Dietary Salt Impairs Circadian Physiological Metabolic Adaptations in Salt-Sensitive Hypertension
The body's circadian rhythm is coordinated by a central hypothalamic and peripheral molecular clocks, which involve clock proteins (PER, CRY, CLOCK, and BMAL1). Our recent study demonstrated that deletion of Per1 in Dahl salt-sensitive (SS) rats (SSPer1-/-) exacerbated SS hypertension (HTN), kidney injury, and disrupted blood pressure rhythms. To define time-of-day, genotype-, and diet-dependent alterations in the renal transcriptome and proteome associated with SS HTN, we collected kidney cortex from SS and SSPer1-/- rats fed either a normal salt (NS, 0.4% NaCl) or high salt (HS, 4% NaCl) diet. Samples were obtained during both the active (night) and inactive (day) phases. The diet challenges were conducted for 3 weeks in male rats. Bulk RNA-sequencing was performed on both NS and HS-fed groups, and proteomic analyses were performed in HS-fed groups. In SS rats, HS intake markedly blunted time-of-day-dependent transcriptional changes, including reduced differential expression of core circadian genes such as Bmal1 and Nr1d1 when transitioning from the inactive to the active phase. Pathway analyses revealed significant stress and immune response, as well as metabolic adaptations caused by the HS diet. Specifically, the remodeling of the pyruvate dehydrogenase complex was identified as a key prediction in both transcriptomic and phosphoproteomic datasets. As anticipated, Per1 deletion further exacerbated disruptions in immune regulation and metabolic adaptation. Collectively, our findings demonstrate that numerous renal genes exhibit diurnal oscillations under physiological conditions and are profoundly disrupted in SS HTN, likely contributing to impaired kidney function and circadian misalignment of blood pressure regulation. Overall design: To define time-of-day, genotype-, and diet-dependent alterations in the renal transcriptome and proteome associated with SS HTN, we collected kidney cortex from SS and SSPer1-/- rats fed either a normal salt (NS, 0.4% NaCl) or high salt (HS, 4% NaCl) diet. Samples were obtained during both the active (night) and inactive (day) phases. The diet challenges were conducted for 3 weeks in male rats. Bulk RNA-sequencing was performed on both NS and HS-fed groups, and proteomic analyses were performed in HS-fed groups.