Regulatory Subunit Of Protein Kinase Research Articles

Muscle RING-finger proteins (MuRF) regulate protein kinase A activity via retrograde vesicular transport of PKA RI-alpha

Abstract Background Muscle RING finger (MuRF) proteins are muscle-restricted E3 ubiquitin ligases that control protein degradation in striated muscles. MuRF proteins have coordinate functions for maintenance of striated muscle structure and function that depends on their target proteins. MuRF1 is a key enzyme in muscle atrophy. MuRF2 and MuRF3 bind to and stabilize microtubules which affects striated muscle differentiation and contraction. Although some MuRF-interaction partners have been described only few have been proven to be targeted for proteasomal degradation. To better understand the function of MuRF proteins, we set out to identify and functionally characterize novel MuRF target proteins. Methods and Results Stable isotope labeling of amino acids in cell culture followed by affinity purification and quantitative mass spectrometry analysis (SILAC-AP-MS) was used to identify the interactome of MuRF proteins. We identified the mammalian retromer subunit sorting nexin 5 (SNX5) that is involved in subcellular trafficking as a novel MuRF2 and MuRF3 interaction partner. Coimmunoprecipitation experiments and immunocytochemistry confirmed physical interaction and colocalization between SNX5 and MuRF2 or MuRF3. The interaction domains were mapped. MuRF2, MuRF3 and SNX5 were colocalized to early endosomes at microtubules in myocytes. MuRF2 mediated the ubiquitin proteasome system-dependent degradation of SNX5 in a RING-finger dependent manner, whereas MuRF3 stabilized SNX5. Using mass spectrometry, we identified the regulatory subunit of protein kinase A (PKA-RI-α) as a cargo of SNX5 coated early endosomes in myocytes. CRISPR-Cas9 and siRNA experiments showed that SNX5 regulates PKA activity by stabilizing PKA-RI-α in myocytes. Deletion of SNX5 resulted in PKA activation and inhibition of the HDAC5-MEF2 axis that disturbed myogenic differentiation. Conclusion MuRF2 and MuRF3 play opposing roles in SNX5-mediated retrograde transport of early endosomes along microtubules in myocytes. This mechanism is involved in regulation of PKA catalytic activity via stabilization of PKA-RI-α and controls differentiation of striated muscles.

Partial deletion of the Akap1 gene promotes abnormalities in gut barrier function, gut microbiota composition and cardiac function during cardiovascular aging in mice

Abstract Background Cardiovascular aging is characterized by mitochondrial dysfunction, changes in intestinal permeability and microbiota composition. Mitochondria-targeted A-kinase anchoring proteins (mitoAKAPs) are a group of structurally diverse proteins binding the regulatory subunits of protein kinase A (PKA), and targeting PKA at discrete intracellular locations. We analyzed the effects of global partial genetic deletion of Akap1 on intestinal barrier permeability, microbiota composition, inflammation, and cardiac function during aging in mice. Purpose The proposal of this study was to determine the role of mitoAKAPs in the gut-heart axis during cardiovascular aging. Methods Young (4-6-month) and old (18-24-month) genetically modified Akap1+/+ and Akap1+/− mice of either sex underwent evaluation of cardiac function by transthoracic echocardiography. To evaluate gut barrier integrity, we analyzed expression levels of intestinal junction proteins occludin (Ocln), zonulin (Tjp1) in colonic samples and FITC-dextran permeability in vivo, circulating levels of Tumor Necrosis Factor-alpha (TNF-alpha), Lipopolysaccharide (LPS), Interleukin-1 (IL-1) and Interleukin-10 (IL-10). Fecal microbial composition was evaluated by Illumina Mi-Seq, Gut microbiota differences based on 16S rDNA sequencing at genus and species taxonomic levels were identified using linear discriminant analysis (LDA) combined with effect size (LEfSe) algorithm. Finally, faecal microbiota transplantation (FMT) was performed for five weeks to test whether modification of gut microbiota composition can affect cardiac function. Results A reduction in % left ventricular shortening (FS%) was observed in young and old Akap1+/- mice compared to Akap1+/+ mice. This finding was associated to increased intestinal permeability, as indicated by reduced mRNA levels of Ocln and Tjp1, increased LPS traslocation across intestinal epitelium into blood in 24m Akap1+/- mice compared to Akap1+/+. Through the analysis of the microbial signature, we observed the different bacterial species present in the microbiota of the experimental groups. FMT of bacteria species from old Akap1+/− to young Akap1+/+ mice induced gut abnormalities and cardiac dysfunction, while FMT from young Akap1+/+ donors ameliorated cardiac dysfunction in old Akap1+/+ mice. Conclusions MitoAKAPs play a crucial role in the maintenance of intestinal barrier function, gut microbiota composition and cardiac function during aging. Modulation of the composition of the intestinal microbiota influences intestinal permeability and cardiac function. MitoAKAPs could represent an important diagnostic and therapeutic target for cardiac and intestinal dysfunction.

