E3 ubiquitin ligase HRD1 modulates the circadian clock through regulation of BMAL1 stability

α-Synuclein-Induced Destabilized BMAL1 mRNA Leads to Circadian Rhythm Disruption in Parkinson's Disease

Circadian dysfunction is a common non-motor symptom in Parkinson's disease (PD). The potential influence of aggravated α-synuclein (SNCA) on circadian disruption remains unclear. SNCA^A53T-overexpressing transgenic mice (SNCA^A53T mice) and wild-type (WT) littermates were used in this study. The energy metabolism cage test showed differences in 24-h activity pattern between SNCA^A53T and WT mice. When compared with the age-matched littermates, brain and muscle ARNT-like 1 (BMAL1) was downregulated in SNCA^A53T mice. BMAL1 was downregulated in PC12 cells overexpressing SNCA. Degradation of BMAL1 protein remained unchanged after overexpression of SNCA, while its mRNA level decreased. miRNA (miR)-155 was upregulated by overexpression of SNCA, and downregulation of BMAL1 was partially reversed by transfection with miR-155 inhibitor. Our findings demonstrated that overexpression of SNCA induced biorhythm disruption and downregulated BMAL1 expression through decreasing stability of BMAL1 mRNA via miR-155.

Impact of Exposure to Chronic Light-Dark Phase Shifting Circadian Rhythm Disruption on Muscle Proteome in Periparturient Dairy Cows

Muscle tissue serves as a key nutrient reservoir that dairy cows utilize to meet energy and amino acid requirements for fetal growth and milk production. Circadian clocks act as homeostatic regulators so that organisms can anticipate regular environmental changes. The objective of this study was to use liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine how chronic circadian disruption in late gestation affected the muscle tissue proteome. At five weeks before expected calving (BEC), multiparous Holstein cows were assigned to either a control (CON, n = 8) or a 6 h forward phase shift (PS, n = 8) of the light-dark cycle every 3 days. At calving, all animals were exposed to CON light-dark cycles. Muscle biopsies were collected from longissimus dorsi muscles at 21 days BEC and at 21 days postpartum (PP). At p < 0.1, 116 and 121 proteins were differentially abundant between PS and CON at 21 days BEC and 21 days PP, respectively. These proteins regulate beta oxidation and glycolysis. Between pregnancy and lactation, 134 and 145 proteins were differentially abundant in CON and PS cows, respectively (p < 0.1). At both timepoints, PS cows exhibited an oxidative stress signature. Thus, dairy cattle management strategies that minimize circadian disruptions may ensure optimal health and production performance.