The circadian clock links our daily cycles of sleep and activity to the external environment. Deregulation of the clock is implicated in a number of human disorders, including depression, seasonal affective disorder, and metabolic disorders. Casein kinase 1 epsilon (CK1) and casein kinase 1 delta (CK1␦) are closely related Ser-Thr protein kinases that serve as key clock regulators as demonstrated by mammalian mutations in each that dramatically alter the circadian period. Therefore, inhibitors of CK1␦/ may have utility in treating circadian disorders. Although we previously demonstrated that a pan-CK1␦/ inhibitor, 4-[3-cyclohexyl-5-(4-fluoro-phenyl)-3H-imidazol-4-yl]-pyrimidin-2-ylamine (PF-670462), causes a significant phase delay in animal models of circadian rhythm, it remains unclear whether one of the kinases has a predominant role in regulating the circadian clock. To test this, we have characterized 3-(3-, a novel and potent inhibitor of CK1 (IC 50 ϭ 32 nM) with greater than 20-fold selectivity over CK1␦. PF-4800567 completely blocks CK1-mediated PER3 nuclear localization and PER2 degradation. In cycling Rat1 fibroblasts and a mouse model of circadian rhythm, however, PF-4800567 has only a minimal effect on the circadian clock at concentrations substantially over its CK1 IC 50 . This is in contrast to the pan-CK1␦/ inhibitor PF-670462 that robustly alters the circadian clock under similar conditions. These data indicate that CK1 is not the predominant mediator of circadian timing relative to CK1␦. PF-4800567 should prove useful in probing unique roles between these two kinases in multiple signaling pathways.All living things, from fungi to humans, have regular cycles aligning them with the daily events in their environment. These cycles, known as circadian rhythms, are controlled in mammals by the master clock located in the suprachiasmatic nucleus of the hypothalamus (Antle and Silver, 2005;Gallego and Virshup, 2007). At the cellular level, the molecular events behind clock cycling are described by the regular increase and decrease in mRNAs and proteins that define feedback loops, resulting in approximately 24-h cycles. The suprachiasmatic nucleus is primarily regulated, or entrained, directly by light via the retinohypothalamic tract. The cycling outputs of the suprachiasmatic nucleus, not fully identified, regulate multiple downstream rhythms, such as those in sleep and awakening, body temperature, and hormone secretion (Schibler et al., 2003;Ko and Takahashi, 2006). As anyone who has experienced jet lag knows, misalignment of the internal clock with the external environment profoundly affects well being. Furthermore, diseases, such as depression, seasonal affective disorder, and metaArticle, publication date, and citation information can be found at

Amyotrophic lateral sclerosis (ALS) is a lethal disease characterized by the unremitting degeneration of motor neurons. Multiple processes involving motor neurons and other cell types have been implicated in its pathogenesis. Neural stem cells (NSCs) perform multiple actions within the nervous system to fulfill their functions of organogenesis and homeostasis. We test the hypothesis that transplanted, undifferentiated multipotent migratory NSCs may help to ameliorate an array of pathological mechanisms in the SOD1(G93A) transgenic mouse model of ALS. On the basis of a meta-analysis of 11 independent studies performed by a consortium of ALS investigators, we propose that transplanted NSCs (both mouse and human) can slow both the onset and the progression of clinical signs and prolong survival in ALS mice, particularly if regions sustaining vital functions such as respiration are rendered chimeric. The beneficial effects of transplanted NSCs seem to be mediated by a number of actions including their ability to produce trophic factors, preserve neuromuscular function, and reduce astrogliosis and inflammation. We conclude that the widespread, pleiotropic, modulatory actions exerted by transplanted NSCs may represent an accessible therapeutic application of stem cells for treating ALS and other untreatable degenerative diseases.

Circadian rhythms can be entrained by a light-dark (LD) cycle and can also be reset pharmacologically, for example, by the CK1δ/ε inhibitor PF-670462. Here, we determine how these two independent signals affect circadian timekeeping from the molecular to the behavioral level. By developing a systems pharmacology model, we predict and experimentally validate that chronic CK1δ/ε inhibition during the earlier hours of a LD cycle can produce a constant stable delay of rhythm. However, chronic dosing later during the day, or in the presence of longer light intervals, is not predicted to yield an entrained rhythm. We also propose a simple method based on phase response curves (PRCs) that predicts the effects of a LD cycle and chronic dosing of a circadian drug. This work indicates that dosing timing and environmental signals must be carefully considered for accurate pharmacological manipulation of circadian phase.

Casein kinase 1 delta (CK1δ) and casein kinase 1 epsilon (CK1ε) inhibitors are potential therapeutic agents for a range of psychiatric disorders. The feasibility of developing a CNS kinase inhibitor has been limited by an inability to identify safe brain-penetrant compounds with high kinome selectivity. Guided by structure-based drug design, potent and selective CK1δ/ε inhibitors have now been identified that address this gap, through the design and synthesis of novel 4-[4-(4-fluorophenyl)-1-(piperidin-4-yl)-1H-imidazol-5-yl]pyrimidin-2-amine derivatives. PF-5006739 (6) possesses a desirable profile, with low nanomolar in vitro potency for CK1δ/ε (IC50 = 3.9 and 17.0 nM, respectively) and high kinome selectivity. In vivo, 6 demonstrated robust centrally mediated circadian rhythm phase-delaying effects in both nocturnal and diurnal animal models. Further, 6 dose-dependently attenuated opioid drug-seeking behavior in a rodent operant reinstatement model in animals trained to self-administer fentanyl. Collectively, our data supports further development of 6 as a promising candidate to test the hypothesis of CK1δ/ε inhibition in treating multiple indications in the clinic.