6564 A Case of Severe Hypercalcemia in Carney's Complex

Abstract Disclosure: J. Chippior: None. M. Rayan: None. L. Wright: None. L.S. Kirschner: Grant Recipient; Self; Medpace, Sparrow, Corcept Therapeutics, Corcept, Spruce, CinCor, Crinetics, Adrenas. S.W. Ing: Grant Recipient; Self; Alexion Pharmaceuticals, Inc., Amgen Inc, Radius Health, Inc, Takeda, Ultragenyx, Amolyt, Bridge Bio. Carney complex is a rare syndrome with fewer than 750 reported cases, characterized by lentigniosis, myxomas, and the occurrence of both endocrine and non-endocrine tumors. An inactivating mutation PRKAR1A, which encodes for the type 1A regulatory subunit of Protein kinase A, is responsible for over 70% of familial cases and 37% of sporadic cases. A 31-year-old female with a history of Carney complex, Cushing syndrome due to primary pigmented nodular adrenocortical disease (PPNAD), facial lentigines, spinal Schwannomas, and recent ischemic stroke secondary to embolization of a cardiac atrial myxoma, was transferred to our medical center for hyperemesis and severe hypercalcemia. Albumin-corrected serum calcium measured 15.4 mg/dL (8.6-10.5 mg/dL), ionized calcium 7.8 mg/dL (4.6-5.3 mg/dL) associated with suppressed PTH, normal PTH-related protein, and elevated bone turnover markers, C-telopeptide 4,273 pg/ml (150-635) and Procollagen Type 1 N-terminal Propeptide 222 mcg/L (19-83). Evaluation for etiology of hypercalcemia revealed elevated 1,25 dihydroxy vitamin D at 107.0 pg/ml (20-79) and elevated interleukin-6 at 11 pg/ml (<6.4). IL-6 is expressed by cardiac myxomas. Serum angiotensin-converting enzyme level was 50 U/L (16-85) and infectious workup was negative for potential granulomatous causes of elevated calcitriol (including testing for tuberculosis, histoplasma, blastomyces, bartonella, and coccidioides). CT angiogram of the abdomen and pelvis (completed in preparation of atrial myxoma resection) revealed ground-glass opacities in bilateral posterior lung fields and multiple pulmonary nodules, with the largest measuring 8 mm. After treatment with aggressive intravenous fluid resuscitation, intramuscular calcitonin, and intravenous zoledronic acid, corrected calcium normalized to 9.4 mg/dL at discharge. Urinary cortisol was 6.2 mcg per 24-hr (3.5-45), for which she started hydrocortisone 20 mg daily to treat suspected adrenal insufficiency as excess cortisol secretion in PPNAD may be episodic. Thus remission of hypercortisolism may have unmasked an underlying hypercalcemia, and adrenal insufficiency itself may have contributed to this finding. She had excision of left atrial myxoma and has continued to exhibit normal calcium levels on steroid replacement therapy. Repeat chest CT to further characterize these pulmonary findings is planned. This case illustrates a unique constellation of endocrine features associated with severe hypercalcemia in Carney complex. Presentation: 6/1/2024

6564 A Case Of Severe Hypercalcemia In Carney's Complex

Abstract Disclosure: J. Chippior: None. M. Rayan: None. L. Wright: None. L.S. Kirschner: Grant Recipient; Self; Medpace, Sparrow, Corcept Therapeutics, Corcept, Spruce, CinCor, Crinetics, Adrenas. S.W. Ing: Grant Recipient; Self; Alexion Pharmaceuticals, Inc., Amgen Inc, Radius Health, Inc, Takeda, Ultragenyx, Amolyt, Bridge Bio. Carney complex is a rare syndrome with fewer than 750 reported cases, characterized by lentigniosis, myxomas, and the occurrence of both endocrine and non-endocrine tumors. An inactivating mutation PRKAR1A, which encodes for the type 1A regulatory subunit of Protein kinase A, is responsible for over 70% of familial cases and 37% of sporadic cases. A 31-year-old female with a history of Carney complex, Cushing syndrome due to primary pigmented nodular adrenocortical disease (PPNAD), facial lentigines, spinal Schwannomas, and recent ischemic stroke secondary to embolization of a cardiac atrial myxoma, was transferred to our medical center for hyperemesis and severe hypercalcemia. Albumin-corrected serum calcium measured 15.4 mg/dL (8.6-10.5 mg/dL), ionized calcium 7.8 mg/dL (4.6-5.3 mg/dL) associated with suppressed PTH, normal PTH-related protein, and elevated bone turnover markers, C-telopeptide 4,273 pg/ml (150-635) and Procollagen Type 1 N-terminal Propeptide 222 mcg/L (19-83). Evaluation for etiology of hypercalcemia revealed elevated 1,25 dihydroxy vitamin D at 107.0 pg/ml (20-79) and elevated interleukin-6 at 11 pg/ml (<6.4). IL-6 is expressed by cardiac myxomas. Serum angiotensin-converting enzyme level was 50 U/L (16-85) and infectious workup was negative for potential granulomatous causes of elevated calcitriol (including testing for tuberculosis, histoplasma, blastomyces, bartonella, and coccidioides). CT angiogram of the abdomen and pelvis (completed in preparation of atrial myxoma resection) revealed ground-glass opacities in bilateral posterior lung fields and multiple pulmonary nodules, with the largest measuring 8 mm. After treatment with aggressive intravenous fluid resuscitation, intramuscular calcitonin, and intravenous zoledronic acid, corrected calcium normalized to 9.4 mg/dL at discharge. Urinary cortisol was 6.2 mcg per 24-hr (3.5-45), for which she started hydrocortisone 20 mg daily to treat suspected adrenal insufficiency as excess cortisol secretion in PPNAD may be episodic. Thus remission of hypercortisolism may have unmasked an underlying hypercalcemia, and adrenal insufficiency itself may have contributed to this finding. She had excision of left atrial myxoma and has continued to exhibit normal calcium levels on steroid replacement therapy. Repeat chest CT to further characterize these pulmonary findings is planned. This case illustrates a unique constellation of endocrine features associated with severe hypercalcemia in Carney complex. Presentation: 6/1/2024

A SNF1-related protein kinase regulatory subunit functions as a molecular tuner

Metabolic processes in prokaryotic and eukaryotic organisms are often modulated by kinases which are in turn, dependent on Ca2+ and the cyclic mononucleotides cAMP and cGMP. It has been established that some proteins have both kinase and cyclase activities and that active cyclases can be embedded within the kinase domains. Here, we identified phosphodiesterase (PDE) sites, enzymes that hydrolyse cAMP and cGMP, to AMP and GMP, respectively, in some of these proteins in addition to their kinase/cyclase twin-architecture. As an example, we tested the Arabidopsis thaliana KINγ, a subunit of the SnRK2 kinase, to demonstrate that all three enzymatic centres, adenylate cyclase (AC), guanylate cyclase (GC) and PDE, are catalytically active, capable of generating and hydrolysing cAMP and cGMP. These data imply that the signal output of the KINγ subunit modulates SnRK2, consequently affecting the downstream kinome. Finally, we propose a model where a single protein subunit, KINγ, is capable of regulating cyclic mononucleotide homeostasis, thereby tuning stimulus specific signal output.

Molecular determinants and signaling effects of PKA RIα phase separation

Spatiotemporal regulation of intracellular signaling molecules, such as the 3',5'-cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA), ensures proper cellular function. Liquid-liquid phase separation (LLPS) of the ubiquitous PKA regulatory subunit RIα promotes cAMP compartmentation and signaling specificity. However, the molecular determinants of RIα LLPS remain unclear. Here, we reveal that two separate dimerization interfaces, combined with the cAMP-induced unleashing of the PKA catalytic subunit (PKA-C) from the pseudosubstrate inhibitory sequence, drive RIα condensate formation in the cytosol of mammalian cells, which is antagonized by docking to A-kinase anchoring proteins. Strikingly, we find that the RIα pseudosubstrate region is critically involved in forming a non-canonical R:C complex, which recruits active PKA-C to RIα condensates to maintain low basal PKA activity in the cytosol. Our results suggest that RIα LLPS not only facilitates cAMP compartmentation but also spatially restrains active PKA-C, thus highlighting the functional versatility of biomolecular condensates in driving signaling specificity.

Unraveling the Intricate Network of lncRNAs in Corneal Epithelial Wound Healing: Insights Into the Regulatory Role of linc17500.

Epigenetic mechanisms orchestrate a harmonious process of corneal epithelial wound healing (CEWH). However, the precise role of long non-coding RNAs (lncRNAs) as key epigenetic regulators in mediating CEWH remains elusive. Here, we aimed to elucidate the functional contribution of lncRNAs in regulating CEWH. We used a microarray to characterize lncRNA expression profiling during mouse CEWH. Subsequently, the aberrant lncRNAs and their cis-associated genes were subjected to comprehensive Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and western blot analyses were performed to determine the expression profiles of key markers during CEWH. The in vivo effects of linc17500 on this process were investigated through targeted small interfering RNA (siRNA) injection. Post-siRNA treatment, corneal re-epithelialization was assessed, alongside the expression of cytokeratins 12 and 14 (Krt12 and Krt14) and Ki67. Effects of linc17500 on mouse corneal epithelial cell (TKE2) proliferation, cell cycle, and migration were assessed by multicellular tumor spheroids (MTS), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, and scratch-wound assay, respectively. Microarray analysis revealed dysregulation of numerous lncRNA candidates during CEWH. Bioinformatic analysis provided valuable annotations regarding the cis-associated genes of these lncRNAs. In vivo experiments demonstrated that knockdown of linc17500 resulted in delayed CEWH. Furthermore, the knockdown of linc17500 and its cis-associated gene, CDC28 protein kinase regulatory subunit 2 (Cks2), was found to impede TKE2 cell proliferation and migration. Notably, downregulation of linc17500 in TKE2 cells led to suppression of the activation status of Akt and Rb. This study sheds light on the significant involvement of lncRNAs in mediating CEWH and highlights the regulatory role of linc17500 on TKE2 cell behavior. These findings provide valuable insights for future therapeutic research aimed at addressing corneal wound complications.

