The role of ARMC5 in human cell cultures from nodules of primary macronodular adrenocortical hyperplasia (PMAH).

The participation of aberrant receptors and intra-adrenal ACTH in hyperplastic tissue are considered mechanisms that regulate hypercortisolism in PMAH. Additionally, germline ARMC5 mutations have been described as the most frequent genetic abnormality found in patients diagnosed with PMAH. Previous functional studies analyzed ARMC5 role using H295R cells. Therefore, we investigated the role of ARMC5 in cell cultures obtained from PMAH nodules containing steroidogenic cells, aberrant receptors and intra-adrenal ACTH. ARMC5 silencing in non-mutated PMAH cell cultures decreased steroidogenesis-related genes and increased CCNE1 mRNA expression and proliferative capacity without affecting cell viability. Additionally, ARMC5 overexpression induced cell death in PMAH mutated cell cultures, thereby decreasing cell viability. We confirmed the role of ARMC5 as an important pro-apoptotic protein involved in PMAH-related steroidogenesis. We also report for the first time the involvement of ARMC5 in controlling proliferation and regulating cell cycle in PMAH cell cultures; these effects need to be explored further.

SOCS3 expression in SF1 cells regulates adrenal differentiation and exercise performance.

Many hormones/cytokines are secreted in response to exercise and cytokine signaling may play a pivotal role in the training adaptations. To investigate the importance of cytokine signaling during vertical ladder climbing, a resistance exercise model, we produced mice lacking SOCS3 protein exclusively in steroidogenic factor-1 (SF1) cells (SF1 Socs3 KO mice). SF1 expression is found in steroidogenic cells of the adrenal cortex and gonads, as well as in neurons of the ventromedial nucleus of the hypothalamus. Histological markers of the fetal adrenal zone (or X-zone in rodents) were still present in adult males and postpartum SF1 Socs3 KO females, suggesting a previously unrecognized effect of SOCS3 on the terminal differentiation of the adrenal gland. This change led to a distinct distribution of lipid droplets along the adrenal cortex. Under basal conditions, adult SF1 Socs3 KO mice exhibited similar adrenal weight, and plasma ACTH and corticosterone concentrations. Nonetheless, SF1 Socs3 KO mice exhibited a blunted ACTH-induced corticosterone secretion. The overall metabolic responses induced by resistance training remained unaffected in SF1 Socs3 KO mice, including changes in body adiposity, glucose tolerance and energy expenditure. However, training performance and glucose control during intense resistance exercise were impaired in SF1 Socs3 KO mice. Furthermore, a reduced counter-regulatory response to 2-deoxy-d-glucose was observed in mutant mice. These findings revealed a novel participation of SOCS3 regulating several endocrine and metabolic aspects. Therefore, cytokine signaling in SF1 cells exerts an important role to sustain training performance possibly by promoting the necessary metabolic adjustments during exercise.

Anatomical Organization of Urocortin 3-Synthesizing Neurons and Immunoreactive Terminals in the Central Nervous System of Non-Human Primates [Sapajus spp.].

Urocortin 3 (UCN3) is a neuropeptide member of the corticotropin-releasing factor (CRF) peptide family that acts as a selective endogenous ligand for the CRF, subtype 2 (CRF2) receptor. Immunohistochemistry and in situ hybridization data from rodents revealed UCN3-containing neurons in discrete regions of the central nervous system (CNS), such as the medial preoptic nucleus, the rostral perifornical area (PFA), the medial nucleus of the amygdala and the superior paraolivary nucleus. UCN3-immunoreactive (UCN3-ir) terminals are distributed throughout regions that mostly overlap with regions of CRF2 messenger RNA (mRNA) expression. Currently, no similar mapping exists for non-human primates. To better understand the role of this neuropeptide, we aimed to study the UCN3 distribution in the brains of New World monkeys of the Sapajus genus. To this end, we analyzed the gene and peptide sequences in these animals and performed immunohistochemistry and in situ hybridization to identify UCN3 synthesis sites and to determine the distribution of UCN3-ir terminals. The sequencing of the Sapajus spp. UCN3-coding gene revealed 88% and 65% identity to the human and rat counterparts, respectively. Additionally, using a probe generated from monkey cDNA and an antiserum raised against human UCN3, we found that labeled cells are mainly located in the hypothalamic and limbic regions. UCN3-ir axons and terminals are primarily distributed in the ventromedial hypothalamic nucleus (VMH) and the lateral septal nucleus (LS). Our results demonstrate that UCN3-producing neurons in the CNS of monkeys are phylogenetically conserved compared to those of the rodent brain, that the distribution of fibers agrees with the distribution of CRF2 in other primates and that there is anatomical evidence for the participation of UCN3 in neuroendocrine control in primates.

