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The human 18S rRNA base methyltransferases DIMT1L and WBSCR22-TRMT112 but not rRNA modification are required for ribosome biogenesis.

Zorbas C, Nicolas E, Wacheul L, Huvelle E, Heurgué-Hamard V, Lafontaine DL - Mol. Biol. Cell (2015)

Bottom Line: We conclude that a quality control mechanism has been conserved from yeast to human by which binding of a methyltransferase to nascent pre-rRNAs is a prerequisite to processing, so that all cleaved RNAs are committed to faithful modification.We further report that 18S rRNA dimethylation is nuclear in human cells, in contrast to yeast, where it is cytoplasmic.Yeast and human ribosome biogenesis thus have both conserved and distinctive features.

View Article: PubMed Central - PubMed

Affiliation: RNA Molecular Biology, Fonds de la Recherche Scientifique (FRS/FNRS), Université Libre de Bruxelles, B-6041 Charleroi-Gosselies, Belgium.

No MeSH data available.


Subcellular distribution of DIMT1L, WBSCR22, and TRMT112. (A–C) DIMT1L is a nucleolar protein. WBSCR22 and TRMT112 localize to the nucleoplasm, with nucleolar exclusion for TRMT112, and to a polarized perinuclear structure (white arrows), overlapping partially with the Golgi and lysosomes. Cells were counterstained with DAPI for DNA labeling. Image sections were captured in confocal mode with a Yokogawa spinning disk on a Zeiss Axiovert microscope at 40× magnification. Scale bar, 10 μm. (A) HeLa cells stably expressing the nucleolar protein fibrillarin fused to GFP (FIB-GFP) were processed for immuno­fluorescence with a primary antibody specific to DIMT1L, WBSCR22, or TRMT112 and a red fluorescent secondary antibody. The intrinsic GFP fluorescence was used to visualize fibrillarin. (B) HeLa cells decorated with a WBSCR22- or TRMT112-specific primary antibody, revealed with a green fluorescent secondary antibody. (C) HeLa cells incubated with either Lyso- or Golgi-tracker and decorated with a TRMT112-specific primary antibody, revealed with a red fluorescent secondary antibody.
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Figure 2: Subcellular distribution of DIMT1L, WBSCR22, and TRMT112. (A–C) DIMT1L is a nucleolar protein. WBSCR22 and TRMT112 localize to the nucleoplasm, with nucleolar exclusion for TRMT112, and to a polarized perinuclear structure (white arrows), overlapping partially with the Golgi and lysosomes. Cells were counterstained with DAPI for DNA labeling. Image sections were captured in confocal mode with a Yokogawa spinning disk on a Zeiss Axiovert microscope at 40× magnification. Scale bar, 10 μm. (A) HeLa cells stably expressing the nucleolar protein fibrillarin fused to GFP (FIB-GFP) were processed for immuno­fluorescence with a primary antibody specific to DIMT1L, WBSCR22, or TRMT112 and a red fluorescent secondary antibody. The intrinsic GFP fluorescence was used to visualize fibrillarin. (B) HeLa cells decorated with a WBSCR22- or TRMT112-specific primary antibody, revealed with a green fluorescent secondary antibody. (C) HeLa cells incubated with either Lyso- or Golgi-tracker and decorated with a TRMT112-specific primary antibody, revealed with a red fluorescent secondary antibody.

Mentions: To gain initial insight into the functions of DIMT1L, WBSCR22, and TRMT112, we determined the subcellular distribution of the endogenous proteins by fluorescence microscopy in HeLa cells expressing the nucleolar antigen fibrillarin as a green fluorescent fusion (FIB-GFP; Figure 2A). DIMT1L was detected almost exclusively in the nucleoli, with weak nucleoplasmic staining (Figure 2A). WBSCR22 and TRMT112 were observed in the nucleoplasm, with for TRMT112 a clear exclusion from the nucleolus. In addition, TRMT112 was found to decorate a perinuclear “basket” polarized at one end of the nucleus (arrows; Figure 2A), which was even more evident in nonmanipulated HeLa cells, in which FIB-GFP is not stably expressed (Figure 2B). The TRMT112 perinuclear “basket” was always detected on the same side of the nucleus as the Golgi and lysosomes, showing partial colocalization with these structures (Figure 2C). Some WBSCR22 signal was consistently detected outside the nucleus, suggesting that this protein might also be part of such a perinuclear structure (Figure 1B). The nucleolar and nuclear localization of DIMT1L and WBSCR22 was confirmed in cells expressing Flag-tagged constructs (see later discussion; unpublished data).


