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Rapid genomic changes induced by PTH, SIK-inhibition, FGF23, and 1,25(OH)2D3 in the mouse kidney

ABSTRACT: In vivo ChIP-seq in mouse kidney: we examine the genomic recruitment of VDR, RXR, pCREB, CBP, CRTC2 (TORC2), SRC1, SRC3, BRD4, RNApolII, H3K9ac, H3K27ac, and H3K36me3 after intraperitoneal injection of 10 mg/kg body weight (bw) 1,25(OH)2D3 (in propylene glycol), 230 mg/kg bw PTH (1–84) (in phosphate buffered saline (PBS)), 50 mg/kg bw FGF23 (in PBS + 0.1% BSA), 30 mg/kg YKL-05-099 (PBS + 25mM HCl), 40 mg/kg SK-124 (15% HPBCD (hydroxypropyl β-cyclodextrin)), or vehicle (EtOH, PBS, or HPBCD). YKL-05-099 and SK-124 are salt-inducible kinase inhibitors that liberate CRTC2 from sequestration in the cytoplasm and allow CRTC2 translocation to the nucleus. Our findings show that these TFs and coactivators contribute to transcription of genes in the kidney involved in vitamin D metabolism, demonstrates SIK-inhibition as a key modulator of vitamin D metabolism, and provides molecular insight into the coordinated mechanistic actions of PTH, FGF23, and 1,25(OH)2D3 in the mouse kidney that regulate mineral homeostasis.

ORGANISM(S): Mus musculus

PROVIDER: GSE206777 | GEO | 2022/09/30

REPOSITORIES: GEO

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Project description:Human kidney was obtained from the University of Wisconsin Madison Organ Procurement Program from a deceased 69 year old female patient and the cortex was dissected from 3 different cortex locations. Associated publication abstract: Targeted genomic deletions identify diverse enhancer functions and generate a kidney-specific, endocrine-deficient Cyp27b1 pseudo-null mouse Vitamin D3 is terminally bioactivated in the kidney to 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) via cytochrome P450 family 27 subfamily B member 1 (CYP27B1), whose gene is regulated by parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and 1,25(OH)2D3. Our recent genomic studies in the mouse have revealed a complex kidney-specific enhancer module within the introns of adjacent methyltransferase like 1 (Mettl1) and Mettl21b that mediate basal and PTH induced expression of Cyp27b1 and FGF23- and 1,25(OH)2D3-mediated repression. Gross deletion of these segments in mice has severe consequences on Cyp27b1 regulation and skeletal phenotype, but does not affect Cyp27b1 expression in non-renal target cells (NRTCs). Here, we report a bimodal activity in the Mettl1 intronic enhancer with components responsible for PTH-mediated Cyp27b1 induction and 1,25(OH)2D3-mediated repression and additional activities, including FGF23 repression, within the Mettl21b enhancers. Deletion of both submodules eliminated basal Cyp27b1 expression and regulation in the kidney, leading to systemic and skeletal phenotypes similar to those of Cyp27b1-null mice. However, basal expression and lipopolysaccharide-induced regulation of Cyp27b1 in NRTCs was unperturbed. Importantly, dietary normalization of calcium, phosphate, PTH, and FGF23 rescued the skeletal phenotype of this mutant mouse, creating an ideal in vivo model to study non-renal 1,25(OH)2D3 production in health and disease. Finally, we confirmed a conserved chromatin landscape in human kidney that is similar to that in mouse. These findings define a finely balanced homeostatic mechanism involving PTH and FGF23 together with protection from 1,25(OH)2D3 toxicity that is responsible for both adaptive vitamin D metabolism and mineral regulation.

Project description: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)2D3), its precursor (calcifediol, 25(OH)D3), and numerous other vitamin D metabolites at the 23- and 24-carbon positions. Cyp24a1 gene expression is induced by 1,25(OH)2D3 in all tissues that contain the vitamin D receptor in a feedback mechanism. In the kidney, Cyp24a1 is induced by 1,25(OH)2D3, induced by FGF23, and potently suppressed by PTH to tightly control the circulating blood levels of 1,25(OH)2D3. This gene is known 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 collection was found to respond to PTH and FGF23 actions in a kidney-specific manner. The DS2 enhancers were found to assist in the response of 1,25(OH)2D3 in kidney, as well as other target tissues. Despite this knowledge, there remain several outstanding questions for the regulation of Cyp24a1 such as the in vivo contribution of the PRO VDREs to expression and the chromatin architecture of the locus, what drives Cyp24a1 basal expression in the kidney, how FGF23 activates Cyp24a1, and importantly, how PTH suppresses Cyp24a1. 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 more proximal VDRE (VDRE1) 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)2D3 induction in the intestine. FGF23 induction of Cyp24a1 was reduced with mutation of the PRO VDREs, however, co-treatment of 1,25(OH)2D3 and FGF23 synergistically increased Cyp24a1 expression even with the loss of the PRO VDREs. PTH suppression of Cyp24a1 expression was unchanged with PRO VDRE mutations, despite a minor reduction in total pCREB occupancy that remained unaffected by PTH treatment. 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)2D3 and FGF23, and despite the overall reduction of CREB on the genome it was unchanged with PTH treatment indicating that suppression either does not rely on CREB or that the PRO VDREs are unconnected to PTH suppression altogether. These studies help further define the interconnected genomic control of these hormones on vitamin D catabolism.

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Rapid genomic changes induced by PTH, SIK-inhibition, FGF23, and 1,25(OH)2D3 in the mouse kidney

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