Identification of neuronal substrates implicates Pak5 in synaptic vesicle trafficking

Strochlic, Todd I.; Concilio, Susanna; Viaud, Julien; Eberwine, Ryan; Wong, Lisa Epstein; Minden, Audrey; Turk, Benjamin E.; Plomann, Markus; Peterson, Jeffrey R.

doi:10.1073/pnas.1116560109

Cited by 22 publications

(30 citation statements)

References 44 publications

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“…Logos were generated using either positional scanning peptide library data (top) or data from all reported sites of phosphorylation in protein substrates (bottom) as compiled on the PhosphoSitePlus database (98). Sites of phosphorylation for the reported type II PAK substrates androgen receptor, LIMK1, Pacsin-1, Synaptojanin-1, MDM2, and PAR6B, which are not included in PhosphoSitePlus, were taken from the literature (9,16,23,33,38). Logos were generated using the program EnoLOGOS (99) and are scaled such that the height of the letter is proportional to the frequency of the residue at the indicated position.…”

Section: Resultsmentioning

confidence: 99%

“…From studies in animal models, only PAK4 has been found to be essential for life; Pak4 knock-out mice display severe defects in angiogenesis, in the cardiovascular system, and in neuronal development (29,30). Pak5 and Pak6 knock-out mice are viable and show few phenotypes; their double knock-out, however, is associated with cognition and locomotive defects (31,32), which are potentially associated with disruption of the interaction between two PAK substrates, Pacsin-1 and Synaptojanin-1, that normally control synaptic vesicle trafficking (33). There are clear differences between the type II PAKs in tissue expression profile (3,8,34), with PAK4 widely expressed and most abundant in prostate, testis, and colon (35), PAK5 predominantly found in the brain and pancreas (32,36), and PAK6 found largely in testis, prostate, and brain, and possibly the kidneys and placenta (34,37,38).…”

Section: Type II Paks In Signal Transductionmentioning

confidence: 99%

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Signaling, Regulation, and Specificity of the Type II p21-activated Kinases

Ha¹,

Morse

Turk³

et al. 2015

Journal of Biological Chemistry

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The p21-activated kinases (PAKs) are a family of six serine/ threonine kinases that act as key effectors of RHO family GTPases in mammalian cells. PAKs are subdivided into two groups: type I PAKs (PAK1, PAK2, and PAK3) and type II PAKs (PAK4, PAK5, and PAK6). Although these groups are involved in common signaling pathways, recent work indicates that the two groups have distinct modes of regulation and have both unique and common substrates. Here, we review recent insights into the molecular level details that govern regulation of type II PAK signaling. We also consider mechanisms by which signal transduction is regulated at the level of substrate specificity. Finally, we discuss the implications of these studies for clinical targeting of these kinases.The type II PAKs 2 are members of the Sterile 20 (Ste20) family of STE (homologs of yeast Sterile 7, Sterile 11, and Sterile 20) group serine/threonine kinases. They are important for signaling from small GTPases of the RHO family, particularly the CDC42 (cell division cycle 42) and to a lesser extent RAC (Rasrelated C3 botulinum toxin substrate) isoforms, to the actin cytoskeleton and to growth and survival pathways. Type II PAKs share significant sequence similarity with the well studied type I PAKs (PAK1, PAK2, and PAK3), which are extensively reviewed elsewhere (1-5), but the roles of the type I and type II PAKs in GTPase signaling pathways, and their mechanisms of regulation, differ considerably. In the sections below, we consider the function of the type II PAK serine/threonine kinases in small GTPase pathways, the structural and biochemical basis for their regulation, mechanisms of their targeting to substrates, and some of the current strategies for targeted small molecule inhibition of these enzymes. Type II PAKs in Signal TransductionThe type II PAKs are binding partners of RHO family small GTPases. Their dominant role in signal transduction is as serine/threonine kinases, where transfer of the ␥-phosphate from an ATP molecule to a substrate protein results in consequent regulation of downstream effector pathways. The activation of type II PAK kinase signaling is associated with small GTPase binding, but as discussed below, direct activation does not seem to occur upon small GTPase binding. Rather, GTPases are thought to primarily regulate type II PAKs by controlling their subcellular localization. Type II PAKs also have reported kinase-independent roles as scaffolding proteins, with functions that are still emerging.The type II PAKs are placed at critical nodal points in multiple signaling pathways that are associated with cell growth, cytoskeletal dynamics, cell polarity, survival, and development (6 -8). They are located directly downstream of RHO family GTPase activation. Numerous substrates of type II PAKs have been identified that are thought to act as downstream effectors in distinct cellular processes. For example, direct phosphorylation of LIM kinases (9, 10), p210/␤-catenin (11, 12), slingshot phosphatase (SSH) (13), 14), and PDZ-RHOGEF (15) has...