The human 18S rRNA base methyltransferases DIMT1L and WBSCR22-TRMT112 but not rRNA modification are required for ribosome biogenesis.

Zorbas C, Nicolas E, Wacheul L, Huvelle E, Heurgué-Hamard V, Lafontaine DL - Mol. Biol. Cell (2015)

Subcellular distribution of DIMT1L, WBSCR22, and TRMT112. (A–C) DIMT1L is a nucleolar protein. WBSCR22 and TRMT112 localize to the nucleoplasm, with nucleolar exclusion for TRMT112, and to a polarized perinuclear structure (white arrows), overlapping partially with the Golgi and lysosomes. Cells were counterstained with DAPI for DNA labeling. Image sections were captured in confocal mode with a Yokogawa spinning disk on a Zeiss Axiovert microscope at 40× magnification. Scale bar, 10 μm. (A) HeLa cells stably expressing the nucleolar protein fibrillarin fused to GFP (FIB-GFP) were processed for immuno­fluorescence with a primary antibody specific to DIMT1L, WBSCR22, or TRMT112 and a red fluorescent secondary antibody. The intrinsic GFP fluorescence was used to visualize fibrillarin. (B) HeLa cells decorated with a WBSCR22- or TRMT112-specific primary antibody, revealed with a green fluorescent secondary antibody. (C) HeLa cells incubated with either Lyso- or Golgi-tracker and decorated with a TRMT112-specific primary antibody, revealed with a red fluorescent secondary antibody.
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Related In: Results  -  Collection

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Figure 2: Subcellular distribution of DIMT1L, WBSCR22, and TRMT112. (A–C) DIMT1L is a nucleolar protein. WBSCR22 and TRMT112 localize to the nucleoplasm, with nucleolar exclusion for TRMT112, and to a polarized perinuclear structure (white arrows), overlapping partially with the Golgi and lysosomes. Cells were counterstained with DAPI for DNA labeling. Image sections were captured in confocal mode with a Yokogawa spinning disk on a Zeiss Axiovert microscope at 40× magnification. Scale bar, 10 μm. (A) HeLa cells stably expressing the nucleolar protein fibrillarin fused to GFP (FIB-GFP) were processed for immuno­fluorescence with a primary antibody specific to DIMT1L, WBSCR22, or TRMT112 and a red fluorescent secondary antibody. The intrinsic GFP fluorescence was used to visualize fibrillarin. (B) HeLa cells decorated with a WBSCR22- or TRMT112-specific primary antibody, revealed with a green fluorescent secondary antibody. (C) HeLa cells incubated with either Lyso- or Golgi-tracker and decorated with a TRMT112-specific primary antibody, revealed with a red fluorescent secondary antibody.
Mentions: To gain initial insight into the functions of DIMT1L, WBSCR22, and TRMT112, we determined the subcellular distribution of the endogenous proteins by fluorescence microscopy in HeLa cells expressing the nucleolar antigen fibrillarin as a green fluorescent fusion (FIB-GFP; Figure 2A). DIMT1L was detected almost exclusively in the nucleoli, with weak nucleoplasmic staining (Figure 2A). WBSCR22 and TRMT112 were observed in the nucleoplasm, with for TRMT112 a clear exclusion from the nucleolus. In addition, TRMT112 was found to decorate a perinuclear “basket” polarized at one end of the nucleus (arrows; Figure 2A), which was even more evident in nonmanipulated HeLa cells, in which FIB-GFP is not stably expressed (Figure 2B). The TRMT112 perinuclear “basket” was always detected on the same side of the nucleus as the Golgi and lysosomes, showing partial colocalization with these structures (Figure 2C). Some WBSCR22 signal was consistently detected outside the nucleus, suggesting that this protein might also be part of such a perinuclear structure (Figure 1B). The nucleolar and nuclear localization of DIMT1L and WBSCR22 was confirmed in cells expressing Flag-tagged constructs (see later discussion; unpublished data).

Bottom Line: We conclude that a quality control mechanism has been conserved from yeast to human by which binding of a methyltransferase to nascent pre-rRNAs is a prerequisite to processing, so that all cleaved RNAs are committed to faithful modification.We further report that 18S rRNA dimethylation is nuclear in human cells, in contrast to yeast, where it is cytoplasmic.Yeast and human ribosome biogenesis thus have both conserved and distinctive features.

View Article: PubMed Central - PubMed

Affiliation: RNA Molecular Biology, Fonds de la Recherche Scientifique (FRS/FNRS), Université Libre de Bruxelles, B-6041 Charleroi-Gosselies, Belgium.

No MeSH data available.