Somatic KCNJ5 mutation occurring early in adrenal development may cause a novel form of juvenile primary aldosteronism

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Ai Tamura, Koshiro Nishimoto, Tsugio Seki, Yoko Matsuzawa, Jun Saito, Masao Omura, Celso E. Gomez-Sanchez, Kohzoh Makita, Seishi Matsui, Nobukazu Moriya, Atsushi Inoue, Maki Nagata, Hironobu Sasano, Yasuhiro Nakamura, Yuto Yamazaki, Yasuaki Kabe, Kuniaki Mukai, Takeo Kosaka, Mototsugu Oya, Sachiko Suematsu, Tetsuo Nishikawa
We report a case of non-familial juvenile primary aldosteronism (PA). Super-selective adrenal venous sampling identified less aldosterone production in the right inferior adrenal segment than others. Bilateral adrenalectomy sparing the segment normalized blood pressure and improved PA. Both adrenals had similar histologies, consisting of a normal adrenal cortex and aldosterone synthase-positive hyperplasia/adenoma. An aldosterone-driving KCNJ5 mutation was detected in the lesions, but not in the histologically normal cortex. After taking into account that the two adrenal glands displayed a similar histological profile, as well as the fact that hyperplastic lesions in both glands exhibited a common KCNJ5 mutation, we conclude that the specific mutation may have occurred at an adrenal precursor mesodermal cell, at an early stage of development; its daughter cells were mixed with non-mutant cells and dispersed into both adrenal glands, resulting into a form of the condition known as genetic mosaicism.



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Electrochemistry of cytochrome P450 17α-hydroxylase/17,20-lyase (P450c17)

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Lisandra L. Martin, Clemens Kubeil, Alexandr N. Simonov, Vladimir L. Kuznetsov, C. Jo Corbin, Richard J. Auchus, Alan J. Conley, Alan M. Bond, Raymond J. Rodgers
Within the superfamily of cytochrome P450 enzymes (P450s), there is a small class which is functionally employed for steroid biosynthesis. The enzymes in this class appear to have a small active site to accommodate the steroid substrates specifically and snuggly, prior to the redox transformation or hydroxylation to form a product. Cytochrome P450c17 is one of these and is also a multi-functional P450, with two activities, the first 17α-hydroxylation of pregnenolone is followed by a subsequent 17,20-lyase transformation to dehydroepiandrosterone (DHEA) as the dominant pathways to cortisol precursors or androgens in humans, respectively. How P450c17 regulates these two redox reactions is of special interest. There is a paucity of direct electrochemical studies on steroidogenic P450s, and in this mini-review we provide an overview of these studies with P450c17. Historical consideration as to the difficulties in obtaining reliable electrochemistry due to issues of handling proteins on an electrode, together with advances in the electrochemical techniques are addressed. Recent work using Fourier transformed alternating current voltammetry is highlighted as this technique can provide both catalytic information simultaneously with the underlying redox transfer with the P450 haem.



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A new dawn for androgens: Novel lessons from 11-oxygenated C19 steroids

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Elzette Pretorius, Wiebke Arlt, Karl-Heinz Storbeck
The abundant adrenal C19 steroid 11β-hydroxyandrostenedione (11OHA4) has been written off as a dead-end product of adrenal steroidogenesis. However, recent evidence has demonstrated that 11OHA4 is the precursor to the potent androgenic 11-oxygenated steroids, 11-ketotestosterone and 11-ketodihydrotestosterone, that bind and activate the human androgen receptor similarly to testosterone and DHT. The significance of this discovery becomes apparent when considering androgen dependent diseases such as castration resistant prostate cancer and diseases associated with androgen excess, e.g. congenital adrenal hyperplasia and polycystic ovary syndrome. In this review we describe the production and metabolism of 11-oxygenated steroids. We subsequently discuss their androgenic activity and highlight the putative role of these androgens in disease states.



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Genes and proteins of the alternative steroid backdoor pathway for dihydrotestosterone synthesis are expressed in the human ovary and seem enhanced in the polycystic ovary syndrome

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Nesa Marti, José A. Galván, Amit V. Pandey, Mafalda Trippel, Coya Tapia, Michel Müller, Aurel Perren, Christa E. Flück
Recently, dihydrotestosterone biosynthesis through the backdoor pathway has been implicated for the human testis in addition to the classic pathway for testosterone (T) synthesis. In the human ovary, androgen precursors are crucial for estrogen synthesis and hyperandrogenism in pathologies such as the polycystic ovary syndrome is partially due to ovarian overproduction. However, a role for the backdoor pathway is only established for the testis and the adrenal, but not for the human ovary. To investigate whether the backdoor pathway exists in normal and PCOS ovaries, we performed specific gene and protein expression studies on ovarian tissues.We found aldo-keto reductases (AKR1C1-1C4), 5α-reductases (SRD5A1/2) and retinol dehydrogenase (RoDH) expressed in the human ovary, indicating that the ovary might produce dihydrotestosterone via the backdoor pathway. Immunohistochemical studies showed specific localization of these proteins to the theca cells. PCOS ovaries show enhanced expression, what may account for the hyperandrogenism.

