R01AR077664

Mechanisms of cAMP-Dependent Regulation of Melanosome pH - Summary

Melanosome pH controls pigmentation and affects skin cancer risk; however, the signaling pathways that affect this important pigment mechanism are poorly understood. The melanocortin 1 receptor (MC1R), through transmembrane adenylyl cyclase (TMAC)-defined cAMP signaling pathways, has an important role in pigmentation and affects skin cancer risk by activating the expression of key pigment synthesizing enzymes. But whether MC1R signaling affects melanosome pH has remained unclear.

We recently identified a new cAMP signaling pathway in melanocytes, defined by the soluble adenylyl cyclase (SAC), that regulates melanosome pH. Whereas elevation of TMAC-dependent cAMP increases eumelanin by upregulating key pigment enzymes (e.g., tyrosinase), a reduction in SAC-dependent cAMP also increases eumelanin by inducing the alkalization of melanosome pH and enhancing tyrosinase activity. Thus, our overarching hypothesis is that SAC and TMACs regulate distinct cAMP signaling cascades in melanocytes and function in concert to control pigmentation. What remains unclear are the upstream and downstream mechanisms that control SAC-dependent regulation of melanosome pH and pigmentation.

In our first aim, we will use human primary melanocytes expressing either wild type MC1R or MC1R polymorphisms, along with MC1RE mouse melanocytes and a novel MC1RE (E/E) conditional SAC knockout mouse, to determine the interplay between MC1R signaling and SAC-dependent control of melanosome pH and pigmentation. In our first aim, we will also assess whether bicarbonate, a known stimulator of SAC that has been linked to melanin synthesis, affects melanosome pH and pigmentation in human and mouse melanocytes in a SAC-dependent manner.

In Aim 2, we will determine how SAC regulates melanosome pH and pigmentation. Our preliminary data suggests that SAC activates the cAMP effector protein exchange protein activated by cAMP (EPAC), which then stimulates the melanosome ion channel two-pore channel 2 (TPC2). Using genetic and pharmacological methods in mouse and human melanocytes, we will establish which EPAC isoforms and melanosome channels are required for SAC-dependent control of melanosome pH.

Finally, our preliminary data suggest that SAC inhibition rescues the defective melanosome pH and tyrosinase activity in OCA2 deleted mouse melanocytes both in vitro and in mice. Thus, pharmacological SAC inhibitors are potential therapeutics for oculocutaneous albinism type 2. We will further explore this therapeutic possibility with a new conditional SAC knockout OCA2-/- (P/P) mouse model.

Overall, the experiments in this proposal will systematically examine the cAMP-dependent signaling cascades that regulate melanosome pH and pigmentation. The proposed studies will establish new models that will overcome limitations in our investigation of cAMP signaling in pigmentation, will provide greater insight into the cAMP-dependent mechanisms that control melanosome pH, and may lead to new therapeutics for diseases of pigmentation.

