Constitutive activity of JNK2 alpha2 is dependent on a unique mechanism of MAPK activation

Stress pathway outputs are encoded by pH-dependent clustering of kinase components

Signal processing by intracellular kinases controls near all biological processes but how signal pathway functions evolve with changed cellular context is poorly understood. Functional specificity of c-Jun N-terminal Kinases (JNK) are partly encoded by signal strength. Here we reveal that intracellular pH (pHi) is a significant component of the JNK network and defines signal response to specific stimuli. We show pHi regulates JNK activity in response to cell stress, with the relationship between pHi and JNK activity dependent on specific stimuli and upstream kinases activated. Using the optogenetic clustering tag CRY2, we show that an increase in pHi promotes the light-induced phase transition of ASK1 to augment JNK activation. While increased pHi similarly promoted CRY2-tagged JNK2 to form light-induced condensates, this attenuated JNK activity. Mathematical modelling of feedback signalling incorporating pHi and differential contributions by ASK1 and JNK2 condensates was sufficient to delineate signal responses to specific stimuli. Taking pHi and ASK1/JNK2 signal contributions into consideration may delineate oncogenic versus tumour suppressive JNK functions and cancer cell drug responses.

Deregulated JNK signaling enhances apoptosis during hyperthermia

PURPOSE

c-Jun N-terminal kinases (JNKs) comprise a subfamily of mitogen-activated protein kinases (MAPKs). The JNK group is known to be activated by a variety of stimuli. However, the molecular mechanism underlying heat-induced JNK activation is largely unknown. The aim of this study was to clarify how JNK activity is stimulated by heat.

METHODS AND MATERIALS

The expression levels of various MAPK members in HeLa cells, with or without hyperthermia treatment, were evaluated via western blotting. The kinase activity of MAPK members was assessed through in vitro kinase assays. Cell death was assessed in the absence or presence of siRNAs targeting MAPK-related members.

RESULTS

Hyperthermia decreased the levels of MAP3Ks, such as ASK1 and MLK3 which are JNK kinase kinase members, but not those of the downstream MAP2K/SEK1 and MAPK/JNK. Despite the reduced or transient phosphorylation of ASK1, MLK3, or SEK1, downstream JNK was phosphorylated in a temperature-dependent manner. In vitro kinase assays demonstrated that heat did not directly stimulate SEK1 or JNK. However, the expression levels of DUSP16, a JNK phosphatase, were decreased upon hyperthermia treatment. DUSP16 knockdown enhanced the heat-induced activation of ASK1-SEK1-JNK pathway and apoptosis.

CONCLUSION

JNK was activated in a temperature-dependent manner despite reduced or transient phosphorylation of the upstream MAP3K and MAP2K. Hyperthermia-induced degradation of DUSP16 may induce activation of the ASK1-SEK1-JNK pathway and subsequent apoptosis.

Avoiding or Co-Opting ATP Inhibition: Overview of Type III, IV, V, and VI Kinase Inhibitors

As described in the previous chapter, most kinase inhibitors that have been developed for use in the clinic act by blocking ATP binding; however, there is growing interest in identifying compounds that target kinase activities and functions without interfering with the conserved features of the ATP-binding site. This chapter will highlight alternative approaches that exploit unique kinase structural features that are being targeted to identify more selective and potent inhibitors. The figure below, adapted from (Sammons et al., Molecular Carcinogenesis 58:1551–1570, 2019), provides a graphical description of the various approaches to manipulate kinase activity. In addition to the type I and II inhibitors, type III kinase inhibitors have been identified to target sites adjacent to the ATP-binding site in the catalytic domain. New information on kinase structure and substrate-binding sites has enabled the identification of type IV kinase inhibitor compounds that target regions outside the catalytic domain. The combination of targeting unique allosteric sites outside the catalytic domain with ATP-targeted compounds has yielded a number of novel bivalent type V kinase inhibitors. Finally, emerging interest in the development of irreversible compounds that form selective covalent interactions with key amino acids involved in kinase functions comprise the class of type VI kinase inhibitors.

