The cellular and extracellular proteomic signature of human dopaminergic neurons carrying the LRRK2 G2019S mutation.

Background: Extracellular vesicles are easily accessible in various biofluids and allow the assessment of disease-related changes in the proteome. This has made them a promising target for biomarker studies, especially in the field of neurodegeneration where access to diseased tissue is very limited. Genetic variants in the LRRK2 gene have been linked to both familial and sporadic forms of Parkinson's disease.

Intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism.

The Parkinson's disease (PD)-linked protein Leucine-Rich Repeat Kinase 2 (LRRK2) consists of seven domains, including a kinase and a Roc G domain. Despite the availability of several high-resolution structures, the dynamic regulation of its unique intramolecular domain stack is nevertheless still not well understood. By in-depth biochemical analysis, assessing the Michaelis-Menten kinetics of the Roc G domain, we have confirmed that LRRK2 has, similar to other Roco protein family members, a K value of LRRK2 that lies within the range of the physiological GTP concentrations within the cell.

Structural insights into the GTP-driven monomerization and activation of a bacterial LRRK2 homolog using allosteric nanobodies.

Roco proteins entered the limelight after mutations in human LRRK2 were identified as a major cause of familial Parkinson's disease. LRRK2 is a large and complex protein combining a GTPase and protein kinase activity, and disease mutations increase the kinase activity, while presumably decreasing the GTPase activity. Although a cross-communication between both catalytic activities has been suggested, the underlying mechanisms and the regulatory role of the GTPase domain remain unknown.

Proteomics elucidating physiological and pathological functions of TDP-43.

Trans-activation response DNA binding protein of 43 kDa (TDP-43) regulates a great variety of cellular processes in the nucleus and cytosol. In addition, a defined subset of neurodegenerative diseases is characterized by nuclear depletion of TDP-43 as well as cytosolic mislocalization and aggregation. To perform its diverse functions TDP-43 can associate with different ribonucleoprotein complexes.

Doubly Constrained C-terminal of Roc (COR) Domain-Derived Peptides Inhibit Leucine-Rich Repeat Kinase 2 (LRRK2) Dimerization.

Missense mutations along the leucine-rich repeat kinase 2 (LRRK2) protein are a major contributor to Parkinson's Disease (PD), the second most commonly occurring neurodegenerative disorder worldwide. We recently reported the development of allosteric constrained peptide inhibitors that target and downregulate LRRK2 activity through disruption of LRRK2 dimerization. In this study, we designed doubly constrained peptides with the objective of inhibiting C-terminal of Roc (COR)-COR mediated dimerization at the LRRK2 dimer interface.

Nanobodies as allosteric modulators of Parkinson's disease-associated LRRK2.

Mutations in the gene coding for leucine-rich repeat kinase 2 (LRRK2) are a leading cause of the inherited form of Parkinson's disease (PD), while LRRK2 overactivation is also associated with the more common idiopathic form of PD. LRRK2 is a large multidomain protein, including a GTPase as well as a Ser/Thr protein kinase domain. Common, disease-causing mutations increase LRRK2 kinase activity, presenting LRRK2 as an attractive target for drug discovery.

Allosteric Inhibition of Parkinson's-Linked LRRK2 by Constrained Peptides.

Leucine-Rich Repeat Kinase 2 (LRRK2) is a large, multidomain protein with dual kinase and GTPase function that is commonly mutated in both familial and idiopathic Parkinson's Disease (PD). While dimerization of LRRK2 is commonly detected in PD models, it remains unclear whether inhibition of dimerization can regulate catalytic activity and pathogenesis. Here, we show constrained peptides that are cell-penetrant, bind LRRK2, and inhibit LRRK2 activation by downregulating dimerization.

TRAF6 Phosphorylation Prevents Its Autophagic Degradation and Re-Shapes LPS-Triggered Signaling Networks.

The ubiquitin E3 ligase TNF Receptor Associated Factor 6 (TRAF6) participates in a large number of different biological processes including innate immunity, differentiation and cell survival, raising the need to specify and shape the signaling output. Here, we identify a lipopolysaccharide (LPS)-dependent increase in TRAF6 association with the kinase IKKε (inhibitor of NF-κB kinase subunit ε) and IKKε-mediated TRAF6 phosphorylation at five residues. The reconstitution of TRAF6-deficient cells, with TRAF6 mutants representing phosphorylation-defective or phospho-mimetic TRAF6 variants, showed that the phospho-mimetic TRAF6 variant was largely protected from basal ubiquitin/proteasome-mediated degradation, and also from autophagy-mediated decay in autolysosomes induced by metabolic perturbation.

Human Dopaminergic Neurons Lacking PINK1 Exhibit Disrupted Dopamine Metabolism Related to Vitamin B6 Co-Factors.

PINK1 loss-of-function mutations cause early onset Parkinson disease. PINK1-Parkin mediated mitophagy has been well studied, but the relevance of the endogenous process in the brain is debated. Here, the absence of PINK1 in human dopaminergic neurons inhibits ionophore-induced mitophagy and reduces mitochondrial membrane potential.

Guilt-by-Association - Functional Insights Gained From Studying the LRRK2 Interactome.

The Parkinson's disease-associated Leucine-rich repeat kinase 2 (LRRK2) is a complex multi-domain protein belonging to the Roco protein family, a unique group of G-proteins. Variants of this gene are associated with an increased risk of Parkinson's disease. Besides its well-characterized enzymatic activities, conferred by its GTPase and kinase domains, and a central dimerization domain, it contains four predicted repeat domains, which are, based on their structure, commonly involved in protein-protein interactions (PPIs).

