TheprohormoneconvertasesPC1/3andPC2,encodedbythegenesPCSK1andPCSK2respectively,arethe endoproteolytic enzymes responsible for the liberation of opioid?active peptides from larger precursor proteins.Prohormoneconvertasesplayimportantrolesnotonlyinopioidpeptide?mediatedpainsignaling but also function in many other neuronal circuits, including in reward pathways and in hypothalamic circuits involved in feeding and energy homeostasis. For example, both rare and common variations in PCSK1 function as major risk factors for human obesity, potentially due to deficiencies in hypothalamic peptidergicprocessing.Incollaborationwithclinicianswhohaveidentifiedchildrenwithnovelmutations in PCSK1, we have recently determined that mutant human and mouse PC1/3 proteins are subject to targetingdefectswhicharelikelytoresultinhypothalamicproteostaticstress.Basedonourpriorfinding thatmousePC1/3proteinsoligomerizeduringsynthesis,weproposethatdominant?negativeinteractions play a major role in human PC1/3 heterozygote obesity phenotypes, affecting precursor processing to bioactive peptides involved in satiety signaling. We propose that external stressors will exacerbate even mildformsofPC1/3conformationaldistress,impairingC?terminalcleavageofPC1/3tothesmaller,more active forms. These processes will ultimately converge to strongly impair precursor processing, eg. proopiomelanocortincleavagetobeta?endorphin,ACTH,andmostimportantly,totheanorexicpeptide?? MSH.InthepresentproposalwewilluseCRISPR?engineeredcellmodelstoelucidatethecellbiologyand precursorprocessingefficacyofthreehumanPC1/3variantsandmutantsknowntobestronglyassociated with increased risk of obesity. Secondly, we will create mouse models of two common human PCSK1 obesitymutants,andathirdmodelofararebuthighlyimpairedmutant,toextendfindingsmadeincell culture to actual secretory tissues, and to identify the specific physiologic alterations which underlie the PCSK1?mediated obesity phenotype. Lastly, we will test our hypothesis that processing deficits in proopiomelanocortin?synthesizingneuronsunderlietheobesityphenotypebyselectivelyeliminatingPcsk1 expressioninproopiomelanocortin?expressingcellsusingafloxedPcsk1nullmousemodel.Theresultsof these studies will illuminate the biosynthetic mechanisms controlling hypothalamic peptide production thatcontributetohumansusceptibilitytoavarietyofdiseases,fromobesitytorewardpathwaysindrug addiction.

Public Health Relevance

This proposal addresses the production of peptide signaling hormones by studying human mutations within the proteases which cut these peptides out of larger proteins. Because people with these particular protease mutations are obese, we will learn about peptide-mediated obesity mechanisms through these studies.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
1R01DA042351-01A1
Application #
9382537
Study Section
Molecular Neuropharmacology and Signaling Study Section (MNPS)
Program Officer
Rapaka, Rao
Project Start
2017-07-15
Project End
2022-05-31
Budget Start
2017-07-15
Budget End
2018-05-31
Support Year
1
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Ivanova, Teodora; Hardes, Kornelia; Kallis, Stephanie et al. (2017) Optimization of Substrate-Analogue Furin Inhibitors. ChemMedChem 12:1953-1968