Healing following full-thickness skin damage repairs the defect but does not restore normal skin structures and function. Even with the best clinical management currently available, the skin that is formed is often scarred, dry, fragile, and at risk for repeated skin breakdown. Our long-term goal is to study proteins that regulate signaling pathways in dermal fibroblasts that promote skin regeneration and improve healing. TSC2 is a protein that inhibits mTORC1 and other growth signaling pathways, and it appears to regulate hair follicle morphogenesis and skin regeneration. Fibroblast-like cells with loss of TSC2, derived from angiofibromas and forehead plaques in patients with tuberous sclerosis complex (TSC), induced hair follicle formation, angiogenesis, and lymphangiogenesis in grafted skin equivalents. The capacity of these cells to induce de novo hair follicle formation overcomes a barrier to studies of skin regeneration, and increased vessels are expected to promote wound healing. Our objective is to identify the molecular basis for the regenerative characteristics of fibroblasts with loss of TSC2.
Our specific aims are: 1) to identify the cellular contexts in which loss of TSC2 promotes skin regeneration, 2) to determine the signaling pathway alterations in fibroblasts deficient for TSC2 that promote skin regeneration, and 3) to determine the mechanisms by which TSC2-null cells interact with their cellular microenvironment to promote skin regeneration.
In aim 1, in vivo hair follicle formation, angiogenesis, and lymphangiogenesis will be measured using cells with loss or presence of TSC2, including TSC2-null cells from TSC patients, human fibroblasts with stable knockdown of TSC2 using shRNA, and Tsc2-null mouse fibroblasts obtained by lineage-specific deletion of Tsc2.
In aim 2, the pathways controlling the effects of TSC2-null cells on hair follicle and vessel formation will be identified by knocking dow raptor, a component of mTORC1. Preliminary data indicates cross-talk between TSC2 and TGF? signaling, and the basis for this interaction will be elucidated.
In aim 3, the in vivo effect of certain paracrine factors will be blocked to define their contributions to angiogenesis and lymphangiogenesis promoted by TSC2-null cells. Completion of the proposed studies will provide mechanistic information that will be critical to design new therapeutic interventions to promote skin regeneration over repair. In particular, they are expected to provide new strategies to promote hair follicle formation and vascularization in bioengineered skin.

Public Health Relevance

Skin wounds, such as those after large burns, heal in a way that fails to restore normal skin, and the scars that result may cause lifelong disability. The goas of this research are to manipulate signaling pathways that control the responses of skin cells to wounding and that induce formation of hair follicles and blood and lymphatic vessels. Altering these signaling pathways, or the proteins regulated by them, is expected to change the ways that these cells behave, improving the regeneration of skin structures and restoring normal skin functions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
4R01AR062080-05
Application #
9129601
Study Section
Arthritis, Connective Tissue and Skin Study Section (ACTS)
Program Officer
Tseng, Hung H
Project Start
2012-09-01
Project End
2017-08-31
Budget Start
2016-09-01
Budget End
2017-08-31
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Henry M. Jackson Fdn for the Adv Mil/Med
Department
Type
DUNS #
144676566
City
Bethesda
State
MD
Country
United States
Zip Code
20817
Julian, Lisa M; Delaney, Sean P; Wang, Ying et al. (2017) Human Pluripotent Stem Cell-Derived TSC2-Haploinsufficient Smooth Muscle Cells Recapitulate Features of Lymphangioleiomyomatosis. Cancer Res 77:5491-5502
Bongiorno, Michelle A; Nathan, Neera; Oyerinde, Oyetewa et al. (2017) Clinical Characteristics of Connective Tissue Nevi in Tuberous Sclerosis Complex With Special Emphasis on Shagreen Patches. JAMA Dermatol 153:660-665
Klover, Peter J; Thangapazham, Rajesh L; Kato, Jiro et al. (2017) Tsc2 disruption in mesenchymal progenitors results in tumors with vascular anomalies overexpressing Lgals3. Elife 6:
Cao, Juxiang; Tyburczy, Magdalena E; Moss, Joel et al. (2017) Tuberous sclerosis complex inactivation disrupts melanogenesis via mTORC1 activation. J Clin Invest 127:349-364
Nathan, Neera; Keppler-Noreuil, Kim M; Biesecker, Leslie G et al. (2017) Mosaic Disorders of the PI3K/PTEN/AKT/TSC/mTORC1 Signaling Pathway. Dermatol Clin 35:51-60
Nathan, N; Burke, K; Moss, J et al. (2017) A diagnostic and management algorithm for individuals with an isolated skin finding suggestive of tuberous sclerosis complex. Br J Dermatol 176:220-223
Nathan, Neera; Tyburczy, Magdalena E; Hamieh, Lana et al. (2016) Nipple Angiofibromas with Loss of TSC2 Are Associated with Tuberous Sclerosis Complex. J Invest Dermatol 136:535-538
Nathan, Neera; Wang, Ji-an; Li, Shaowei et al. (2015) Improvement of tuberous sclerosis complex (TSC) skin tumors during long-term treatment with oral sirolimus. J Am Acad Dermatol 73:802-8
Tyburczy, Magdalena E; Wang, Ji-An; Li, Shaowei et al. (2014) Sun exposure causes somatic second-hit mutations and angiofibroma development in tuberous sclerosis complex. Hum Mol Genet 23:2023-9
Cai, Xiong; Pacheco-Rodriguez, Gustavo; Haughey, Mary et al. (2014) Sirolimus decreases circulating lymphangioleiomyomatosis cells in patients with lymphangioleiomyomatosis. Chest 145:108-12