Weill Medical College Of Cornell University

THE NATIONAL INSTITUTE OF AND MUSCULOSKELETAL AND SKIN DISEASES (NIAMS) MISSION IS TO SUPPORT RESEARCH INTO THE CAUSES, TREATMENT, AND PREVENTION OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES, TRAINING OF BASIC AND CLINICAL SCIENTISTS TO CARRY OUT THIS RESEARCH, AND DISSEMINATION OF INFORMATION ON RESEARCH PROGRESS IN THESE DISEASES. THE EXTRAMURAL PROGRAM PROMOTES AND SUPPORTS BASIC, TRANSLATIONAL, AND CLINICAL STUDIES OF SYSTEMIC RHEUMATIC AND AUTOIMMUNE DISEASES, SKIN BIOLOGY AND DISEASES, BONE BIOLOGY AND DISEASES, MUSCLE BIOLOGY AND DISEASES, AND JOINT BIOLOGY AND DISEASES AND ORTHOPAEDICS. NIAMS SYSTEMIC RHEUMATIC AND AUTOIMMUNE DISEASES PROGRAMS ADDRESS BASIC, TRANSLATIONAL, AND CLINICAL RESEARCH, INCLUDING CLINICAL TRIALS AND OBSERVATIONAL AND MECHANISTIC STUDIES, FOCUSED ON IMMUNE-MEDIATED ARTHRITIS AND AUTOIMMUNE-RELATED ACUTE AND CHRONIC DISORDERS IN ADULTS AND CHILDREN. NIAMS SKIN BIOLOGY AND DISEASES PROGRAMS SUPPORT BASIC, TRANSLATIONAL, AND CLINICAL RESEARCH IN SKIN, INCLUDING BOTH COMMON AND RARE SKIN DISEASES. THESE PROGRAMS INCLUDE INVESTIGATIONS OF THE BASIC MOLECULAR, CELLULAR, AND DEVELOPMENTAL BIOLOGY OF SKIN, AS WELL AS STUDIES OF SKIN AS AN IMMUNE, SENSORY, ENDOCRINE, AND METABOLIC ORGAN. NIAMS BONE BIOLOGY AND DISEASES PROGRAMS SUPPORT RESEARCH ON THE CONTROL OF BONE FORMATION, RESORPTION, AND MINERALIZATION AS WELL AS THE EFFECTS OF SIGNALING MOLECULES ON BONE CELLS. THEY SUPPORT CLINICAL STUDIES OF INTERVENTIONS TO PREVENT FRACTURES ASSOCIATED WITH OSTEOPOROSIS AND RESEARCH INTO LESS COMMON BONE DISEASES. NIAMS MUSCLE BIOLOGY AND DISEASES PROGRAMS ENCOURAGE RESEARCH ON MUSCLE DEVELOPMENTAL BIOLOGY, GROWTH, MAINTENANCE, AND HYPERTROPHY, PHYSIOLOGY OF CONTRACTION, STRUCTURAL BIOLOGY OF THE CONTRACTILE APPARATUS, DISEASE MECHANISMS, BIOMARKERS AND OUTCOME MEASURES, AND DEVELOPMENT AND CLINICAL TESTING OF THERAPIES FOR CONDITIONS INCLUDING THE MUSCULAR DYSTROPHIES. NIAMS JOINT BIOLOGY, DISEASES, AND ORTHOPAEDICS PROGRAMS SUPPORT A BROAD SPECTRUM OF RESEARCH CENTERED ON THE INTERPLAY AMONG THE BODY'S MUSCLES, BONES, AND CONNECTIVE TISSUES. THEY ENCOURAGE TISSUE ENGINEERING AND REGENERATIVE MEDICINE RESEARCH, MOLECULAR BIOLOGY, IMAGING, AND CLINICAL RESEARCH, AND THE TREATMENT AND PREVENTION OF ORTHOPAEDIC CONDITIONS. NIAMS PARTICIPATES IN THE SMALL BUSINESS INNOVATION RESEARCH (SBIR) AND SMALL BUSINESS TECHNOLOGY TRANSFER (STTR) PROGRAMS. THE SBIR PROGRAM IS INTENDED TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, TO INCREASE SMALL BUSINESS PARTICIPATION IN FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION. THE STTR PROGRAM IS INTENDED TO STIMULATE AND FOSTER SCIENTIFIC AND TECHNOLOGICAL INNOVATION THROUGH COOPERATIVE RESEARCH AND DEVELOPMENT CARRIED OUT BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO FOSTER TECHNOLOGY TRANSFER BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION.

93.846 - Arthritis, Musculoskeletal and Skin Diseases Research

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) [HHS - NIH]

New York, New York 100654805 United States

Single Zip Code

NIH Research Project Grant (Parent R01 Clinical Trial Not Allowed) (PA-20-185)

Amendment Since initial award the total obligations have increased 388% from $633,749 to $3,089,547.