Regulatory Small RNAs
V. A. Gvozdev
Institute of Molecular Genetics, Russian Academy of Sciences, pl.
Kurchatova 2, 123182 Moscow, Russia; E-mail:
gvozdev@img.ras.ru
Received March 22, 2013
Recent years have been marked by a burst of studies on the role of
various RNAs in the regulation of gene expression. These regulatory
effects act on the level of both chromatin in the nuclei and the
cytoplasm during translation. The review papers of this issue are
mainly dedicated to different types of small RNAs of 20-30 nucleotides.
The small RNAs control diverse cellular functions including genome
protection against transpositions of mobile elements of the genome.
KEY WORDS: microRNAs, siRNAs, piRNAs, heterochromatin, transposon
DOI: 10.1134/S0006297913060011
This issue of
Biochemistry (Moscow) contains papers of Russian
and foreign authors whose works contributed to the studies of the role
of small RNAs (of 20-30 nucleotides) in the regulation of gene
expression in various model organisms. Small RNAs also embrace the
best-known microRNAs, whose functions have been studied rather well.
However, multiple functions of other types of small RNAs, siRNAs, and
especially of piRNAs still need to be investigated. The manuscripts
contained in this issue were written by authors who have contributed to
knowledge about functioning of small RNAs. Under discussion is the role
of small RNAs in the regulation of translation, formation of inactive
“silent chromatin”, and in defense of the cell against
translocating mobile elements (transposons). Even this incomplete
itemization of regulatory abilities of small RNAs shows their important
role in cellular regulation believed to be a new “layer” of
genetic information that up to recently somehow escaped the attention
of researchers. Functioning of small RNAs involves their complementary
interaction with cytoplasmic or nuclear transcripts by mechanism of the
so-called RNA-interference (RNAi). Generally speaking, RNAi includes
interactions of various small RNAs with the complementary sequences of
cellular transcripts guided by proteins of the Argonaute family, which
is evolutionary conserved but functionally extremely diverse. Pathways
of these interactions and their biological effects are very variable.
Some papers consider the role of piRNAs, the most diverse population of
small RNA molecules responsible for very diverse functions as it has
now become evident. The papers in this issue fail to address some
problems concerning functions of small RNAs, in particular because of
the worldwide burst-like character of studies in this field. Mechanisms
of formation of “inactive heterochromatin” regions in
eukaryotes are considered from different standpoints, and on reading
separate papers the reader will understand why these words are put in
quote marks. Certainly, many extremely important and interesting
studies of biological effects of RNAi mechanism related, for instance,
to cancer biology, neurobiology, or the struggle against infectious
agents are not considered here. The manuscripts are written for an
advanced and rather interested reader who, on comparing information
from different papers on overlapping problems, will make some effort to
imagine the state of this very rapidly developing field of molecular
and cellular biology.
