Mitochondria-associated satellite I RNA binds to hnRNP K protein.
hnRNP K protein, which localizes to the nucleus, cytoplasm and mitochondria, is involved in the various cellular processes that compose gene expression. We used a SAGE-based assay to profile RNAs associated with hnRNP K protein in rat mitochondria. RNA was isolated from mitoplasts obtained from highly purified and RNase-treated mitochondria. Total RNA and RNA associated with hnRNP K protein were then used as input material for generating two SAGE libraries. Mitochondrion-derived tags isolated from the total mitoplast RNA library represented 86.3%, while those isolated from the library constructed from RNA associated with hnRNP K protein represented only 28.2% of selected tags. Thus, an unexpected number of nuclear-encoded RNAs were purified from mitochondria. Many of these transcripts were co-purified with hnRNP K protein, and high levels of nuclear-encoded RNAs co-immunoprecipitating with K protein corresponded to elevated hnRNP K protein levels of the organelle. The most abundant RNAs that were co-purified with hnRNP K protein represented transcripts originating from satellite I DNA. While satellite I RNA levels were higher in the nucleus and cytoplasm than in mitochondria, the most abundant binding of satellite I transcripts to hnRNP K protein was found in mitochondria. The role of satellite I RNA in mitochondria remains to be elucidated.
Department of Gastroenterology, Medical Center for Postgraduate Education and the Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Warszawa, Poland.
Karolina
K
Klimek-Tomczak
Michał
M
Mikula
Artur
A
Dzwonek
Agnieszka
A
Paziewska
Lucjan S
LS
Wyrwicz
Ewa E
EE
Hennig
Jerzy
J
Ostrowski
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D045744:Cell Line, Tumor; D015723:Gene Library; D005821:Genetic Techniques; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000737:chemistry*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry; D008928:Mitochondria / Q000378:metabolism*; D011485:Protein Binding; D019244:RNA, Satellite / Q000235:genetics*; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D000069816:SEC Translocation Channels
D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D008565:Membrane Proteins; D019244:RNA, Satellite; D000069816:SEC Translocation Channels; D011972:Receptor, Insulin