POD-1 binding to the E-box sequence inhibits SF-1 and StAR expression in human adrenocortical tumor cells.

Pod-1/Tcf21 is expressed at epithelial-mesenchymal interaction sites during development of many organs. Different approaches have demonstrated that Pod-1 transcriptionally inhibits Sf-1/NR5A1 during gonadal development. Disruption of Sf-1 can lead to disorders of adrenal development, while increased dosage of SF-1 has been related to increased adrenal cell proliferation and tumorigenesis. In this study, we analyzed whether POD-1 overexpression inhibits the endogenous Sf-1 expression in human and mouse adrenocortical tumor cells. Cells were transiently transfected with luciferase reporter gene under the control of Sf-1 promoter and with an expression vector encoding Pod-1. Pod-1 construct inhibited the transcription of the Sf1/Luc reporter gene in a dose-dependent manner in mouse Y-1 adrenocortical carcinoma (ACC) cells, and inhibited endogenous SF-1 expression in the human H295R and ACC-T36 adrenocortical carcinoma cells. These results were validated by chromatin immunoprecipitation assay with POD-1-transfected H295R cells using primers specific to E-box sequence in SF-1 promoter region, indicating that POD-1 binds to the SF-1 E-box promoter. Moreover, POD-1 over-expression resulted in a decrease in expression of the SF-1 target gene, StAR (Steroidogenic Acute Regulatory Protein). Lastly, while the induced expression of POD-1 did not affect the cell viability of H295R/POD-1 or ACC-T36/POD-1 cells, the most significantly enriched KEGG pathways for genes negatively correlated to POD-1/TCF21 in 33 human ACCs were those associated with cell cycle genes.

N-POMC1-28 increases cyclin D expression and inhibits P27(kip1) in the adrenal cortex.

The Adrenocorticotropic hormone (ACTH) and Pro-opimelanocortin (POMC) 1-28N-terminal peptide (N-POMC(1-28)) have been shown to act as an adrenal mitogen in vivo. A possible role for cyclin E in the zona glomerulosa (ZG) proliferation, following ACTH and/or N-POMC(1-28) administration, has been previously demonstrated. In this study, we investigated the effect of ACTH and N-POMC(1-28) on the expression of adrenal cortex proteins related to cell cycle control such as cyclins D and P27(kip1). The administration of N-POMC upregulated cyclin D1 and D2 expression in the outer zone of the adrenal cortex; cyclin D3 expression was upregulated in the cortex inner zone even after administration of ACTH. Both ACTH and N-POMC peptides induced a decrease in the P27(kip1) expression in the ZG. These novel findings suggest that the POMC-derivate peptides, ACTH and N-POMC, promote proliferation in the adrenal cortex by upregulating the D2 and D3 cyclins and downregulating the P27(kip1) expression.

The proliferative effect of synthetic N-POMC(1-28) peptides in rat adrenal cortex: a possible role for cyclin E.

Modified synthetic N-POMC(1-28) without disulfide bridges has been shown to act as an adrenal mitogen. Cyclins and their inhibitors are the major cell cycle controls, but in the adrenal cortex the effect of ACTH and N-POMC on the expression of these proteins remains unclear. In this work, we evaluate the effect of different synthetic N-POMC peptides on the S-phase of the cell cycle. In addition, we examine the cyclin E expression in rat adrenal cortex. Rats treated with dexamethasone were injected with ACTH and/or synthetic modified N-POMC and/or synthetic N-POMC with disulfide bridges. DNA synthesis was determined by BrdU incorporation and protein expression was analyzed by immunoblotting and immunohistochemistry. The results showed that similarly to modified N-POMC without disulfide bridges, administration of synthetic N-POMC with disulfide bridges and the combination of ACTH and N-POMC promoted an increase of BrdU-positive nuclei in adrenal cortex. However, the proliferative effect of N-POMC was comparable to that of ACTH only in the zona glomerulosa. An increase in cyclin E expression was observed 6 h after N-POMC treatment in the outer fraction of the adrenal cortex, in agreement with immunohistochemical findings in the zona glomerulosa. In summary, the effect of synthetic N-POMC with disulfide bridges was similar to modified synthetic N-POMC, increasing proliferation in the adrenal cortex, confirming previous evidence that disulfide bridges are not essential to the N-POMC mitogenic effect. Moreover, cyclin E appears to be involved in the N-POMC- and ACTH-stimulated proliferation in the zona glomerulosa of the adrenal cortex.

