Human Alpha-herpesvirus MicroRNAs
MicroRNAs (miRNAs) are an extensive class of approx 22 nucleotide long regulatory RNAs expressed by all mammalian cells and also by several DNA viruses, including many members of the herpesvirus family. Using deep sequencing technology, it has now been demonstrated that Herpes Simplex Virus 1 (HSV-1) encodes at least eight viral miRNAs, seven of which are expressed in latently infected human neurons. Similarly, HSV-2 has also been shown to encode at least six miRNAs, four of which are evolutionarily conserved between HSV-2 and HSV-1. Perhaps surprisingly, varicella zoster virus does not appear to express any viral miRNAs in latently infected cells. A recent review discusses the potential functions of the currently known HSV-1 and HSV-2 miRNAs, focusing on a possible role in stabilizing viral latency in infected neurons.
Further reading: Alphaherpesviruses: Molecular Virology
Further reading: Alphaherpesviruses: Molecular Virology
RNA Silencing in Plants
RNA Silencing in Plants and the Role of Viral Suppressors
from Ana Giner, Juan Jose Lopez-Moya and Lorant Lakatos writing in RNA Interference and Viruses
The term RNA silencing refers to several pathways present in eukaryotic organisms that lead to the sequence specific elimination or functional blocking of RNAs with homology to double stranded RNAs (dsRNAs) that have previously triggered the mechanism. Besides playing important roles in developmental control, RNA silencing forms part of the defence against viruses in plants, acting as a potent antiviral mechanism. To escape from the RNA silencing-based defence, most plant viruses make use of different strategies, the most common relying in the action of viral proteins with the capacity to suppress RNA silencing. The characterization of these viral suppressors is providing useful insights to understand how RNA silencing works, revealing components and steps in the silencing pathways.
Further reading: Recent Advances in Plant Virology | RNA Interference and Viruses | RNA and the Regulation of Gene Expression
from Ana Giner, Juan Jose Lopez-Moya and Lorant Lakatos writing in RNA Interference and Viruses
The term RNA silencing refers to several pathways present in eukaryotic organisms that lead to the sequence specific elimination or functional blocking of RNAs with homology to double stranded RNAs (dsRNAs) that have previously triggered the mechanism. Besides playing important roles in developmental control, RNA silencing forms part of the defence against viruses in plants, acting as a potent antiviral mechanism. To escape from the RNA silencing-based defence, most plant viruses make use of different strategies, the most common relying in the action of viral proteins with the capacity to suppress RNA silencing. The characterization of these viral suppressors is providing useful insights to understand how RNA silencing works, revealing components and steps in the silencing pathways.
Further reading: Recent Advances in Plant Virology | RNA Interference and Viruses | RNA and the Regulation of Gene Expression
RNA Silencing
RNA Silencing and the Interplay Between Plants and Viruses
from Lourdes Fernández-Calvino, Livia Donaire and César Llave writing in Recent Advances in Plant Virology
In eukaryotes, RNA silencing controls gene expression to regulate development, genome stability and stress-induced responses. In plants, this process is also recognized as a major immune system targeted against plant viruses. Plant viruses stimulate RNA silencing responses though formation of viral RNA with double-stranded features that are subsequently processed into functional small RNAs (sRNAs). Recent studies highlight the complexity of the viral sRNA populations and their potential to associate with multiple silencing effector complexes. This fact has profound implications in the cross-talk interactions between plants and viruses since both virus genomes and host genes are putative targets of viral sRNAs. The concept of RNA silencing is an elegant natural antiviral mechanism in plants. Viral sRNA-mediated regulation of gene expression is important in the frame of compatible interactions between plants and viruses.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
from Lourdes Fernández-Calvino, Livia Donaire and César Llave writing in Recent Advances in Plant Virology
