Tuesday, July 1, 2025 7/1/2025

Tissue Size and Precision Control in Growing Hair Follicles

Award Number: R01AR079150
ORGANIZATION: NATIONAL INSTITUTE OF ARTHRITIS & MUSCULOSKELETAL & SKIN DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 02/01/2022
PERIOD OF PERFORMANCE END DATE: 11/30/2026

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Tissue Size and Precision Control in Growing Hair Follicles - PROJECT SUMMARY Biological tissues appear to “know” their intended final sizes and achieve them precisely and robustly. While, in principle, a simple negative signaling feedback should be sufficient to explain how a given stem cell lineage regulates its cellular outputs, in reality it cannot work because most tissues are physically large, with stem cells and their progeny spread out over centimeter-scale distances. How tissues overcome the microscopic decay limits of diffusible molecular signals to breach distances orders-of-magnitude in spatial scale remains elusive. This application is inspired by our serendipitous discovery that FGF and BMP mutant mice are able to grow super-long and highly imprecise hairs that can exceed the length of normal mouse hairs by 7-fold. Our lineage analyses suggest that hair stem cells continuously replenish short-lived transit-amplifying (TA) cells spatially located nearly 1 cm away from the stem cells. Interestingly, our single-cell RNA-sequencing analyses reveal previously unappreciated heterogeneity of the intermediate epithelial progenitor cells physically located between the stem and TA cells. Through an integrated mathematical and experimental approach, this application will focus on testing our new hypothesis that dynamic equilibrium between two or more intermediate cell states and their associated cell-cell communications enable feedback information propagation over large spatial scale from TA cells to stem cells to regulate the new progenitor cell production for hair size control. The first aim of the proposed research is to profile and quantify the heterogeneity of intermediate epithelial progenitors, and computationally and experimentally determine the functional link between specific intermediate progenitor states in the hair follicle and the hair length and its precision. The second aim is to define the cell-cell communication networks within the epithelial hair follicle lineage, and computationally and experimentally establish how multiple short-range signaling activities coordinate to form a long-range feedback mechanism that controls progenitor flux between distant stem and TA cell compartments for proper hair growth. The third aim is to determine the signaling impact of mesenchymal niche cells, which surround the hair follicle, on the epithelial lineage cells for hair size control. The study premise is based on novel and extensive preliminary experimental and computational data. The proposed studies are significant because they will establish new long-range signaling mechanisms and uncover novel roles of intermediate cell states in tissue size control. The proposed studies are innovative because they will establish new experimental models for studying tissue size regulation using super-long and extra-short hair mutant mice and will result in numerous new genetic mouse tools for epithelial stem cell research. They will also result in several novel mathematical and computational tools for analyzing single-cell RNA- sequencing data and new spatial models for complex cell lineages, such as in the hair follicle.


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 = $531,355 )
2025	2025	UNIVERSITY OF CALIFORNIA IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	001	4	6/5/2025	NON-COMPETING CONTINUATION	$38,345
2025	2025	UNIVERSITY OF CALIFORNIA IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	000	4	11/7/2024	NON-COMPETING CONTINUATION	$493,010
														Subtotal = $531,355

Issue Date FY: 2024 ( Subtotal = $531,355 )
2024	2024	UNIVERSITY OF CALIFORNIA IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	001	3	6/18/2024	NON-COMPETING CONTINUATION	$38,345
2024	2024	UNIVERSITY OF CALIFORNIA IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	000	3	11/30/2023	NON-COMPETING CONTINUATION	$493,010
														Subtotal = $531,355

Issue Date FY: 2023 ( Subtotal = $551,933 )
2023	2023	UNIVERSITY OF CALIFORNIA, IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	000	2	11/22/2022	NON-COMPETING CONTINUATION	$496,740
2023	2023	UNIVERSITY OF CALIFORNIA, IRVINE	160 ALDRICH HALL	IRVINE	CA	92697	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	001	2	5/11/2023	NON-COMPETING CONTINUATION	$55,193
														Subtotal = $551,933

Issue Date FY: 2022 ( Subtotal = $546,851 )
2022	2022	UNIVERSITY OF CALIFORNIA, IRVINE	141 INNOVATION DR STE 250	IRVINE	CA	92617	ORANGE	USA	Arthritis, Musculoskeletal and Skin Diseases Research	000	1	1/31/2022	NEW	$546,851
														Subtotal = $546,851

Grand Total All Awards = $2,161,494

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Tissue Size and Precision Control in Growing Hair Follicles

Award Number: R01AR079150

ORGANIZATION: NATIONAL INSTITUTE OF ARTHRITIS & MUSCULOSKELETAL & SKIN DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

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

PERIOD OF PERFORMANCE START DATE: 02/01/2022

PERIOD OF PERFORMANCE END DATE: 11/30/2026

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