scholarly journals LYSOSOMAL ENZYMES IN CELLS INFECTED WITH CYTOPATHIC AND NON-CYTOPATHIC VIRUSES

1965 ◽  
Vol 121 (3) ◽  
pp. 477-485 ◽  
Author(s):  
L. Mallucci ◽  
A. C. Allison
Keyword(s):  
Influenza A ◽  
Lysosomal Enzymes ◽  
De Novo ◽  
Cell System ◽  
Supernatant Fraction ◽  
Cytopathic Effects ◽  
Embryo Cells ◽  
High Concentrations ◽  
De Novo Protein Synthesis

In chick embryo cells infected with fowl plague virus, an avian strain of influenza A which produces cytopathic effects, lysosomal enzymes were released from the particulate to the supernatant fraction of homogenates within 6 hours of infection. This change occurred in the presence of high concentrations of parafluorophenylalanine, suggesting that the changes were due to redistribution of preformed enzymes rather than to de novo protein synthesis. No such changes were observed when the Melbourne strain of influenza A virus multiplied in the same cell system without cytopathic effects. The possible role of lysosomal enzymes in virus uncoating and in the genesis of cytopathic effects is discussed.

scholarly journals Role of Initiating Nucleoside Triphosphate Concentrations in the Regulation of Influenza Virus Replication and Transcription

2008 ◽  
Vol 82 (14) ◽  
pp. 6902-6910 ◽  
Author(s):  
Frank T. Vreede ◽  
Hugh Gifford ◽  
George G. Brownlee
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Influenza A ◽  
De Novo ◽  
Nucleoside Triphosphate ◽  
Ribonucleoprotein Complexes ◽  
Influenza Virus Replication ◽  
High Concentrations

ABSTRACT The mechanisms regulating the synthesis of mRNA, cRNA, and viral genomic RNA (vRNA) by the influenza A virus RNA-dependent RNA polymerase are not fully understood. Previous studies in our laboratory have shown that virion-derived viral ribonucleoprotein complexes synthesize both mRNA and cRNA in vitro and early in the infection cycle in vivo. Our continued studies showed that de novo synthesis of cRNA in vitro is more sensitive to the concentrations of ATP, CTP, and GTP than capped-primer-dependent synthesis of mRNA. Using rescued recombinant influenza A/WSN/33 viruses, we now demonstrate that the 3′-terminal sequence of the vRNA promoter dictates the requirement for a high nucleoside triphosphate (NTP) concentration during de novo-initiated replication to cRNA, whereas this is not the case for the extension of capped primers during transcription to mRNA. In contrast to some other viral polymerases, for which only the initiating NTP is required at high concentrations, influenza virus polymerase requires high concentrations of the first three NTPs. In addition, we show that base pair mutations in the vRNA promoter can lead to nontemplated dead-end mutations during replication to cRNA in vivo. Based on our observations, we propose a new model for the de novo initiation of influenza virus replication.

scholarly journals Ceramide Suppresses Influenza A Virus Replication In Vitro

2019 ◽  
Vol 93 (7) ◽  
Author(s):  
Nadia Soudani ◽  
Rouba Hage-Sleiman ◽  
Walid Karam ◽  
Ghassan Dbaibo ◽  
Hassan Zaraket
Keyword(s):  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
De Novo ◽  
Dependent Manner ◽  
Biosynthesis Pathway ◽  
Influenza A H1n1 ◽  
Ceramide Accumulation ◽  
Antiviral Role

ABSTRACT Annual influenza outbreaks are associated with significant morbidity and mortality worldwide despite the availability of seasonal vaccines. Influenza pathogenesis depends on the manipulation of host cell signaling to promote virus replication. Ceramide is a sphingosine-derived lipid that regulates diverse cellular processes. Studies highlighted the differential role of ceramide de novo biosynthesis on the propagation of various viruses. Whether ceramide plays, a role in influenza virus replication is not known. In this study, we assessed the potential interplay between the influenza A (IAV) and ceramide biosynthesis pathways. The accumulation of ceramide in human lung epithelial cells infected with influenza A/H1N1 virus strains was evaluated using thin-layer chromatography and/or confocal microscopy. Virus replication was assessed upon the regulation of the de novo ceramide biosynthesis pathway. A significant increase in ceramide accumulation was observed in cells infected with IAV in a dose- and time-dependent manner. Inoculating the cells with UV-inactivated IAV did not result in ceramide accumulation in the cells, suggesting that the induction of ceramide required an active virus replication. Inhibiting de novo ceramide significantly decreased ceramide accumulation and enhanced virus replication. The addition of exogenous C6-ceramide prior to infection mediated an increase in cellular ceramide levels and significantly attenuated IAV replication and reduced viral titers (≈1 log10 PFU/ml unit). Therefore, our data demonstrate that ceramide accumulation through de novo biosynthesis pathway plays a protective and antiviral role against IAV infection. These findings propose new avenues for development of antiviral molecules and strategies. IMPORTANCE Understanding the effect of sphingolipid metabolism on viral pathogenesis provide important insights into the development of therapeutic strategies against microbial infections. In this study, we demonstrate a critical role of ceramide during influenza A virus infection. We demonstrate that ceramide produced through de novo biosynthesis possess an antiviral role. These observations unlock new opportunities for the development of novel antiviral therapies against influenza.

