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Gotter AL, Webber AL, Coleman PJ, Renger JJ, Winrow CJ. International Union of Basic and Clinical Pharmacology. LXXXVI. Orexin Receptor Function, Nomenclature and Pharmacology. Pharmacol Rev 2012; 64:389-420. [DOI: 10.1124/pr.111.005546] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Fitzpatrick K, Winrow CJ, Gotter AL, Millstein J, Arbuzova J, Brunner J, Kasarskis A, Vitaterna MH, Renger JJ, Turek FW. Altered sleep and affect in the neurotensin receptor 1 knockout mouse. Sleep 2012; 35:949-56. [PMID: 22754041 DOI: 10.5665/sleep.1958] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
STUDY OBJECTIVE Sleep and mood disorders have long been understood to have strong genetic components, and there is considerable comorbidity of sleep abnormalities and mood disorders, suggesting the involvement of common genetic pathways. Here, we examine a candidate gene implicated in the regulation of both sleep and affective behavior using a knockout mouse model. DESIGN Previously, we identified a quantitative trait locus (QTL) for REM sleep amount, REM sleep bout number, and wake amount in a genetically segregating population of mice. Here, we show that traits mapping to this QTL correlated with an expression QTL for neurotensin receptor 1 (Ntsr1), a receptor for neurotensin, a ligand known to be involved in several psychiatric disorders. We examined sleep as well as behaviors indicative of anxiety and depression in the NTSR1 knockout mouse. MEASUREMENTS AND RESULTS NTSR1 knockouts had a lower percentage of sleep time spent in REM sleep in the dark phase and a larger diurnal variation in REM sleep duration than wild types under baseline conditions. Following sleep deprivation, NTSR1 knockouts exhibited more wake and less NREM rebound sleep. NTSR1 knockouts also showed increased anxious and despair behaviors. CONCLUSIONS Here we illustrate a link between expression of the Ntsr1 gene and sleep traits previously associated with a particular QTL. We also demonstrate a relationship between Ntsr1 and anxiety and despair behaviors. Given the considerable evidence that anxiety and depression are closely linked with abnormalities in sleep, the data presented here provide further evidence that neurotensin and Ntsr1 may be a component of a pathway involved in both sleep and mood disorders.
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Coleman PJ, Schreier JD, Cox CD, Breslin MJ, Whitman DB, Bogusky MJ, McGaughey GB, Bednar RA, Lemaire W, Doran SM, Fox SV, Garson SL, Gotter AL, Harrell CM, Reiss DR, Cabalu TD, Cui D, Prueksaritanont T, Stevens J, Tannenbaum PL, Ball RG, Stellabott J, Young SD, Hartman GD, Winrow CJ, Renger JJ. Cover Picture: Discovery of [(2R,5R)-5-{[(5-Fluoropyridin-2-yl)oxy]methyl}-2-methylpiperidin-1-yl][5-methyl-2-(pyrimidin-2-yl)phenyl]methanone (MK-6096): A Dual Orexin Receptor Antagonist with Potent Sleep-Promoting Properties (ChemMedChem 3/2012). ChemMedChem 2012. [DOI: 10.1002/cmdc.201290006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Coleman PJ, Schreier JD, Cox CD, Breslin MJ, Whitman DB, Bogusky MJ, McGaughey GB, Bednar RA, Lemaire W, Doran SM, Fox SV, Garson SL, Gotter AL, Harrell CM, Reiss DR, Cabalu TD, Cui D, Prueksaritanont T, Stevens J, Tannenbaum PL, Ball RG, Stellabott J, Young SD, Hartman GD, Winrow CJ, Renger JJ. Discovery of [(2R,5R)-5-{[(5-Fluoropyridin-2-yl)oxy]methyl}-2-methylpiperidin-1-yl][5-methyl-2-(pyrimidin-2-yl)phenyl]methanone (MK-6096): A Dual Orexin Receptor Antagonist with Potent Sleep-Promoting Properties. ChemMedChem 2012; 7:415-24, 337. [DOI: 10.1002/cmdc.201200025] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Indexed: 11/09/2022]
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Winrow CJ, Gotter AL, Cox CD, Tannenbaum PL, Garson SL, Doran SM, Breslin MJ, Schreier JD, Fox SV, Harrell CM, Stevens J, Reiss DR, Cui D, Coleman PJ, Renger JJ. Pharmacological characterization of MK-6096 – A dual orexin receptor antagonist for insomnia. Neuropharmacology 2012; 62:978-87. [DOI: 10.1016/j.neuropharm.2011.10.003] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 08/26/2011] [Accepted: 10/04/2011] [Indexed: 01/02/2023]