Lasting mesothalamic dopamine imbalance and altered exploratory behavior in rats after a mild neonatal hypoxic event.

Adversities during the perinatal period can decrease oxygen supply to the fetal brain, leading to various hypoxic brain injuries, which can compromise the regularity of brain development in different aspects. To examine the catecholaminergic contribution to the link between an early-life hypoxic insult and adolescent behavioral aberrations, we used a previously established rat model of perinatal hypoxia but altered the hypobaric to normobaric conditions. Exploratory and social behavior and learning abilities were tested in 70 rats of both sexes at adolescent age. Inherent vertical locomotion, sensory-motor functions and spatial learning abilities were explored in a subset of animals to clarify the background of altered exploratory behavior. Finally, the concentrations of dopamine (DA) and noradrenaline in midbrain and pons, and the relative expression of genes for DA receptors D1 and D2, and their down-stream targets (DA- and cAMP-regulated phosphoprotein, Mr 32 kDa, the regulatory subunit of protein kinase A, and inhibitor-5 of protein phosphatase 1) in the hippocampus and thalamus were investigated in 31 rats. A lesser extent of alterations in exploratory and cognitive aspects of behavior in the present study suggests that normobaric conditions mitigate the hypoxic injury compared to the one obtained under hypobaric conditions. Increased exploratory rearing was the most prominent consequence, with impaired spatial learning in the background. In affected rats, increased midbrain/pons DA content, as well as mRNA levels for DA receptors and their down-stream elements in the thalamus, but not the hippocampus, were found. We can conclude that a mild hypoxic event induced long-lasting disbalances in mesothalamic DA signaling, contributing to the observed behavioral alterations. The thalamus was thereby indicated as another structure, besides the well-established striatum, involved in mediating hypoxic effects on behavior through DA signaling.

Refeeding-associated AMPKγ1 complex activity is a hallmark of health and longevity

Late-life-initiated dietary interventions show limited efficacy in extending longevity or mitigating frailty, yet the underlying causes remain unclear. Here we studied the age-related fasting response of the short-lived killifish Nothobranchius furzeri. Transcriptomic analysis uncovered the existence of a fasting-like transcriptional program in the adipose tissue of old fish that overrides the feeding response, setting the tissue in persistent metabolic quiescence. The fasting–refeeding cycle triggers an inverse oscillatory expression of genes encoding the AMP-activated protein kinase (AMPK) regulatory subunits Prkag1 (γ1) and Prkag2 (γ2) in young individuals. Aging blunts such regulation, resulting in reduced Prkag1 expression. Transgenic fish with sustained AMPKγ1 countered the fasting-like transcriptional program, exhibiting a more youthful feeding and fasting response in older age, improved metabolic health and longevity. Accordingly, Prkag1 expression declines with age in human tissues and is associated with multimorbidity and multidimensional frailty risk. Thus, selective activation of AMPKγ1 prevents metabolic quiescence and preserves healthy aging in vertebrates, offering potential avenues for intervention.

Appressorium formation is regulated by the Msb2‐ and Sho1‐dependent hierarchical transcriptional network in Colletotrichum gloeosporioides

AbstractColletotrichum gloeosporioides, which penetrates the plant hosts via special infection structures called appressoria, causes anthracnose in many plants worldwide. However, the biological mechanism underlying appressorium formation is not fully characterized in this pathogen. In the present study, the overall gene expression pattern of appressorium formation was studied by targeted gene deletion and expression analysis during the conidial germination of wildtype and ΔCgMsb2Sho1 double mutant strains of C. gloeosporioides on hydrophobic surfaces. Significant transcriptional changes were detected for nearly 41.9% and 45.4% of the genes in the wildtype and ΔCgMsb2Sho1 strains, respectively. Two genes encoding the cAMP‐dependent protein kinase regulatory subunit and adenylate cyclase had higher expression in the wild type than in the ΔCgMsb2Sho1 mutant; cAMP then activates the mitogen‐activated protein kinase (MAPK) signalling pathway. However, we revealed that genes involved in the MAPK signalling pathway may inhibit appressorium formation by encoding proteins that disrupt the downstream signal transduction process after recognition of the host by the cell membrane surface receptor proteins mucin (Msb2) and the sensor protein Sho, encoded by CgMsb2 and CgSho1, respectively. Finally, the regulation of transcription factors on lipid metabolism and plant cell wall‐degrading enzymes was affected. The results provide a comprehensive overview of the changes in the expression of important genes during the early stage of appressorium formation, which may be useful for understanding the molecular mechanism of appressorium formation in C. gloeosporioides.