Antagonistic activities of CDC14B and CDK1 on USP9X regulate WT1-dependent mitotic transcription and survival.

Regulation of mitosis secures cellular integrity and its failure critically contributes to the development, maintenance, and treatment resistance of cancer. In yeast, the dual phosphatase Cdc14 controls mitotic progression by antagonizing Cdk1-mediated protein phosphorylation. By contrast, specific mitotic functions of the mammalian Cdc14 orthologue CDC14B have remained largely elusive.

Auto-regulation of Rab5 GEF activity in Rabex5 by allosteric structural changes, catalytic core dynamics and ubiquitin binding.

Intracellular trafficking depends on the function of Rab GTPases, whose activation is regulated by guanine exchange factors (GEFs). The Rab5 GEF, Rabex5, was previously proposed to be auto-inhibited by its C-terminus. Here, we studied full-length Rabex5 and Rabaptin5 proteins as well as domain deletion Rabex5 mutants using hydrogen deuterium exchange mass spectrometry.

LMO2 activation by deacetylation is indispensable for hematopoiesis and T-ALL leukemogenesis.

Hematopoietic transcription factor LIM domain only 2 (LMO2), a member of the TAL1 transcriptional complex, plays an essential role during early hematopoiesis and is frequently activated in T-cell acute lymphoblastic leukemia (T-ALL) patients. Here, we demonstrate that LMO2 is activated by deacetylation on lysine 74 and 78 via the nicotinamide phosphoribosyltransferase (NAMPT)/sirtuin 2 (SIRT2) pathway. LMO2 deacetylation enables LMO2 to interact with LIM domain binding 1 and activate the TAL1 complex.

Understanding the role of genetic variability in LRRK2 in Indian population.

Background: Genetic variability in LRRK2 has been unequivocally established as a major risk factor for familial and sporadic forms of PD in ethnically diverse populations.

Objectives: To resolve the role of LRRK2 in the Indian population.

Methods: We performed targeted resequencing of the LRRK2 locus in 288 cases and 298 controls and resolved the haplotypic structure of LRRK2 in a combined cohort of 800 cases and 402 controls in the Indian population.

Physiological and pathophysiological characteristics of ataxin-3 isoforms.

Ataxin-3 is a deubiquitinating enzyme and the affected protein in the neurodegenerative disorder Machado-Joseph disease (MJD). The gene is alternatively spliced, resulting in protein isoforms that differ in the number of ubiquitin-interacting motifs. Additionally, nonsynonymous SNPs in cause amino acid changes in ataxin-3, and one of these polymorphisms introduces a premature stop codon in one isoform.

Identification and characterization of ubiquitinylation sites in TAR DNA-binding protein of 43 kDa (TDP-43).

TAR DNA-binding protein of 43 kDa (TDP-43) forms pathological aggregates in neurodegenerative diseases, particularly in certain forms of frontotemporal dementia and amyotrophic lateral sclerosis. Pathological modifications of TDP-43 include proteolytic fragmentation, phosphorylation, and ubiquitinylation. A pathognomonic TDP-43 C-terminal fragment (CTF) spanning amino acids 193-414 contains only four lysine residues that could be potentially ubiquitinylated.

Biochemical and kinetic properties of the complex Roco G-protein cycle.

Roco proteins have come into focus after mutations in the gene coding for the human Roco protein Leucine-rich repeat kinase 2 (LRRK2) were discovered to be one of the most common genetic causes of late onset Parkinson's disease. Roco proteins are characterized by a Roc domain responsible for GTP binding and hydrolysis, followed by a COR dimerization device. The regulation and function of this RocCOR domain tandem is still not completely understood.

Phosphorylation Modulates the Subcellular Localization of SOX11.

SOX11 is a key Transcription Factor (TF) in the regulation of embryonic and adult neurogenesis, whose mutation has recently been linked to an intellectual disability syndrome in humans. SOX11's transient activity during neurogenesis is critical to ensure the precise execution of the neurogenic program. Here, we report that SOX11 displays differential subcellular localizations during the course of neurogenesis.

Regulation of LRRK2: insights from structural and biochemical analysis.

Leucine-rich repeat kinase 2 (LRRK2) is a multi-domain protein and its mutations can lead to Parkinson's disease. Recent studies on LRRK2 and homologue proteins have advanced our mechanistic understanding of LRRK2 regulation. Here, we summarize the available data on the biochemistry and structure of LRRK2 and postulate three possible layers of regulation, translocation, monomer-dimer equilibrium and intramolecular activation of domains.

Analysis of the expression pattern of the schizophrenia-risk and intellectual disability gene TCF4 in the developing and adult brain suggests a role in development and plasticity of cortical and hippocampal neurons.

Background: Haploinsufficiency of the class I bHLH transcription factor TCF4 causes Pitt-Hopkins syndrome (PTHS), a severe neurodevelopmental disorder, while common variants in the gene have been identified as susceptibility factors for schizophrenia. It remains largely unknown, which brain regions are dependent on TCF4 for their development and function.

Methods: We systematically analyzed the expression pattern of TCF4 in the developing and adult mouse brain.

The LRRK2 Variant E193K Prevents Mitochondrial Fission Upon MPP+ Treatment by Altering LRRK2 Binding to DRP1.

Mutations in leucine-rich repeat kinase 2 gene () are associated with familial and sporadic Parkinson's disease (PD). LRRK2 is a complex protein that consists of multiple domains, including 13 putative armadillo-type repeats at the N-terminus. In this study, we analyzed the functional and molecular consequences of a novel variant, E193K, identified in an Italian family.