scholarly journals SULFATION PATHWAYS: Formation and hydrolysis of sulfonated estrogens in the porcine testis and epididymis

2018 ◽  
Vol 61 (2) ◽  
pp. M13-M25 ◽  
Author(s):  
G Schuler ◽  
Y Dezhkam ◽  
L Tenbusch ◽  
MC Klymiuk ◽  
B Zimmer ◽  
...  
Keyword(s):  
Leydig Cells ◽  
De Novo ◽  
Rete Testis ◽  
New Information ◽  
Testicular Steroidogenesis ◽  
High Concentrations ◽  
Hydrolysis Of ◽  
Low Activity ◽  
Porcine Testis

Boars exhibit high concentrations of sulfonated estrogens (SE) mainly originating from the testicular-epididymal compartment. Intriguingly, in porcine Leydig cells, sulfonation of estrogens is colocalized with aromatase and steroid sulfatase (STS), indicating that de novo synthesis of unconjugated estrogens (UE), their sulfonation and hydrolysis of SE occur within the same cell type. So far in boars no plausible concept concerning the role of SE has been put forward. To obtain new information on SE formation and hydrolysis, the porcine testicular-epididymal compartment was screened for the expression of the estrogen-specific sulfotransferase SULT1E1 and STS applying real-time RT-qPCR, Western blot and immunohistochemistry. The epididymal head was identified as the major site of SULT1E1 expression, whereas in the testis, it was virtually undetectable. However, SE tissue concentrations are clearly consistent with the testis as the predominant site of estrogen sulfonation. Results from measurements of estrogen sulfotransferase activity indicate that in the epididymis, SULT1E1 is the relevant enzyme, whereas in the testis, estrogens are sulfonated by a different sulfotransferase with a considerably lower affinity. STS expression and activity was high in the testis (Leydig cells, rete testis epithelium) but also present throughout the epididymis. In the epididymis, SULT1E1 and STS were colocalized in the ductal epithelium, and there was evidence for their apocrine secretion into the ductal lumen. The results suggest that in porcine Leydig cells, SE may be produced as a reservoir to support the levels of bioactive UE via the sulfatase pathway during periods of low activity of the pulsatile testicular steroidogenesis.

Reevaluation of the Role of de Novo Protein Synthesis in Rat Thymocyte Apoptosis

1995 ◽  
Vol 216 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Sek C. Chow ◽  
Iris Peters ◽  
Sten Orrenius
Keyword(s):  
Protein Synthesis ◽  
De Novo ◽  
Thymocyte Apoptosis ◽  
De Novo Protein Synthesis

Evidence for cAMP as a mediator of gonadotropin secretion from male pituitaries

1987 ◽  
Vol 253 (3) ◽  
pp. E296-E299
Author(s):  
G. A. Bourne ◽  
D. M. Baldwin
Keyword(s):  
Protein Synthesis ◽  
Potential Role ◽  
De Novo ◽  
Follicle Stimulating Hormone ◽  
Gonadotropin Releasing Hormone ◽  
Dibutyryl Camp ◽  
Camp Production ◽  
Gonadotropin Secretion ◽  
De Novo Protein Synthesis

The purpose of this study was to use sodium flufenamate, a compound that inhibits gonadotropin-releasing hormone (GnRH)-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) production in the pituitary, to evaluate the potential role of cAMP as a mediator of GnRH-stimulated gonadotropin secretion from male pituitaries. Quartered male pituitaries were perifused at 37 degrees C and sequential effluent fractions collected every 10 min. Infusions of GnRH resulted in a twofold increase in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion. Cycloheximide, 5 microM, completely inhibited the GnRH-stimulated LH and FSH secretion. Infusions of 0.1 mM flufenamate had similar effects on gonadotropin secretion as cycloheximide, whereas the administration of 5 mM dibutyryl cAMP in combination with GnRH and flufenamate restored the secretory responses of both hormones. The flufenamate-inhibited GnRH stimulated LH and FSH release, which was restored by DBcAMP and appeared to be protein synthesis dependent and specific for cAMP. These results suggest an indirect role for cAMP as a mediator of gonadotropin secretion from male pituitaries. However, in contrast to female pituitaries, the secretion of these hormones from male pituitaries is completely dependent on cAMP and de novo protein synthesis.

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