title: Nerve growth factor induces neurite outgrowth of PC12 cells by promoting Gβγ-microtubule interaction.
abstract: BACKGROUND
  Assembly and disassembly of microtubules (MTs) is critical for neurite outgrowth and differentiation. Evidence suggests that nerve growth factor (NGF) induces neurite outgrowth from PC12 cells by activating the receptor tyrosine kinase, TrkA. G protein-coupled receptors (GPCRs) as well as heterotrimeric G proteins are also involved in regulating neurite outgrowth. However, the possible connection between these pathways and how they might ultimately converge to regulate the assembly and organization of MTs during neurite outgrowth is not well understood.
  
  
  RESULTS
  Here, we report that Gβγ, an important component of the GPCR pathway, is critical for NGF-induced neuronal differentiation of PC12 cells. We have found that NGF promoted the interaction of Gβγ with MTs and stimulated MT assembly. While Gβγ-sequestering peptide GRK2i inhibited neurite formation, disrupted MTs, and induced neurite damage, the Gβγ activator mSIRK stimulated neurite outgrowth, which indicates the involvement of Gβγ in this process. Because we have shown earlier that prenylation and subsequent methylation/demethylation of γ subunits are required for the Gβγ-MTs interaction in vitro, small-molecule inhibitors (L-28 and L-23) targeting prenylated methylated protein methyl esterase (PMPMEase) were tested in the current study. We found that these inhibitors disrupted Gβγ and ΜΤ organization and affected cellular morphology and neurite outgrowth. In further support of a role of Gβγ-MT interaction in neuronal differentiation, it was observed that overexpression of Gβγ in PC12 cells induced neurite outgrowth in the absence of added NGF. Moreover, overexpressed Gβγ exhibited a pattern of association with MTs similar to that observed in NGF-differentiated cells.
  
  
  CONCLUSIONS
  Altogether, our results demonstrate that βγ subunit of heterotrimeric G proteins play a critical role in neurite outgrowth and differentiation by interacting with MTs and modulating MT rearrangement.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Sierra-Fonseca
authors.forename: Omar
authors.initials: O
authors.lastname: Najera
authors.forename: Jessica
authors.initials: J
authors.lastname: Martinez-Jurado
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Walker
authors.forename: Armando
authors.initials: A
authors.lastname: Varela-Ramirez
authors.forename: Arshad M
authors.initials: AM
authors.lastname: Khan
authors.forename: Manuel
authors.initials: M
authors.lastname: Miranda
authors.forename: Nazarius S
authors.initials: NS
authors.lastname: Lamango
authors.forename: Sukla
authors.initials: S
authors.lastname: Roychowdhury
mesh_terms: D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D049108:Cell Enlargement; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D008870:Microtubules / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000378:metabolism*; D016501:Neurites / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D016716:PC12 Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D014404:Tubulin / Q000378:metabolism
chemical_list: D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D014404:Tubulin; D020932:Nerve Growth Factor; D002265:Carboxylic Ester Hydrolases; C508954:prenylated methylated protein methyl esterase, rat