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Studies of polyomavirus trafficking from late endosomes towards the cell nucleus
Štach, Martin ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee)
Mouse polyomavirus (MPyV) is a model virus of the Polyomaviridae family. Polyomaviruses are small non-enveloped DNA viruses. They cause severe problems to immunocompromised patients. Their oncogenic potential is known in animals and humans. Trafficking of MPyV within the cell is not clear yet. The virus enters via smooth monopinocytic vesicles and continues to early and late endosomes. From there, the virus is transported to the ER by unknown mechanism. It bypasses Golgi aparatus (GA). One possible pathway is from late endosomes to trans-Golgi network (TGN) facilitated by Rab9 GTPase and then in COPI vesicles to the ER. In this thesis, the effect of inhibitors of retrograde transport (Brefeldin A, Golgicide A) on MPyV infection was evaluated. Brefeldin A is not completely specific; it has effect on whole endosomal system. Golgicide A causes specific disruption of transport via TGN and GA. Both inhibitors suppressed infection of MPyV. Confocal microscopy revealed colocalization of some MPyV virions with markers of TGN and COPI vesicles. MPyV didn't colocalize with cis-Golgi marker. Unfortunately, the effect of overexpression of Rab9 dominant negative mutant couldn't been evaluated due to its high cytotoxicity. However, overexpression of wild type Rab9 slightly increased infectivity. The results...
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Vesicular trafficking from acidic compartments to the endoplasmic reticulum
Polidarová, Markéta ; Forstová, Jitka (advisor) ; Plocek, Vítězslav (referee)
The cell uses retrograde transport from endosomes to Golgi apparatus and further to the endoplasmic reticulum to recycle its receptors and other proteins. There are several pathways starting on different types of endosomes aimed to the trans-Golgi network and from it further to the endoplasmic reticulum. From the early and maturing endosomes the proteins are transported using the retromer complex. Rab9 GTPase is essential for transport from the late endosomes. Rab6 and Rab11 play major role in the transport form the recycling endosomes. There are two pathways going through the Golgi apparatus. The first one is mediated by COPI vesicles which are regulated by Arf1 GTPase and the pathway is sensitive to brefeldin A. The second pathway is regulated by Rab6 GTPase. Except for endogenous proteins the retrograde transport is used by protein toxins and small unenveloped DNA viruses as well. Rab6 pathway from the recycling endosomes and through the Golgi apparatus is characteristic for Shiga toxin. The retrograde transport of ricin starts on the early endosomes and is less clear. Scientists only started uncovering the transport of small unenveloped DNA viruses.
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Mechanisms of retromer - dependent protein recycling from endosomes
Horázná, Monika ; Macůrková, Marie (advisor) ; Černý, Jan (referee)
Most processes in nature are very effective concerning saving energy and minimizing waste. A good example of saving on cellular level is receptor recycling. Whether it concerns receptors for lysosomal enzymes or for proteins destined for secretion, after releasing their cargo protein the fate of the receptor would be sealed in lysosomes. Nevertheless, some transmembrane receptors contain a signal motif through which they are recognized by specific proteins or protein complexes and they escape the degradation in lysosomes. One such complex is the retromer. Its first discovered function was the recycling of receptors for lysosomal hydrolases in yeast. Later it was proved that it has a similar role in transport of many other proteins in other eukaryotes. The task for retromer is to sort the cargo proteins on the endosomal membrane and together with others auxiliary proteins create a transport vesicle which is then transported to the Golgi. This makes the cell able to recycle proteins that would otherwise be transported from endosomes to lysosomes for degradation.
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Studies of polyomavirus trafficking from late endosomes towards the cell nucleus
Štach, Martin ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee)
Mouse polyomavirus (MPyV) is a model virus of the Polyomaviridae family. Polyomaviruses are small non-enveloped DNA viruses. They cause severe problems to immunocompromised patients. Their oncogenic potential is known in animals and humans. Trafficking of MPyV within the cell is not clear yet. The virus enters via smooth monopinocytic vesicles and continues to early and late endosomes. From there, the virus is transported to the ER by unknown mechanism. It bypasses Golgi aparatus (GA). One possible pathway is from late endosomes to trans-Golgi network (TGN) facilitated by Rab9 GTPase and then in COPI vesicles to the ER. In this thesis, the effect of inhibitors of retrograde transport (Brefeldin A, Golgicide A) on MPyV infection was evaluated. Brefeldin A is not completely specific; it has effect on whole endosomal system. Golgicide A causes specific disruption of transport via TGN and GA. Both inhibitors suppressed infection of MPyV. Confocal microscopy revealed colocalization of some MPyV virions with markers of TGN and COPI vesicles. MPyV didn't colocalize with cis-Golgi marker. Unfortunately, the effect of overexpression of Rab9 dominant negative mutant couldn't been evaluated due to its high cytotoxicity. However, overexpression of wild type Rab9 slightly increased infectivity. The results...
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Vesicular trafficking from acidic compartments to the endoplasmic reticulum
Polidarová, Markéta ; Forstová, Jitka (advisor) ; Plocek, Vítězslav (referee)
The cell uses retrograde transport from endosomes to Golgi apparatus and further to the endoplasmic reticulum to recycle its receptors and other proteins. There are several pathways starting on different types of endosomes aimed to the trans-Golgi network and from it further to the endoplasmic reticulum. From the early and maturing endosomes the proteins are transported using the retromer complex. Rab9 GTPase is essential for transport from the late endosomes. Rab6 and Rab11 play major role in the transport form the recycling endosomes. There are two pathways going through the Golgi apparatus. The first one is mediated by COPI vesicles which are regulated by Arf1 GTPase and the pathway is sensitive to brefeldin A. The second pathway is regulated by Rab6 GTPase. Except for endogenous proteins the retrograde transport is used by protein toxins and small unenveloped DNA viruses as well. Rab6 pathway from the recycling endosomes and through the Golgi apparatus is characteristic for Shiga toxin. The retrograde transport of ricin starts on the early endosomes and is less clear. Scientists only started uncovering the transport of small unenveloped DNA viruses.
|
|
|
Mechanisms of retromer - dependent protein recycling from endosomes
Horázná, Monika ; Macůrková, Marie (advisor) ; Černý, Jan (referee)
Most processes in nature are very effective concerning saving energy and minimizing waste. A good example of saving on cellular level is receptor recycling. Whether it concerns receptors for lysosomal enzymes or for proteins destined for secretion, after releasing their cargo protein the fate of the receptor would be sealed in lysosomes. Nevertheless, some transmembrane receptors contain a signal motif through which they are recognized by specific proteins or protein complexes and they escape the degradation in lysosomes. One such complex is the retromer. Its first discovered function was the recycling of receptors for lysosomal hydrolases in yeast. Later it was proved that it has a similar role in transport of many other proteins in other eukaryotes. The task for retromer is to sort the cargo proteins on the endosomal membrane and together with others auxiliary proteins create a transport vesicle which is then transported to the Golgi. This makes the cell able to recycle proteins that would otherwise be transported from endosomes to lysosomes for degradation.
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