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ArpC3-mediated actin remodeling in insulin granule exocytosis and diabetes

Award Number: R01DK132088
ORGANIZATION: NATIONAL INSTITUTE OF DIABETES & DIGESTIVE & KIDNEY DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 01/01/2023
PERIOD OF PERFORMANCE END DATE: 12/31/2026

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ArpC3-mediated actin remodeling in insulin granule exocytosis and diabetes - PROJECT SUMMARY Insulin secretion deficiency is a hallmark of diabetes. In this process, the cortical actin of β cells has recently been recognized as a critical player contributing to diabetes pathogenesis. β cells from type-2 diabetes (T2D) patients show significant signaling alteration associated with cortical actin remodeling, and restoring such abnormality rescues insulin secretion to normal levels. Cortical actin is thought initially as a simple barrier to prevent insulin secretion, but recent studies challenge this view and imply an active role. Mounting evidence further indicates that cortical actin is a converging point and effector of multiple metabolic signals in β cells. However, the molecule and nanostructure basis of its remodeling remains unresolved. Addressing this question becomes imperative to understanding the regulation of insulin secretion and developing new therapeutics to restore β cell function in T2D. This proposal will investigate ArpC3, a gene encoding a subunit of the Arp2/3 complex that dictates actin filament branching and cortical remodeling. Although multiple signaling pathways converge on Arp2/3, the mechanism downstream Arp2/3 activity to regulate insulin secretion remains unknown. Based on recent progress in the field and our new data on β cell imaging and functional assays, we hypothesize that ArpC3-dependent actin polymerization regulates insulin exocytosis by driving the local cortical actin disassembly-reassembly cycles. Through this remodeling, cortical actin filaments may actively coordinate the critical steps of granule trafficking and insulin secretion. We have assembled a team of investigators with expertise in diabetes, β cell biology, vesicle trafficking, and super-resolution microscopy to test this hypothesis. We will focus on three specific aims. First, determine the in vivo role of ArpC3-mediated cortical actin remodeling in insulin secretion and glucose homeostasis. We have generated a new mouse model where ArpC3 is deleted selectively in adult β cells to ablate Arp2/3 activity and cortical actin branching. Second, define ArpC3 function in cortical actin nano-remodeling and its role in insulin granule recruitment, docking, and exocytosis. Third, evaluate the role of cortical actin branching in human β cells and its dysfunction in T2D patients. The results from this work will fill a long-standing knowledge gap between cortical actin remodeling and insulin secretion, providing mechanistic insights into T2D pathogenesis induced by cortical actin dysfunction.


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: 2025 ( Subtotal = $351,000 )
2025	2025	THE MEDICAL COLLEGE OF WISCONSIN, INC.	8701 WATERTOWN PLANK RD	MILWAUKEE	WI	53226	MILWAUKEE	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	3	12/12/2024	NON-COMPETING CONTINUATION	$351,000
														Subtotal = $351,000

Issue Date FY: 2024 ( Subtotal = $374,400 )
2024	2024	THE MEDICAL COLLEGE OF WISCONSIN, INC.	8701 WATERTOWN PLANK RD	MILWAUKEE	WI	53226	MILWAUKEE	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	001	2	5/8/2024	NON-COMPETING CONTINUATION	$23,400
2024	2024	THE MEDICAL COLLEGE OF WISCONSIN, INC.	8701 WATERTOWN PLANK RD	MILWAUKEE	WI	53226	MILWAUKEE	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	2	12/18/2023	NON-COMPETING CONTINUATION	$351,000
														Subtotal = $374,400

Issue Date FY: 2023 ( Subtotal = $390,000 )
2023	2023	MEDICAL COLLEGE OF WISCONSIN, INC., THE	8701 WATERTOWN PLANK RD	MILWAUKEE	WI	53226	MILWAUKEE	USA	Diabetes, Digestive, and Kidney Diseases Extramural Research	000	1	12/19/2022	NEW	$390,000
														Subtotal = $390,000

Grand Total All Awards = $1,115,400

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ArpC3-mediated actin remodeling in insulin granule exocytosis and diabetes

Award Number: R01DK132088

ORGANIZATION: NATIONAL INSTITUTE OF DIABETES & DIGESTIVE & KIDNEY DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 01/01/2023

PERIOD OF PERFORMANCE END DATE: 12/31/2026

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