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Lamellipodin promotes actin assembly by clustering Ena/VASP proteins and tethering them to actin filaments.

Hansen SD, Mullins RD - Elife (2015)

Bottom Line: We find that Lpd binds directly to actin filaments and that this interaction regulates its subcellular localization and enhances its effect on VASP polymerase activity.We propose that Lpd delivers Ena/VASP proteins to growing barbed ends and increases their polymerase activity by tethering them to filaments.This interaction represents one more pathway by which growing actin filaments produce positive feedback to control localization and activity of proteins that regulate their assembly.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, United States.

ABSTRACT
Enabled/Vasodilator (Ena/VASP) proteins promote actin filament assembly at multiple locations, including: leading edge membranes, focal adhesions, and the surface of intracellular pathogens. One important Ena/VASP regulator is the mig-10/Lamellipodin/RIAM family of adaptors that promote lamellipod formation in fibroblasts and drive neurite outgrowth and axon guidance in neurons. To better understand how MRL proteins promote actin network formation we studied the interactions between Lamellipodin (Lpd), actin, and VASP, both in vivo and in vitro. We find that Lpd binds directly to actin filaments and that this interaction regulates its subcellular localization and enhances its effect on VASP polymerase activity. We propose that Lpd delivers Ena/VASP proteins to growing barbed ends and increases their polymerase activity by tethering them to filaments. This interaction represents one more pathway by which growing actin filaments produce positive feedback to control localization and activity of proteins that regulate their assembly.

No MeSH data available.


Related in: MedlinePlus

Membrane tethered Lyn-GFP-Lpd (850–1250aa) requires basic residue for leading edge localization.(A) Plasma membrane localization of Lyn-GFP-Lpd850−1250aa, wild-type and mutants, visualized using TIRF microscopy. Mutations affecting the interaction with either Ena/VASP proteins (AAPPP)x6 or Abi1/Endophilin (SH3*) did not abolish the leading edge localization of Lyn-GFP-Lpd850−1250aa. Mutating all lysine and arginine residues (44A) or only those outside of the Abi1/Endophilin SH3 BDs (35A) eliminated the leading edge localization of Lyn- GFP-Lpd850−1250aa. Membrane localization of Lyn-GFP-Lpd (44A and 35A) phenocopy the uniform distribution of membrane anchored Lyn-GFP. Cell images highlighted with the red dashed box include representative images of cells expressing low level of Lyn- GFP-Lpd850−1250aa. The intensity of these images was scaled differently than images to the left to better visualize the localization.DOI:http://dx.doi.org/10.7554/eLife.06585.017
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fig5s3: Membrane tethered Lyn-GFP-Lpd (850–1250aa) requires basic residue for leading edge localization.(A) Plasma membrane localization of Lyn-GFP-Lpd850−1250aa, wild-type and mutants, visualized using TIRF microscopy. Mutations affecting the interaction with either Ena/VASP proteins (AAPPP)x6 or Abi1/Endophilin (SH3*) did not abolish the leading edge localization of Lyn-GFP-Lpd850−1250aa. Mutating all lysine and arginine residues (44A) or only those outside of the Abi1/Endophilin SH3 BDs (35A) eliminated the leading edge localization of Lyn- GFP-Lpd850−1250aa. Membrane localization of Lyn-GFP-Lpd (44A and 35A) phenocopy the uniform distribution of membrane anchored Lyn-GFP. Cell images highlighted with the red dashed box include representative images of cells expressing low level of Lyn- GFP-Lpd850−1250aa. The intensity of these images was scaled differently than images to the left to better visualize the localization.DOI:http://dx.doi.org/10.7554/eLife.06585.017


Lamellipodin promotes actin assembly by clustering Ena/VASP proteins and tethering them to actin filaments.

Hansen SD, Mullins RD - Elife (2015)

Membrane tethered Lyn-GFP-Lpd (850–1250aa) requires basic residue for leading edge localization.(A) Plasma membrane localization of Lyn-GFP-Lpd850−1250aa, wild-type and mutants, visualized using TIRF microscopy. Mutations affecting the interaction with either Ena/VASP proteins (AAPPP)x6 or Abi1/Endophilin (SH3*) did not abolish the leading edge localization of Lyn-GFP-Lpd850−1250aa. Mutating all lysine and arginine residues (44A) or only those outside of the Abi1/Endophilin SH3 BDs (35A) eliminated the leading edge localization of Lyn- GFP-Lpd850−1250aa. Membrane localization of Lyn-GFP-Lpd (44A and 35A) phenocopy the uniform distribution of membrane anchored Lyn-GFP. Cell images highlighted with the red dashed box include representative images of cells expressing low level of Lyn- GFP-Lpd850−1250aa. The intensity of these images was scaled differently than images to the left to better visualize the localization.DOI:http://dx.doi.org/10.7554/eLife.06585.017
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543927&req=5

fig5s3: Membrane tethered Lyn-GFP-Lpd (850–1250aa) requires basic residue for leading edge localization.(A) Plasma membrane localization of Lyn-GFP-Lpd850−1250aa, wild-type and mutants, visualized using TIRF microscopy. Mutations affecting the interaction with either Ena/VASP proteins (AAPPP)x6 or Abi1/Endophilin (SH3*) did not abolish the leading edge localization of Lyn-GFP-Lpd850−1250aa. Mutating all lysine and arginine residues (44A) or only those outside of the Abi1/Endophilin SH3 BDs (35A) eliminated the leading edge localization of Lyn- GFP-Lpd850−1250aa. Membrane localization of Lyn-GFP-Lpd (44A and 35A) phenocopy the uniform distribution of membrane anchored Lyn-GFP. Cell images highlighted with the red dashed box include representative images of cells expressing low level of Lyn- GFP-Lpd850−1250aa. The intensity of these images was scaled differently than images to the left to better visualize the localization.DOI:http://dx.doi.org/10.7554/eLife.06585.017
Bottom Line: We find that Lpd binds directly to actin filaments and that this interaction regulates its subcellular localization and enhances its effect on VASP polymerase activity.We propose that Lpd delivers Ena/VASP proteins to growing barbed ends and increases their polymerase activity by tethering them to filaments.This interaction represents one more pathway by which growing actin filaments produce positive feedback to control localization and activity of proteins that regulate their assembly.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, United States.

ABSTRACT
Enabled/Vasodilator (Ena/VASP) proteins promote actin filament assembly at multiple locations, including: leading edge membranes, focal adhesions, and the surface of intracellular pathogens. One important Ena/VASP regulator is the mig-10/Lamellipodin/RIAM family of adaptors that promote lamellipod formation in fibroblasts and drive neurite outgrowth and axon guidance in neurons. To better understand how MRL proteins promote actin network formation we studied the interactions between Lamellipodin (Lpd), actin, and VASP, both in vivo and in vitro. We find that Lpd binds directly to actin filaments and that this interaction regulates its subcellular localization and enhances its effect on VASP polymerase activity. We propose that Lpd delivers Ena/VASP proteins to growing barbed ends and increases their polymerase activity by tethering them to filaments. This interaction represents one more pathway by which growing actin filaments produce positive feedback to control localization and activity of proteins that regulate their assembly.

No MeSH data available.


Related in: MedlinePlus