Mechanism for neurotropic action of vorinostat, a pan histone deacetylase inhibitor.
In this study we investigated the neurotrophic actions of vorinostat (suberoylanilide hydroxamic acid, SAHA), a class I and class II HDAC inhibitor, on the differentiation of Neuroscreen-1 (NS-1) cells. NS-1 cell is a subclone of the rat pheochromocytoma cell line (PC 12). Vorinostat independently induced neurite outgrowth in NS-1 cells. The NS-1 cells were further interrogated for the effects of vorinostat on intracellular neurotrophin signaling pathways, to understand its mechanism of neurotrophic action. Selective inhibitors of MEK1/2 (PD98059 and U0126), phosphoinositide 3-kinase (PI3K) (LY294002) and tyrosine kinase A (TrkA) (GW441756) were employed for these interrogations. Our results suggest that neurite outgrowth mediated by both nerve growth factor (NGF), an intrinsic neurotrophin, and vorinostat were blocked by the inhibitors of MEK1/2 & PI3K. Vorinostat induced phosphorylation of ERK1/2 occurs at 2h post treatment. Phosphorylation of ERK was abolished in presence of U0126, further confirming the role of ERK pathway in vorinostat-induced differentiation of NS-1 cells. Vorinostat-induced neurite outgrowth also involves the activation of upstream extracellular kinase TrkA, as both vorinostat mediated neurite outgrowth and activation of ERK were attenuated in presence of the TrkA inhibitor, GW441756. Vorinostat also stimulated hyperacetylation of α-tubulin and histones H3/H4 in NS-1 cells. The results suggest that vorinostat exerts a positive effect on the neuritogenesis via activation of MEK1/2 & PI3K pathways involving an upstream kinase, TrkA. Bioactive small molecules with neurotrophic and neuritogenic actions, like vorinostat identified in the present study, hold great promise as therapeutic agents for treatment of neurodegenerative diseases and neuronal injuries by virtue of their ability to stimulate neuritic outgrowth.
National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA; Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA.
Surabhi
S
Shukla
Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA.
Zia
Z
Shariat-Madar
National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA; Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA.
Larry A
LA
Walker
National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA; Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA. Electronic address: btekwani@olemiss.edu.
Babu L
BL
Tekwani
D000818:Animals; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006877:Hydroxamic Acids / Q000494:pharmacology*; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System; D000071446:Neuronal Outgrowth / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011134:Polysaccharides / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D020917:Receptor, trkA / Q000037:antagonists & inhibitors / Q000378:metabolism; D000077337:Vorinostat
D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D018696:Neuroprotective Agents; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011134:Polysaccharides; D047428:Protein Kinase Inhibitors; D020917:Receptor, trkA; D000077337:Vorinostat; C010491:neurotropin; C482127:Map2k1 protein, mouse; C482129:Map2k2 protein, mouse
Histone deacetylase; MAPK; Neuritogenesis; Neurotrophic; PC12 cells; Phosphoinositide 3-kinase; Suberoylanilohydroxamic acid; Vorinostat