Redox activation of JNK2α2 mediates thyroid hormone-stimulated proliferation of neonatal murine cardiomyocytes

Mitochondria-generated reactive oxygen species (mROS) are frequently associated with DNA damage and cell cycle arrest, but physiological increases in mROS serve to regulate specific cell functions. T3 is a major regulator of mROS, including hydrogen peroxide (H₂O₂). Here we show that exogenous thyroid hormone (T3) administration increases cardiomyocyte numbers in neonatal murine hearts. The mechanism involves signaling by mitochondria-generated H₂O₂ (mH₂O₂) acting via the redox sensor, peroxiredoxin-1, a thiol peroxidase with high reactivity towards H₂O₂ that activates c-Jun N-terminal kinase-2α2 (JNK2α2). JNK2α2, a relatively rare member of the JNK family of mitogen-activated protein kinases (MAPK), phosphorylates c-Jun, a component of the activator protein 1 (AP-1) early response transcription factor, resulting in enhanced insulin-like growth factor 1 (IGF-1) expression and activation of proliferative ERK1/2 signaling. This non-canonical mechanism of MAPK activation couples T3 actions on mitochondria to cell cycle activation. Although T3 is regarded as a maturation factor for cardiomyocytes, these studies identify a novel redox pathway that is permissive for T3-mediated cardiomyocyte proliferation—this because of the expression of a pro-proliferative JNK isoform that results in growth factor elaboration and ERK1/2 cell cycle activation.

H2O2 oxidation of cysteine residues in c-Jun N-terminal kinase 2 (JNK2) contributes to redox regulation in human articular chondrocytes

Reactive oxygen species (ROS), in particular H₂O₂, regulate intracellular signaling through reversible oxidation of reactive protein thiols present in a number of kinases and phosphatases. H₂O₂ has been shown to regulate mitogen-activated protein kinase (MAPK) signaling depending on the cellular context. We report here that in human articular chondrocytes, the MAPK family member c-Jun N-terminal kinase 2 (JNK2) is activated by fibronectin fragments and low physiological levels of H₂O₂ and inhibited by oxidation due to elevated levels of H₂O₂ The kinase activity of affinity-purified, phosphorylated JNK2 from cultured chondrocytes was reversibly inhibited by 5-20 μm H₂O₂ Using dimedone-based chemical probes that react specifically with sulfenylated cysteines (RSOH), we identified Cys-222 in JNK2, a residue not conserved in JNK1 or JNK3, as a redox-reactive site. MS analysis of human recombinant JNK2 also detected further oxidation at Cys-222 and other cysteines to sulfinic (RSO₂H) or sulfonic (RSO₃H) acid. H₂O₂ treatment of JNK2 resulted in detectable levels of peptides containing intramolecular disulfides between Cys-222 and either Cys-213 or Cys-177, without evidence of dimer formation. Substitution of Cys-222 to alanine rendered JNK2 insensitive to H₂O₂ inhibition, unlike C177A and C213A variants. Two other JNK2 variants, C116A and C163A, were also resistant to oxidative inhibition. Cumulatively, these findings indicate differential regulation of JNK2 signaling dependent on H₂O₂ levels and point to key cysteine residues regulating JNK2 activity. As levels of intracellular H₂O₂ rise, a switch occurs from activation to inhibition of JNK2 activity, linking JNK2 regulation to the redox status of the cell.

JNKs function as CDK4-activating kinases by phosphorylating CDK4 and p21

Cyclin D-CDK4/6 are the first cyclin-dependent kinase (CDK) complexes to be activated by mitogenic/oncogenic pathways. They have a central role in the cell multiplication decision and in its deregulation in cancer cells. We identified T172 phosphorylation of CDK4 rather than cyclin D accumulation as the distinctly regulated step determining CDK4 activation. This finding challenges the view that the only identified metazoan CDK-activating kinase, cyclin H-CDK7-Mat1 (CAK), which is constitutively active, is responsible for the activating phosphorylation of all cell cycle CDKs. We previously showed that T172 phosphorylation of CDK4 is conditioned by an adjacent proline (P173), which is not present in CDK6 and CDK1/2. Although CDK7 activity was recently shown to be required for CDK4 activation, we proposed that proline-directed kinases might specifically initiate the activation of CDK4. Here, we report that JNKs, but not ERK1/2 or CAK, can be direct CDK4-activating kinases for cyclin D-CDK4 complexes that are inactivated by p21-mediated stabilization. JNKs and ERK1/2 also phosphorylated p21 at S130 and T57, which might facilitate CDK7-dependent activation of p21-bound CDK4, however, mutation of these sites did not impair the phosphorylation of CDK4 by JNKs. In two selected tumor cells, two different JNK inhibitors inhibited the phosphorylation and activation of cyclin D1-CDK4-p21 but not the activation of cyclin D3-CDK4 that is mainly associated to p27. Specific inhibition by chemical genetics in MEFs confirmed the involvement of JNK2 in cyclin D1-CDK4 activation. Therefore, JNKs could be activating kinases for cyclin D1-CDK4 bound to p21, by independently phosphorylating both CDK4 and p21.

