the modified leader resulted in a cell type-dependent reduced cytopathic effect (CPE); in an earlier study a similar mutant derived from SeV Z was shown to prevent the induction of any CPE. Finally, blocking of caspases through z-VAD-fmk combined with Fctr48z infection led to complete abrogation of CPE, clearly demonstrating the existence of two separate mechanisms inducing cell death during SeV F infections. Interestingly, a cell type-specific interference between these two mechanisms could be detected during infection with the mutant virus Fctr48z: RNA transcribed from the mutated leader was able to trans-dominantly inhibit caspase-mediated apoptosis. Thus, virus-expressed factors enabling a well-balanced ratio of suppression and triggering of apoptosis seem to be essential for optimal virus replication.

scholarly journals Differential Role of Basal Keratinocytes in UV-Induced Immunosuppression and Skin Cancer

2006 ◽  
Vol 26 (22) ◽  
pp. 8515-8526 ◽  
Author(s):  
Judith Jans ◽  
George A. Garinis ◽  
Wouter Schul ◽  
Adri van Oudenaren ◽  
Michael Moorhouse ◽  
...  
Keyword(s):  
Skin Cancer ◽  
Biological Effects ◽  
Mouse Skin ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Basal Keratinocytes ◽  
Expression Of Genes ◽  
Pyrimidine Dimers ◽  
Response To Stress

ABSTRACT Cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs) comprise major UV-induced photolesions. If left unrepaired, these lesions can induce mutations and skin cancer, which is facilitated by UV-induced immunosuppression. Yet the contribution of lesion and cell type specificity to the harmful biological effects of UV exposure remains currently unclear. Using a series of photolyase-transgenic mice to ubiquitously remove either CPDs or 6-4PPs from all cells in the mouse skin or selectively from basal keratinocytes, we show that the majority of UV-induced acute effects to require the presence of CPDs in basal keratinocytes in the mouse skin. At the fundamental level of gene expression, CPDs induce the expression of genes associated with repair and recombinational processing of DNA damage, as well as apoptosis and a response to stress. At the organismal level, photolyase-mediated removal of CPDs, but not 6-4PPs, from the genome of only basal keratinocytes substantially diminishes the incidence of skin tumors; however, it does not affect the UVB-mediated immunosuppression. Taken together, these findings reveal a differential role of basal keratinocytes in these processes, providing novel insights into the skin's acute and chronic responses to UV in a lesion- and cell-type-specific manner.

scholarly journals C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1233 ◽  
Author(s):  
Leskelä ◽  
Huber ◽  
Rostalski ◽  
Natunen ◽  
Remes ◽  
...  
Keyword(s):  
Neuroblastoma Cells ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Serum Starvation ◽  
Dependent Manner ◽  
Cell Type ◽  
Proteasomal Activity ◽  
N2a Cells ◽  
Autophagy Induction ◽  
A Cell

Dysfunctional autophagy or ubiquitin-proteasome system (UPS) are suggested to underlie abnormal protein aggregation in neurodegenerative diseases. Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS)-associated C9orf72 is implicated in autophagy, but whether it activates or inhibits autophagy is partially controversial. Here, we utilized knockdown or overexpression of C9orf72 in mouse N2a neuroblastoma cells or cultured neurons to elucidate the potential role of C9orf72 proteins in autophagy and UPS. Induction of autophagy in C9orf72 knockdown N2a cells led to decreased LC3BI to LC3BII conversion, p62 degradation, and formation of LC3-containing autophagosomes, suggesting compromised autophagy. Proteasomal activity was slightly decreased. No changes in autophagy nor proteasomal activity in C9orf72-overexpressing N2a cells were observed. However, in these cells, autophagy induction by serum starvation or rapamycin led to significantly decreased C9orf72 levels. The decreased levels of C9orf72 in serum-starved N2a cells were restored by the proteasomal inhibitor lactacystin, but not by the autophagy inhibitor bafilomycin A1 (BafA1) treatment. These data suggest that C9orf72 undergoes proteasomal degradation in N2a cells during autophagy. Lactacystin significantly elevated C9orf72 levels in N2a cells and neurons, further suggesting UPS-mediated regulation. In rapamycin and BafA1-treated neurons, C9orf72 levels were significantly increased. Altogether, these findings corroborate the previously suggested regulatory role for C9orf72 in autophagy and suggest cell type-dependent regulation of C9orf72 levels via UPS and/or autophagy.

scholarly journals The Anticoagulant Nafamostat Potently Inhibits SARS-CoV-2 S Protein-Mediated Fusion in a Cell Fusion Assay System and Viral Infection In Vitro in a Cell-Type-Dependent Manner

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 629 ◽  
Author(s):  
Mizuki Yamamoto ◽  
Maki Kiso ◽  
Yuko Sakai-Tagawa ◽  
Kiyoko Iwatsuki-Horimoto ◽  
Masaki Imai ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Assay System ◽  
Dependent Manner ◽  
Cell Type ◽  
S Protein ◽  
Candidate Drug ◽  
A Cell ◽  
Transmembrane Serine Protease ◽  
Nafamostat Mesylate

