LRP130, a single-stranded DNA/RNA-binding protein, localizes at the outer nuclear and endoplasmic reticulum membrane, and interacts with mRNA in vivo.
LRP130 (also known as a LRPPRC) is an RNA and single-stranded DNA-binding protein, and recently identified as a candidate gene responsible for the Leigh syndrome, a French-Canadian type cytochrome c oxidase deficiency. However, the biological function of LRP130 still remains largely unresolved. In the present study, we found that the C-terminal half of the mouse LRP130 located within a 120 amino acid sequence (a.a. 845-964) binds to synthetic RNA homopolymers, poly(G), poly(U), and poly(C), as well as r(CUGCC)(6). Assessment of the subcellular localization indicated both nuclear/endoplasmic reticulum (ER) and mitochondrial fractions to be positive. To further analyze the subcellular localization of LRP130, a nuclear/ER fraction was fractionated into the nucleoplasm (NP) and nuclear envelope (NE)/ER, and the latter was further separated into outer nuclear membrane (ONM)/ER and inner nuclear membrane (INM) by treatment with Triton X-100. LRP130 was detectable in all three fractions, and the distribution pattern was in good accordance with that known for ONM/ER proteins. Interestingly, immunostaining of HeLa cells demonstrated nuclear rim staining of LRP130, specifically at the outside of the NE and also at ER, and association of LRP130 with poly(A)(+) RNA was restricted only to the ONM/ER fraction. Overexpression of full-length mouse LRP130 fused with EGFP resulted in nuclear accumulation of poly(A)(+) RNA in HeLa cells. Taking all these results together, it is suggested that LRP130, a novel type of RNA-binding protein, associates with mRNA/mRNP complexes at the outside of NE and ER, and plays a role in control of mRNA metabolisms.
Tsuchiya
Naoto
N
Biochemistry Division, National Cancer Center Research Institute, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045, Japan.
Fukuda
Hirokazu
H
Nakashima
Katsuhiko
K
Nagao
Minako
M
Sugimura
Takashi
T
Nakagama
Hitoshi
H
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D009363:Neoplasm Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism
C087940:LRPPRC protein, human; C486222:Lrpprc protein, mouse; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins