@phdthesis{Weigand2021,
  author    = {Weigand, Isabel},
  title     = {Consequences of Protein Kinase A mutations in adrenocortical cells and tumours},
  doi       = {10.25972/OPUS-16064},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-160646},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Adrenal Cushing's Syndrome (CS) is a rare but life-threatening disease and therefore it is of great importance to understand the pathogenesis leading to adrenal CS. It is well accepted that Protein Kinase A (PKA) signalling mediates steroid secretion in adrenocortical cells. PKA is an inactive heterotetramer, consisting of two catalytic and two regulatory subunits. Upon cAMP binding to the regulatory subunits, the catalytic subunits are released and are able to phosphorylate their target proteins. Recently, activating somatic mutations affecting the catalytic subunit a of PKA have been identified in a sub-population of cortisol-producing adenomas (CPAs) associated with overt CS. Interestingly, the PKA regulatory subunit IIb has long been known to have significantly lower protein levels in a sub-group of CPAs compared to other adrenocortical tumours. Yet, it is unknown, why these CPAs lack the regulatory subunit IIb, neither are any functional consequences nor are the underlying regulation mechanisms leading to reduced RIIb levels known. The results obtained in this thesis show a clear connection between Ca mutations and reduced RIIb protein levels in CPAs but not in other adrenocortical tumours. Furthermore, a specific pattern of PKA subunit expression in the different zones of the normal adrenal gland is demonstrated. In addition, a Ca L206R mutation-mediated degradation of RIIb was observed in adrenocortical cells in vitro. RIIb degradation was found to be mediated by caspases and by performing mutagenesis experiments of the regulatory subunits IIb and Ia, S114 phosphorylation of RIIb was identified to make RIIb susceptible for degradation. LC-MS/MS revealed RIIb interaction partners to differ in the presence of either Ca WT and Ca L206R. These newly identified interaction partners are possibly involved in targeting RIIb to subcellular compartments or bringing it into spatial proximity of degrading enzymes. Furthermore, reducing RIIb protein levels in an in vitro system were shown to correlate with increased cortisol secretion also in the absence of PRKACA mutations. The inhibiting role of RIIb in cortisol secretion demonstrates a new function of this regulatory PKA subunit, improving the understanding of the complex regulation of PKA as key regulator in many cells.},
  subject      = {Cushing-Syndrom},
  language  = {en}
}
@phdthesis{Rehm2022,
  author    = {Rehm, Alexandra},
  title     = {Etablierung von USP8 und USP48 Mutationen in Zelllinien f{\"u}r Cushing-Syndrom Analysen mittels CRISPR/Cas9},
  doi       = {10.25972/OPUS-23450},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-234503},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Morbus Cushing ist die h{\"a}ufigste Ursache f{\"u}r endogenes Cushing-Syndrom und f{\"u}hrt auf Grund eines kortikotropen Hypophysenadenoms zu einem Glucocorticoid {\"U}berschuss und wiederum zu einer hohen Morbidit{\"a}t und Mortalit{\"a}t. Die Ursache hierf{\"u}r sind unter anderem somatische Mutationen in den Deubiquitinasen USP8 und USP48. Das Ziel dieser Arbeit war es mittels der CRISPR/Cas9-Methode, die Mutationen USP8 und USP48 in Zelllinien zu etablieren und diese f{\"u}r Cushing-Syndrom Analysen zu verwenden. Hierf{\"u}r wurden in dieser Arbeit gRNAs f{\"u}r USP8 und USP48 designt, welche anschließend in die humane embryonale Zelllinie HEK293AD Zellen transfiziert wurden. Diese Zellen wurden zu monoklonalen Zellen vereinzelt. Ziel war einen Knock-out von USP8 bzw. USP48 zu generieren. Es konnte ein erfolgreicher Zellklon generiert werden mit einem Knock-out von USP48. Ebenfalls konnte ein Genomediting von USP8 in Exon 20 durchgef{\"u}hrt werden. Zusammenfassend konnte die CRISPR/Cas9 Methode f{\"u}r ein M. Cushing-Zellmodells etabliert und eine gute Ausgangsbasis f{\"u}r weitere Experimente (z.B. ein gezielter Knock-in von USP8- und USP48- Mutationen) generiert werden.},
  subject      = {Cushing-Syndrom},
  language  = {de}
}
@phdthesis{Borgemeister2001,
  author    = {Borgemeister, Markus},
  title     = {Nahrungsabh{\"a}ngige ACTH- und Kortisolsekretion bei Patienten mit Nebennieren-Zufallstumor},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-657},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2001},
