Circadian rhythms are generated by transcriptional and translational feedback loops. Stress-activated protein kinases (SAPKs) are known to regulate transcription factors in response to a variety of extracellular stimuli. In the present study, we examined whether the SAPKs play a role in the circadian system in cultured Xenopus retinal photoreceptor layers. A 6-h pulse of SB 203580, an inhibitor of SAPKs, reset the circadian rhythm of melatonin in a phase-dependent manner similar to dark pulses. This phase-shifting effect was dose-dependent over the range of 1-100 microm. Treatment with SB 203580 also affected light-induced phase shifts, and light had no effect on the circadian oscillator in the presence of 100 microm SB 203580. In-gel kinase assays showed that SB 203580 selectively inhibited a small group of protein kinases in the photoreceptor cells. These SB 203580-sensitive kinases correspond to two isoforms of phosphorylated p38 MAPK and three isoforms of c-Jun N-terminal kinase (JNK). Further in vitro study demonstrated that SB 203580 also inhibited casein kinase Iepsilon (CKIepsilon), which has been shown to regulate circadian rhythms in several organisms. However, a pharmacological inhibition of CKI reset the circadian oscillator in a phase-dependent manner distinct from that of SB 203580. This argues against a primary role of CKI in the phase-shifting effects of SB 203580. These results suggest that SB 203580 affects the circadian system by inhibiting p38 MAPKs or JNKs and that these protein kinases are candidate cellular signals in the regulation of the circadian oscillator in the Xenopus retinal photoreceptors.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1074/jbc.M401389200 | DOI Listing |
Plant Cell Environ
January 2025
Department of Biology, Trivedi School of Biosciences, Ashoka University, Sonipat, India.
Circadian clocks execute temporal regulation of metabolism by modulating the timely expression of genes. Clock regulation of mRNA synthesis was envisioned as the primary driver of these daily rhythms. mRNA oscillations often do not concur with the downstream protein oscillations, revealing the importance to study protein oscillations.
View Article and Find Full Text PDFImmunology
January 2025
Oncology Department, The Affiliated Changzhou Second People's Hospital of Nanjing Medical University, Changzhou Second People's Hospital, Changzhou, China.
Circadian rhythm is a physiological process that oscillates in a 24 h cycle. It has a complex connection with the function of the human immune system and even with the development of tumours. Previous studies demonstrated the time-dependent effects of chemotherapy and radiotherapy; however, there are few studies on the timing effects of immunotherapy.
View Article and Find Full Text PDFNew Phytol
January 2025
Instituto de Investigaciones Forestales y Agropecuarias Bariloche, Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Bariloche - Consejo Nacional de Investigaciones Científicas y Técnicas (INTA EEA Bariloche-CONICET), San Carlos de Bariloche, Río Negro, R8403DVZ, Argentina.
Plant survival in a warmer world requires the timely adjustment of biological processes to cyclical changes in the new environment. Circadian oscillators have been proposed to contribute to thermal adaptation and plasticity. However, the influence of temperature on circadian clock performance and its impact on plant behaviour in natural ecosystems are not well-understood.
View Article and Find Full Text PDFInvest Ophthalmol Vis Sci
January 2025
Department of Ophthalmology, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China.
Purpose: Chronic jet lag (CJL) is known to disrupt circadian rhythms, which regulate various physiological processes, including ocular surface homeostasis. However, the specific effects of CJL on lacrimal gland function and the underlying cellular mechanisms remain poorly understood.
Methods: A CJL model was established using C57BL/6J mice.
Proc Natl Acad Sci U S A
January 2025
Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, MA 02115.
Sleep spindles are cortical electrical oscillations considered critical for memory consolidation and sleep stability. The timing and pattern of sleep spindles are likely to be important in driving synaptic plasticity during sleep as well as preventing disruption of sleep by sensory and internal stimuli. However, the relative importance of factors such as sleep depth, cortical up/down-state, and temporal clustering in governing sleep spindle dynamics remains poorly understood.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!