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Gotter AL, Roecker AJ, Hargreaves R, Coleman PJ, Winrow CJ, Renger JJ. Orexin receptors as therapeutic drug targets. PROGRESS IN BRAIN RESEARCH 2012; 198:163-88. [PMID: 22813974 DOI: 10.1016/b978-0-444-59489-1.00010-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Orexin (hypocretin) receptor antagonists stand as a model for the development of targeted CNS small-molecule therapeutics. The identification of mutations in the gene for the orexin 2 receptor responsible for canine narcolepsy, the demonstration of a hypersomnolence phenotype in hypocretin knockout mice and the disruption in orexin signaling in narcoleptic patients provides clear genetic proof of concept for targeting orexin-induced arousal for the treatment of insomnia. The full characterization of the genes encoding orexin and its two cognate receptors enabled the rapid development of in vitro and ex vivo assays with which to identify lead compound structures and to optimize potency and pharmacokinetic properties. Polysomnographic measures with cross-species translatability capable of measuring the sleep-promoting effects of orexin receptor antagonists from mice to man, and the existence of knockout models not only allow efficacy assessment but also the demonstration of mechanism of action. Focused efforts by a number of groups have identified potent compounds of diverse chemical structure with differential orexin receptor selectivity for either the orexin 1 receptor (OX₁R) or the orexin 2 receptor (OX₂R), or both. This work has yielded tool compounds that, along with genetic models, have been used to specifically define the role these receptors in mediating orexin-induced arousal and vigilance state control. Optimized dual receptor antagonists with favorable pharmacokinetic and safety profiles have now demonstrated efficacy in clinical development and represent a distinct mechanism of action for the treatment of insomnia relative to current standard of care.
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Coburn CA, Luo Y, Cui M, Wang J, Soll R, Dong J, Hu B, Lyon MA, Santarelli VP, Kraus RL, Gregan Y, Wang Y, Fox SV, Binns J, Doran SM, Reiss DR, Tannenbaum PL, Gotter AL, Meinke PT, Renger JJ. Discovery of a Pharmacologically Active Antagonist of the Two-Pore-Domain Potassium Channel K2P9.1 (TASK-3). ChemMedChem 2011; 7:123-33. [DOI: 10.1002/cmdc.201100351] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Indexed: 11/11/2022]
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Gotter AL, Santarelli VP, Doran SM, Tannenbaum PL, Kraus RL, Rosahl TW, Meziane H, Montial M, Reiss DR, Wessner K, McCampbell A, Stevens J, Brunner JI, Fox SV, Uebele VN, Bayliss DA, Winrow CJ, Renger JJ. TASK-3 as a potential antidepressant target. Brain Res 2011; 1416:69-79. [PMID: 21885038 DOI: 10.1016/j.brainres.2011.08.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 08/09/2011] [Indexed: 10/17/2022]
Abstract
Modulation of TASK-3 (Kcnk9) potassium channels affect neurotransmitter release in thalamocortical centers and other sleep-related nuclei having the capacity to regulate arousal cycles and REM sleep changes associated with mood disorders and antidepressant action. Circumstantial evidence from this and previous studies suggest the potential for TASK-3 to be a novel antidepressant therapeutic target; TASK-3 knock-out mice display augmented circadian amplitude and exhibit sleep architecture characterized by suppressed REM activity. Detailed analysis of locomotor activity indicates that the amplitudes of activity bout duration and bout number are augmented in TASK-3 mutants well beyond that seen in wildtypes, findings substantiated by amplitude increases in body temperature and EEG recordings of sleep stage bouts. Polysomnographic analysis of TASK-3 mutants reveals increases in nocturnal active wake and suppressed REM sleep time while increased slow wave sleep typifies the inactive phase, findings that have implications for the cognitive impact of reduced TASK-3 activity. In direct measures of their resistance to despair behavior, TASK-3 knock-outs displayed significant decreases in immobility relative to wildtype controls in both tail suspension and forced swim tests. Treatment of wildtype animals with the antidepressant Fluoxetine markedly reduced REM sleep, while leaving active wake and slow wave sleep relatively intact. Remarkably, these effects were absent in TASK-3 mutants indicating that TASK-3 is either directly involved in the mechanism of this drug's action, or participates in parallel pathways that achieve the same effect. Together, these results support the TASK-3 channel to act as a therapeutic target for antidepressant action.