The thyroid hormone receptor (TR) beta-selective agonist GC-1 inhibits proliferation but induces differentiation and TR beta mRNA expression in mouse and rat osteoblast-like cells.

Previous studies showed anabolic effects of GC-1, a triiodothyronine (T3) analogue that is selective for both binding and activation functions of thyroid hormone receptor (TR) beta1 over TRalpha1, on bone tissue in vivo. The aim of this study was to investigate the responsiveness of rat (ROS17/2.8) and mouse (MC3T3-E1) osteoblast-like cells to GC-1. As expected, T3 inhibited cellular proliferation and stimulated mRNA expression of osteocalcin or alkaline phosphatase in both cell lineages. Whereas equimolar doses of T3 and GC-1 equally affected these parameters in ROS17/2.8 cells, the effects of GC-1 were more modest compared to those of T3 in MC3T3-E1 cells. Interestingly, we showed that there is higher expression of TRalpha1 than TRbeta1 mRNA in rat (approximately 20-90%) and mouse (approximately 90-98%) cell lineages and that this difference is even higher in mouse cells, which highlights the importance of TRalpha1 to bone physiology and may partially explain the modest effects of GC-1 in comparison with T3 in MC3T3-E1 cells. Nevertheless, we showed that TRbeta1 mRNA expression increases (approximately 2.8- to 4.3-fold) as osteoblastic cells undergo maturation, suggesting a key role of TRbeta1 in mediating T3 effects in the bone forming cells, especially in mature osteoblasts. It is noteworthy that T3 and GC-1 induced TRbeta1 mRNA expression to a similar extent in both cell lineages (approximately 2- to 4-fold), indicating that both ligands may modulate the responsiveness of osteoblasts to T3. Taken together, these data show that TRbeta selective T3 analogues have the potential to directly induce the differentiation and activity of osteoblasts.

Distribution of cells expressing Jun and Fos proteins and synthesizing DNA in the adrenal cortex of hypophysectomized rats: regulation by ACTH and FGF2.

Protein expression of the early response genes, jun and fos, has been suggested to play an important role in the in vitro and in vivo proliferation of adrenal cells. To elucidate the immunolocalization of proliferative cells and the patterns of adrenal gland expression of members of the activating protein-1 (AP-1) family of oncogenes, we used hypophysectomized rats. The effects of adrenocorticotropic hormone (ACTH) and fibroblast growth factor 2 (FGF2) on Fos and Jun protein expression were investigated, and DNA synthesis was assessed by using bromodeoxyuridine (BrdU) incorporation. No change was detectable in the adrenal cortex at 2 days after hypophysectomy, although a reduction occurred in the number of BrdU-positive cells in the zona fasciculata. This hypophysectomy-induced early phase of adrenal cortex atrophy in the zona fasciculata was correlated with JunB protein induction, suggesting the formation of an inhibitory AP-1 complex. Accumulation of c-Jun/JunD and c-Fos/FosB, but not of JunB, in the zona fasciculata and zona reticularis implied that, after ACTH stimulation, these proteins were the principal AP-1 components in these zones. In these same zones, ACTH increased BrdU-positive cell counts, indicating that the composition of the AP-1 complex in these zones was proliferation-related. However, FGF2 induced an antagonistic modulation of the response to ACTH, by reducing the numbers of Jun-/Fos-positive cells and inhibiting DNA synthesis. Our results implicate the AP-1 family of transcription factors (in particular, the dynamics within the Jun protein family) in the regulation of cell control during ACTH-induced proliferation of the adrenal cortex.

Immunohistochemical Jun/Fos protein localization and DNA synthesis in rat adrenal cortex after treatment with ACTH or FGF2.

