A large-scale chemical screen for regulators of the arginase 1 promoter identifies the soy isoflavone daidzeinas a clinically approved small molecule that can promote neuronal protection or regeneration via a cAMP-independent pathway.
An ideal therapeutic for stroke or spinal cord injury should promote survival and regeneration in the CNS. Arginase 1 (Arg1) has been shown to protect motor neurons from trophic factor deprivation and allow sensory neurons to overcome neurite outgrowth inhibition by myelin proteins. To identify small molecules that capture Arg1's protective and regenerative properties, we screened a hippocampal cell line stably expressing the proximal promoter region of the arginase 1 gene fused to a reporter gene against a library of compounds containing clinically approved drugs. This screen identified daidzein as a transcriptional inducer of Arg1. Both CNS and PNS neurons primed in vitro with daidzein overcame neurite outgrowth inhibition from myelin-associated glycoprotein, which was mirrored by acutely dissociated and cultured sensory neurons primed in vivo by intrathecal or subcutaneous daidzein infusion. Further, daidzein was effective in promoting axonal regeneration in vivo in an optic nerve crush model when given intraocularly without lens damage, or most importantly, when given subcutaneously after injury. Mechanistically, daidzein requires transcription and induction of Arg1 activity for its ability to overcome myelin inhibition. In contrast to canonical Arg1 activators, daidzein increases Arg1 without increasing CREB phosphorylation, suggesting its effects are cAMP-independent. Accordingly, it may circumvent known CNS side effects of some cAMP modulators. Indeed, daidzein appears to be safe as it has been widely consumed in soy products, crosses the blood-brain barrier, and is effective without pretreatment, making it an ideal candidate for development as a therapeutic for spinal cord injury or stroke.
Ma
Thong C
TC
Burke-Cornell Medical Research Institute, White Plains, New York 10605, USA.
Campana
Aline
A
Lange
Philipp S
PS
Lee
Hsin-Hwa
HH
Banerjee
Kasturi
K
Bryson
J Barney
JB
Mahishi
Lata
L
Alam
Shabnam
S
Giger
Roman J
RJ
Barnes
Stephen
S
Morris
Sidney M
SM
Willis
Dianna E
DE
Twiss
Jeffrey L
JL
Filbin
Marie T
MT
Ratan
Rajiv R
RR
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001119:Arginase / Q000235:genetics* / Q000378:metabolism; D016466:CHO Cells; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019922:GAP-43 Protein / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology; D057166:High-Throughput Screening Assays / Q000379:methods; D006624:Hippocampus / Q000166:cytology; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D018992:Myelin-Associated Glycoprotein / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009901:Optic Nerve Diseases / Q000188:drug therapy / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000378:metabolism; D054852:Small Molecule Libraries
D004791:Enzyme Inhibitors; D019922:GAP-43 Protein; D007529:Isoflavones; D018992:Myelin-Associated Glycoprotein; D018696:Neuroprotective Agents; D011960:Receptors, Estrogen; D054852:Small Molecule Libraries; C004742:daidzein; D000242:Cyclic AMP; C544448:Arg1 protein, mouse; D001119:Arginase