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Dheekollu J, Wiedmer A, Hayden J, Speicher D, Gotter AL, Yen T, Lieberman PM. Timeless links replication termination to mitotic kinase activation. PLoS One 2011; 6:e19596. [PMID: 21573113 PMCID: PMC3089618 DOI: 10.1371/journal.pone.0019596] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/01/2011] [Indexed: 02/04/2023] Open
Abstract
The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.
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Winrow CJ, Gotter AL, Cox CD, Doran SM, Tannenbaum PL, Breslin MJ, Garson SL, Fox SV, Harrell CM, Stevens J, Reiss DR, Cui D, Coleman PJ, Renger JJ. Promotion of sleep by suvorexant-a novel dual orexin receptor antagonist. J Neurogenet 2011; 25:52-61. [PMID: 21473737 DOI: 10.3109/01677063.2011.566953] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Orexins/hypocretins are key neuropeptides responsible for regulating central arousal and reward circuits. Two receptors respond to orexin signaling, orexin 1 receptor (OX(1)R) and orexin 2 receptor (OX(2)R) with partially overlapping nervous system distributions. Genetic studies suggest orexin receptor antagonists could be therapeutic for insomnia and other disorders with disruptions of sleep and wake. Suvorexant (MK-4305) is a potent, selective, and orally bioavailable antagonist of OX(1)R and OX(2)R currently under clinical investigation as a novel therapy for insomnia. Examination of Suvorexant in radioligand binding assays using tissue from transgenic rats expressing the human OX(2)R found nearly full receptor occupancy (>90%) at plasma exposures of 1.1 μM. Dosed orally Suvorexant significantly and dose-dependently reduced locomotor activity and promoted sleep in rats (10, 30, and 100 mg/kg), dogs (1 and 3 mg/kg), and rhesus monkeys (10 mg/kg). Consistent cross-species sleep/wake architecture changes produced by Suvorexant highlight a unique opportunity to develop dual orexin antagonists as a novel therapy for insomnia.
