[Respiratory impairment in a patient with acrodysostosis: A rare association of an uncommon pathology]. / Afectación respiratoria en paciente con acrodisostosis: una asociación infrecuente de una enfermedad rara.

Acrodysostosis is a rare skeletal displasia, of autosomal dominant inheritance, characterized by the presence of facial and peripheral dysostosis, short stature and obesity. Type 1 acrodysostosis is secondary to a mutation in the PRKAR1A (17q24.2) gene, which results in multi hormonal resistance and skeletal anomalities. This syndrome is under-diagnosed as it shares analytical and clinical characteristics with other entities, such as pseudohypoparathyroidism. We report the case of an eight-year-old girl with genetically confirmed type 1 acrodysostosis. In addition to the characteristic phenotype described, the short stature and the hormonal resistance, the Afectación respiratoria en paciente con acrodisostosis: una asociación infrecuente de una enfermedad rara Respiratory impairment in a patient with acrodysostosis: A rare association of an uncommon pathology patient suffered a progressive lung function deterioration: an irreversible pulmonary obstructive pattern. We have not found in previous literature cases reporting an association between acrodysostosis and lung function impairement.

La acrodisostosis es una displasia esquelética rara, de herencia autosómica dominante, que se caracteriza por la presencia de disostosis facial y periférica, talla baja y diferentes grados de obesidad. La acrodisostosis de tipo 1, secundaria a la mutación heterocigota en el gen PRKAR1A (17q24.2), se caracteriza por la asociación de resistencia hormonal múltiple con anomalías esqueléticas. Su incidencia está infradiagnosticada debido a que comparte rasgos clínicos y de laboratorio con otras entidades como el seudohipoparatiroidismo. Presentamos el caso de una niña de 8 años, con acrodisostosis tipo 1, confirmada mediante estudio genético. Además del fenotipo característico descrito, la talla baja y la resistencia hormonal, la paciente presentó una afectación progresiva de la función pulmonar: un patrón pulmonar obstructivo no reversible. En la literatura revisada, no se han encontrado otros casos que describan esta asociación entre acrodisostosis y afectación respiratoria.

A novel mutation in PRKAR1A gene in a patient with Carney complex presenting with pituitary macroadenoma, acromegaly, Cushing's syndrome and recurrent atrial myxoma

SUMMARY Carney complex (CNC) is a rare syndrome of multiple endocrine and non-endocrine tumors. In this paper we present a 23-year-old Iranian woman with CNC who harbored a novel mutation (c.642dupT) in PRKAR1A gene. This patient presented with pituitary macroadenoma, acromegaly, recurrent atrial myxoma, Cushing's syndrome secondary to primary pigmented nodular adrenocortical disease and pigmented schwanoma of the skin. PRKAR1A gene was PCR amplified using genomic DNA and analyzed for sequence variants which revealed the novel mutation resulting in substitution of amino acid cysteine instead of the naturally occurring valine in the peptide chain and a premature stop codon at position 18 (V215CfsX18). This change leads to development of tumors in different organs due to lack of tumor suppressive activity secondary to failure of synthesis of the related protein.

A novel mutation in PRKAR1A gene in a patient with Carney complex presenting with pituitary macroadenoma, acromegaly, Cushing's syndrome and recurrent atrial myxoma.

Carney complex (CNC) is a rare syndrome of multiple endocrine and non-endocrine tumors. In this paper we present a 23-year-old Iranian woman with CNC who harbored a novel mutation (c.642dupT) in PRKAR1A gene. This patient presented with pituitary macroadenoma, acromegaly, recurrent atrial myxoma, Cushing's syndrome secondary to primary pigmented nodular adrenocortical disease and pigmented schwanoma of the skin. PRKAR1A gene was PCR amplified using genomic DNA and analyzed for sequence variants which revealed the novel mutation resulting in substitution of amino acid cysteine instead of the naturally occurring valine in the peptide chain and a premature stop codon at position 18 (V215CfsX18). This change leads to development of tumors in different organs due to lack of tumor suppressive activity secondary to failure of synthesis of the related protein.

