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Vitamin D and soluble Klotho inhibit FGF23-mediated cardiac hypertrophy in Chronic Kidney Disease

Award Number: F31DK115074
ORGANIZATION: NATIONAL INSTITUTE OF DIABETES & DIGESTIVE & KIDNEY DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: FELLOWSHIP/SCHOLARSHIP/STUDENT LOANS

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PROJECT SUMMARY Chronic kidney disease (CKD) is a public health problem that increases the risk of cardiovascular disease and death. By promoting heart failure, cardiac hypertrophy is an important pathology in CKD and affects up to 90% of patients by the time they reach dialysis. Elevated serum levels of bone-derived fibroblast growth factor (FGF) 23 are a common, early metabolic complication of CKD that is strongly associated with cardiovascular events and mortality. In recent experimental studies, we demonstrated that in this context, FGF23 might act as a causal factor by directly targeting cardiac myocytes and inducing cardiac hypertrophy. We could show that FGF23 can specifically activate FGF receptor isoform 4 (FGFR4) and subsequent PLC¿/calcineurin/NFAT signaling leading to hypertrophic growth of cardiac myocytes that occurs independently of elevations in blood pressure. Administration of an FGFR4-specific blocking antibody reduced cardiac hypertrophy in the 5/6 nephrectomy rat model of CKD, suggesting that pharmacological interference with myocardial FGF23/FGFR4 signaling might serve as a novel cardio-protective therapeutic approach in CKD. Here, we will study if active vitamin D (VitD) and soluble klotho (sKL), two endocrine factors with known cardio-protective functions and whose serum levels are significantly reduced in CKD, confer their anti-hypertrophic actions by blocking FGF23/FGFR4/PLC¿/calcineurin/NFAT signaling in cardiac myocytes. This hypothesis is supported by our preliminary data showing that sKL and VitD block FGF23-induced hypertrophic growth of cultured cardiac myocytes. In Aim 1, we will determine if these inhibitory actions of sKL and VitD are associated with a reduction in FGF23-induced PLC¿ and NFAT activity. Our preliminary work indicates that VitD inhibits the FGFR4/PLC¿ interaction in FGF23-stimulated cardiac myocytes, and we will study if activated VitD receptor (VDR) can directly bind PLC¿ and/or FGFR4 to block PLC¿ activation post FGF23 treatment. Klotho is a transmembrane protein that binds to FGFRs and acts as co-receptor for FGF23 in the kidney. Here, we will determine if sKL can also interact with FGF23 and/or FGFR4 thereby blocking FGF23/FGFR4 binding and subsequent PLC¿/calcineurin/NFAT signaling in cardiac myocytes. It has been shown that administration of VitD or sKL in rodent models of CKD reduces cardiac hypertrophy, and our preliminary data in 5/6 nephrectomized rats indicates that VitD inhibits myocardial calcineurin/NFAT activity. In Aim 2, we will determine if delivery of VitD or sKL can block FGFR4/PLC¿/calcineurin/NFAT signaling in 5/6 nephrectomized rats and reduce cardiac hypertrophy. Furthermore, we will study if administration of VitD or sKL to an established genetic mouse model for cardiac hypertrophy induced by expression of a constitutively active FGFR4 mutant form, inhibits FGFR4/PLC¿/calcineurin/NFAT signaling and improves cardiac morphology and function. We postulate that by interfering with FGF23-induced cardiac hypertrophy, administration of sKL and VitD might serve as a novel therapeutic strategy to tackle cardiac injury and death in patients with CKD.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2022 ( Subtotal = -$590 )
2022	2019	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	001	3	4/22/2022	NON-COMPETING CONTINUATION	-$590
2022	2018	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	2	4/22/2022	NON-COMPETING CONTINUATION	$0
														Subtotal = -$590

Issue Date FY: 2019 ( Subtotal = $35,820 )
2019	2019	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	3	8/1/2019	NON-COMPETING CONTINUATION	$35,820
														Subtotal = $35,820

Issue Date FY: 2018 ( Subtotal = $35,328 )
2018	2018	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	2	8/20/2018	NON-COMPETING CONTINUATION	$35,328
														Subtotal = $35,328

Issue Date FY: 2017 ( Subtotal = $34,848 )
2017	2017	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	002	1	9/4/2017	NEW	$0
2017	2017	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	1	9/1/2017	NEW	$34,848
2017	2017	UNIVERSITY OF ALABAMA AT BIRMINGHAM	701 S 20TH ST	BIRMINGHAM	AL	35294	JEFFERSON	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	001	1	9/4/2017	NEW	$0
														Subtotal = $34,848

Grand Total All Awards = $105,406

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Vitamin D and soluble Klotho inhibit FGF23-mediated cardiac hypertrophy in Chronic Kidney Disease

Award Number: F31DK115074

ORGANIZATION: NATIONAL INSTITUTE OF DIABETES & DIGESTIVE & KIDNEY DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: FELLOWSHIP/SCHOLARSHIP/STUDENT LOANS

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