JNK Signaling in the Control of the Tumor-Initiating Capacity Associated with Cancer Stem Cells

Deregulation of c-Jun NH2-terminal kinase (JNK) signaling occurs frequently in a variety of human cancers, yet the exact role(s) of JNK deregulation in cancer cell biology remains to be fully elucidated. Our recent demonstration that the activity of JNK is required not only for self-renewal of glioma stem cells but also for their tumor initiation has, however, identified a new role for JNK in the control of the stemness and tumor-initiating capacity of cancer cells. Significantly, transient JNK inhibition was sufficient to cause sustained loss of the tumor-initiating capacity of glioma stem cells, suggesting that the phenotype of "lost tumor-initiating capacity" may be as stable as the differentiated state and that the tumor-initiating capacity might therefore be under the control of JNK through an epigenetic mechanism that also governs stemness and differentiation. Here, in this article, we review the role and mechanism of JNK in the control of this "stemness-associated tumor-initiating capacity" (STATIC), a new hypothetical concept we introduce in this review article. Since the idea of STATIC is essentially applicable to both cancer types that do and do not follow the cancer stem cell hypothesis, we also give consideration to the possible involvement of JNK-mediated control of STATIC in a wide range of human cancers in which JNK is aberrantly activated. Theoretically, successful targeting of STATIC through JNK could contribute to long-term control of cancer. Issues to be considered before clinical application of therapies targeting this JNK-STATIC axis are also discussed.

Mechanism of dual specificity kinase activity of DYRK1A

The function of many protein kinases is controlled by the phosphorylation of a critical tyrosine residue in the activation loop. Dual specificity tyrosine-phosphorylation-regulated kinases (DYRKs) autophosphorylate on this tyrosine residue but phosphorylate substrates on aliphatic amino acids. This study addresses the mechanism of dual specificity kinase activity in DYRK1A and related kinases. Tyrosine autophosphorylation of DYRK1A occurred rapidly during in vitro translation and did not depend on the non-catalytic domains or other proteins. Expression in bacteria as well as in mammalian cells revealed that tyrosine kinase activity of DYRK1A is not restricted to the co-translational autophosphorylation in the activation loop. Moreover, mature DYRK1A was still capable of tyrosine autophosphorylation. Point mutants of DYRK1A and DYRK2 lacking the activation loop tyrosine showed enhanced tyrosine kinase activity. A series of structurally diverse DYRK1A inhibitors was used to pharmacologically distinguish different conformational states of the catalytic domain that are hypothesized to account for the dual specificity kinase activity. All tested compounds inhibited substrate phosphorylation with higher potency than autophosphorylation but none of the tested inhibitors differentially inhibited threonine and tyrosine kinase activity. Finally, the related cyclin-dependent kinase-like kinases (CLKs), which lack the activation loop tyrosine, autophosphorylated on tyrosine both in vitro and in living cells. We propose a model of DYRK autoactivation in which tyrosine autophosphorylation in the activation loop stabilizes a conformation of the catalytic domain with enhanced serine/threonine kinase activity without disabling tyrosine phosphorylation. The mechanism of dual specificity kinase activity probably applies to related serine/threonine kinases that depend on tyrosine autophosphorylation for maturation.

Interleukins in glioblastoma pathophysiology: implications for therapy

Despite considerable amount of research, the poor prognosis of patients diagnosed with glioblastoma multiforme (GBM) critically needs new drug development to improve clinical outcomes. The development of an inflammatory microenvironment has long been considered important in the initiation and progression of glioblastoma; however, the success of developing therapeutic approaches to target inflammation for GBM therapy has yet been limited. Here, we summarize the accumulating evidence supporting a role for inflammation in the pathogenesis of glioblastoma, discuss anti-inflammatory targets that could be relevant for GBM treatment and provide a perspective on the challenges faced in the development of drugs that target GBM inflammation. In particular, we will review the function of IL-1β, IL-6 and IL-8 as well as the potential of kinase inhibitors targeting key players in inflammatory cell signalling cascades such as JAK, JNK and p38 MAPK.

