LIMK1 regulates Golgi dynamics, traffic of Golgi-derived vesicles, and process extension in primary cultured neurons.
In this study, we examined the subcellular distribution and functions of LIMK1 in developing neurons. Confocal microscopy, subcellular fractionation, and expression of several epitope-tagged LIMK1 constructs revealed that LIMK1 is enriched in the Golgi apparatus and growth cones, with the LIM domain required for Golgi localization and the PDZ domain for its presence at neuritic tips. Overexpression of wild-type LIMK1 suppresses the formation of trans-Golgi derived tubules, and prevents cytochalasin D-induced Golgi fragmentation, whereas that of a kinase-defective mutant has the opposite effect. Transfection of wild-type LIMK1 accelerates axon formation and enhances the accumulation of Par3/Par6, insulin-like growth factor (IGF)1 receptors, and neural cell adhesion molecule (NCAM) at growth cones, while inhibiting the Golgi export of synaptophysin-containing vesicles. These effects were dependent on the Golgi localization of LIMK1, paralleled by an increase in cofilin phosphorylation and phalloidin staining in the region of the Golgi apparatus, and prevented by coexpression of constitutive active cofilin. The long-term overexpression of LIMK1 produces growth cone collapse and axon retraction, an effect that is dependent on its growth cone localization. Together, our results suggest an important role for LIMK1 in axon formation that is related with its ability to regulate Golgi dynamics, membrane traffic, and actin cytoskeletal organization.
Rosso
Silvana
S
Instituto Investigacion Medica Mercedes y Martin Ferreya-CONICET-Consejo Nacional de Investigaciones Científicas y Técnicas, 5000 Cordoba, Argentina.
Bollati
Flavia
F
Bisbal
Mariano
M
Peretti
Diego
D
Sumi
Tomoyuki
T
Nakamura
Toshikazu
T
Quiroga
Santiago
S
Ferreira
Adriana
A
Cáceres
Alfredo
A
D000818:Animals; D001369:Axons / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D006056:Golgi Apparatus / Q000276:immunology / Q000378:metabolism*; D054461:Lim Kinases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport; D017966:Pyramidal Cells / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis; D018179:Receptors, Thrombin / Q000096:biosynthesis; D016708:Synaptophysin / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism*
D004268:DNA-Binding Proteins; D018179:Receptors, Thrombin; D016708:Synaptophysin; C105295:protease-activated receptor 3; D011494:Protein Kinases; D020794:Receptor Protein-Tyrosine Kinases; D054461:Lim Kinases; C515894:Limk1 protein, rat; D017346:Protein Serine-Threonine Kinases