Modificações pós-traducionais durante o processo de amastigogênese do Trypanosoma cruzi / Post-translational modifications during the amastigogenesis of Trypanosoma cruzi

A doença de Chagas é uma doença negligenciada causada pelo protozoário Trypanosoma cruzi constituindo-se em um problema de saúde pública em vários países da América Latina. No seu complexo ciclo de vida, o protozoário passa por quatro estágios diferentes: tripomastigota metacíclica, amastigota, tripomastigota sanguíneo e epimastigota, que permitem sua sobrevivência nos diferentes ambientes com os quais o parasita entra em contato. A diferenciação dos tripomastigotas de T. cruzi em amastigotas (amastigogênese) ocorre com grandes mudanças morfológicas, estruturais e metabólicas no parasita e pode ser reproduzido in vitro por exemplo, pela acidificação do meio extracelular. Apesar dos vários trabalhos descritos na literatura, o processo ainda não é totalmente compreendido. A participação de NO na transdução de sinal durante a amastigogênese, sugerida por dados não publicados de nosso grupo, assim como a via de sinalização dependente de AMPc, foram o foco do presente estudo. A indução da amastigogênese foi obtida por incubação de tripomastigotas em meio de cultura acidificado (pH 6,0) e os parâmetros estudados comparados com parasitas controle (meio de cultura, pH 7,4). Estudamos a variação no perfil de nucleotídios cíclicos (AMPc, GMPc), de quinases (PKA, MAPK- ERK1/2), de uma fosfatase (PP2A), assim como o perfil de proteínas fosforiladas, S-nitrosiladas e nitradas até 6 h do início da amastigogênese. O processo foi dividido nas etapas: inicial (até 60 minutos) e tardio (em torno de 3-4 h), caracterizados por um aumento de formas amastigotas na etapa tardia. Houve um aumento de aproximadamente 17 vezes no nível de AMPc nos primeiros 15 minutos da amastigogênese (meio pH 6,0), seguido por aumento discreto no nível de PKA fosforilada, utilizado como indicador de atividade enzimática, este mais evidente na etapa tardia (360 minutos). Quanto à subunidade catalítica fosforilada da MAPK (ativa), há uma aparente diminuição no nível de fosforilação na fase inicial (30 minutos) e aumento na etapa tardia (120 minutos) do processo de amastigogênese. Quanto ao perfil geral de fosforilação de proteínas, há uma diminuição de fosforilação em torno de 30 minutos, seguida de aumento de fosforilação em proteínas de aproximadamente 5 e 100 kDa, mas de maneira geral, não se observaram grandes mudanças nesse perfil com a metodologia utilizada. Quanto às modificações por NO e seus derivados, foram observadas modificações por S-nitrosilação e nitração das proteínas, além do aumento de GMPc em torno de 60 minutos. Embora essas modificações modulem a atividade biológica de uma grande diversidade de proteínas, seu papel biológico não foi explorado.8 Em resumo, nossos resultados apontam para uma variação no perfil de fosforilação, S-nitrosilação e nitração de proteínas, além do aumento de AMPc e GMPc ao longo do processo de amastigogênese in vitro, com a via de sinalização dependente de quinases/ fosfatases e de óxido nítrico ocorrendo ao longo do processo de amastigogênese