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Kraus RL, Li Y, Gregan Y, Gotter AL, Uebele VN, Fox SV, Doran SM, Barrow JC, Yang ZQ, Reger TS, Koblan KS, Renger JJ. In vitro characterization of T-type calcium channel antagonist TTA-A2 and in vivo effects on arousal in mice. J Pharmacol Exp Ther 2010; 335:409-17. [PMID: 20682849 DOI: 10.1124/jpet.110.171058] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
T-type calcium channels have been implicated in many behaviorally important neurophysiological processes, and altered channel activity has been linked to the pathophysiology of neurological disorders such as insomnia, epilepsy, Parkinson's disease, depression, schizophrenia, and pain. We have previously identified a number of potent and selective T-type channel antagonists (Barrow et al., 2007; Shipe et al., 2008; Yang et al., 2008). Here we describe the properties of the antagonist TTA-A2 [2-(4-cyclopropylphenyl)-N-((1R)-1-{5-[(2,2,2-trifluoroethyl)oxo]-pyridin-2-yl}ethyl)acetamide], assessed in patch-clamp experiments. TTA-A2 blocks T-type channels (Ca(v)3.1, 3.2, 3.3) voltage dependently and with high potency (IC(50) ∼100 nM). Stimulation at 3 Hz revealed additional use dependence of inhibition. A hyperpolarized shift of the channel availability curve and delayed channel recovery from inactivation suggest that the compound preferentially interacts with and stabilizes inactivated channels. The compound showed a ∼300-fold selectivity for Ca(v)3 channels over high-voltage activated calcium channels. Inhibitory effects on native T-type currents were confirmed in brain slice recordings from the dorsal lateral geniculate nucleus and the subthalamic nucleus. Furthermore, we demonstrate that in vivo T-type channel inhibition by TTA-A2 suppresses active wake and promotes slow-wave sleep in wild-type mice but not in mice lacking both Ca(v)3.1 and Ca(v)3.3, suggesting the selective effect of TTA-A2 on recurrent thalamocortical network activity. The discovery of the potent and selective T-type channel antagonist TTA-A2 has enabled us to study the in vivo effects of pharmacological T-channel inhibition on arousal in mice, and it will help to explore the validity of these channels as potential drug targets for sleep-related and other neurological diseases.
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Melamed JY, Zartman AE, Kett NR, Gotter AL, Uebele VN, Reiss DR, Condra CL, Fandozzi C, Lubbers LS, Rowe BA, McGaughey GB, Henault M, Stocco R, Renger JJ, Hartman GD, Bilodeau MT, Trotter BW. Synthesis and evaluation of a new series of Neuropeptide S receptor antagonists. Bioorg Med Chem Lett 2010; 20:4700-3. [PMID: 20510609 DOI: 10.1016/j.bmcl.2010.04.143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 04/28/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
Abstract
Administration of Neuropeptide S (NPS) has been shown to produce arousal, that is, independent of novelty and to induce wakefulness by suppressing all stages of sleep, as demonstrated by EEG recordings in rat. Medicinal chemistry efforts have identified a quinolinone class of potent NPSR antagonists that readily cross the blood-brain barrier. We detail here optimization efforts resulting in the identification of a potent NPSR antagonist which dose-dependently and specifically inhibited (125)I-NPS binding in the CNS when administered to rats.
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Winrow CJ, Tanis KQ, Reiss DR, Rigby AM, Uslaner JM, Uebele VN, Doran SM, Fox SV, Garson SL, Gotter AL, Levine DM, Roecker AJ, Coleman PJ, Koblan KS, Renger JJ. Orexin receptor antagonism prevents transcriptional and behavioral plasticity resulting from stimulant exposure. Neuropharmacology 2010; 58:185-94. [DOI: 10.1016/j.neuropharm.2009.07.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 07/02/2009] [Accepted: 07/03/2009] [Indexed: 12/20/2022]
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Uebele VN, Gotter AL, Nuss CE, Kraus RL, Doran SM, Garson SL, Reiss DR, Li Y, Barrow JC, Reger TS, Yang ZQ, Ballard JE, Tang C, Metzger JM, Wang SP, Koblan KS, Renger JJ. Antagonism of T-type calcium channels inhibits high-fat diet-induced weight gain in mice. J Clin Invest 2009; 119:1659-67. [PMID: 19451696 DOI: 10.1172/jci36954] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 04/01/2009] [Indexed: 11/17/2022] Open
Abstract
The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens. Pharmacologic treatments for these diseases remain unsatisfactory with respect to both efficacy and side-effect profiles. Here, we have identified a potential central role for T-type calcium channels in regulating body weight maintenance and sleep. Previously, it was shown that mice lacking CaV3.1 T-type calcium channels have altered sleep/wake activity. We found that these mice were also resistant to high-fat diet-induced weight gain, without changes in food intake or sensitivity to high-fat diet-induced disruptions of diurnal rhythm. Administration of a potent and selective antagonist of T-type calcium channels, TTA-A2, to normal-weight animals prior to the inactive phase acutely increased sleep, decreased body core temperature, and prevented high-fat diet-induced weight gain. Administration of TTA-A2 to obese rodents reduced body weight and fat mass while concurrently increasing lean muscle mass. These effects likely result from better alignment of diurnal feeding patterns with daily changes in circadian physiology and potentially an increased metabolic rate during the active phase. Together, these studies reveal what we believe to be a previously unknown role for T-type calcium channels in the regulation of sleep and weight maintenance and suggest the potential for a novel therapeutic approach to treating obesity.