The role of cAMP-dependent protein kinase A in the formation of long-term memory in Bactrocera dorsalis

The cAMP-dependent protein kinase A (PKA) signaling pathway has long been considered critical for long-term memory (LTM) formation. Previous studies have mostly focused on the role of PKA signaling in LTM induction by multiple spaced conditioning with less attention to LTM induction by a single conditioning. Here, we conducted behavioral-pharmacology, enzyme immunoassay and RNA interference experiments to study the role of the PKA signaling pathway in LTM formation in the agricultural pest Bactrocera dorsalis, which has a strong memory capacity allowing it to form a two-day memory even from a single conditioning trial. We found that either blocking or activating PKA prior to conditioning pretreatment affected multiple spaced LTM, and conversely, they did not affect LTM formed by single conditioning. This was further confirmed by enzyme-linked immunosorbent assay (ELISA) and silencing of the protein kinase regulatory subunit 2 and catalytic subunit 1. Taken together, these results suggest that activating PKA during memory acquisition helps to induce the LTM formed by multiple spaced conditioning but not by a single conditioning. Our findings challenge the conserved role of PKA signaling in LTM, which provides a basis for the greater diversity of molecular mechanisms underlying LTM formation across species, as well as possible functional and evolutionary implications.

Conformational changes in protein kinase A along its activation cycle are rooted in the folding energetics of cyclic-nucleotide binding domains

Cyclic-nucleotide binding (CNB) domains are structurally and evolutionarily conserved signaling modules that regulate proteins with diverse folds and functions. Despite a wealth of structural information, the mechanisms by which CNB domains couple cyclic-nucleotide binding to conformational changes involved in signal transduction remain unknown. Here we combined single-molecule and computational approaches to investigate the conformation and folding energetics of the two CNB domains of the regulatory subunit of protein kinase A (PKA). We found that the CNB domains exhibit different conformational and folding signatures in the apo state, when bound to cAMP, or when bound to the PKA catalytic subunit, underscoring their ability to adapt to different binding partners. Moreover, we show while the two CNB domains have near-identical structures, their thermodynamic coupling signatures are divergent, leading to distinct cAMP responses and differential mutational effects. Specifically, we demonstrate mutation W260A exerts local and allosteric effects that impact multiple steps of the PKA activation cycle. Taken together, these results highlight the complex interplay between folding energetics, conformational dynamics, and thermodynamic signatures that underlies structurally conserved signaling modules in response to ligand binding and mutational effects.

PD03-02 NOVEL STRUCTURAL VARIANTS IN CTNNB1 AND MOLECULAR CLASSIFICATION IN CORTISOL-PRODUCING ADENOMA

You have accessJournal of UrologyCME1 Apr 2023PD03-02 NOVEL STRUCTURAL VARIANTS IN CTNNB1 AND MOLECULAR CLASSIFICATION IN CORTISOL-PRODUCING ADENOMA Yoichi Fujii, Seiichiro Higuchi, Yusuke Sato, Yuichi Shiraishi, Kenichi Yoshida, Satoru Miyano, Haruki Kume, Tomohiko Ichikawa, Atsushi Iwama, Tomoaki Tanaka, and Seishi Ogawa Yoichi FujiiYoichi Fujii More articles by this author , Seiichiro HiguchiSeiichiro Higuchi More articles by this author , Yusuke SatoYusuke Sato More articles by this author , Yuichi ShiraishiYuichi Shiraishi More articles by this author , Kenichi YoshidaKenichi Yoshida More articles by this author , Satoru MiyanoSatoru Miyano More articles by this author , Haruki KumeHaruki Kume More articles by this author , Tomohiko IchikawaTomohiko Ichikawa More articles by this author , Atsushi IwamaAtsushi Iwama More articles by this author , Tomoaki TanakaTomoaki Tanaka More articles by this author , and Seishi OgawaSeishi Ogawa More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003220.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Cortisol-producing adenoma (CPA) is the most common hormone-producing adrenal tumor. Although several hotspot mutations of driver genes (PRKACA, GNAS, and CTNNB1) have been identified in the previous studies, genotypes have not been confirmed in approximately 30% of CPAs. In addition, the association between genotypes and clinical characteristics of CPAs are poorly understood. METHODS: Genomic DNA and RNA was extracted from 125 surgical specimens of adrenal CPAs, including 60 cases with Cushing’s syndrome (CS) and 65 with subclinical Cushing’s syndrome (SCS), and subjected to targeted-capture sequencing and RNA sequencing. RESULTS: Novel structural variants (SVs) in CTNNB1, including long deletion and inversion, were identified in 8% (10/125) of CPA cases. All these SVs resulted in the lack of exon 3, which encodes the phosphorylation site of beta-catenin and plays an important role in its degradation, leading to the constitutive activation of the Wnt pathway by disrupting the degradation of beta-catenin. In addition, several mutations in PRKACA, which encodes the catalytic subunit of cyclic adenosine monophosphate (cAMP)–dependent protein kinase (PKA), were identified around the known hotspot p.L206. Subsequent functional assay showed that these PRAKACA mutants abolished its binding ability to PRKAR1A, the regulatory subunit of PKA, leading to the constitutive, cAMP-independent PKA activation. In total, 82.4% (103/125) of CPAs had alterations in PRKACA, GNAS, and wnt pathway genes (CTNNB1, APC, and MED12) in almost mutually exclusive manner, based on which CPAs are classified into three distinct subgroups. These mutational subtypes showed distinct genetic and clinical characteristics. RNA sequencing revealed that the expression level of steroidogenic enzymes such as CYP17A1 and CYP21A2 were more upregulated in PRKACA-mutated subtype than wnt-mutated subtype. Consistent with this observation, PRKACA-mutated subtype showed significantly higher cortisol-producing autonomous secretion level, more frequent CS than wnt-mutated subtype. In contrast, wnt-mutated subtype more tended to be SCS, showed lower cortisol-producing ability and largar tumor volume compared to the other two subtypes. CONCLUSIONS: Novel CTNNB1 structural variants were identified. CPAs showed distinct genetic landscape, associated with various clinical features. Source of Funding: No © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e74 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Yoichi Fujii More articles by this author Seiichiro Higuchi More articles by this author Yusuke Sato More articles by this author Yuichi Shiraishi More articles by this author Kenichi Yoshida More articles by this author Satoru Miyano More articles by this author Haruki Kume More articles by this author Tomohiko Ichikawa More articles by this author Atsushi Iwama More articles by this author Tomoaki Tanaka More articles by this author Seishi Ogawa More articles by this author Expand All Advertisement PDF downloadLoading ...

Edmond Fischer's kinase legacy: History of the protein kinase inhibitor and protein kinaseA.

Although Fischer's extraordinary career came to focus mostly on the protein phosphatases, after his co-discovery of Phosphorylase Kinase with Ed Krebs he was clearly intrigued not only by cAMP-dependent protein kinase (PKA), but also by the heat-stable, high-affinity protein kinase inhibitor (PKI). PKI is an intrinsically disordered protein that contains at its N-terminus a pseudo-substrate motif that binds synergistically and with high-affinity to the PKA catalytic (C) subunit. The sequencing and characterization of this inhibitor peptide (IP20) were validated by the structure of the PKA C-subunit solved first as a binary complex with IP20 and then as a ternary complex with ATP and two magnesium ions. A second motif, nuclear export signal (NES), was later discovered in PKI. Both motifs correspond to amphipathic helices that convey high-affinity binding. The dynamic features of full-length PKI, recently captured by NMR, confirmed that the IP20 motif becomes dynamically and sequentially ordered only in the presence of the C-subunit. The type I PKA regulatory (R) subunits also contain a pseudo-substrate ATPMg2-dependent high-affinity inhibitor sequence. PKI and PKA, especially the Cβ subunit, are highly expressed in the brain, and PKI expression is also cell cycle-dependent. In addition, PKI is now linked to several cancers. The full biological importance of PKI and PKA signaling in the brain, and their importance in cancer thus remains to be elucidated.

Very Low Protein Diets Induce a Rapid Decrease in Hepatic cAMP-Dependent Protein Kinase Followed by a Slower Increase in Adenylyl Cyclase Activity in Rats

Recent evidence indicates that cAMP-mediated responses are desensitized in liver during malnutrition. While receptor-stimulated production of cAMP is increased in hepatocytes from rats fed very low protein diets for 14 d, activity of cAMP-dependent protein kinase (PKA) is decreased in liver cytosol. The present study investigated the time course for this desensitization. Weanling rats were fed either a 0.5 (malnourished) or 15% protein (control) diet for 1, 3, 7 or 14 d. Total PKA activity decreased after only 3 d of feeding the low protein diet. This decrease was confined to the cytosolic compartment and was associated with a lower quantity of immunoreactive RI regulatory subunit of PKA, with no difference in the quantity of immunoreactive RII regulatory subunit. In contrast, basal-, MnCl2- and guanine nucleotide regulatory protein-stimulated adenylyl cyclase activities were not greater in liver membranes of malnourished rats than in those of the control rats until the 2nd wk of feeding. Greater activity was paralleled by an increase in the quantity of the stimulatory guanine nucleotide regulatory protein at d 14. The inhibitory guanine nucleotide regulatory protein quantity did not differ between dietary groups. Greater cAMP production was not mediated by changes in PKA phosphorylation of adenylyl cyclase because preincubation of membranes with purified PKA catalytic subunit decreased MnCl2-stimulated cAMP production equally in liver membranes of both control and malnourished rats. Similarly, treatment with alkaline phosphatase decreased adenylyl cyclase activity but did not eliminate the difference in adenylyl cyclase activity between control and malnourished rats. These data demonstrate that loss of PKA activity is an early response to a low protein diet and that, subsequently, a number of molecular adaptations occur which increase cAMP production. These changes may be adaptive responses to malnutrition that maintain essential cAMP-dependent functions.