Chagas disease is a neglected disease caused by the parasite Trypanosoma cruzi and is a public health problem in several Latin American countries. In its complex life cycle, the protozoan goes through four different stages: metacyclic trypomastigote, amastigote, blood trypomastigote and epimastigote, which allow its survival in the different environments which the parasite comes into contact. The differentiation of T. cruzi trypomastigotes into amastigotes (amastigogenesis) occurs with large morphological, structural and metabolic changes in the parasite and can be reproduced in vitro by, for example, acidification of the extracellular medium. Despite the many data described in the literature, the process is not yet fully understood. The participation of NO in signal transduction during amastigogenesis, suggested by unpublished data from our group, as well as the cAMP-dependent signaling pathway, were the focus of the present study. The induction of amastigogenesis was obtained by incubating trypomastigotes in acidified culture medium (pH 6.0) and the studied parameters compared with control parasites (culture medium, pH 7.4). We studied the variation in the profile of cyclic nucleotides (cAMP, cGMP), kinases (PKA, MAPK-ERK1 / 2), phosphatase (PP2A), as well as the profile of phosphorylated, S-nitrosylated and nitrated proteins up to 6 h. onset of amastigogenesis. The process was divided into early (up to 60 minutes) and late (around 3-4 hours), characterized by an increase in amastigote forms in the late stage. There was an approximately 17-fold increase in cAMP level in the first 15 minutes of amastigogenesis (pH 6.0 medium), followed by a slight increase in phosphorylated PKA level, most evident in the late stage (360 minutes). As for the phosphorylated catalytic subunit of MAPK (active), there is an apparent decrease in the phosphorylation level in the early phase (30 minutes) and increase in the late stage (120 minutes) of the amastigogenesis process. As for the general protein phosphorylation profile, there is a decrease in phosphorylation around 30 minutes, followed by an increase in phosphorylation of proteins (approximately 5 and 100 kDa), but overall, no major changes were observed in this profile with the methodology used. As for modifications by NO and its derivatives, modifications were observed by S-nitrosylation and protein nitration, besides the increase of cGMP around 60 minutes. Although these modifications modulate the biological activity of a wide range of proteins, their biological role has not been explored. In summary, our results point to a variation in phosphorylation, S-nitrosylation and nitration profile of proteins, as well as an increase in cAMP and cGMP along the amastigogenesis process, implicating kinases / phosphatases and nitric oxide dependent signaling pathways in this differentiation

Carney complex with PRKAR1A gene mutation: A case report and literature review.

RATIONALE: Carney complex (CNC) is a multiple neoplasia syndrome with autosomal dominant inheritance. CNC is characterized by the presence of myxomas, spotty skin pigmentation, and endocrine overactivity. No direct correlation has been established between disease-causing mutations and phenotype. PATIENT CONCERNS: A 16-year-old boy was admitted because of excessive weight gain over 3 years and purple striae for 1 year. Physical examination revealed Cushingoid features and spotty skin pigmentation on his face, lip, and sclera. DIAGNOSES: The patient was diagnosed as Carney complex. INTERVENTIONS: the patient underwent right adrenalectomy and partial adrenalectomy of the left adrenal gland. OUTCOME: Results of imaging showed bilateral adrenal nodular hyperplasia, multiple microcalcifications of the bilateral testes, and compression fracture of the thoracolumbar spine. Histopathological results confirmed multiple pigmented nodules in the adrenal glands. DNA sequencing revealed a nonsense mutation in the gene encoding regulatory subunit type 1-alpha of protein kinase A (PRKAR1A; c.205C > T). After the second adrenalectomy, the Cushingoid features disappeared, and cortisol levels returned to normal. LESSONS: Carney complex is a rare disease that lacks consistent genotype-phenotype correlations. Our patient, who carried a germline PRKAR1A nonsense mutation (c.205C > T), clinical features included spotty skin pigmentation, osteoporosis, and primary pigmented nodular adrenal disease. Adrenalectomy is the preferred treatment for Cushing syndrome due to primary pigmented nodular adrenal disease.

Children with Cushing's syndrome: Primary Pigmented Nodular Adrenocortical Disease should always be suspected.

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare form of bilateral adrenocortical hyperplasia that is inherited in an autosomal dominant manner and leads to ACTH-independent Cushing's syndrome (CS). PPNAD may be isolated or associated with Carney Complex (CNC). For the diagnosis of PPNAD and CNC, in addition to the hormonal and imaging tests, searching for PRKAR1A mutations may be recommended. The aims of the present study are to discuss the clinical and molecular findings of two Brazilian patients with ACTH-independent CS due to PPNAD and to show the diagnostic challenge CS represents in childhood. Description of two patients with CS and the many sequential steps for the diagnosis of PPNAD is provided. Sequencing analysis of all coding exons of PRKAR1A in the blood, frozen adrenal nodules (patients 1 and 2) and testicular tumor (patient 1) is performed. After several clinical and laboratory drawbacks that misled the diagnostic investigation in both patients, the diagnosis of PPNAD was finally established and confirmed through pathology and molecular studies. In patient 1, sequencing of PRKAR1A gene revealed a novel heterozygous 10-bp deletion in exon 3, present in his blood, adrenal gland and testicular tumor. The etiologic diagnosis of endogenous CS in children is a challenge that requires expertise and a multidisciplinary collaboration for its prompt and correct management. Although rare, PPNAD should always be considered among the possible etiologies of CS, due to the high prevalence of this disease in this age group.