Graphical abstract

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Regulation of zonation and homeostasis in the adrenal cortex

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Emanuele Pignatti, Sining Leng, Diana L. Carlone, David T. Breault
The adult adrenal cortex is organized into concentric zones, each specialized to produce distinct steroid hormones. Cellular composition of the cortex is highly dynamic and subject to diverse signaling controls. Cortical homeostasis and regeneration rely on centripetal migration of steroidogenic cells from the outer to the inner cortex, which is accompanied by direct conversion of zona glomerulosa (zG) into zona fasciculata (zF) cells. Given the important impact of tissue structure and growth on steroidogenic function, it is essential to understand the mechanisms governing adrenal zonation and homeostasis. Towards this end, we review the distinctions between each zone by highlighting their morphological and ultra-structural features, discuss key signaling pathways influencing zonal identity, and evaluate current evidence for long-term self-renewing stem cells in the adult cortex. Finally, we review data supporting zG-to-zF transdifferentiation/direct conversion as a major mechanism of adult cortical renewal.



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Immunohistochemistry of aldosterone synthase leads the way to the pathogenesis of primary aldosteronism

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Koshiro Nishimoto, Minae Koga, Tsugio Seki, Kenji Oki, Elise P. Gomez-Sanchez, Celso E. Gomez-Sanchez, Mitsuhide Naruse, Tomokazu Sakaguchi, Shinya Morita, Takeo Kosaka, Mototsugu Oya, Tadashi Ogishima, Masanori Yasuda, Makoto Suematsu, Yasuaki Kabe, Masao Omura, Tetsuo Nishikawa, Kuniaki Mukai
Our group previously purified human and rat aldosterone synthase (CYP11B2 and Cyp11b2, respectively) from their adrenals and verified that it is distinct from steroid 11β-hydroxylase (CYP11B1 or Cyp11b1), the cortisol- or corticosterone-synthesizing enzyme. We now describe their distributions immunohistochemically with specific antibodies. In rats, there is layered functional zonation with the Cyp11b2-positive zona glomerulosa (ZG), Cyp11b1-positive zona fasciculata (ZF), and Cyp11b2/Cyp11b1-negative undifferentiated zone between the ZG and ZF. In human infants and children (<12 years old), the functional zonation is similar to that in rats. In adults, the adrenal cortex remodels and subcapsular aldosterone-producing cell clusters (APCCs) replace the continuous ZG layer. We recently reported possible APCC-to-APA transitional lesions (pAATLs) in 2 cases of unilateral multiple adrenocortical micro-nodules. In this review, we present 4 additional cases of primary aldosteronism, from which the extracted adrenals contain pAATLs, with results of next generation sequencing for these lesions. Immunohistochemistry for CYP11B2 and CYP11B1 has become an important tool for the diagnosis of and research on adrenocortical pathological conditions and suggests that APCCs may be the origin of aldosterone-producing adenoma.



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Function of CYP11A1 in the mitochondria

Publication date: 5 February 2017
Source:Molecular and Cellular Endocrinology, Volume 441
Author(s): Yu Chien, Karen Rosal, Bon-chu Chung
Steroids are synthesized from the adrenal glands and gonads by enzymes of the cytochromes P450 and hydroxysteroid dehydrogenase in nature. These enzymes are located in the membrane of endoplasmic reticulum and mitochondria to catalyze redox reactions using electrons transported from the membrane. In the mitochondria, steroidogenic enzymes are inserted into the inner membrane with the bulk of the protein facing the matrix. They are not only important for steroid biosynthesis, their presence also affects mitochondrial morphology. Mitochondria undergo constant fission and fusion; they play important roles in energy production, apoptosis, and metabolism. Their defects often lead to human diseases. Mitochondrial cristae are usually lamellar in shape, but can also assume different shapes. Cristae in the mitochondria of steroidogenic cells are tubular-vesicular in shape. This cristae shape is also related to the degree of steroidogenic cell differentiation. Steroidogenic enzymes in the mitochondria appear to have a dual role in shaping the morphology of mitochondria and in steroid production.



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