A novel human multiple myeloma cell line with a 1q21 gain genetic abnormality and CKS1B overexpression.

Multiple myeloma (MM) is an incurable hematologic malignancy mainly due to its cytogenetic abnormalities. Therefore, it is important to establish permanent malignant MM cell lines as tools to develop more effective therapies. Pleural effusion cells of a 70-year-old patient was collected to establish the CZ2 cell line. Characterization of CZ2 was determined with nephelometry, flow cytometry, fluorescence in situ hybridization (FISH), and chromosomal microarray analysis (CMA). Western blotting analysis was adopted to determine protein expression. Cell viability was measured by the 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. We established and characterized a new MM cell line, CZ2. Using nephelometry and flow cytometry, cells with typical plasma cell morphology but not classical plasma cell phenotype were found to be non-immunoglobulin-secretary cells. FISH analysis of cells revealed a unique characteristic, namely, that there was only gain of the 1q21 region (1q21+). No other common cytogenetic abnormalities in MM, such as deletion of 17p (17p-), deletion of 13q (13q-), or translocation of immunoglobulin heavy chain (IgH), were observed. In addition, the original cell line maintains its single cytogenetic abnormality. Meanwhile, we observed through western blotting that CDC28 protein kinase regulatory subunit 1B (CKS1B), an adverse prognostic gene located in the 1q21 region, was highly expressed in CZ2. Knockdown of CKS1B reduced cell viability and also increased the levels of cleaved-poly(ADP-ribose) polymerase (cleaved-PARP) and cleaved-caspase3. CZ2 provides a suitable material for cellular and molecular studies of MM with only a 1q21 abnormality. This cell line is characterized by a gain of 1q21, and the high expression of CKS1B is an important model for studies of myeloma cell growth and drug resistance during therapy.

Comprehensive Expression Profiling and Molecular Basis of CDC28 Protein Kinase Regulatory Subunit 2 in Cervical Cancer.

More and more evidence suggests the oncogenic function of overexpressed CDC28 protein kinase regulatory subunit 2 (CKS2) in various human cancers. However, CKS2 has rarely been studied in cervical cancer. Herein, taking advantage of massive genetics data from multicenter RNA-seq and microarrays, we were the first group to perform tissue microarrays for CKS2 in cervical cancer. We were also the first to evaluate the clinical significance of CKS2 with large samples (980 cervical cancer cases and 422 noncancer cases). We further excavated the mechanism of the tumor-promoting activities of CKS2 in cervical cancer through analysis of genetic mutation profiles, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) significant enrichment of genes coexpressed with CKS2. According to the results, expression data from multilevels unanimously supported the overexpression of CKS2 in cervical cancer. Patients with cervical cancer in stage II from inhouse microarrays had significantly higher expression of CKS2, and CKS2 overexpression had an adverse impact on the disease-free survival status of cervical cancer patients in GSE44001. Both mutation types of mRNA high and mRNA low appeared in cervical cancer cases from the TCGA Firehose project. Gene coexpressed with CKS2 participated in pathways including the cell cycle, estrogen signaling pathway, and DNA replication. In summary, upregulated CKS2 is closely associated with the malignant clinical development of cervical cancer and might serve as a valuable therapeutic target in cervical cancer.

Integrated regulation of PKA by fast and slow neurotransmission in the nucleus accumbens controls plasticity and stress responses

Cortical glutamate and midbrain dopamine neurotransmission converge to mediate striatum-dependent behaviors, while maladaptations in striatal circuitry contribute to mental disorders. However, the crosstalk between glutamate and dopamine signaling has not been entirely elucidated. Here we uncover a molecular mechanism by which glutamatergic and dopaminergic signaling integrate to regulate cAMP-dependent protein kinase (PKA) via phosphorylation of the PKA regulatory subunit, RIIβ. Using a combination of biochemical, pharmacological, neurophysiological, and behavioral approaches, we find that glutamate-dependent reduction in cyclin-dependent kinase 5 (Cdk5)-dependent RIIβ phosphorylation alters the PKA holoenzyme autoinhibitory state to increase PKA signaling in response to dopamine. Furthermore, we show that disruption of RIIβ phosphorylation by Cdk5 enhances cortico-ventral striatal synaptic plasticity. In addition, we demonstrate that acute and chronic stress in rats inversely modulate RIIβ phosphorylation and ventral striatal infusion of a small interfering peptide that selectively targets RIIβ regulation by Cdk5 improves behavioral response to stress. We propose this new signaling mechanism integrating ventral striatal glutamate and dopamine neurotransmission is important to brain function, may contribute to neuropsychiatric conditions, and serves as a possible target for the development of novel therapeutics for stress-related disorders.