In eukaryotes, RNA silencing controls gene expression to regulate development, genome stability and stress-induced responses. In plants, this process is also recognized as a major immune system targeted against plant viruses. Plant viruses stimulate RNA silencing responses though formation of viral RNA with double-stranded features that are subsequently processed into functional small RNAs (sRNAs). Recent studies highlight the complexity of the viral sRNA populations and their potential to associate with multiple silencing effector complexes. This fact has profound implications in the cross-talk interactions between plants and viruses since both virus genomes and host genes are putative targets of viral sRNAs. The concept of RNA silencing is an elegant natural antiviral mechanism in plants. Viral sRNA-mediated regulation of gene expression is important in the frame of compatible interactions between plants and viruses.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
Small RNAs
The small RNAs of Salmonella
from Sridhar Javayel, Kai Papenfort and Jörg Vogel writing in Salmonella: From Genome to Function
To date, close to one hundred distinct small noncoding RNAs (sRNAs) have been identified in Salmonella by a variety of biocomputational or wet-lab approaches including RNA sequencing. The function of more than twenty of these sRNAs is known from studies in Salmonella itself or can be inferred from conserved homologs in E. coli Many of these sRNAs act in conjunction with the RNA-chaperone Hfq to post-transcriptionally repress or activate trans-encoded target genes, but cis-antisense RNAs and regulators of protein activity are also abundantly present. In addition to a large number of sRNAs conserved in other enteric bacteria, Salmonella also expresses a set of sRNAs specific to this genus. Interestingly, such regulators have been shown to control the expression of conserved genes encoded on the "core" Salmonella genome. Conversely, conserved sRNA can act as regulators of recently acquired Salmonella-specific genes, indicating significant cross-talk of conserved and horizontally acquired elements at the RNA level. A recent review covers strategies for the identification of sRNAs as well as their characterized functional roles in Salmonella.
Further reading: Salmonella: From Genome to Function | RNA and the Regulation of Gene Expression
from Sridhar Javayel, Kai Papenfort and Jörg Vogel writing in Salmonella: From Genome to Function
To date, close to one hundred distinct small noncoding RNAs (sRNAs) have been identified in Salmonella by a variety of biocomputational or wet-lab approaches including RNA sequencing. The function of more than twenty of these sRNAs is known from studies in Salmonella itself or can be inferred from conserved homologs in E. coli Many of these sRNAs act in conjunction with the RNA-chaperone Hfq to post-transcriptionally repress or activate trans-encoded target genes, but cis-antisense RNAs and regulators of protein activity are also abundantly present. In addition to a large number of sRNAs conserved in other enteric bacteria, Salmonella also expresses a set of sRNAs specific to this genus. Interestingly, such regulators have been shown to control the expression of conserved genes encoded on the "core" Salmonella genome. Conversely, conserved sRNA can act as regulators of recently acquired Salmonella-specific genes, indicating significant cross-talk of conserved and horizontally acquired elements at the RNA level. A recent review covers strategies for the identification of sRNAs as well as their characterized functional roles in Salmonella.
Further reading: Salmonella: From Genome to Function | RNA and the Regulation of Gene Expression
Conference Alert: Non-Coding Genome
October 13 - 16, 2010 The Non-Coding Genome
Heidelberg, Germany Further information
This symposium will provide an interdisciplinary discussion of the roles of non-coding RNAs with the aim of enhancing our understanding of gene regulation and function. Topics will include recent discoveries in the fields of prokaryotic and eukaryotic long and short non-coding RNAs. The functional roles of non-coding RNAs in a wide variety of cell processes will be discussed.
Suggested reading: RNA Interference and Viruses: Current Innovations and Future Trends
Heidelberg, Germany Further information
This symposium will provide an interdisciplinary discussion of the roles of non-coding RNAs with the aim of enhancing our understanding of gene regulation and function. Topics will include recent discoveries in the fields of prokaryotic and eukaryotic long and short non-coding RNAs. The functional roles of non-coding RNAs in a wide variety of cell processes will be discussed.
Suggested reading: RNA Interference and Viruses: Current Innovations and Future Trends