Department of Biochemistry and Molecular Pharmacology
Medical Subject Headings
Apoptosis; Apoptosis Inducing Factor; Blotting, Western; Calcium; Cell Nucleus; Cell Proliferation; *Gene Expression Regulation, Developmental; Humans; Hydrolases; Immunoenzyme Techniques; Immunoprecipitation; In Situ Hybridization; Neural Stem Cells; RNA, Messenger; RNA, Small Interfering; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction
Biochemistry | Enzymes and Coenzymes | Medicinal-Pharmaceutical Chemistry | Therapeutics
PADs (peptidylarginine deiminases) are calcium-dependent enzymes that change protein-bound arginine to citrulline (citrullination/deimination) affecting protein conformation and function. PAD up-regulation following chick spinal cord injury has been linked to extensive tissue damage and loss of regenerative capability. Having found that human neural stem cells (hNSCs) expressed PAD2 and PAD3, we studied PAD function in these cells and investigated PAD3 as a potential target for neuroprotection by mimicking calcium-induced secondary injury responses. We show that PAD3, rather than PAD2 is a modulator of cell growth/death and that PAD activity is not associated with caspase-3-dependent cell death, but is required for AIF (apoptosis inducing factor)-mediated apoptosis. PAD inhibition prevents association of PAD3 with AIF and AIF cleavage required for its translocation to the nucleus. Finally, PAD inhibition also hinders calcium-induced cytoskeleton disassembly and association of PAD3 with vimentin, that we show to be associated also with AIF; together this suggests that PAD-dependent cytoskeleton disassembly may play a role in AIF translocation to the nucleus. This is the first study highlighting a role of PAD activity in balancing hNSC survival/death, identifying PAD3 as an important upstream regulator of calcium-induced apoptosis, which could be targeted to reduce neural loss, and shedding light on the mechanisms involved.
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Citation: Biochim Biophys Acta. 2014 Jun;1843(6):1162-71. doi: 10.1016/j.bbamcr.2014.02.018. Epub 2014 Mar 5. Link to article on publisher's site
U, Kin Pong; Subramanian, Venkataraman; Nicholas, Antony P.; Thompson, Paul R.; and Ferretti, Patrizia, "Modulation of calcium-induced cell death in human neural stem cells by the novel peptidylarginine deiminase-AIF pathway." (2014). Thompson Lab Publications. 14.
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