# Biased AKAP signaling mechanisms

> **NIH NIH R01** · UNIVERSITY OF WASHINGTON · 2024 · $575,394

## Abstract

ABSTRACT
Enzymes do not drift aimlessly within a cytoplasmic soup. Rather cell regulatory events occur within the confines
of highly organized intracellular signaling nanodomains. Protein kinase compartmentalization enhances the
fidelity of signal transduction and permits the parallel processing of chemical signals within the same cell. Our
lab discovered and defined A-Kinase Anchoring Proteins (AKAPs), a prototypic class of signal organizing
proteins. The physiological significance of this mechanism is validated in several diseases. This proposal
explores new PKAc mutants that locally drive cortisol secretion in adrenal Cushing’s syndrome. This is an
endocrine disorder where adrenal cells release excess stress hormone cortisol. This disease afflicts about fifteen
per million people annually and is 3-5 times more prevalent in women than men. Symptoms include adrenal
hyperplasia, midsection weight gain and comorbidities such as hypertension, hyperglycemia, and psychiatric
disorders. Adrenal (also called non-ACTH) Cushing’s is driven by somatic mutations in the catalytic subunit of
protein kinase A (PKAc). Most mutations occur within regions of PKAc that bind regulatory subunits. This protein-
protein interaction is not only necessary for autoinhibition of kinase activity but directs compartmentalization of
PKA holoenzymes through association with AKAPs. The most prevalent mutant PKAc-L205R is found in ~45%
of Cushing’s patients. Other PKAc mutations occur at frequencies of less than 1%. Using an innovative
personalized medicine workflow to screen clinical samples we have discovered a new PKAc-W196G variant in
~20% of adrenal Cushing's patients. This single amino acid change promotes structural perturbations in PKAc.
Preliminary analyses of patient tissues harboring PKAcW196G detect elevated levels of type I regulatory subunit
(RIa). Proximity proteomic screening of adrenal cell lines reveals that PKAcW196G interfaces with RI, dual-function
AKAPs, and the steroidogenic acute regulatory protein. StAR is a PKA substrate that controls the rate-limiting
step in cortisol biosynthesis. CRISPR/Cas knockout of dual-function AKAP220 in adrenal cells attenuates stress
hormone release. This exciting new data has forged an experimental plan of two specific aims.
AIM 1: EVALUATES THE MUTATIONAL FREQUENCY AND IMPACT OF PKACW196G? Genetic, biochemical, and cellular
approaches will monitor a) mutational frequencies of PKAcW196G and its localization in patient tissues, b) the
physiochemical and activity profile of PKAcW196G and c) how this Cushing's kinase alters endocrine responses.
AIM 2: TESTS IF ANCHORED TYPE I PKA SIGNALING PREDOMINATES IN ADRENAL CUSHING’S SYNDROME? PKAcW196G
and the less common PKAcW196R analog are incorporated into AKAP220 signaling islands via association with
RIa. Whole animal physiology studies and a novel precision pharmacology strategy will establish if a) PKAcW196G
(& W196R) signal through AKAP220 and if b) organellar targeting enhanc...

## Key facts

- **NIH application ID:** 10998762
- **Project number:** 1R01DK141129-01
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** John D Scott
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $575,394
- **Award type:** 1
- **Project period:** 2024-09-01 → 2029-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10998762

## Citation

> US National Institutes of Health, RePORTER application 10998762, Biased AKAP signaling mechanisms (1R01DK141129-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10998762. Licensed CC0.

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