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Gotter AL, Nimmakayalu MA, Jalali GR, Hacker AM, Vorstman J, Conforto Duffy D, Medne L, Emanuel BS. A palindrome-driven complex rearrangement of 22q11.2 and 8q24.1 elucidated using novel technologies. Genome Res 2007; 17:470-81. [PMID: 17351131 PMCID: PMC1832094 DOI: 10.1101/gr.6130907] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Constitutional translocations at the same 22q11.21 low copy repeat B (LCR-B) breakpoint involved in the recurrent t(11;22) are relatively abundant. A novel 46,XY,t(8;22)(q24.13;q11.21) rearrangement was investigated to determine whether the recurrent LCR-B breakpoint is involved. Investigations demonstrated an inversion of the 3Mb region typically deleted in patients with the 22q11.2 deletion syndrome. The 22q11.21 inversion appears to be mediated by low copy repeats, and is presumed to have taken place prior to translocation with 8q24.13. Despite predictions based on inversions observed in other chromosomes harboring low copy repeats, this 22q11.2 inversion has not been observed previously. The current studies utilize novel laser microdissection and MLPA (multiplex ligation-dependent probe amplification) approaches, as adjuncts to FISH, to map the breakpoints of the complex rearrangements of 22q11.21 and 8q24.21. The t(8;22) occurs between the recurrent site on 22q11.21 and an AT-rich site at 8q24.13, making it the fifth different chromosomal locus characterized at the nucleotide level engaged in a translocation with the unstable recurrent breakpoint at 22q11.21. Like the others, this breakpoint occurs at the center of a palindromic sequence. This sequence appears capable of forming a perfect 145 bp stem-loop. Remarkably, this site appears to have been involved in a previously reported t(3;8) occurring between 8q24.13 and FRA3B on 3p14.2. Further, the fragile site-like nature of all of the breakpoint sites involved in translocations with the recurrent site on 22q11.21, suggests a mechanism based on delay of DNA replication in the initiation of these chromosomal rearrangements.
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Gotter AL, Suppa C, Emanuel BS. Mammalian TIMELESS and Tipin are evolutionarily conserved replication fork-associated factors. J Mol Biol 2006; 366:36-52. [PMID: 17141802 PMCID: PMC4151250 DOI: 10.1016/j.jmb.2006.10.097] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 10/26/2006] [Accepted: 10/30/2006] [Indexed: 12/16/2022]
Abstract
The function of the mammalian TIMELESS protein (TIM) has been enigmatic. TIM is essential for early embryonic development, but little is known regarding its biochemical and cellular function. Although identified based on similarity to a Drosophila circadian clock factor, it also shares similarity with a second family of proteins that is more widely conserved throughout eukaryotes. Members of this second protein family in yeast (S.c. Tof1p, S.p. Swi1p) have been implicated in DNA synthesis, S-phase-dependent checkpoint activation and chromosome cohesion, three processes coordinated at the level of the replication fork complex. The present work demonstrates that mammalian TIM and its constitutive binding partner, Tipin (ortholog of S.c. Csm3p, S.p. Swi3p), are replisome-associated proteins. Both proteins associate with components of the endogenous replication fork complex, and are present at BrdU-positive DNA replication sites. Knock-down of TIM also compromises DNA replication efficiency. Further, the direct binding of the TIM-Tipin complex to the 34 kDa subunit of replication protein A provides a biochemical explanation for the potential coupling role of these proteins. Like TIM, Tipin is also involved in the molecular mechanism of UV-dependent checkpoint activation and cell growth arrest. Tipin additionally associates with peroxiredoxin2 and appears to be involved in checkpoint responses to H(2)O(2), a role recently described for yeast versions of TIM and Tipin. Together, this work establishes TIM and Tipin as functional orthologs of their replisome-associated yeast counterparts capable of coordinating replication with genotoxic stress responses, and distinguishes mammalian TIM from the circadian-specific paralogs from which it was originally identified.