[Cardiac myxomas and the Carney complex]. / Mixomas cardiacos y complejo de Carney.

The study involved 63 patients with an echocardiographic, surgical and histopathologic diagnosis of cardiac myxoma who were seen over a period of 20 years. Tumor recurrence or relapse was documented in five of these patients (7.9%), 3 of whom had a confirmed diagnosis of Carney complex, while one other patient had a probable diagnosis. Genetic studies demonstrated abnormalities in the PRKAR1A gene on chromosome 17 in 2 patients and their immediate family. In 11 of the 58 patients who did not experience relapse of the myxoma, genetic studies failed to show any abnormality. In conclusion, the possible presence of the Carney complex should be investigated in patients with multiple myxomas or with a cardiac myxoma whose location is atypical.

Absence of PRKAR1A loss of heterozygosity in laser-captured microdissected pigmented nodular adrenocortical tissue from a patient with Carney complex caused by the novel nonsense mutation p. Y21X / Ausência da perda de heterozigose do PRKAR1A em células capturadas por microdissecção a laser de tecido de nódulo pigmentoso adrenocortical de um paciente com complexo de Carney causado por uma nova mutação nonsense

OBJECTIVE: Primary pigmented nodular adrenocortical disease (PPNAD) is the main endocrine manifestation of Carney complex, a multiple neoplasia syndrome caused by PRKAR1A gene mutations. The presence of PRKAR1A loss of heterozygosity (LOH) in adrenocortical tumorigenesis remains controversial. The aim of the present study is to investigate the presence of PRKAR1A LOH in adrenocortical cells in a patient with Carney complex. METHODS: The LOH was investigated using a PRKAR1A informative intragenic marker by GeneScan software analysis in DNA obtained from laser-captured microdissected cells of several adrenal nodules. Patients: A young adult male patient with Carney complex and his family were studied. RESULTS: A novel heterozygous mutation (p. Y21X) was identified at PRKAR1A in blood DNA of the male proband and his relatives. No PRKAR1A LOH was evidenced in the laser-captured microdissected cells from PPNAD tissue by different methodologies. CONCLUSION: We identified a new PRKAR1A nonsense mutation and in addition we did not evidence PRKAR1A LOH in laser-captured nodules cells, suggesting that adrenocortical tumorigenesis in PPNAD may occurs apart from the second hit.

OBJETIVO: A doença adrenocortical nodular pigmentosa primária (PPNAD) é uma das manifestações do complexo de Carney, uma neoplasia endócrina múltipla causada por mutações no PRKAR1A. A perda de heterozigose (LOH) do PRKAR1A na tumorigenese adrenal permanece controversa dada à possibilidade de contaminação com o tecido normal. Nosso objetivo foi investigar a presença de LOH no PRKAR1A a partir de células do nódulo adrenal de um paciente com complexo de Carney. MÉTODOS: A pesquisa da LOH do PRKAR1A foi realizada através do estudo de um marcador intragênico em DNA de células do nódulo adrenal microdissecadas a laser, evitando contaminação com o tecido normal. Pacientes: Um paciente com PPNAD e cinco familiares foram estudados. RESULTADOS: A nova mutação (p. Y21X) foi identificada no PRKAR1A sem evidência de LOH no tecido adrenal. CONCLUSÃO: Identificamos uma nova mutação no PRKAR1A e não evidenciamos LOH nas células dos nódulos adrenocorticais, sugerindo que a PPNAD possa ocorrer na ausência de um segundo evento molecular.

[Absence of PRKAR1A loss of heterozygosity in laser-captured microdissected pigmented nodular adrenocortical tissue from a patient with Carney complex caused by the novel nonsense mutation p.Y21X]. / Ausência da perda de heterozigose do PRKAR1A em células capturadas por microdissecção a laser de tecido de nódulo pigmentoso adrenocortical de um paciente com complexo de Carney causado por uma nova mutação nonsense.