  abstract  = {Die zuf{\"a}llige Entdeckung von Tumoren der Nebenniere durch heute h{\"a}ufig eingesetzte bildgebende Verfahren f{\"u}hrt zu einer Diagnose-Pr{\"a}valenz solcher sogenannter Inzidentalome von 0,6-1,3 Prozent. Die m{\"o}gliche subklinische Hormonaktivit{\"a}t im Sinne eines subklinischen Cushing-Syndroms und der in Verlaufsstudien festgestellte Progress - bis hin zum manifesten Cushing-Syndroms - erfordern ein sensitives Screening auf hormonelle Aktivit{\"a}t und engmaschige Verlaufskontrollen. In elf publizierten F{\"a}llen ist eine nahrungsabh{\"a}ngige Sonderform des Hyperkortisolismus vorgestellt worden. Ektope Rezeptoren f{\"u}r das Glukoseabh{\"a}ngige- Insulinotrope-Peptid in der Nebennierenrinde f{\"u}hrten zu einem durch Glukoseabh{\"a}ngiges-Insulinotropes-Peptid vermittelten, nahrungsabh{\"a}ngigen Cushing-Syndrom. In einigen anderen F{\"a}llen wurden an Hypophysentumoren operierter Patienten mit zentralem CS Rezeptoren f{\"u}r gastrointestinale Botenstoffe nachgewiesen. Pr{\"a}operativ war hier ebenfalls ein nahrungsabh{\"a}ngiges Kortisolprofil messbar. Subklinische Vorstufen dieser Pathophysiologien sind bisher nur in einem Fall einer durch Glukoseabh{\"a}ngiges-Insulinotropes-Peptid vermittelten Kortisolsekretion beschrieben. In unserer Studie untersuchten wir Patienten mit Inzidentalom auf das Vorliegen einer subklinischen Nahrungsabh{\"a}ngigkeit ihrer Kortisolsekretion. Vier der 15 Patienten zeigten einen durch orale Glukosebelastung hervorgerufenen Kortisolanstieg mit signifikant h{\"o}heren Kortisolwerten als unter i.v.-Glukosebelastung oder i.v.-Infusion von Glukoseabh{\"a}ngigem-Insulinotropen-Peptid. Bei den Kontrollkollektiven aus gesunden Normalpersonen und Patienten mit Metabolischem Syndrom konnte dieses Ph{\"a}nomen nicht beobachtet werden. Der Kortisolanstieg erwies sich als ACTH-vermittelt. Es fanden sich bei diesen Patienten signifikant h{\"o}here Kortisolwerte im 24h-Sammelurin und niedrigere N{\"u}chtern-ACTH-Werte im Vergleich zu den restlichen Inzidentalom-Patienten. Bei den von uns untersuchten Inzidentalom-Patienten ergaben sich keine Hinweise auf eine durch Glukoseabh{\"a}ngiges-Insulinotropes-Peptid vermittelte Kortisolsekretion, wohl aber auf das Vorliegen von die ACTH-Sekretion beeinflussenden, nahrungsabh{\"a}ngigen Faktoren, die noch zu identifizieren sind.},
  language  = {de}
}
@phdthesis{Bathon2019,
  author    = {Bathon, Kerstin},
  title     = {Mutations in protein kinase A catalytic subunit as a cause of adrenal Cushing's syndrome: mechanisms and functional consequences},
  doi       = {10.25972/OPUS-16893},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168937},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Protein kinase A (PKA) is the main effector of cyclic-adenosine monophosphate (cAMP) and plays an important role in steroidogenesis and proliferation of adrenal cells. In a previous study we found two mutations (L206R, 199_200insW) in the main catalytic subunit of protein kinase A (PKA C) to be responsible for cortisol-producing adrenocortical adenomas (CPAs). These mutations interfere with the formation of a stable holoenzyme, thus causing constitutive PKA activation. More recently, we identified additional mutations affecting PKA C in CPAs associated with overt Cushing syndrome: S213R+insIILR, 200_201insV, W197R, d244 248+E249Q, E32V. This study reports a functional characterization of those PKA Cmutations linked to CPAs of Cushing's patients. All analyzed mutations except for E32V showed a reduced interaction with at least one tested regulatory (R) subunit. Interestingly the results of the activity differed among the mutants and between the assays employed. For three mutants (L206R, 199_200insW, S213R+insIILR), the results showed enhanced translocation to the nucleus. This was also observed in CRISPR/Cas9 generated PRKACA L206R mutated HEK293T cells. The enhanced nuclear translocation of this mutants could be due to the lack of R subunit binding, but also other mechanisms could be at play. Additionally, I used an algorithm, which predicted an effect of the mutation on substrate specificity for four mutants (L206R, 199_200insW, 200_201insV, d244 248+E249Q). This was proven using phosphoproteomics for three mutants (L206R, 200_201insV, d244 248+E249Q). In PRKACA L206R mutated CPAs this change in substrate specificity also caused hyperphosphorylation of H1.4 on serine 36, which has been reported to be implicated in mitosis. Due to these observations, I hypothesized, that there are several mechanisms of action of PRKACA mutations leading to increased cortisol secretion and cell proliferation in adrenal cells: interference with the formation of a stable holoenzyme, altered subcellular localization and a change in substrate specificity. My data indicate that some PKA C mutants might act via just one, others by a combination of these mechanisms. Altogether, these findings indicate that several mechanisms contribute to the development of CPAs caused by PRKACA mutations. Moreover, these findings provide a highly illustrative example of how alterations in a protein kinase can cause a human disease.},
  subject      = {Proteinkinase A},
  language  = {en}
}