Abstract 2494: Pathogenesis of fibrolamellar: Proteome and phosphome of an oncokinase driven cancer

Abstract Fibrolamellar hepatocellular carcinoma, FLC, is a usually lethal cancer affecting children, and young adults. We have shown that all patients have a disruption in the ecology of protein kinase A activity. Hundreds of patients tested have a fusion of the first exon of DNABJ1, a heat shock protein cofactor, to PRKACA, the catalytic subunit of protein kinase A and expression of this DNAJB1-PRKACA fusion oncokinase is sufficient to produce the tumor. One patient is missing the regulatory subunit of protein kinase A and three patients have a fusion of the first exon of a different protein, ATP1B1, to the catalytic subunit of protein kinase A. We characterized the proteome and phosphoproteome of FLC cells relative to adjacent normal tissue. The changes were sufficiently characteristic to identify cell extracts from FLC, based solely on the proteome or phosphoproteome, and distinguishable from other tumor or normal liver. By calibrating protein level we found that tumor cells have an increase of catalytic subunit to such an extent as to exceed the capacity of protein kinase A regulatory subunits. This has two implications. First, there is free catalytic subunit that is unregulated, creating a high basal level of kinase activity. Second, the catalytic subunit is no longer localized by tethering to the regulatory subunit. Thus, the catalytic subunit has access to novel substrates. As an independent confirmation, we found the free basal kinase activity was higher in FLC cells. As a further test, we showed free catalytic subunit, that is not conjugated to regulatory subunit, is higher in FLC cells. We next tested whether these changes were solely due to overexpression of the catalytic subunit or if there was some additional change in the intrinsic activity of the kinase as a result of the fusion. We purified, without using an affinity tag, either PRKACA (which is myristoylated), DNAJB1-PRKACA, and PRKACA which was not myristoylated (the DNAJB1-PRKACA is not myristoylated). As a further control we also used the PRKACAL206R mutation, which does not engage regulatory subunits and is present in some forms of Cushing’s disease. We purified cytosol from human liver, blocked activity of all the endogenous kinases, and added our purified kinase. Mass spectrometry was then used to identify all newly phosphorylated proteins. While many proteins were equally phosphorylated by all four kinases (PRKACA, DNAJB1-PRKACA, PRKACA not myristoylated, PRKACAL206R) there were some distinct differences. From an analysis of these we found alterations in the optimal recognition sequence for phosphorylation for each variant of the kinase. Significantly, when we examined the human tissue data, we found many proteins that were phosphorylated by the DNAJB1-PRKACA in vitro were also phosphorylated in patient tumor tissue, but not in adjacent non-transformed tissue. This validated these observations of altered phosphorylation from the in vitro assays. Citation Format: Solomon Levin, Mahsa Shironi, Melissa Jarmel, Michael Tomasini, Bassem Shebl, Tova Finkelstein, David Requena, Soeren Heissel, Henrik Molina, Philip Coffino, Barbara Lyons, Sanford M. Simon. Pathogenesis of fibrolamellar: Proteome and phosphome of an oncokinase driven cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2494.

Sporadic superficial angiomyxomas demonstrate loss of PRKAR1A expression.

Superficial angiomyxomas are cutaneous mesenchymal tumours that typically present clinically as slow-growing, solitary, asymptomatic nodules that can occur at any age. Histopathologically, these dermal and subcutaneous tumours are characterized by abundant myxoid stroma, numerous thin-walled and often arbourising blood vessels, and spindled to stellate fibroblast-like cells. While usually sporadic, superficial angiomyxomas can occasionally be associated with Carney complex (CNC), an autosomal dominant disorder characterized by inactivating germline mutations in the 1-alpha regulatory subunit of protein kinase A (PRKAR1A) and various clinical manifestations, including cardiac myxomas, facial lentigines, epithelioid blue naevi, endocrinopathies and psammomatous melanotic schwannomas. In this study, we sought to characterize the presence or absence of PRKAR1A expression by immunohistochemistry (IHC) in sporadic superficial angiomyxomas based on our observations in an index case. In total, PRKAR1A immunohistochemical expression was determined in 15 sporadic superficial angiomyxoma cases retrieved from the surgical pathology archives. IHC demonstrated that the lesional cells in 12 cases (80%) were non-reactive to antibodies against PRKAR1A. This study provides evidence in support of a role for PRKAR1A in the development of clinically non-syndromic superficial angiomyxomas. Together with previous studies, this report demonstrates that PRKAR1A may play an important role in the development of a variety of myxomatous mesenchymal tumours.