Manipulating JNK signaling with (--)-zuonin A

Recently, in a virtual screening strategy to identify new compounds targeting the D-recruitment site (DRS) of the c-Jun N-terminal kinases (JNKs), we identified the natural product (-)-zuonin A. Here we report the asymmetric synthesis of (-)-zuonin A and its enantiomer (+)-zuonin A. A kinetic analysis for the inhibition of c-Jun phosphorylation by (-)-zuonin A revealed a mechanism of partial competitive inhibition. Its binding is proposed to weaken the interaction of c-Jun to JNK by approximately 5-fold, without affecting the efficiency of phosphorylation within the complex. (-)-Zuonin A inhibits the ability of both MKK4 and MKK7 to phosphorylate and activate JNK. The binding site of (-)-zuonin A is predicted by docking and molecular dynamics simulation to be located in the DRS of JNK. (+)-Zuonin A also binds JNK but barely impedes the binding of c-Jun. (-)-Zuonin A inhibits the activation of JNK, as well as the phosphorylation of c-Jun in anisomycin-treated HEK293 cells, with the inhibition of JNK activation being more pronounced. (-)-Zuonin A also inhibits events associated with constitutive JNK2 activity, including c-Jun phosphorylation, basal Akt activation, and MDA-MB-231 cell migration. Mutations in the predicted binding site for (-)-zuonin A can render it significantly more or less sensitive to inhibition than wild type JNK2, allowing for the design of potential chemical genetic experiments. These studies suggest that the biological activity reported for other lignans, such as saucerneol F and zuonin B, may be the result of their ability to impede protein-protein interactions within MAPK cascades.

MAP kinase signalling cascades and transcriptional regulation

The MAP kinase (MAPK) signalling pathways play fundamental roles in a wide range of cellular processes and are often deregulated in disease states. One major mode of action for these pathways is in controlling gene expression, in particular through regulating transcription. In this review, we discuss recent significant advances in this area. In particular we focus on the mechanisms by which MAPKs are targeted to the nucleus and chromatin, and once there, how they impact on chromatin structure and subsequent gene regulation. We also discuss how systems biology approaches have contributed to our understanding of MAPK signaling networks, and also how the MAPK pathways intersect with other regulatory pathways in the nucleus. Finally, we summarise progress in studying the physiological functions of key MAPK transcriptional targets.

Osmostress induces autophosphorylation of Hog1 via a C-terminal regulatory region that is conserved in p38α

Many protein kinases require phosphorylation at their activation loop for induction of catalysis. Mitogen-activated protein kinases (MAPKs) are activated by a unique mode of phosphorylation, on neighboring Tyrosine and Threonine residues. Whereas many kinases obtain their activation via autophosphorylation, MAPKs are usually phosphorylated by specific, dedicated, MAPK kinases (MAP2Ks). Here we show however, that the yeast MAPK Hog1, known to be activated by the MAP2K Pbs2, is activated in pbs2Δ cells via an autophosphorylation activity that is induced by osmotic pressure. We mapped a novel domain at the Hog1 C-terminal region that inhibits this activity. Removal of this domain provides a Hog1 protein that is partially independent of MAP2K, namely, partially rescues osmostress sensitivity of pbs2Δ cells. We further mapped a short domain (7 amino acid residues long) that is critical for induction of autophosphorylation. Its removal abolishes autophosphorylation, but maintains Pbs2-mediated phosphorylation. This 7 amino acids stretch is conserved in the human p38α. Similar to the case of Hog1, it’s removal from p38α abolishes p38α’s autophosphorylation capability, but maintains, although reduces, its activation by MKK6. This study joins a few recent reports to suggest that, like many protein kinases, MAPKs are also regulated via induced autoactivation.

Computational insights for the discovery of non-ATP competitive inhibitors of MAP kinases

Due to their role in cellular signaling mitogen activated protein (MAP) kinases represent targets of pharmaceutical interest. However, the majority of known MAP kinase inhibitors compete with cellular ATP and target an ATP binding pocket that is highly conserved in the 500 plus representatives of the human protein kinase family. Here we review progress toward the development of non-ATP competitive MAP kinase inhibitors for the extracellular signal regulated kinases (ERK1/2), the c-jun N-terminal kinases (JNK1/2/3) and the p38 MAPKs (α, β, γ, and δ). Special emphasis is placed on the role of computational methods in the drug discovery process for MAP kinases. Topics include recent advances in X-ray crystallography theory that improve the MAP kinase structures essential to structurebased drug discovery, the use of molecular dynamics to understand the conformational heterogeneity of the activation loop and inhibitors discovered by virtual screening. The impact of an advanced polarizable force field such as AMOEBA used in conjunction with sophisticated kinetic and thermodynamic simulation methods is also discussed.

