Alterations in protein kinase A substrate specificity as a potential cause of Cushing’s Syndrome

Research output: Contribution to journalArticlepeer-review


  • Kerstin Bathon
  • Isabel Wigand
  • Jens T. Vanselow
  • Silviu Sbiera
  • Andreas Schlosser
  • Martin Fassnacht

Colleges, School and Institutes

External organisations

  • University of Würzburg


Cushing syndrome is a severe endocrine disorder of cortisol excess associated with major metabolic and cardiovascular sequelae. We recently identified somatic mutations in PRKACA, the gene encoding the catalytic (C) α subunit of protein kinase A (PKA), as being responsible for cortisol-producing adrenocortical adenomas (CPAs), which are a major cause of Cushing syndrome. In spite of previous studies on the two initially identified mutations (L206R, 199_200insW), the mechanisms of action of the clinically highly relevant PRKACA mutations remain poorly understood. Here, by investigating a large panel of PRKACA mutations, including all those identified so far in Cushing syndrome, we unexpectedly found that not all mutations interfere with the binding of regulatory (R) subunits as previously hypothesized. Because several mutations lie in a region of PKA Cα involved in substrate recognition, we investigated their consequences on substrate specificity by quantitative phosphoproteomics. We found that all three mutations analyzed (L206R, 200_201insV, and d244−248+E249Q) cause major changes in the preference of PKA for its targets, leading to hyperphosphorylation of several PKA substrates, most notably including histone H1.4 at Ser36, which is required for and promotes mitosis. This is reflected by a ninefold hyperphosphorylation of H1.4 in CPAs carrying the L206R mutation. Thus, our findings suggest that in addition to hampering binding to R subunits, PRKACA mutations act by altering PKA substrate specificity. These findings shed light on the molecular events leading to Cushing syndrome and illustrate how mutations altering substrate specificity of a protein kinase may cause human disease.

Bibliographic note

Kerstin Bathon, Isabel Weigand, Jens T Vanselow, Cristina L Ronchi, Silviu Sbiera, Andreas Schlosser, Martin Fassnacht, Davide Calebiro; Alterations in Protein Kinase A Substrate Specificity as a Potential Cause of Cushing Syndrome, Endocrinology, Volume 160, Issue 2, 1 February 2019, Pages 447–459,


Original languageEnglish
Pages (from-to)447-459
Number of pages13
Issue number2
Early online date4 Jan 2019
Publication statusPublished - 1 Feb 2019

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