title: Mitochondrial dynamics regulate growth cone motility, guidance, and neurite growth rate in perinatal retinal ganglion cells in vitro.
abstract: OBJECTIVE
  Retinal ganglion cell (RGC) death and failed axonal regeneration after trauma or disease, including glaucomatous and mitochondrial optic neuropathies, are linked increasingly to dysfunctional mitochondrial dynamics. However, how mitochondrial dynamics influence axon growth largely is unstudied. We examined intrinsic mitochondrial organization in embryonic and postnatal RGCs and the roles that mitochondrial dynamics have in regulating neurite growth and guidance.
  
  
  METHODS
  RGCs were isolated from embryonic day 20 (E20) or postnatal days 5 to 7 (P5-7) Sprague-Dawley rats by anti-Thy1 immunopanning. After JC-1 loading, mitochondria were analyzed in acutely purified RGCs by flow cytometry and in RGC neurites by fluorescence microscopy. Intrinsic axon growth was modulated by overexpressing Krüppel-like family (KLF) transcription factors, or mitochondrial dynamics were altered by inhibiting dynamin related protein-1 (DRP-1) pharmacologically or by overexpressing mitofusin-2 (Mfn-2). Mitochondrial organization, neurite growth, and growth cone motility and guidance were analyzed.
  
  
  RESULTS
  Mitochondrial dynamics and function are regulated developmentally in acutely purified RGCs and in nascent RGC neurites. Mitochondrial dynamics are modulated differentially by KLFs that promote or suppress growth. Acutely inhibiting mitochondrial fission reversibly suppressed axon growth and lamellar extension. Inhibiting DRP-1 or overexpressing Mfn-2 altered growth cone responses to chondroitin sulfate proteoglycan, netrin-1, and fibronectin.
  
  
  CONCLUSIONS
  These results support the hypothesis that mitochondria locally modulate signaling in the distal neurite and growth cone to affect the direction and the rate of neurite growth.
authors.affiliation: Bascom Palmer Eye Institute, Miami, Florida, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Steketee
authors.forename: Stavros N
authors.initials: SN
authors.lastname: Moysidis
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Weinstein
authors.forename: Alex
authors.initials: A
authors.lastname: Kreymerman
authors.forename: Jose P
authors.initials: JP
authors.lastname: Silva
authors.forename: Siraj
authors.initials: S
authors.lastname: Iqbal
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Goldberg
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005260:Female; D020439:Growth Cones / Q000502:physiology*; D008297:Male; D063154:Mitochondrial Dynamics; D016501:Neurites / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology*; D011247:Pregnancy; D011270:Pregnancy, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000166:cytology*