Although infection by SARS-CoV-2, the causative agent of coronavirus pneumonia disease (COVID-19), is spreading rapidly worldwide, no drug has been shown to be sufficiently effective for treating COVID-19. We previously found that nafamostat mesylate, an existing drug used for disseminated intravascular coagulation (DIC), effectively blocked Middle East respiratory syndrome coronavirus (MERS-CoV) S protein-mediated cell fusion by targeting transmembrane serine protease 2 (TMPRSS2), and inhibited MERS-CoV infection of human lung epithelium-derived Calu-3 cells. Here we established a quantitative fusion assay dependent on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein, angiotensin I converting enzyme 2 (ACE2) and TMPRSS2, and found that nafamostat mesylate potently inhibited the fusion while camostat mesylate was about 10-fold less active. Furthermore, nafamostat mesylate blocked SARS-CoV-2 infection of Calu-3 cells with an effective concentration (EC)50 around 10 nM, which is below its average blood concentration after intravenous administration through continuous infusion. On the other hand, a significantly higher dose (EC50 around 30 μM) was required for VeroE6/TMPRSS2 cells, where the TMPRSS2-independent but cathepsin-dependent endosomal infection pathway likely predominates. Together, our study shows that nafamostat mesylate potently inhibits SARS-CoV-2 S protein-mediated fusion in a cell fusion assay system and also inhibits SARS-CoV-2 infection in vitro in a cell-type-dependent manner. These findings, together with accumulated clinical data regarding nafamostat’s safety, make it a likely candidate drug to treat COVID-19.

scholarly journals Either ZEB1 or ZEB2/SIP1 Can Play a Central Role in Regulating the Epstein-Barr Virus Latent-Lytic Switch in a Cell-Type-Specific Manner

2010 ◽  
Vol 84 (12) ◽  
pp. 6139-6152 ◽  
Author(s):  
Amy L. Ellis ◽  
Zhenxun Wang ◽  
Xianming Yu ◽  
Janet E. Mertz
Keyword(s):  
Cell Lines ◽  
Epstein Barr Virus ◽  
Cellular Protein ◽  
Lytic Replication ◽  
Viral Reactivation ◽  
Dependent Manner ◽  
Cell Type ◽  
Barr Virus ◽  
A Cell ◽  
Epstein Barr

ABSTRACT We previously reported that the cellular protein ZEB1 can repress expression of the Epstein-Barr virus (EBV) BZLF1 gene in transient transfection assays by directly binding its promoter, Zp. We also reported that EBV containing a 2-bp substitution mutation in the ZEB-binding ZV element of Zp spontaneously reactivated out of latency into lytic replication at a higher frequency than did wild-type EBV. Here, using small interfering RNA (siRNA) and short hairpin RNA (shRNA) technologies, we definitively show that ZEB1 is, indeed, a key player in maintaining EBV latency in some epithelial and B-lymphocytic cell lines. However, in other EBV-positive epithelial and B-cell lines, another zinc finger E-box-binding protein, ZEB2/SIP1, is the key player. Both ZEB1 and ZEB2 can bind Zp via the ZV element. In EBV-positive cells containing only ZEB1, knockdown of ZEB1 led to viral reactivation out of latency, with synthesis of EBV immediate-early and early lytic gene products. However, in EBV-positive cells containing both ZEBs, ZEB2, not ZEB1, was the primary ZEB family member bound to Zp. Knockdown of ZEB2, but not ZEB1, led to EBV lytic reactivation. Thus, we conclude that either ZEB1 or ZEB2 can play a central role in the maintenance of EBV latency, doing so in a cell-type-dependent manner.

scholarly journals Multiple roles of COUP-TFII in cancer initiation and progression

2012 ◽  
Vol 49 (3) ◽  
pp. R135-R148 ◽  
Author(s):  
Lacey M Litchfield ◽  
Carolyn M Klinge
Keyword(s):  
Current Data ◽  
Multiple Roles ◽  
Dependent Manner ◽  
Orphan Nuclear Receptor ◽  
Cell Type ◽  
Mouse Development ◽  
Factor Ii ◽  
Upstream Promoter ◽  
A Cell ◽  
Cell Type Specific

Chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) is an orphan nuclear receptor that acts as a transcriptional activator or repressor in a cell type-dependent manner. Best characterized for its role in the regulation of angiogenesis during mouse development, COUP-TFII also plays important roles in glucose metabolism and cancer. Expression of COUP-TFII is altered in various endocrine conditions. Cell type-specific functions and the regulation of COUP-TFII expression result in its varying physiological and pathological actions in diverse systems. Evidence will be reviewed for oncogenic and tumor-suppressive functions of COUP-TFII, with roles in angiogenesis, metastasis, steroidogenesis, and endocrine sensitivity of breast cancer described. The applicability of current data to our understanding of the role of COUP-TFII in cancer will be discussed.

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