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Abstract
Mammalian TIMELESS (TIM) was identified due to its sequence similarity to Drosophila TIM, an essential circadian clock protein in flies. Published literature is inconsistent regarding the rhythmic expression of mammalian Tim, the interaction of the TIM protein with other clock proteins and its role in regulating clock gene transcription. Comprehensive sequence analysis not only demonstrates that mammalian TIM is more similar to a second, TIM-like sequence in Drosophila (TIMEOUT), but is also a member of an evolutionarily conserved family of TIM orthologs that is distinct from the circadian-specific TIM proteins found in insects. The vital cellular function of these widely conserved TIM orthologs makes it difficult to determine the specific role of mammalian TIM in the circadian clock mechanism.
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Gotter AL, Shaikh TH, Budarf ML, Rhodes CH, Emanuel BS. A palindrome-mediated mechanism distinguishes translocations involving LCR-B of chromosome 22q11.2. Hum Mol Genet 2003; 13:103-15. [PMID: 14613967 PMCID: PMC2818528 DOI: 10.1093/hmg/ddh004] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Two known recurrent constitutional translocations, t(11;22) and t(17;22), as well as a non-recurrent t(4;22), display derivative chromosomes that have joined to a common site within the low copy repeat B (LCR-B) region of 22q11.2. This breakpoint is located between two AT-rich inverted repeats that form a nearly perfect palindrome. Breakpoints within the 11q23, 17q11 and 4q35 partner chromosomes also fall near the center of palindromic sequences. In the present work the breakpoints of a fourth translocation involving LCR-B, a balanced ependymoma-associated t(1;22), were characterized not only to localize this junction relative to known genes, but also to further understand the mechanism underlying these rearrangements. FISH mapping was used to localize the 22q11.2 breakpoint to LCR-B and the 1p21 breakpoint to single BAC clones. STS mapping narrowed the 1p21.2 breakpoint to a 1990 bp AT-rich region, and junction fragments were amplified by nested PCR. Junction fragment-derived sequence indicates that the 1p21.2 breakpoint splits a 278 nt palindrome capable of forming stem-loop secondary structure. In contrast, the 1p21.2 reference genomic sequence from clones in the database does not exhibit this configuration, suggesting a predisposition for regional genomic instability perhaps etiologic for this rearrangement. Given its similarity to known chromosomal fragile site (FRA) sequences, this polymorphic 1p21.2 sequence may represent one of the FRA1 loci. Comparative analysis of the secondary structure of sequences surrounding translocation breakpoints that involve LCR-B with those not involving this region indicate a unique ability of the former to form stem-loop structures. The relative likelihood of forming these configurations appears to be related to the rate of translocation occurrence. Further analysis suggests that constitutional translocations in general occur between sequences of similar melting temperature and propensity for secondary structure.
