tailieunhanh - Báo cáo khoa học: Prokineticin 2 and circadian clock output

Circadian timing from the suprachiasmatic nucleus (SCN) is a critical component of sleep regulation. Animal lesion and genetic studies have indi-cated an essential interaction between the circadian signals and the homeo-static processes that regulate sleep. Here we summarize the biological functions of prokineticins, a pair of newly discovered regulatory proteins, with focus on the circadian function of prokineticin 2 (PK2) and its poten-tial role in sleep-wake regulation. | ềFEBS Journal MINIREVIEW Prokineticin 2 and circadian clock output Qun-Yong Zhou and Michelle Y. Cheng Department of Pharmacology University of California Irvine CA USA Keywords circadian G-protein coupled receptor locomotor PK2 prokineticin secretory protein sleep wakefulness suprachiasmatic nucleus Correspondence Qun-Yong Zhou Department of Pharmacology University of California Irvine CA 92697-4625 USA Fax 1 949 824 4855 Tel 1 949 824 2232 E-mail qzhou@ Received 21 June 2005 accepted 15 September 2005 Circadian timing from the suprachiasmatic nucleus SCN is a critical component of sleep regulation. Animal lesion and genetic studies have indicated an essential interaction between the circadian signals and the homeostatic processes that regulate sleep. Here we summarize the biological functions of prokineticins a pair of newly discovered regulatory proteins with focus on the circadian function of prokineticin 2 PK2 and its potential role in sleep-wake regulation. PK2 has been shown as a candidate SCN output molecule that regulates circadian locomotor behavior. The PK2 molecular rhythm in the SCN is predominantly controlled by the circadian transcriptional translational loops but also regulated directly by light. The receptor for PK2 is expressed in the primary SCN output targets that regulate circadian behavior including sleep-wake. The depolarizing effect of PK2 on neurons that express PK2 receptor may represent a possible mechanism for the regulatory role of PK2 in circadian rhythms. doi Introduction The regulation of sleep has been modeled as a two-process system consisting of a homeostatic process and a circadian timing process which together determine the propensity length and incidence of episodes and intensity of sleep 1 . The circadian control of sleep is evident because the sleep-wake cycle continues on a near 24 h basis even when the environment is devoid of any timing cues 2 3 . Early studies in rats with lesions .