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The transcription coactivator CBP is a dynamic component of the promyelocytic leukemia nuclear body.

Boisvert FM, Kruhlak MJ, Box AK, Hendzel MJ, Bazett-Jones DP - J. Cell Biol. (2001)

Bottom Line: In cells where CBP does not normally accumulate in PML bodies, it can be induced to accumulate in PML bodies through overexpression of either CBP or Pml, but not Sp100.They possess the characteristics expected of proteins that would play a structural role in the integrity of these subnuclear domains.Our results are consistent with CBP being a dynamic component of PML bodies and that the steady-state level in these structures can be modulated by Pml.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta T2N 4N1, Canada.

ABSTRACT
The transcription coactivator and histone acetyltransferase CAMP response element-binding protein (CBP) has been demonstrated to accumulate in promyelocytic leukemia (PML) bodies. We show that this accumulation is cell type specific. In cells where CBP does not normally accumulate in PML bodies, it can be induced to accumulate in PML bodies through overexpression of either CBP or Pml, but not Sp100. Using fluorescence recovery after photobleaching, we demonstrate that CBP moves rapidly into and out of PML bodies. In contrast, Pml and Sp100 are relatively immobile in the nucleoplasm and within PML nuclear bodies. They possess the characteristics expected of proteins that would play a structural role in the integrity of these subnuclear domains. Our results are consistent with CBP being a dynamic component of PML bodies and that the steady-state level in these structures can be modulated by Pml.

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FRAP of subregions of PML bodies. A line of photobleaching through the middle of one PML nuclear body (boxes) was created in 293 cells expressing GFP-Sp100 (A) and GFP–CBP (B). After the bleaching, images were recorded over time. Bleached boxes are ∼300 nm in length.
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Figure 5: FRAP of subregions of PML bodies. A line of photobleaching through the middle of one PML nuclear body (boxes) was created in 293 cells expressing GFP-Sp100 (A) and GFP–CBP (B). After the bleaching, images were recorded over time. Bleached boxes are ∼300 nm in length.

Mentions: We wished to determine whether Sp100 and Pml could be distinguished from CBP on the basis of mobility within the PML nuclear body itself. To determine whether GFP-Sp100 is moving within the PML nuclear body, we performed FRAP at high resolution, bleaching a line passing through the middle of a single PML nuclear body (Fig. 5 A). We found that the fluorescence within the PML nuclear body only recovers after relatively long periods (4 min). The same result was obtained for Pml within PML nuclear bodies (data not shown). In contrast, GFP–CBP (Fig. 5 B) fluorescence recovers rapidly from such a treatment, making it difficult to observe the bleached line inside the PML nuclear body in the first image recorded after the bleaching step. After 5 s, the fluorescence of GFP–CBP has been completely redistributed throughout the PML nuclear bodies. The rate of redistribution is greater than that observed when a half nucleus is bleached because the distance the proteins have to travel is comparatively much less. Again, the lack of movement of Sp100 and Pml within the PML nuclear bodies lead us to conclude that they play a structural role in these domains and that the steady-state accumulations of Sp100 and Pml are very stable.


The transcription coactivator CBP is a dynamic component of the promyelocytic leukemia nuclear body.

Boisvert FM, Kruhlak MJ, Box AK, Hendzel MJ, Bazett-Jones DP - J. Cell Biol. (2001)

FRAP of subregions of PML bodies. A line of photobleaching through the middle of one PML nuclear body (boxes) was created in 293 cells expressing GFP-Sp100 (A) and GFP–CBP (B). After the bleaching, images were recorded over time. Bleached boxes are ∼300 nm in length.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198823&req=5

Figure 5: FRAP of subregions of PML bodies. A line of photobleaching through the middle of one PML nuclear body (boxes) was created in 293 cells expressing GFP-Sp100 (A) and GFP–CBP (B). After the bleaching, images were recorded over time. Bleached boxes are ∼300 nm in length.
Mentions: We wished to determine whether Sp100 and Pml could be distinguished from CBP on the basis of mobility within the PML nuclear body itself. To determine whether GFP-Sp100 is moving within the PML nuclear body, we performed FRAP at high resolution, bleaching a line passing through the middle of a single PML nuclear body (Fig. 5 A). We found that the fluorescence within the PML nuclear body only recovers after relatively long periods (4 min). The same result was obtained for Pml within PML nuclear bodies (data not shown). In contrast, GFP–CBP (Fig. 5 B) fluorescence recovers rapidly from such a treatment, making it difficult to observe the bleached line inside the PML nuclear body in the first image recorded after the bleaching step. After 5 s, the fluorescence of GFP–CBP has been completely redistributed throughout the PML nuclear bodies. The rate of redistribution is greater than that observed when a half nucleus is bleached because the distance the proteins have to travel is comparatively much less. Again, the lack of movement of Sp100 and Pml within the PML nuclear bodies lead us to conclude that they play a structural role in these domains and that the steady-state accumulations of Sp100 and Pml are very stable.

Bottom Line: In cells where CBP does not normally accumulate in PML bodies, it can be induced to accumulate in PML bodies through overexpression of either CBP or Pml, but not Sp100.They possess the characteristics expected of proteins that would play a structural role in the integrity of these subnuclear domains.Our results are consistent with CBP being a dynamic component of PML bodies and that the steady-state level in these structures can be modulated by Pml.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta T2N 4N1, Canada.

ABSTRACT
The transcription coactivator and histone acetyltransferase CAMP response element-binding protein (CBP) has been demonstrated to accumulate in promyelocytic leukemia (PML) bodies. We show that this accumulation is cell type specific. In cells where CBP does not normally accumulate in PML bodies, it can be induced to accumulate in PML bodies through overexpression of either CBP or Pml, but not Sp100. Using fluorescence recovery after photobleaching, we demonstrate that CBP moves rapidly into and out of PML bodies. In contrast, Pml and Sp100 are relatively immobile in the nucleoplasm and within PML nuclear bodies. They possess the characteristics expected of proteins that would play a structural role in the integrity of these subnuclear domains. Our results are consistent with CBP being a dynamic component of PML bodies and that the steady-state level in these structures can be modulated by Pml.

Show MeSH
Related in: MedlinePlus