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Nimmakayalu MA, Gotter AL, Shaikh TH, Emanuel BS. A novel sequence-based approach to localize translocation breakpoints identifies the molecular basis of a t(4;22). Hum Mol Genet 2003; 12:2817-25. [PMID: 12952865 DOI: 10.1093/hmg/ddg301] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Low copy repeats (LCRs) located in 22q11.2, especially LCR-B, are susceptible to rearrangements associated with several relatively common constitutional disorders. These include DiGeorge syndrome, Velocardiofacial syndrome, Cat-eye syndrome and recurrent translocations of 22q11 including the constitutional t(11;22) and t(17;22). The presence of palindromic AT-rich repeats (PATRRs) within LCR-B of 22q11.2, as well as within the 11q23 and 17q11 regions, has suggested a palindrome-mediated, stem-loop mechanism for the generation of such recurring constitutional 22q11.2 translocations. The mechanism responsible for non-recurrent 22q11.2 rearrangements is presently unknown due to the extensive effort required for breakpoint cloning. Thus, we have developed a novel fluorescence in-situ hybridization and primed in-situ hybridization (PRINS) approach and rapidly localized the breakpoint of a non-recurrent 22q11.2 translocation, a t(4;22). Multiple primer pairs were designed from the sequence of a 200 kb, chromosome 4, breakpoint-spanning BAC to generate PRINS probes. Amplification of adjacent primer pairs, labeled in two colors, allowed us to narrow the 4q35.1 breakpoint to a 6.7 kb clonable region. Application of our improved PRINS protocol facilitated fine-mapping the translocation breakpoints within 4q35.1 and 22q11.2, and permitted rapid cloning and analysis of translocation junction fragments. To confirm the PRINS localization results, PCR mapping of t(4;22) somatic cell hybrid DNA was employed. Analysis of the breakpoints demonstrates the presence of a 554 bp palindromic sequence at the chromosome 4 breakpoint and a 22q11.2 location within the same PATRR as the recurrent t(11;22) and t(17;22). The sequence of this breakpoint further suggests that a stem-loop secondary structure mechanism is responsible for the formation of other, non-recurrent translocations involving LCR-B of 22q11.2.
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Chang DC, McWatters HG, Williams JA, Gotter AL, Levine JD, Reppert SM. Constructing a feedback loop with circadian clock molecules from the silkmoth, Antheraea pernyi. J Biol Chem 2003; 278:38149-58. [PMID: 12869551 DOI: 10.1074/jbc.m306937200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Circadian clocks are important regulators of behavior and physiology. The circadian clock of Drosophila depends on an autoinhibitory feedback loop involving dCLOCK, CYCLE (also called dBMAL, for Drosophila brain and muscle ARNT-like protein), dPERIOD, and dTIMELESS. Recent studies suggest that the clock mechanism in other insect species may differ strikingly from that of Drosophila. We cloned Clock, Bmal, and Timeless homologs (apClock, apBmal, and apTimeless) from the silkmoth Antheraea pernyi, from which a Period homolog (apPeriod) has already been cloned. In Schneider 2 (S2) cell culture assays, apCLOCK:apBMAL activates transcription through an E-box enhancer element found in the 5' region of the apPeriod gene. Furthermore, apPERIOD can robustly inhibit apCLOCK: apBMAL-mediated transactivation, and apTIMELESS can augment this inhibition. Thus, a complete feedback loop, resembling that found in Drosophila, can be constructed from silkmoth CLOCK, BMAL, PERIOD, and TIMELESS. Our results suggest that the circadian autoinhibitory feedback loop discovered in Drosophila is likely to be widespread among insects. However, whereas the transactivation domain in Drosophila lies in the C terminus of dCLOCK, in A. pernyi, it lies in the C terminus of apBMAL, which is highly conserved with the C termini of BMALs in other insects (except Drosophila) and in vertebrates. Our analysis sheds light on the molecular function and evolution of clock genes in the animal kingdom.
