Sema-3A indirectly disrupts the regeneration process of goldfish optic nerve after controlled injury.
BACKGROUND
Neurons of adult mammalian CNS are prevented from regenerating injured axons due to formation of a non-permissive environment. The retinal ganglion cells (RGC), which are part of the CNS, share this characteristic. In sharp contrast, the RGC of lower vertebrates, such as fish, are capable of re-growing injured optic nerve axons, and achieve, through a complex multi-factorial process, functional vision after injury. Semaphorin-3A (sema-3A), a member of the class 3 semaphorins known for its repellent and apoptotic activities, has previously been shown to play a key role in the formation of a non-permissive environment after CNS injury in mammalians.


METHODS
The expression of sema-3A and its effect on regenerative processes in injured gold fish retina and optic nerve were investigated in this study. Unilateral optic nerve axotomy or crush was induced in goldfish. 2 microl sema-3A was injected intraviterally 48 hours post injury. Neuronal viability was measured using the lipophilic neurotracer dye 4-Di-10-Asp. Axonal regeneration was initiated using the anterograde dye dextran. Retinas and optic nerves were collected at intervals of 2, 3, 7, 14 and 28 days after the procedure. Using Western blot and immunohistochemical analysis, the expression levels of semaphorin-3A, axonal regeneration, the removal of myelin debris and macrophage invasion were studied.


RESULTS
We found a decrease in sema-3A levels in the retina at an early stage after optic nerve injury, but no change in sema-3A levels in the injured optic nerve. Intravitreal injection of sema-3A to goldfish eye, shortly after optic nerve injury, led to destructive effects on several pathways of the regenerative processes, including the survival of retinal ganglion cells, axonal growth, and clearance of myelin debris from the lesion site by macrophages.


CONCLUSIONS
Exogenous administration of sema-3A in fish indirectly interferes with the regeneration process of the optic nerve. The findings corroborate our previous findings in mammals, and further validate sema-3A as a key factor in the generation of a non-permissive environment after transection of the optic nerve.
Rosenzweig
Shira
S
Departments of Neurobiology, George S. Wise, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel.
Raz-Prag
Dorit
D
Nitzan
Anat
A
Galron
Ronit
R
Paz
Ma'ayan
M
Jeserich
Gunnar
G
Neufeld
Gera
G
Barzilai
Ari
A
Solomon
Arieh S
AS
D000818:Animals; D001369:Axons / Q000502:physiology*; D019771:Axotomy; D015153:Blotting, Western; D002452:Cell Count; D002470:Cell Survival; D019084:Fluorescent Antibody Technique, Indirect; D006054:Goldfish; D007267:Injections; D008264:Macrophages / Q000502:physiology; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D009900:Optic Nerve / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D040121:Semaphorin-3A / Q000494:pharmacology / Q000502:physiology*; D014822:Vitreous Body
D040121:Semaphorin-3A
Annu Rev Neurosci. 1993;16:565-95
7681638
Brain Res Bull. 1999 Apr;48(6):581-93
10386838
Invest Ophthalmol Vis Sci. 2004 Dec;45(12):4554-62
15557467
Gene Expr Patterns. 2005 Jun;5(5):647-53
15939377
Dev Dyn. 1999 Jan;214(1):13-25
9915572
Blood. 2006 Apr 15;107(8):3321-9
16380453
Curr Opin Neurobiol. 1991 Oct;1(3):401-6
1688352
Exp Neurol. 1982 May;76(2):318-30
7095057
J Neurosci. 2008 Mar 12;28(11):2735-44
18337403
J Neurocytol. 1982 Dec;11(6):949-66
7153791
Trends Neurosci. 1996 Nov;19(11):507-13
8931278
J Neurocytol. 1980 Dec;9(6):733-51
7205335
Curr Opin Neurobiol. 2003 Feb;13(1):133-9
12593992
J Neurocytol. 1998 Nov;27(11):791-803
10451426
Annu Rev Neurosci. 2001;24:1217-81
11520933
Neurodegener Dis. 2007;4(1):51-6
17429219
J Comp Neurol. 2007 Apr 1;501(4):631-46
17278142
Curr Opin Neurobiol. 2000 Feb;10(1):88-94
10679438
Bioessays. 1992 Jun;14(6):401-6
1323962
Mol Cell Neurosci. 2005 Nov;30(3):452-64
16169247
Glia. 2006 Nov 1;54(6):545-56
16906543
J Neurobiol. 2004 Apr;59(1):162-80
15007834
Brain Res Bull. 2004 Feb 15;62(6):467-71
15036559
Neuron. 1994 Oct;13(4):805-11
7524558
Exp Neurol. 1999 Jun;157(2):223-40
10364435
J Neurosci Methods. 1996 Dec;70(1):21-5
8982977
Eur J Immunol. 2006 Jul;36(7):1782-93
16791896
J Biol Chem. 2007 Sep 7;282(36):26294-305
17569671
Dev Biol. 2001 Apr 1;232(1):62-76
11254348
Hum Immunol. 2009 Apr;70(4):211-7
19480842
Graefes Arch Clin Exp Ophthalmol. 2009 Jan;247(1):73-86
18815803
Brain Res Brain Res Rev. 2001 Mar;35(1):36-54
11245885
J Neurobiol. 1993 Jan;24(1):23-36
8419522
Mol Cell Neurosci. 1999 Feb;13(2):143-66
10192772
Exp Neurol. 2008 Feb;209(2):302-12
17706966
J Neurosci. 2006 Feb 8;26(6):1730-8
16467521
Prog Retin Eye Res. 2004 Mar;23(2):183-94
15094130
Biol Pharm Bull. 2004 Apr;27(4):445-51
15056844
Mol Cell Neurosci. 2005 Oct;30(2):265-78
16098761
Exp Neurol. 2002 May;175(1):61-75
12009760
Neuron. 1995 Jun;14(6):1131-40
7605628
Annu Rev Neurosci. 1996;19:341-77
8833447
Vision Res. 2003 Apr;43(8):927-36
12668062
Curr Biol. 1999 Mar 25;9(6):R201-4
10209089
J Biol Chem. 2002 Dec 20;277(51):49799-807
12376549
Adv Exp Med Biol. 2002;515:115-39
12613548
Graefes Arch Clin Exp Ophthalmol. 2003 Aug;241(8):673-81
12827374
Nat Med. 2006 Dec;12(12):1380-9
17099709
J Immunol. 2001 Apr 1;166(7):4348-54
11254688
Vision Res. 1999 Jan;39(1):169-75
10211404
Invest Ophthalmol Vis Sci. 2003 Aug;44(8):3388-93
12882786
Neuron. 1995 May;14(5):949-59
7748562
Nature. 1980 Mar 20;284(5753):264-5
7360259
Restor Neurol Neurosci. 1998;12(1):1-11
12671316