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Introduction Vitamin D plays a critical role in bone and mineral metabolism and also controls other physiologic and pathophysiologic processes, including skeletal muscle function, reproductive health, cancer risk and progression, [...], The renal actions of parathyroid hormone (PTH) promote 1,25-vitamin D generation; however, the signaling mechanisms that control PTH-dependent vitamin D activation remain unknown. Here, we demonstrated that salt-inducible kinases (SIKs) orchestrated renal 1,25-vitamin D production downstream of PTH signaling. PTH inhibited SIK cellular activity by cAMP-dependent PKA phosphorylation. Whole-tissue and single-cell transcriptomics demonstrated that both PTH and pharmacologic SIK inhibitors regulated a vitamin D gene module in the proximal tubule. SIK inhibitors increased 1,25-vitamin D production and renal Cyp27b1 mRNA expression in mice and in human embryonic stem cell-derived kidney organoids. Global- and kidney-specific Sik2/Sik3 mutant mice showed Cyp27b1 upregulation, elevated serum 1,25- vitamin D, and PTH-independent hypercalcemia. The SIK substrate CRTC2 showed PTH and SIK inhibitor-inducible binding to key Cyp27b1 regulatory enhancers in the kidney, which were also required for SIK inhibitors to increase Cyp27b1 in vivo. Finally, in a podocyte injury model of chronic kidney disease-mineral bone disorder (CKD-MBD), SIK inhibitor treatment stimulated renal Cyp27b1 expression and 1,25-vitamin D production. Together, these results demonstrated a PTH/SIK/CRTC signaling axis in the kidney that controls Cyp27b1 expression and 1,25-vitamin D synthesis. These findings indicate that SIK inhibitors might be helpful for stimulation of 1,25-vitamin D production in CKD-MBD.

CYP24A1 is a multifunctional, P450 mitochondrial enzyme that catabolizes the vitamin D hormone (calcitriol, 1,25(OH)2D3), its precursor (calcifediol, 25(OH)D3), and numerous vitamin D metabolites. In the kidney, Cyp24a1 is induced by 1,25(OH)2D3 and fibroblast growth factor 23 (FGF23) and potently suppressed by PTH to control the circulating levels of 1,25(OH)2D3. Cyp24a1 is controlled by a pair of promoter proximal (PRO) vitamin D response elements (VDREs) that are aided by distal, downstream (DS) enhancers. The downstream 1 region of Cyp24a1 (DS1) enhancer is kidney-specific and responsible for PTH and FGF23 actions, and the downstream 2 region of Cyp24a1 enhancer responds to 1,25(OH)2D3 in all tissues. Despite this knowledge, in vivo contributions of the PRO VDREs to basal expression, FGF23 activation, and PTH suppression of Cyp24a1 remain unknown. In this study, we selectively mutated the PRO VDREs in the mouse to address these questions. We found mutation of the VDREs leads to a dramatic loss of VDR occupancy, a reduction of 1,25(OH)D3-induced kidney Cyp24a1 expression, and near elimination of intestinal Cyp24a1 induction. FGF23 induction of Cyp24a1 was reduced but not eliminated and still showed a synergistic increase with 1,25(OH)2D3. PTH suppression of Cyp24a1 was unchanged, despite minor reductions in total for phosphorylated cAMP-response element binding protein occupancy. Finally, VDR recruitment was dramatically reduced across the DS enhancers in the Cyp24a1 locus. Taken together, our data suggest a cooperative relationship between the DS and PRO enhancers in the regulation of Cyp24a1 by 1,25(OH)2D3 and FGF23 and points to the DS1 region as a crucial basal switch for Cyp24a1 activity that further defines the interconnected genomic control in vitamin D catabolism. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to identify a preference-based health-related quality of life (HRQOL) measure that best reflects disease-specific features in patients with neck pain by comparing the characteristics of the instruments., Design: Pooled data from three multicentre randomised controlled clinical trials (RCTs) on neck pain were included for analysis in this study., Setting: All three RCTs were conducted between 2017 and 2020 in Korea, and patients were recruited from four hospitals and one university teaching hospital., Participants: In total, 313 patients with neck pain were included in the three RCTs., Primary and Secondary Outcome Measures: A correlation analysis was conducted using Spearman's correlation coefficients between preference-based HRQOL scores (EuroQol-5 Dimension 5 Levels (EQ-5D-5L) and Short-Form 6-Dimension version 1 (SF-6Dv1)) and the disease-specific measures for pain and function (Numerical Rating Scale (NRS), Visual Analogue Scale (VAS), Neck Disability Index (NDI) and Northwick Park Questionnaire)., Results: Spearman's correlation analyses (p value <0.01 for all) showed that EQ-5D-5L exhibited slightly stronger negative correlations with pain-related measures (VAS: -0.277, NRS: -0.262) compared with SF-6Dv1 (VAS: -0.207, NRS: -0.182). For functional outcomes, EQ-5D-5L demonstrated stronger negative correlations with function-related measures such as NDI (-0.636 to -0.711) compared with SF-6Dv1 (-0.506 to -0.579). In patients with moderate-to-severe neck pain (VAS>5), EQ-5D-5L appeared to better capture functional and pain aspects. Despite these differences, both instruments consistently reflected treatment-related improvements in pain and function. Distribution analysis further indicated that EQ-5D-5L and SF-6Dv1 were not fully interchangeable due to variations in domain-level scoring patterns and ceiling effects observed in EQ-5D-5L., Conclusions: EQ-5D-5L showed stronger negative correlations with both pain and functional outcomes compared with SF-6Dv1, suggesting that it may better capture the functional aspects of chronic neck pain, particularly in moderate-to-severe conditions. However, the ceiling effect observed in EQ-5D-5L warrants caution when interpreting results in patients with mild neck pain. These findings provide practical guidance for selecting preference-based HRQOL measures in economic evaluations of musculoskeletal conditions, supporting more informed healthcare decision-making.Trial registration numberNCT03294785, Post-results; NCT03558178, Results; NCT04035018, Post-results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.)