OBJECTIVE: Primary pigmented nodular adrenocortical disease (PPNAD) is the main endocrine manifestation of Carney complex, a multiple neoplasia syndrome caused by PRKAR1A gene mutations. The presence of PRKAR1A loss of heterozygosity (LOH) in adrenocortical tumorigenesis remains controversial. The aim of the present study is to investigate the presence of PRKAR1A LOH in adrenocortical cells in a patient with Carney complex. METHODS: The LOH was investigated using a PRKAR1A informative intragenic marker by GeneScan software analysis in DNA obtained from laser-captured microdissected cells of several adrenal nodules. PATIENTS: A young adult male patient with Carney complex and his family were studied. RESULTS: A novel heterozygous mutation (p. Y21X) was identified at PRKAR1A in blood DNA of the male proband and his relatives. No PRKAR1A LOH was evidenced in the laser-captured microdissected cells from PPNAD tissue by different methodologies. CONCLUSION: We identified a new PRKAR1A nonsense mutation and in addition we did not evidence PRKAR1A LOH in laser-captured nodules cells, suggesting that adrenocortical tumorigenesis in PPNAD may occurs apart from the second hit.

Primary pigmented nodular adrenocortical disease and Cushing's syndrome

Primary pigmented nodular adrenocortical disease (PPNAD) is a form of bilateral adrenocortical hyperplasia that is often associated with corticotrophin (ACTH)-independent Cushing's syndrome (CS) and is characterized by small to normal-sized adrenal glands containing multiple small cortical pigmented nodules (1,2). PPNAD may occur in an isolated form or associated with a multiple neoplasia syndrome, the complex of spotty skin pigmentation, myxomas, and endocrine overactivity, or Carney complex, in which Cushing's syndrome is the most common endocrine manifestation (3). Molecular studies have led to the identification of several genes, defects in which may predispose PPNAD formation; all of these molecules play important role for the cAMP signaling pathway. This review intends to present the most recent knowledge of the pathology and molecular genetics of the benign bilateral adrenocortical lesions, as well as to discuss the modern tools for diagnostics and treatment of this condition.

A doença adrenocortical nodular pigmentada primária (PPNAD) é uma forma de hiperplasia adrenocortical bilateral que está freqüentemente associada com a síndrome de Cushing (SC) ACTH-independente, sendo caracterizada por glândulas adrenais de tamanho pequeno ou normal contendo múltiplos nódulos corticais pigmentados pequenos. PPNAD pode ocorrer de forma isolada ou associada com uma síndrome de neoplasia múltipla, o complexo de manchas pigmentadas na pele (lentigíneas), mixomas e hiperatividade endócrina, ou complexo de Carney, no qual a SC é a manifestação endócrina mais comum. Estudos moleculares levaram à identificação de vários genes que, quando mutados, podem predispor à formação da PPNAD; todas essas moléculas têm um papel importante na via de sinalização do AMPc. Esta revisão pretende apresentar os conhecimentos mais recentes sobre a patologia e a genética molecular das lesões adrenocorticais benignas bilaterais e discutir os modernos instrumentos para diagnóstico e tratamento dessa condição.

Primary pigmented nodular adrenocortical disease and Cushing's syndrome.

Primary pigmented nodular adrenocortical disease (PPNAD) is a form of bilateral adrenocortical hyperplasia that is often associated with corticotrophin (ACTH)-independent Cushing's syndrome (CS) and is characterized by small to normal-sized adrenal glands containing multiple small cortical pigmented nodules (1,2). PPNAD may occur in an isolated form or associated with a multiple neoplasia syndrome, the complex of spotty skin pigmentation, myxomas, and endocrine overactivity, or Carney complex, in which Cushing's syndrome is the most common endocrine manifestation (3). Molecular studies have led to the identification of several genes, defects in which may predispose PPNAD formation; all of these molecules play important role for the cAMP signaling pathway. This review intends to present the most recent knowledge of the pathology and molecular genetics of the benign bilateral adrenocortical lesions, as well as to discuss the modern tools for diagnostics and treatment of this condition.