MicroRNA-206 regulates cell movements during zebrafish gastrulation by targeting prickle1a and regulating c-Jun N-terminal kinase 2 phosphorylation

During vertebrate gastrulation, both concurrent inductive events and cell movements are required for axis formation. Convergence and extension (CE) movements contribute to narrowing and lengthening the forming embryonic axis. MicroRNAs (miRNAs) play a critical role in regulating fundamental cellular functions and developmental processes, but their functions in CE movements are not well known. Zebrafish mir206 is maternally expressed and present throughout blastulation and gastrulation periods. Either gain or loss of function of mir206 leads to severe defects of convergent extension movements both cell autonomously and non-cell autonomously. Mosaic lineage tracing studies reveal that the formation of membrane protrusions and actin filaments is disturbed in mir206-overexpressing embryos or mir206 morphants. Mechanistically, mir206 targets prickle1a (pk1a) mRNA and as a result regulates c-Jun N-terminal protein kinase 2 (JNK2) phosphorylation. pk1a overexpression or knockdown can rescue convergent extension defects induced by mir206 overexpression or knockdown, respectively. Therefore, mir206 is an essential, novel regulator for normal convergent and extension movements by regulating mitogen-activated protein kinase (MAPK) JNK signaling.

Molecular cloning and characterization of novel human JNK2 (MAPK9) transcript variants that show different stimulation activities on AP-1

The c-Jun NH(2)-terminal kinase (JNK) signaling pathway participates in many physiological functions. In the current study we reported the cloning and characterization of five novel JNK2 transcript variants, which were designated as JNK2α3, JNK2α4, JNK2β3, JNK2γ1 and JNK2γ2, respectively. Among them, JNK2α4 and JNK2γ2 are potential non-coding RNA because they contain pre-mature stop codons. Both JNK2α3 and JNK2β3 contain an intact kinase domain, and both encode a protein product of 46 kDa, the same as those of JNK2α1 and JNK2β1. JNK2γ1 contains a disrupted kinase domain and it showed a disable function. When over-expressed in mammalian cells, JNK2α3 showed higher activity on AP-1 than that of JNK2β3 and JNK2γ1. Furthermore, JNK2α3 and JNK2β3 showed different levels of substrate phosphorylation, although they both could promote the proliferation of 293T cells. Our results further demonstrate that JNK2 isoforms preferentially target different substrates and may regulate the expression of various target genes.

Measuring the constitutive activation of c-Jun N-terminal kinase isoforms

The c-Jun N-terminal kinases (JNK) are important regulators of cell growth, proliferation, and apoptosis. JNKs are typically activated by a sequence of events that include phosphorylation of its T-P-Y motif by an upstream kinase, followed by homodimerization and translocation to the nucleus. Constitutive activation of JNK has been found in a variety of cancers including non-small cell lung carcinomas, gliomas, and mantle cell lymphoma. In vitro studies show that constitutive activation of JNK induces a transformed phenotype in fibroblasts and enhances tumorigenicity in a variety of cell lines. Interestingly, a subset of JNK isoforms was recently found to autoactivate rendering the proteins constitutively active. These constitutively active JNK proteins were found to play a pivotal role in activating transcription factors that increase cellular growth and tumor formation in mice. In this chapter, we describe techniques and methods that have been successfully used to study the three components of JNK activation. Use of these techniques may lead to a better understanding of the components of JNK pathways and how JNK is activated in cancer cells.

Homodimerization of Nemo-like kinase is essential for activation and nuclear localization

NLK is an evolutionarily conserved protein kinase that phosphorylates several transcription factors. However, the molecular mechanisms that regulate NLK activity have been poorly understood. This study shows that homodimerization of NLK is required for its activation and nuclear localization.

Nemo-like kinase (NLK) is an evolutionarily conserved protein kinase that phosphorylates several transcription factors. However, the molecular mechanisms that regulate NLK activity have been poorly understood. Here we show that homodimerization of NLK is required for its activation and nuclear localization. Biochemical analysis revealed that NLK is activated through intermolecular autophosphorylation of NLK dimers at Thr-286. Mutation of NLK at Cys-425, which corresponds to the defect in the Caenorhabditis elegans NLK homologue lit-1, prevented NLK dimerization, rendering NLK defective in both nuclear localization and kinase activity. By contrast, the external addition of nerve growth factor, which has been previously identified as an NLK activator, induced dimerization and Thr-286 autophosphorylation of endogenous NLK proteins. In addition, both dimerization and Thr-286 phosphorylation of NLK were found to be essential for induction of neurite-like cellular processes by NLK. The present findings suggest that dimerization is an initial key event required for the functional activation of NLK.