CYP24A1 is a multifunctional, P450 mitochondrial 24-hydroxylase enzyme that is responsible for catabolism of the most active vitamin D hormone (calcitriol, 1,25(OH) 2 D 3 ), its precursor (calcifediol, 25(OH)D 3 ), and numerous other vitamin D metabolites at the 23- and 24-carbon positions. In the kidney, Cyp24a1 is induced by 1,25(OH) 2 D 3 , induced by FGF23, and potently suppressed by PTH to tightly control the circulating blood levels of 1,25(OH) 2 D 3 . This gene is believed to be under the control of a pair of classic promoter proximal (PRO) vitamin D response elements (VDREs) that are aided by distal, downstream (DS) containing enhancers that we identified more recently. The DS1 enhancer cluster was found to respond to PTH and FGF23 actions in a kidney-specific manner. The DS2 enhancer cluster was found to assist in the response of 1,25(OH) 2 D 3 in kidney, as well as other target tissues. Despite this knowledge, the in vivo contribution of the PRO VDREs to gene expression, what drives Cyp24a1 basal expression in the kidney, how FGF23 activates Cyp24a1 , and importantly, how PTH suppresses Cyp24a1 , all remain unknown. Here in this study, we utilize homology directed CRISPR to mutate one or both VDREs in the PRO region of the Cyp24a1 gene in vivo in the mouse to address these questions. We found that the VDRE (VDRE1) more proximal to the to the transcriptional start site (TSS) is the dominant VDRE of the pair and mutation of both VDREs leads to a dramatic loss of VDR, a reduction of Cyp24a1 gene expression in the kidney, and a near elimination of 1,25(OH) 2 D 3 induction in the intestine. FGF23 induction of Cyp24a1 was reduced with mutation of the PRO VDREs, however, co-treatment of 1,25(OH) 2 D 3 and FGF23 synergistically increased Cyp24a1 expression even with the loss of the PRO VDREs. PTH suppression of Cyp24a1 gene expression was unchanged with PRO VDRE mutations, despite a minor reduction in total pCREB occupancy. Finally, VDR occupancy was dramatically reduced across the DS enhancers in the Cyp24a1 locus after the PRO VDREs mutation. Taken together, our data suggest a cooperative relationship between the DS and PRO enhancers in the regulation of Cyp24a1 by 1,25(OH) 2 D 3 and FGF23, and despite the overall reduction of CREB on the genome it appeared that suppression either does not rely on CREB or that the PRO VDREs are unconnected to PTH suppression altogether. These studies point to the DS1 region as a basal switch for Cyp24a1 expression and help further define the interconnected genomic control of these hormones on vitamin D catabolism., Competing Interests: Conflict of interest: The authors declare no conflicts of interest with the contents of this article.

The immune benefits of vitamin D3 supplementation beyond calcium and phosphate maintenance are highly clinically debated. Kidney expression of CYP27B1 is the source of endocrine, circulating 1,25(OH)2D3 (active form of vitamin D) that maintains serum calcium and phosphate. 1,25(OH)2D3 may also be made by the CYP27B1 enzyme in nonrenal cells, like immune cells, in a process driven by cellular availability of 25(OH)D3 and inflammation. Due to the endocrine nature of 1,25(OH)2D3 in circulation, it is difficult to discern between these 2 sources. We recently created a regulatory deletion model of Cyp27b1 (M1/M21-DIKO) where mice have normal inflammatory-regulated Cyp27b1 expression in nonrenal tissues (unlike global Cyp27b1-KO) but no expression within the kidney. Here, utilizing on-tissue chemical derivatization and matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI), we investigated the distribution of 1,25(OH)2D3 and 25(OH)D3 in the kidney, liver, spleen, and thymus. MALDI-MSI demonstrated increased 1,25(OH)2D3 in nonrenal tissues such as the spleen after vitamin D3 supplementation in M1/M21-DIKO mice. Additionally, from this, we found increased Il4 and decreased Tnfa in the spleen after vitamin D3 supplementation. Taken together, these data demonstrate nonrenal production of 1,25(OH)2D3 in vivo and provide a consequence of vitamin D3 supplementation and nonrenal 1,25(OH)2D3 production in cytokine changes.