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Nucleocytoplasmic shuttling of endocytic proteins.

Vecchi M, Polo S, Poupon V, van de Loo JW, Benmerah A, Di Fiore PP - J. Cell Biol. (2001)

Bottom Line: Many cellular processes rely on the ordered assembly of macromolecular structures.Here, we uncover an unexpected link between two such processes, endocytosis and transcription.Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy.

ABSTRACT
Many cellular processes rely on the ordered assembly of macromolecular structures. Here, we uncover an unexpected link between two such processes, endocytosis and transcription. Many endocytic proteins, including eps15, epsin1, the clathrin assembly lymphoid myeloid leukemia (CALM), and alpha-adaptin, accumulate in the nucleus when nuclear export is inhibited. Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis. In the nucleus, eps15 and CALM acted as positive modulators of transcription in a GAL4-based transactivation assay, thus raising the intriguing possibility that some endocytic proteins play a direct or indirect role in transcriptional regulation.

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Related in: MedlinePlus

Eps15, Epsin, and CALM bind to hCRM1 in a Ran-dependent manner. Immobilized GST-CALM, GST-epsin1 (a fragment encompassing amino acid positions 402–576 and encompassing a putative NES), GST-eps15, GST-eps15 (amino acids 1–874), and GST-SH3 of Grb2 (as a negative control) were incubated with in vitro–translated hCRM1 (the lane input represents one-fourth of the amount of hCRM1 used in the assay) in the presence or absence of a GTP-loaded constitutively active mutant of the Ran GTPase (RanQ69L).
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Figure 2: Eps15, Epsin, and CALM bind to hCRM1 in a Ran-dependent manner. Immobilized GST-CALM, GST-epsin1 (a fragment encompassing amino acid positions 402–576 and encompassing a putative NES), GST-eps15, GST-eps15 (amino acids 1–874), and GST-SH3 of Grb2 (as a negative control) were incubated with in vitro–translated hCRM1 (the lane input represents one-fourth of the amount of hCRM1 used in the assay) in the presence or absence of a GTP-loaded constitutively active mutant of the Ran GTPase (RanQ69L).

Mentions: We next investigated whether endocytic proteins bind to CRM1. Immobilized GST-eps15, GST-CALM, or GST-epsin1 (Chen et al. 1998) were incubated with an in vitro–translated hCRM1 in the presence or absence of GTP-loaded RanQ69L, a constitutively active mutant of the Ran GTPase. We could detect RanQ69L-dependent binding of all three proteins to hCRM1 (Fig. 2).


Nucleocytoplasmic shuttling of endocytic proteins.

Vecchi M, Polo S, Poupon V, van de Loo JW, Benmerah A, Di Fiore PP - J. Cell Biol. (2001)

Eps15, Epsin, and CALM bind to hCRM1 in a Ran-dependent manner. Immobilized GST-CALM, GST-epsin1 (a fragment encompassing amino acid positions 402–576 and encompassing a putative NES), GST-eps15, GST-eps15 (amino acids 1–874), and GST-SH3 of Grb2 (as a negative control) were incubated with in vitro–translated hCRM1 (the lane input represents one-fourth of the amount of hCRM1 used in the assay) in the presence or absence of a GTP-loaded constitutively active mutant of the Ran GTPase (RanQ69L).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2150719&req=5

Figure 2: Eps15, Epsin, and CALM bind to hCRM1 in a Ran-dependent manner. Immobilized GST-CALM, GST-epsin1 (a fragment encompassing amino acid positions 402–576 and encompassing a putative NES), GST-eps15, GST-eps15 (amino acids 1–874), and GST-SH3 of Grb2 (as a negative control) were incubated with in vitro–translated hCRM1 (the lane input represents one-fourth of the amount of hCRM1 used in the assay) in the presence or absence of a GTP-loaded constitutively active mutant of the Ran GTPase (RanQ69L).
Mentions: We next investigated whether endocytic proteins bind to CRM1. Immobilized GST-eps15, GST-CALM, or GST-epsin1 (Chen et al. 1998) were incubated with an in vitro–translated hCRM1 in the presence or absence of GTP-loaded RanQ69L, a constitutively active mutant of the Ran GTPase. We could detect RanQ69L-dependent binding of all three proteins to hCRM1 (Fig. 2).

Bottom Line: Many cellular processes rely on the ordered assembly of macromolecular structures.Here, we uncover an unexpected link between two such processes, endocytosis and transcription.Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy.

ABSTRACT
Many cellular processes rely on the ordered assembly of macromolecular structures. Here, we uncover an unexpected link between two such processes, endocytosis and transcription. Many endocytic proteins, including eps15, epsin1, the clathrin assembly lymphoid myeloid leukemia (CALM), and alpha-adaptin, accumulate in the nucleus when nuclear export is inhibited. Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis. In the nucleus, eps15 and CALM acted as positive modulators of transcription in a GAL4-based transactivation assay, thus raising the intriguing possibility that some endocytic proteins play a direct or indirect role in transcriptional regulation.

Show MeSH
Related in: MedlinePlus