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Principal Investigator: Jonathan Hale Zippin
Organization: WEILL MEDICAL COLL OF CORNELL UNIV
Fiscal Year: 2024
Award: $606,010
Funding agency: National Institute of Arthritis and Musculoskeletal and Skin Diseases
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 systemically 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.
Terms: <(hydroxymethylglutaryl-CoA reductase (NADPH)) kinase><3'5'-cyclic ester of AMP><3,5 cyclic AMP synthetase><5'-AMP-activated protein kinase><AMP-activated kinase><AMP-activated protein kinase><AMPK enzyme><Address><Adenosine Cyclic 3',5'-Monophosphate><Adenosine Cyclic Monophosphate><Adenosine Cyclic Monophosphate-Dependent Protein Kinases><Adenosine, cyclic 3',5'-(hydrogen phosphate)><Adenyl Cyclase><Adenylate Cyclase><Adenylyl Cyclase><Affect><African><African American group><African American individual><African American people><African American population><African Americans><Albinism><Alleles><Allelomorphs><Basal Transcription Factor><Basal transcription factor genes><Bicarbonates><Cell Body><Cell Communication and Signaling><Cell Line><Cell Signaling><Cell model><CellLine><Cells><Cellular model><Cresolase><Cutaneous><Cyclic AMP><Cyclic AMP-Dependent Protein Kinases><Data><Disease><Disorder><Dopa Oxidase><Enzyme Gene><Enzymes><Gene Expression><General Transcription Factor Gene><General Transcription Factors><Genes><Genetic><Genetic Alteration><Genetic Change><Genetic Models><Genetic Polymorphism><Genetic defect><HCO3><HMG CoA reductase (NADPH) kinase><HMG CoA reductase kinase><HMG coenzyme A reductase (NADPH) kinase><Human><Hydrogen Carbonates><In Vitro><Intracellular Communication and Signaling><Investigation><Ion Channel><Ionic Channels><Isoforms><KO mice><Knock-out><Knock-out Mice><Knockout><Knockout Mice><Link><MC1 Receptor><Malignant Melanoma><Malignant Skin Neoplasm><Mass Photometry/Spectrum Analysis><Mass Spectrometry><Mass Spectroscopy><Mass Spectrum><Mass Spectrum Analyses><Mass Spectrum Analysis><Measures><Melanins><Melanocortin 1 Receptor><Melanocyte Melanocortin Receptor><Melanoma><Melanosomes><Membrane><Membrane Channels><Methods><Mice><Mice Mammals><Microscopy><Modeling><Modern Man><Modification><Monophenol Monooxygenase><Murine><Mus><Mutation><Null Mouse><Oculocutaneous albinism type 2><Organelles><PKA><Pathway interactions><Phenol Oxidase><Phenoloxidase><Pigmentation><Pigmentation physiologic function><Pigments><Prevent skin cancer><Protein Isoforms><Protein Kinase A><Proteins><Publishing><Receptor Activation><Receptor Signaling><Regulation><Risk><Role><Signal Pathway><Signal Transduction><Signal Transduction Systems><Signaling><Skin Cancer><Skin Pigmentation><Strains Cell Lines><Techniques><Testing><Therapeutic><Transcription Factor Proto-Oncogene><Transcription factor genes><Tyrosinase><adenosine 3'5' monophosphate><biological signal transduction><cAMP><cAMP-Dependent Protein Kinases><cancer risk><carcinogenicity><conditional knock-out><conditional knockout><cultured cell line><eumelanin><experiment><experimental research><experimental study><experiments><genome mutation><hydroxymethylglutaryl-CoA-reductase kinase><in vivo><inhibitor><innovate><innovation><innovative><insight><loss of function><malignant skin tumor><melanocyte><membrane structure><monophenol oxidase><mouse model><murine model><new drug target><new drug treatments><new druggable target><new drugs><new pharmacological therapeutic><new pharmacotherapy target><new therapeutic target><new therapeutics><new therapy><new therapy target><next generation therapeutics><novel><novel drug target><novel drug treatments><novel druggable target><novel drugs><novel pharmaco-therapeutic><novel pharmacological therapeutic><novel pharmacotherapy target><novel therapeutic target><novel therapeutics><novel therapy><novel therapy target><pathway><pharmacologic><photoprotection><photoprotective><pigment><pigmentations><polymorphism><skin cancer prevention><social role><solar UV><solar ultraviolet radiation><synergism><tool><transcription factor>