Role of LIMK1 in trafficking of Rab5 vesicles

Abstract

Increasing evidence suggest that epithelial-mesenchymal transition (EMT) is an important source of mesenchymal cells that participate in pathological processes such as tumour invasiveness and metastasis. For the initiation or completion of EMT, reorganization and changes in cytoskeletal proteins have to take place. LIM motif containing protein kinase 1 (LIMK1) is a vital regulator of actin dynamics and overexpression of LIMK1 has been found to contribute to EMT. A growing number of studies are suggesting that LIMK1 plays a role in cytoplasmic dynein dynamics, hence, it is important to identify the downstream molecular targets affected by changes in LIMK1 activity or expression. To investigate the influence of LIMK1 on dynein activity, we performed time-lapse microscopy and immunofluorescence staining on LIMK1-knockdown HeLa cells to monitor Rab5 vesicle trafficking and N-cadherin localization. For cells with LIMK1 knockdown, we observed greater Rab5 vesicle movement speed and less localization of N-cadherin at the plasma membrane. As dynein is essential for the endocytosis of N-cadherin and trafficking of Rab5 endocytic vesicles, we conclude that dynein activity is upregulated when LIMK1 is knocked down. Thus, LIMK1 is potentially a negative regulator of cytoplasmic dynein function.