Abstract
The mammalian cell nucleus is a highly compartmentalized system in which multiple subnuclear structures, called nuclear bodies, exist in the nucleoplasmic spaces. Some of the nuclear bodies contain specific long non-coding RNAs (ncRNAs) as their components, and may serve as sites for long ncRNA functions that remain largely enigmatic. A paraspeckle is a nuclear body that is almost ubiquitously observed in mammalian cultured cells but is cell population-specific in adult mouse tissue. The paraspeckle structure is RNase-sensitive. Long ncRNAs, termed MENε/β ncRNAs (also referred to as NEAT1 ncRNAs), have been identified as the RNA components of the paraspeckles. Specific elimination has revealed that MENε/β ncRNAs are essential components for the formation of the intact paraspeckle structure. Paraspeckle formation requires the continual MENε/β ncRNA biogenesis process, including ongoing transcription, alternative 3′-end processing, and stabilization. Some paraspeckle-localized RNA-binding proteins (p54/nrb and PSF) direct paraspeckle formation through the selective stabilization of MENβ ncRNA. Both MENε/β ncRNA expression and their subsequent interactions with paraspeckle proteins can be regulated under environmental and developmental conditions, which are reflected in the size and number of the paraspeckles. However, how paraspeckles function remains largely unsolved. Paraspeckles appear to serve as the site of nuclear retention of specific mRNAs that are selectively transported to the cytoplasm upon certain signals. Alternatively, MENε/β ncRNAs may sequester paraspeckle proteins that function outside the paraspeckles. This review focuses on known aspects of paraspeckles and provides a model of their structure and function.
About the authors
Tetsuro Hirose received his PhD in 1995 from Nagoya University. From 1995 to 1999 he worked as Research associate at Masahiro Sugiura’s lab in Nagoya University. Between 1999 and 2004, HFSP long-term fellow at Joan A Steitz’s lab in Yale University/HHMI. From 2004–2005, PRESTO fellow and Visiting associate professor, Tokyo Medical and Dental University. In 2005 to present, Group leader, Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology (AIST).
Shinichi Nakagawa received his PhD in 1998 from Kyoto University. From 1998 to 2000, HFSP long-term fellow at Christine Holt’s lab at the University of Cambridge. Between 2000 and 2002, Assistant professor, Kyoto University. From 2002 to 2005 Research associate, RIKEN Center for Developmental Biology. In 2005–2010, Initiative researcher, RIKEN Frontier Research System. From 2010 to present, Associate chief scientist, RIKEN Advanced Science Institute.
©2012 by Walter de Gruyter Berlin Boston
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