Dynein Light Chain 1 Phosphorylation Controls Macropinocytosis*[boxs

Rakesh Kumar,Zhibo Yang,Ratna K Vadlamudi

doi:10.1074/jbc.m408486200

Rakesh Kumar, Zhibo Yang + Show 1 more

Open Access

https://doi.org/10.1074/jbc.m408486200

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Abstract

Recent studies have identified dynein light chain-1 (DLC1), a component of the dynein motor, as a p21-activated kinase 1 (Pak1)-interacting substrate with binding sites mapped to amino acids 61-89 of DLC1 and phosphorylation site at serine 88. Here we investigated the role of DLC1 phosphorylation by Pak1 upon the process of macropinocytosis. We found that Pak1 associates with dynein motor and that Pak1-DLC1 interaction starts at the initiation of pinosome formation and persists in early and late endosomes. Pak1 phosphorylation of DLC1 on Ser-88 controls vesicle formation and trafficking functions, as Ser-88 substitution for alanine prevents macropinocytosis. A peptide spanning the C-terminal 19-amino acid region of DLC1 efficiently blocked Ser-88 phosphorylation and macropinocytosis. These results suggest that the regulation of DLC1 by Pak1 is a novel mechanism by which a signaling kinase might influence macropinocytosis.

Highlights

The p21-activated kinases (Paks),1 an evolutionarily conserved family of serine/threonine kinases, are important for a variety of cellular functions, including cell morphogenesis, cell motility, cell survival, angiogenesis, and mitosis [1, 2]
Recent studies have identified dynein light chain-1 (DLC1), a component of the dynein motor, as a p21activated kinase 1 (Pak1)-interacting substrate with binding sites mapped to amino acids 61– 89 of DLC1 and phosphorylation site at serine 88
Emerging data suggest that the functions of DLC1 are regulated by its phosphorylation on Ser-88 by its upstream kinase Pak1 that interacts with the penultimate C-terminal 19 amino acids of DLC1 [37]

Summary

Introduction

The p21-activated kinases (Paks),1 an evolutionarily conserved family of serine/threonine kinases, are important for a variety of cellular functions, including cell morphogenesis, cell motility, cell survival, angiogenesis, and mitosis [1, 2]. Emerging data suggest that the functions of DLC1 are regulated by its phosphorylation on Ser-88 by its upstream kinase Pak1 that interacts with the penultimate C-terminal 19 amino acids of DLC1 [37]. Consistent with the earlier findings [25], we found Pak1 colocalization with detectable endocytosed FITC-dextran (Fig. 1, a and b) and with endocytosed Lucifer yellow (Fig. 1c), the two commonly used markers of macropinocytosis, in NIH3T3 cells pretreated with either lysophosphatidate (LPA) or serum for 30 min using scanning confocal microscopy.

Results

Conclusion