Protein Kinase D Regulates Trafficking of Dendritic Membrane Proteins in Developing Neurons

Abstract

In non-neuronal cells, inactivation of protein kinase D (PKD) blocks fission of trans-Golgi network (TGN) transport carriers, inducing the appearance of long tubules filled with cargo. We now report on the function of PKD1 in neuronal protein trafficking. In cultured hippocampal pyramidal cells, the transferrin receptor (TfR) and the low-density receptor-related protein (LRP) are predominantly transported to dendrites and excluded from axons. Expression of kinase-inactive PKD1 or its depletion by RNA interference treatment dramatically and selectively alter the intracellular trafficking and membrane delivery of TfR-and LRP-containing vesicles, without inhibiting exit from the TGN or inducing Golgi tubulation. After PKD1 suppression, dendritic membrane proteins are mispackaged into carriers that transport VAMP2; these vesicles are distributed to both axons and dendrites, but are rapidly endocytosed from dendrites and preferentially delivered to the axonal membrane. A kinase-defective mutant of PKD1 lacking the ability to bind diacylglycerol and hence its Golgi localization does not cause missorting of TfR or LRP. These results suggest that in neurons PKD1 regulates TGN-derived sorting of dendritic proteins and hence has a role in neuronal polarity.

Protein Kinase D Controls the Integrity of Golgi Apparatus and the Maintenance of Dendritic Arborization in Hippocampal Neurons

“…PKD activity has been recently implicated in regulating early neuronal polarization (Yin et al, 2008), early dendritic development (Horton et al, 2005), or selective transport and endocytosis of dendritic proteins (Bisbal et al, 2008). In the present work, we have used a newly developed reporter of PKD activity and studied transgenic mice with neuron-specific, inducible expression of a dominant-negative-acting PKD1 mutant to unravel the role of PKD in mature hippocampal neurons, both in vitro and in vivo.…”

Protein kinase D: a new player among the signaling proteins that regulate functions in the nervous system

“…Alteration of PKD activity induces parallel changes in dendritic arborization. PKD knockdown increases the trafficking of proteins destined for dendritic membrane, but has no effect on vesicle fission [54] .…”

“…Unlike other polarity proteins that interact with the cytoskeleton in neurites, PKD regulates polarity through its activity in the Golgi apparatus [52] . The role of PKD in establishing [53,54] . This generates and maintains neuronal polarity, ultimately resulting in specialized postsynaptic functions.…”

“…The role of PKD in establishing [53] . Integral membrane proteins that later fuse with axon or dendrite are enveloped in TGNderived vesicles and their sorting and packaging are regulated by PKD1 [53,54] . This generates and maintains neuronal polarity, ultimately resulting in specialized postsynaptic functions.…”

“…Alteration of PKD activity induces parallel changes in dendritic arborization. PKD knockdown increases the trafficking of proteins destined for dendritic membrane, but has no effect on vesicle fission [54] .Thus, PKDs in hippocampal neurons bind to the Golgi apparatus to regulate the sorting, packaging, and targeting of different proteins, and suppress the endocytosis of dendritic membrane proteins, which are important for the establishment of cell polarity and dendritic specialization.One PKD effector candidate relevant to these processes is Kidins220. PKD1 phosphorylates the scaffold protein Kidins220 [55][56][57][58] .…”