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Gotter AL. Tipin, a novel timeless-interacting protein, is developmentally co-expressed with timeless and disrupts its self-association. J Mol Biol 2003; 331:167-76. [PMID: 12875843 DOI: 10.1016/s0022-2836(03)00633-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The mouse Timeless gene (mTim) was identified originally on the basis of its similarity to a Drosophila circadian gene, but has no substantiated role in the circadian clock mechanism. The importance of mTim in cellular processes involved in development, however, is undeniable, since targeted mutagenesis of this gene arrests embryonic development. To connect mTim to known pathways controlling cellular processes important for early development, a yeast two-hybrid approach was used to identify embryonic mTIM-interacting proteins. One positive interactor, a previously uncharacterized protein that is here termed TIPIN (TIMELESS interacting protein), was shown to interact with mTIM in vitro and in cultured cells. mTim and Tipin transcripts are co-expressed in similar tissues during embryonic development and in the adult brain. In transiently transfected cultures, mTIM promotes the nuclear localization of TIPIN. Immunoprecipitation experiments suggest that TIPIN is capable of regulating mTIM activity by disrupting the ability of mTIM to form homo-multimeric complexes. Together, these results indicate that mTIM forms a functional complex with TIPIN, and provide a starting point from which to link mTim to biochemical pathways controlling vital cellular functions.
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Froy O, Gotter AL, Casselman AL, Reppert SM. Illuminating the circadian clock in monarch butterfly migration. Science 2003; 300:1303-5. [PMID: 12764200 DOI: 10.1126/science.1084874] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Migratory monarch butterflies use a time-compensated Sun compass to navigate to their overwintering grounds in Mexico. Here, we report that constant light, which disrupts circadian clock function at both the behavioral and molecular levels in monarchs, also disrupts the time-compensated component of flight navigation. We further show that ultraviolet light is important for flight navigation but is not required for photic entrainment of circadian rhythms. Tracing these distinct light-input pathways into the brain should aid our understanding of the clock-compass mechanisms necessary for successful migration.
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Abstract
The molecular mechanism of the circadian pacemaker depends on the oscillatory expression of clock gene constituents. The Drosophila period gene is central to the clock mechanism in these animals. Three homologs of this gene identified in mice (mPer1-3) and humans (hPer1-3) display rhythmic expression and are important for normal clock function. Recently, analysis of the draft sequence of the human genome has revealed the presence of a fourth Per gene family member. Surprisingly, the deduced hPer4 cDNA has no open reading frame encoding a full-length PER-like protein. This sequence is characterized by numerous deletions, insertions, frame shifts and base pair changes, and its genomic structure is devoid of introns. The presence of an MER-2 mobile element fossil within the Per4 locus predicted that this gene would also be present in non-human primates. Rhesus monkey Per4 displays similar sequence anomalies and is 92.8% identical to hPer4. Sequence comparisons indicate that Per4 originated from a Per3 predecessor and that it is relatively new to the Period gene family. We conclude that hPer4 and RmPer4 are pseudogenes and descended from the retrotransposition of an ancestral Per3 gene.
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Gotter AL, Manganaro T, Weaver DR, Kolakowski LF, Possidente B, Sriram S, MacLaughlin DT, Reppert SM. A time-less function for mouse timeless. Nat Neurosci 2000; 3:755-6. [PMID: 10903565 DOI: 10.1038/77653] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The timeless (tim) gene is essential for circadian clock function in Drosophila melanogaster. A putative mouse homolog, mTimeless (mTim), has been difficult to place in the circadian clock of mammals. Here we show that mTim is essential for embryonic development, but does not have substantiated circadian function.
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Gotter AL, Levine JD, Reppert SM. Sex-linked period genes in the silkmoth, Antheraea pernyi: implications for circadian clock regulation and the evolution of sex chromosomes. Neuron 1999; 24:953-65. [PMID: 10624958 DOI: 10.1016/s0896-6273(00)81042-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Regulation of the period (per) gene is a critical feature of circadian clock function in insects. Here, we show that per is sex-linked in the silkmoth, Antheraea per-nyi. The previously described silkmoth per gene is found on the Z chromosome. Silkmoth per is not dosage compensated at either the RNA or the protein level. Although earlier studies showed the presence of an oscillating endogenous antisense per transcript, we show that this transcript comes from a locus on the female-specific W chromosome. We further demonstrate the presence of a homolog of per on W that encodes a truncated protein. Rhythmicity of male (ZZ) moths demonstrates that neither of the W-linked per-like genes is essential for clock function. The presence of a per allele with duplications on W provides insight into the evolution of the sex chromosomes.
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