cGMP-Dependent Protein Kinase Type I Is Implicated in the Regulation of the Timing and Quality of Sleep and Wakefulness

Many effects of nitric oxide (NO) are mediated by the activation of guanylyl cyclases and subsequent production of the second messenger cyclic guanosine-3′,5′-monophosphate (cGMP). cGMP activates cGMP-dependent protein kinases (PRKGs), which can therefore be considered downstream effectors of NO signaling. Since NO is thought to be involved in the regulation of both sleep and circadian rhythms, we analyzed these two processes in mice deficient for cGMP-dependent protein kinase type I (PRKG1) in the brain. Prkg1 mutant mice showed a strikingly altered distribution of sleep and wakefulness over the 24 hours of a day as well as reductions in rapid-eye-movement sleep (REMS) duration and in non-REM sleep (NREMS) consolidation, and their ability to sustain waking episodes was compromised. Furthermore, they displayed a drastic decrease in electroencephalogram (EEG) power in the delta frequency range (1–4 Hz) under baseline conditions, which could be normalized after sleep deprivation. In line with the re-distribution of sleep and wakefulness, the analysis of wheel-running and drinking activity revealed more rest bouts during the activity phase and a higher percentage of daytime activity in mutant animals. No changes were observed in internal period length and phase-shifting properties of the circadian clock while chi-squared periodogram amplitude was significantly reduced, hinting at a less robust oscillator. These results indicate that PRKG1 might be involved in the stabilization and output strength of the circadian oscillator in mice. Moreover, PRKG1 deficiency results in an aberrant pattern, and consequently a reduced quality, of sleep and wakefulness, possibly due to a decreased wake-promoting output of the circadian system impinging upon sleep

Cleavage of focal adhesion proteins and PKCdelta during lovastatin-induced apoptosis in spontaneously immortalized rat brain neuroblasts

We have previously shown that lovastatin induces apoptosis in spontaneously immortalized rat brain neuroblasts. Focal adhesion proteins and protein kinase Cdelta (PKCdelta) have been implicated in the regulation of apoptosis. We found that lovastatin exposure induced focal adhesion kinase, Crk-associated substrate (p130(Cas)), PKCdelta cleavage and caspase-3 activation in a concentration-dependent manner. Lovastatin effects were fully prevented by mevalonate. The cleavage of p130(Cas) was almost completely inhibited by z-DEVD-fmk, a specific caspase-3 inhibitor, and z-VAD-fmk, a broad spectrum caspase inhibitor, indicating that cleavage is mediated by caspase-3. In contrast, the lovastatin-induced cleavage of PKCdelta was only blocked by z-VAD-fmk suggesting that PKCdelta cleavage is caspase-dependent but caspase-3-independent. Additionally, z-VAD-fmk partially prevented lovastatin-induced neuroblast apoptosis. The present data show that lovastatin may induce neuroblast apoptosis by both caspase-dependent and independent pathways. These findings may suggest that the caspase-dependent component leading to the neuroblast cell death is likely to involve the cleavage of focal adhesion proteins and PKCdelta, which may be partially responsible for some biochemical features of neuroblast apoptosis induced by lovastatin.Anteriormente hemos demostrado que la lovastatina induce la apoptosis en neuroblastos de cerebro de rata espontáneamente inmortalizados. Las proteínas de adhesión focal y la proteína quinasa Cdelta (PKCdelta) han sido implicadas en la regulación de la apoptosis. Descubrimos que la exposición a lovastatina inducía la quinasa de adhesión focal, el sustrato asociado a Crk (p130(Cas)), la escisión de PKCdelta y la activación de la caspasa-3 de forma dependiente de la concentración. Los efectos de la lovastatina fueron totalmente prevenidos por el mevalonato. El clivaje de p130(Cas) fue inhibido casi por completo por z-DEVD-fmk, un inhibidor específico de la caspasa-3, y z-VAD-fmk, un inhibidor de caspasas de amplio espectro, lo que indica que el clivaje está mediado por la caspasa-3. Por el contrario, los efectos de la lovastatina fueron evitados por completo por el mevalonato. Por el contrario, la escisión de PKCdelta inducida por lovastatina sólo fue bloqueada por z-VAD-fmk, lo que sugiere que la escisión de PKCdelta es dependiente de la caspasa pero independiente de la caspasa-3. Además, z-VAD-fmk previno parcialmente la apoptosis de neuroblastos inducida por lovastatina. Los presentes datos muestran que la lovastatina puede inducir la apoptosis de neuroblastos por vías tanto dependientes como independientes de la caspasa. Estos hallazgos pueden sugerir que el componente dependiente de la caspasa que conduce a la muerte celular de los neuroblastos es probable que implique la escisión de las proteínas de adhesión focal y PKCdelta, que puede ser parcialmente responsable de algunas características bioquímicas de la apoptosis de neuroblastos inducida por lovastatina.Ministerio de Ciencia y Tecnologia, Junta de Extremadura, Fernando Valhondo CalaffpeerReviewe

Peptidergic influences on proliferation, migration, and placement of neural progenitors in the adult mouse forebrain

Neural progenitor proliferation, differentiation, and migration are continually ongoing processes in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the adult brain. There is evidence that peptidergic systems may be involved in the molecular cascades regulating these neurogenic processes, and we examined a possible influence of neuropeptide Y (NPY) and cholecystokinin (CCK) systems in cell proliferation and neuroblast formation in the SVZ and RMS and generation of interneurons in the olfactory bulb (OB). We show that NPY and the Y1 and Y2 receptor (R) proteins are expressed in and surrounding the SVZ and RMS and that Y1R is located on neuroblasts in the anterior RMS. Mice deficient in Y1Rs or Y2Rs have fewer Ki-67-immunoreactive (ir) proliferating precursor cells and doublecortin-ir neuroblasts in the SVZ and RMS than WT mice, and less calbindin-, calretinin-, and tyrosine hydroxylase-ir interneurons in the OB. Mice lacking CCK1Rs have fewer proliferating cells and neuroblasts than normal and a shortage of interneurons in the OB. These findings suggest that both NPY and CCK through their receptors help to regulate the proliferation of precursor cells, the amount of neuroblast cells in the SVZ and RMS, and influence the differentiation of OB interneurons