Melanotic nonpsammomatous trigeminal schwannoma as the first manifestation of Carney complex: case report.

OBJECTIVE: Melanotic schwannoma is a rare neoplasm, classifiable as a peripheral nerve sheath tumor, and differentiated from a typical schwannoma by heavy pigmentation. Psammoma bodies can be visualized in more than 50% of melanotic schwannomas. Half of patients with such "psammomatous melanotic schwannomas" have Carney complex, a dominantly transmitted autosomal disorder. Most recently, the tumor suppressor gene, PRKAR1A, coding for the Type 1alpha regulatory subunit of protein kinase A was found to be mutated in approximately half of the known Carney complex families. Although cranial schwannomas have been described in patients with Carney complex, their numbers are too small to be considered a definite part of the syndrome. Furthermore, only melanotic schwannomas with psammoma bodies are included as diagnostic criteria for Carney complex. The objective of this report is to communicate a case of trigeminal nonpsammomatous melanotic schwannoma as the first manifestation of Carney complex. CLINICAL PRESENTATION: A 34-year-old woman presented with odontalgia, right V3 hypoesthesia, V2 paresthesia, and diplopia. Magnetic resonance imaging scans of the brain revealed a small tumor with homogenous contrast in the right trigeminal pathway. INTERVENTION: We performed an extradural approach to the right cavernous sinus by a middle fossa approach. The lateral wall was opened between the cranial nerves, and a soft and black tumor was resected in a piecemeal fashion. Histology and immunohistochemical analysis of the tumor were compatible with melanotic schwannoma, but no psammomatous bodies were identified. Endocrine evaluation showed that this patient's symptoms fulfilled the diagnostic criteria of Carney complex, with lentiginosis, multiple breast ductal adenomas, multiple hypoechoic nodules on thyroid ultrasonography, and a 4 x 5-cm asymptomatic atrial cardiac myxoma, which was removed 15 days after the neurosurgery. Three months later, a recurrence of melanotic schwannoma was identified. Molecular analyses of genomic and somatic deoxyribonucleic acid from the patient found a 578 to 579delTG mutation of PRKAR1A. CONCLUSION: We present the unusual case of a nonpsammomatous trigeminal melanotic schwannoma associated with Carney complex, with confirmed PRKAR1A gene mutation. Our case highlights that neurosurgeons, in the presence of a melanotic schwannoma, should be aware of the features of the Carney complex because, in such cases, pre- and postoperative management is significantly affected. We also postulate that the absence of psammoma bodies or cranial localization do not exclude this diagnosis.

Molecular and immunohistochemical investigation of protein kinase a regulatory subunit type 1A (PRKAR1A) in odontogenic myxomas.

Odontogenic myxomas are rare benign neoplasms affecting the jaw. Myxomas of bones and other sites occur as part of Carney complex (CNC), a multiple neoplasia syndrome caused by mutations in the PRKAR1A gene, which codes for the regulatory subunit of protein kinase A (PKA). In the present study, 17 odontogenic myxomas from patients without CNC were screened for PRKAR1A mutations and PRKAR1A protein expression by immunohistochemistry (IHC). Mutations of the coding region of the PRKAR1A gene were identified in 2 tumors; both these lesions showed no or significantly decreased immunostaining of PRKAR1A in the tumor compared to that in the surrounding normal tissue. One mutation (c.725C>A) led to a nonconservative amino acid substitution in a highly conserved area of the gene (A213D); the other was a single base-pair deletion that led to a frameshift (del774C) and a stop codon 11 amino acids downstream of the mutation site; both tumors were heterozygous for the respective mutations. Of the remaining tumors, 7 of the 15 without mutations showed almost no PRKAR1A in the tumor cells, whereas IHC showed that the protein was abundant in nontumorous cells. We concluded that PRKAR1A may be involved by its down-regulation in the pathogenesis of odontogenic myxomas caused by mutations and/or other genetic mechanisms. Of the sporadic, nonfamilial tumors associated with PRKAR1A mutations, the odontogenic type was the first myxomatous lesion found to harbor somatic PRKAR1A sequence changes.