Thr-370 is responsible for CDK11(p58) autophosphorylation, dimerization, and kinase activity

CDK11(p58), a member of the p34(cdc2)-related kinase family, is associated with cell cycle progression, tumorigenesis, and proapoptotic signaling. It is also required for the maintenance of chromosome cohesion, the maturation of centrosome, the formation of bipolar spindle, and the completion of mitosis. Here we identified that CDK11(p58) interacted with itself to form homodimers in cells, whereas D224N, the kinase-dead mutant, failed to form homodimers. CDK11(p58) was autophosphorylated, and the main functions of CDK11(p58), such as kinase activity, transactivation of nuclear receptors, and proapoptotic signal transduction, were dependent on its autophosphorylation. Furthermore, the in vitro kinase assay indicated that CDK11(p58) was autophosphorylated at Thr-370. By mutagenesis, we created CDK11(p58) T370A and CDK11(p58) T370D, which mimic the dephosphorylated and phosphorylated forms of CDK11(p58), respectively. The T370A mutant could not form dimers and be phosphorylated by the wild type CDK11(p58) and finally lost the kinase activity. Further functional research revealed that T370A failed to repress the transactivation of androgen receptor and enhance the cell apoptosis. Overall, our data indicated that Thr-370 is responsible for the autophosphorylation, dimerization, and kinase activity of CDK11(p58). Moreover, Thr-370 mutants might affect CDK11(p58)-mediated signaling pathways.

Biotransformed blueberry juice protects neurons from hydrogen peroxide-induced oxidative stress and mitogen-activated protein kinase pathway alterations

A growing body of evidence supports the therapeutic effects of blueberry in neurodegenerative disorders. Biotransformation of blueberry juice by Serratia vaccinii bacteria increases its phenolic content and antioxidant activity. In neuronal cell culture, biotransformed blueberry juice (BJ) significantly increased the activity of antioxidant enzymes, namely catalase and superoxide dismutase. Moreover, BJ protected neurons against H2O2-induced cell death in a dose-dependent manner. This associated with the upregulation of mitogen-activated protein kinase (MAPK) family enzymes p38 and c-Jun N-terminal kinase (JNK) activation, as well as with the protection of extracellular signal-regulated kinase (ERK1/2) and MAPK/ERK kinase (MEK1/2) activity loss induced by H2O2. The present studies demonstrate that BJ can protect neurons against oxidative stress possibly by increasing antioxidant enzyme activities and activating p38- and JNK-dependent survival pathways while blocking MEK1/2- and ERK1/2-mediated cell death. Thus, BJ may represent a novel approach to prevent and to treat neurodegenerative disorders, and it may represent a source of novel therapeutic agents against these diseases.

Dependence of leucine-rich repeat kinase 2 (LRRK2) kinase activity on dimerization

Dominant missense mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common known genetic cause of Parkinson disease. LRRK2 encodes a serine/threonine protein kinase, and pathogenic mutations may increase kinase activity. Intrinsic GTP binding in the GTPase domain may govern kinase activity through an internal signal transduction cascade. As with many protein kinases, LRRK2 self-interacts through mechanisms that may regulate enzymatic activity. We find that the disruption of either GTPase or kinase activity enhances the formation of high molecular weight oligomers and prevents the formation of LRRK2 dimer structures. In addition, brief application of the broad spectrum kinase inhibitor staurosporine ablates LRRK2 dimers and promotes LRRK2 high molecular weight oligomers. LRRK2 interactions with other proteins in cell lines are kinase-independent and include chaperones and cell cytoskeleton components, suggesting that LRRK2 self-assembly principally dictates complex size. To further explore the mechanics of kinase activation, we separate soluble LRRK2 protein that encodes the pathogenic G2019S mutation into high molecular weight oligomers, dimers, and monomers and find that kinase activity resides with dimeric LRRK2. Some PD-associated mutations that increase kinase activity in vitro significantly increase the proportion of dimer structures relative to total LRRK2 protein, providing additional insight into how pathogenic mutations may alter normal enzymatic regulation. Targeting and tracking LRRK2 dimerization may provide a clear way to observe LRRK2 kinase activity in living cells, and disruption of dimeric LRRK2 through kinase inhibition or other means may attenuate pathogenic increases in LRRK2 enzymatic output.