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Section: Resultsmentioning

confidence: 99%

Section: Type II Paks In Signal Transductionmentioning

confidence: 99%

Signaling, Regulation, and Specificity of the Type II p21-activated Kinases

Ha¹,

Morse

Turk³

et al. 2015

Journal of Biological Chemistry

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“…A member of the PAK family of Ser/Thr protein kinases encoded by pak7 , was down-regulated at the 36-week time point (Table 2). Pak7 is involved in neurite outgrowth (Dan et al, 2002) and its disruption suggests that synaptic trafficking may be altered (Strochlic et al, 2012) following prolonged exposure to domoic acid.…”

Section: Discussionmentioning

confidence: 99%

Chronic low-level domoic acid exposure alters gene transcription and impairs mitochondrial function in the CNS

Hiolski¹,

Kendrick²,

Frame³

et al. 2014

Aquatic Toxicology

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Domoic acid is an algal-derived seafood toxin that functions as a glutamate agonist and exerts excitotoxicity via overstimulation of glutamate receptors (AMPA, NMDA) in the central nervous system (CNS). At high (symptomatic) doses, domoic acid is well-known to cause seizures, brain lesions and memory loss; however, a significant knowledge gap exists regarding the health impacts of repeated low-level (asymptomatic) exposure. Here, we investigated the impacts of low-level repetitive domoic acid exposure on gene transcription and mitochondrial function in the vertebrate CNS using a zebrafish model in order to: 1) identify transcriptional biomarkers of exposure; and 2) examine potential pathophysiology that may occur in the absence of overt excitotoxic symptoms. We found that transcription of genes related to neurological function and development were significantly altered, and that asymptomatic exposure impaired mitochondrial function. Interestingly, the transcriptome response was highly-variable across the exposure duration (36 weeks), with little to no overlap of specific genes across the six exposure time points (2, 6, 12, 18, 24, and 36 weeks). Moreover, there were no apparent similarities at any time point with the gene transcriptome profile exhibited by the glud1 mouse model of chronic moderate excess glutamate release. These results suggest that although the fundamental mechanisms of toxicity may be similar, gene transcriptome responses to domoic acid exposure do not extrapolate well between different exposure durations. However, the observed impairment of mitochondrial function based on respiration rates and mitochondrial protein content suggests that repetitive low-level exposure does have fundamental cellular level impacts that could contribute to chronic health consequences.

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“…PACSIN1 is a phosphoprotein with 15 phosphorylation sites identified through proteomics studies or candidate approaches (30)(31)(32)(33)(34)(35). Interestingly, seven of these phosphorylation sites are clustered within the variable region of PACSIN1.…”

Section: Pacsin Interacts With Pick1mentioning

confidence: 99%

“…To directly test if PICK1 binding is modulated by PACSIN1 phosphorylation, we generated a series of mutations on Ser-343, Ser-345, and Ser-346, either individually or in combination, into Ala or Glu to prevent or mimic phosphorylation on these sites. We chose these Ser residues because they have been identified as in vivo phosphorylation sites in the mouse brain (32,34,35). The PACSIN1-variable region, either wild type (WT) or phosphomutants, was expressed as a GST-fusion protein, immobilized on glutathioneSepharose and incubated with total brain extract.…”

Section: Pacsin Interacts With Pick1mentioning

confidence: 99%

PICK1 interacts with PACSIN to regulate AMPA receptor internalization and cerebellar long-term depression

Anggono

Koç-Schmitz

Widagdo

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The dynamic trafficking of AMPA receptors (AMPARs) into and out of synapses is crucial for synaptic transmission, plasticity, learning, and memory. The protein interacting with C-kinase 1 (PICK1) directly interacts with GluA2/3 subunits of the AMPARs. Although the role of PICK1 in regulating AMPAR trafficking and multiple forms of synaptic plasticity is known, the exact molecular mechanisms underlying this process remain unclear. Here, we report a unique interaction between PICK1 and all three members of the protein kinase C and casein kinase II substrate in neurons (PACSIN) family and show that they form a complex with AMPARs. Our results reveal that knockdown of the neuronal-specific protein, PACSIN1, leads to a significant reduction in AMPAR internalization following the activation of NMDA receptors in hippocampal neurons. The interaction between PICK1 and PACSIN1 is regulated by PACSIN1 phosphorylation within the variable region and is required for AMPAR endocytosis. Similarly, the binding of PICK1 to the ubiquitously expressed PACSIN2 is also regulated by the homologous phosphorylation sites within the PACSIN2-variable region. Genetic deletion of PACSIN2, which is highly expressed in Purkinje cells, eliminates cerebellar long-term depression. This deficit can be fully rescued by overexpressing wild-type PACSIN2, but not by a PACSIN2 phosphomimetic mutant, which does not bind PICK1 efficiently. Taken together, our data demonstrate that the interaction of PICK1 and PACSIN is required for the activity-dependent internalization of AMPARs and for the expression of long-term depression in the cerebellum.syndapin | receptor trafficking

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Identification of neuronal substrates implicates Pak5 in synaptic vesicle trafficking

Cited by 22 publications

References 44 publications

Signaling, Regulation, and Specificity of the Type II p21-activated Kinases

Signaling, Regulation, and Specificity of the Type II p21-activated Kinases

Chronic low-level domoic acid exposure alters gene transcription and impairs mitochondrial function in the CNS

PICK1 interacts with PACSIN to regulate AMPA receptor internalization and cerebellar long-term depression

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