Clinical and molecular genetics of primary pigmented nodular adrenocortical disease

Complexo de Carney (CNC) é uma síndrome de neoplasia endócrina múltipla (MEN) associada com outras manifestações não endócrinas, como lentígenes, cardiomixomas e adenomas de células de Schwann. A doença nodular pigmentada primária da adrenal (PPNAD), que apresenta-se como síndrome de Cushing independente de corticotropina é a lesão mais freqüente observada em CNC. O CNC tem sido relacionados aos sítios cromossômicos 2p16 e 17q22-24, entretanto, heterogenicidade pode ocorrer. O gene codificador da proteína reguladora tipo 1A da proteína quinase A(RIa), PRKAR1A, tem sido localizado no cromossomo 17q. A clonagem da estrutura genômica e seqüenciamento do gene PRKAR1A revelou mutações em pacientes com CNC e em formas esporádicas de PPNAD. Em tumores de pacientes com CNC, a proteína quinase A apresenta uma resposta de atividade maior após o estímulo com AMPc. Também, nestes tecidos, é observada a perda de heterozigose do alelo normal. Isto sugere que o gene normal do PRKAR1A pode funcionar como um gene de supressão tumoral nos tecidos estudados. CNC é a primeira doença conhecida a ocorrer devido a mutações de uma das sub-unidades da proteína quinase A, um componente crucial na via de sinalização do AMPc e um potencial participante de outras vias de sinalização celular.

Clinical and molecular genetics of primary pigmented nodular adrenocortical disease.

Carney complex (CNC) is a multiple endocrine neoplasia (MEN) syndrome associated with other, non-endocrine manifestations such as lentigines, cardiac myxomas and schwannomas. Primary pigmented nodular adrenocortical disease (PPNAD), leading to corticotrophin-independent Cushing's syndrome is the most frequent endocrine lesion in CNC. The complex has been mapped to 2p16 and 17q22-24, although additional heterogeneity may exist. The gene coding for the protein kinase A (PKA) type I-a regulatory subunit (RIa), PRKAR1A, had been mapped to 17q. Cloning of the PRKAR1A genomic structure and its sequencing showed mutations in CNC-, CNC with PPNAD- and sporadic PPNAD-patients. In CNC tumors, PKA activity showed increased stimulation by cAMP, whereas PKA activity ratio was decreased, and in CNC tumors, there is LOH of the normal allele, suggesting that normal PRKAR1A may be a tumor suppressor in these tissues. CNC is the first human disease caused by mutations of one of the subunits of the PKA enzyme, a critical component of the cAMP signaling system and a potential participant in many other signaling pathways.

Interactions between regulatory and catalytic subunits of the Candida albicans cAMP-dependent protein kinase are modulated by autophosphorylation of the regulatory subunit.

The cAMP-dependent protein kinase (PKA) from Candida albicans is a tetramer composed of two catalytic subunits (C) and two type II regulatory subunits (R). To evaluate the role of a putative autophosphorylation site of the R subunit (Ser(180)) in the interaction with C, this site was mutated to an Ala residue. Recombinant wild-type and mutant forms of the R subunit were expressed in Escherichia coli and purified. The wild-type recombinant R subunit was fully phosphorylated by the purified C subunit, while the mutant form was not, confirming that Ser(180) is the target for the autophosphorylation reaction. Association and dissociation experiments conducted with both recombinant R subunits and purified C subunit showed that intramolecular phosphorylation of the R subunit led to a decreased affinity for C. This diminished affinity was reflected by an 8-fold increase in the concentration of R subunit needed to reach half-maximal inhibition of the kinase activity and in a 5-fold decrease in the cAMP concentration necessary to obtain half-maximal dissociation of the reconstituted holoenzyme. Dissociation of the mutant holoenzyme by cAMP was not affected by the presence of MgATP. Metabolic labeling of yeast cells with [(32)P]orthophosphate indicated that the R subunit exists as a serine phosphorylated protein. The possible involvement of R subunit autophosphorylation in modulating C. albicans PKA activity in vivo is discussed.