Inhibition of Cell Cycle Pathway by Flavopiridol Promotes Survival of Cerebellar Granule Cells after an Excitotoxic Treatment

Abstract

Kainic acid (KA)-induced neuronal damage and the protective effects of flavopiridol were studied in primary cultures of rat cerebellar granule cells (CGNs). When neurons were treated with 500 M KA, the percentage of cells with condensed nuclei measured by nuclear counting increased by up to 55%. After flavopiridol treatment, an antitumoral drug that is a broad inhibitor of cyclin-dependent kinases, the percentage of condensed nuclei decreased by up to 26%. Furthermore, this KA-mediated cell death was only partially dependent on the activation of the initiator caspase-9 and the effector caspases-3 and -6. This argues for a minor role of caspases in the intracellular pathway leading to KA-induced programmed cell death in CGNs. We examined the possible implication of cell cycle proteins in KA-induced neurotoxicity. We found an increase in the expression of proliferating cell nuclear antigen and E2F-1, two proteins implicated in S-phase, by Western blot. KA increased bromodeoxyuridine incorporation in CGNs, a marker of cell proliferation, and flavopiridol attenuated this effect. These results indicated that flavopiridol decreased the expression of cell cycle markers in CGNs after KA treatment. Flavopiridol might thus be used as a preventive agent against neurodegenerative diseases associated with cell cycle activation.

Brain and Blood microRNA Expression Profiling of Ischemic Stroke, Intracerebral Hemorrhage, and Kainate Seizures

“…Cell cycle re-entry in neurons has been confirmed in many brain diseases, including stroke, brain hemorrhage, traumatic brain injury (TBI), and epilepsy (Di Giovanni et al, 2005;Imai et al, 2002;Nagy and Esiri, 1998;O'Hare et al, 2002). Inhibition of cyclin-dependent kinases increases neuronal survival and improves behavioral outcomes in animal models of these diseases (Di Giovanni et al, 2005;Hilton et al, 2008;Park et al, 2000;Verdaguer et al, 2003;Verdaguer et al, 2004). Thus, the miRNAs involved in the cell cycle in brain could relate to the birth of new cells including glia, and/or relate to neuronal re-entry into the cell cycle and death of these cells.…”

Role of Cell Cycle Proteins in CNS Injury

“…Cell cycle activation also plays an important role in post-traumatic gliosis and microglial activation [1,5,9,10]. Inhibition of cell cycle pathways reduces injury-induced neuronal death in vitro [11] and after CNS injury [12], as well as decreases glial scar formation and release of microglial associated inflammatory factors [1,10].…”

Inhibition of cyclin-dependent kinases is neuroprotective in 1-methyl-4-phenylpyridinium-induced apoptosis in neurons

“…Although the exact mechanism by which neuronal reentry in the cell cycle induces apoptosis is not completely known, several studies suggest that the transcription factor E2F-1 could be the link Hou et al, 2000;Raina et al, 2001;Klein et al, 2002;Biswas et al, 2005;La Thangue, 2003, 2004). Another interesting point lending support to the potential role of cell cycle reentry in neuronal apoptosis is that cyclin-dependent kinase inhibitors, mainly flavopiridol (FLAV), offer strong neuroprotective properties against several experimental apoptotic paradigms both "in vitro" and "in vivo" (Verdaguer et al, 2004;Di Giovanni et al, 2005;Cernak et al, 2005;Mirjany et al, 2002;Wu et al, 2004;Wang et al, 2002;Webber et al, 2005). Since a characteristic common to all neurodegenerative diseases is the generation of oxidative stress production, one of the aims of the present study was to determine a relationship between oxidative stress production and reentry in the cell cycle (Herrup et al, 2004;Langley and Ratan, 2004;Becker and Bonni 2004).…”

“…The hypothesis regarding the role of cell cycle reentry as a potential mechanism involved in neuronal cell death is based on studies performed in brains of Alzheimer's disease and PD patients where there is an increase in the expression of proteins involved in the cell cycle (Yang et al, 2001(Yang et al, , 2003Jordan-Sciutto et al, 2003). Subsequent studies performed in neuronal cell preparations using different neurotoxins such as kainic acid (an agonist of non-NMDA receptors), camptothecin (a DNA damaging agent), and ␤-amyloid (an in vitro model of AD), suggest that re-expression of cell cycle proteins could constitute a common pathway involved in the mechanisms underlying neuronal cell death (Giovanni et al, 1999;Copani et al, 2001a;Verdaguer et al, 2004). Although the exact mechanism by which neuronal reentry in the cell cycle induces apoptosis is not completely known, several studies suggest that the transcription factor E2F-1 could be the link Hou et al, 2000;Raina et al, 2001;Klein et al, 2002;Biswas et al, 2005;La Thangue, 2003, 2004).…”