Robinson-White Audrey, Meoli Elise, Stergiopoulos Sotirios, Horvath Anelia, Boikos Sosipatros, Bossis Ioannis, Stratakis Constantine A
Section on Endocrinology and Genetics, and Pediatric Endocrinology Training Program, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Clin Endocrinol Metab. 2006 Jun;91(6):2380-8. doi: 10.1210/jc.2006-0188. Epub 2006 Mar 28.
Primary pigmented nodular adrenocortical disease, associated with Carney complex, is caused by mutations in PRKAR1A (mt-PRKAR1A), a gene that codes for the regulatory subunit type 1alpha (RIalpha) of cAMP-dependent protein kinase (PKA). PRKAR1A inactivation is associated with dysregulated PKA activity that is thought to result in tumorigenesis. mt-PRKAR1A-bearing lymphocytes from Carney complex patients exhibit enhanced cell proliferation associated with increased expression of the MAPK ERK1/2 pathway.
The objective of the study was to determine how PKA and its subunits and ERK1/2 and their molecular partners change in the presence of PRKAR1A mutations in adrenocortical tissue.
PKA activity and subunit expression, ERK1/2, other immunoassays, and immunohistochemistry on adrenocortical samples from patients with germline normal or mt-PRKAR1A were analyzed.
Increased cAMP-stimulated total kinase activity was associated with mt-PRKAR1A. PKA subunit expression analysis in mt-PRKAR1A tissues, by quantitative mRNA assay and immunoblotting, showed a 2.4-fold (P = 0.02) and 1.8-fold (P = 0.09) decrease in RIalpha's message and protein, respectively, and increases in other PKA subunits. Immunoassays showed 2-fold (P = 0.03) and 6-fold (P = 0.03) decreases in baseline ERK1/2, with corresponding increases in phosphorylated (p) ERK1/2 in mt-PRKAR1A samples. B-raf kinase, p-MEK1/2, and p-c-Myc, but not p-Akt/protein kinase B, were significantly increased. Immunohistochemistry studies supported these data.
mt-PRKAR1A causes increased total cAMP-stimulated kinase activity, likely the result of up-regulation of other PKA subunits caused by down-regulation of RIalpha, as seen in human lymphocytes and mouse animal models. These changes, associated with enhanced MAPK activity, may be, in part, responsible for the proliferative signals that result in primary pigmented nodular adrenocortical disease.
与卡尼综合征相关的原发性色素沉着性结节性肾上腺皮质疾病是由PRKAR1A（线粒体PRKAR1A）基因突变引起的，该基因编码环磷酸腺苷（cAMP）依赖性蛋白激酶（PKA）的1α调节亚基（RIα）。PRKAR1A失活与PKA活性失调有关，而PKA活性失调被认为会导致肿瘤发生。来自卡尼综合征患者的携带线粒体PRKAR1A的淋巴细胞表现出与丝裂原活化蛋白激酶（MAPK）细胞外信号调节激酶1/2（ERK1/2）途径表达增加相关的细胞增殖增强。
本研究的目的是确定在肾上腺皮质组织中存在PRKAR1A突变的情况下，PKA及其亚基以及ERK1/2及其分子伴侣如何变化。
对生殖系正常或携带线粒体PRKAR1A的患者的肾上腺皮质样本进行PKA活性和亚基表达、ERK1/2、其他免疫测定和免疫组织化学分析。
cAMP刺激的总激酶活性增加与线粒体PRKAR1A有关。通过定量mRNA测定和免疫印迹对线粒体PRKAR1A组织中的PKA亚基表达进行分析，结果显示RIα的信使核糖核酸（mRNA）和蛋白质分别下降了2.4倍（P = 0.02）和1.8倍（P = 0.09），而其他PKA亚基增加。免疫测定显示，线粒体PRKAR1A样本中的基线ERK1/2下降了2倍（P = 0.03）和6倍（P = 0.03），而磷酸化（p）ERK1/2相应增加。B-raf激酶、磷酸化MEK1/2和磷酸化c-Myc显著增加，但磷酸化Akt/蛋白激酶B未增加。免疫组织化学研究支持了这些数据。
线粒体PRKAR1A导致cAMP刺激的总激酶活性增加，这可能是人淋巴细胞和小鼠动物模型中RIα下调导致其他PKA亚基上调的结果。这些变化与MAPK活性增强相关，可能部分导致了导致原发性色素沉着性结节性肾上腺皮质疾病的增殖信号。
