LRRK2 guides the actin cytoskeleton at growth cones together with ARHGEF7 and Tropomyosin 4.
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene represent the most common genetic cause of Parkinson's disease (PD). However, LRRK2 function and molecular mechanisms causing the parkinsonian phenotype remain widely unknown. Most of LRRK2 knockdown and overexpression models strengthen the relevance of LRRK2 in regulating neurite outgrowth. We have recently identified ARHGEF7 as the first guanine nucleotide exchange factor (GEF) of LRRK2. This GEF is influencing neurite outgrowth through regulation of actin polymerization. Here, we examined the expression profile of neuroblastoma cells with reduced LRRK2 and ARHGEF7 levels to identify additional partners of LRRK2 in this process. Tropomyosins (TPMs), and in particular TPM4, were the most interesting candidates next to other actin cytoskeleton regulating transcripts in this dataset. Subsequently, enhanced neurite branching was shown using primary hippocampal neurons of LRRK2 knockdown animals. Furthermore, we observed an enhanced number of growth cones per neuron and a mislocalization and dysregulation of ARHGEF7 and TPM4 in these neuronal compartments. Our results reveal a fascinating connection between the neurite outgrowth phenotype of LRRK2 models and the regulation of actin polymerization directing further investigations of LRRK2-related pathogenesis.
Institute of Human Genetics, Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany; Institute of Human Genetics, MFT Services, University of Tuebingen, Tuebingen, Germany. Electronic address: Karina.Haebig@med.uni-tuebingen.de.
Karina
K
Häbig
Sandra
S
Gellhaar
Birgit
B
Heim
Verena
V
Djuric
Florian
F
Giesert
Wolfgang
W
Wurst
Carolin
C
Walter
Thomas
T
Hentrich
Olaf
O
Riess
Michael
M
Bonin
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D020439:Growth Cones / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D051379:Mice; D018345:Mice, Knockout; D041681:NIH 3T3 Cells; D016501:Neurites / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D064067:Rho Guanine Nucleotide Exchange Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014335:Tropomyosin / Q000235:genetics / Q000378:metabolism*
C576606:ARHGEF7 protein, human; D015415:Biomarkers; D020662:Guanine Nucleotide Exchange Factors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D064067:Rho Guanine Nucleotide Exchange Factors; C501213:TPM4 protein, human; D014335:Tropomyosin; C495280:LRRK2 protein, human; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; C495279:Lrrk2 protein, mouse; D017346:Protein Serine-Threonine Kinases
Actin cytoskeleton; F-actin; G-actin; GEF; Growth cone; LIM domain kinase; LIMK; LRRK2; Neurite outgrowth; PAK; Parkinson's disease; TPM; filamentous actin; globular actin; guanine nucleotide exchange factor; leucine-rich repeat kinase 2; p21 protein (Cdc42/Rac)-activated kinase; qRT-PCR; quantitative reverse transcription polymerase chain reaction; shRNA; short hairpin RNA; siRNA; small interfering RNA; tropomyosin