In vitro and in vivo studies have suggested that the expression of the early response genes for Jun and Fos proteins plays an important role in adrenal cell proliferation. In order to study the expression pattern of the activating protein-1 (AP-1) family of oncogenes in the adrenal gland, we have used immunohistochemistry to localize Jun and Fos protein expression in rat adrenal cortex infused in situ with adrenocorticotropic hormone (ACTH), fibroblast growth factor 2 (FGF2), or both. The expression of AP-1 factors has been found to be correlated with in vivo ACTH and FGF2 proliferation in rats treated with dexamethasone and bromodeoxyuridine (BrdU). Induction of c-Jun and c-Fos in the zona fasciculata and of FosB in the zona reticularis suggests that, after ACTH stimulation, these proteins are the main AP-1 components in these zones. In vivo, ACTH increases BrdU-positive cells in the zona fasciculata and zona reticularis suggesting that the composition of AP-1 complexes in these zones is correlated with proliferation. Patterns of Fos and Jun induction by FGF2 do not resemble those after ACTH induction. However, in isolation, neither affects the zona glomerulosa. In the zona fasciculata, and more so in the zona reticularis, FGF2 modulates responses to ACTH, reducing the numbers of Jun-positive cells, Fos-positive cells, and DNA synthesis. This indicates that FGF2 antagonizes ACTH, and that ACTH thus controls the trophic effect independently of exogenous FGF2. Our results implicate the AP-1 family of transcription factors in the regulation of cell progression and the control of ACTH-induced proliferation in the zona fasciculata and zona reticularis.

Differences between the growth regulatory pathways in primary rat adrenal cells and mouse tumor cell line.

In this study, DNA synthesis, phosphorylation of ERK1/2 and CREB proteins, as well as induction of c-Fos protein, were examined in rat adrenocortical, glomerulosa and fasciculata/reticularis cells, as well as in the Y1 cell line. We found that FGF2 was mitogenic only in glomerulosa cells and although ACTH did not activate ERK1/2, it did activate CREB protein, indicating efficient transduction of signals initiated in the ACTH receptors of rat adrenocortical cells. The FGF2 activated ERK1/2 in rat adrenal cells by a mechanism that might be modulated by upstream PKA pathway phosphorylation of MEK and despite the nonmitogenic effect of ACTH on rat adrenal cells it effectively induces c-Fos protein. The results presented herein describe distinct differences between the ACTH and FGF2 signal transduction mechanisms seen in adrenocortical cells and those observed in the Y1 cell line, indicating that, in vitro, ACTH blockage of the mitogenic effect occurs in normal adrenal cells after induction of c-Fos protein.

Urocortin in the central nervous system of a primate (Cebus apella): sequencing, immunohistochemical, and hybridization histochemical characterization.

The urocortin (UCN)-like immunoreactivity and UCN mRNA distribution in various regions of the nonprimate mammalian brain have been reported. However, the Edinger-Westphal nucleus (EW) appears to be the only brain site where UCN expression is conserved across species. Although UCN peptides are present throughout vertebrate phylogeny, the functional roles of both UCN and EW remain poorly understood. Therefore, a study focused on UCN system organization in the primate brain is warranted. By using immunohistochemistry (single and double labeling) and in situ hybridization, we have characterized the organization of UCN-expressing cells and fibers in the central nervous system and pituitary of the capuchin monkey (Cebus apella). In addition, the sequence of the prepro-UCN was determined to establish the level of structural conservation relative to the human sequence. To understand the relationship of acetylcholine cells in the EW, a colocalization study comparing choline acetyltransferase (ChAT) and UCN was also performed. The cloned monkey prepro-UCN is 95% identical to the human preprohormone across the matched sequences. By using an antiserum raised against rat UCN and a probe generated from human cDNA, we found that the EW is the dominant site for UCN expression, although UCN mRNA is also expressed in spinal cord lamina IX. Labeled axons and terminals were distributed diffusely throughout many brain regions and along the length of the spinal cord. Of particular interest were UCN-immunoreactive inputs to the medial preoptic area, the paraventricular nucleus of the hypothalamus, the oral part of the spinal trigeminal nucleus, the flocculus of the cerebellum, and the spinal cord laminae VII and X. We found no UCN hybridization signal in the pituitary. In addition, we observed no colocalization between ChAT and UCN in EW neurons. Our results support the hypothesis that the UCN system might participate in the control of autonomic, endocrine, and sensorimotor functions in primates.

Low amounts of the DNA repair XPA protein are sufficient to recover UV-resistance.

DNA integrity is threatened by the damaging effects of physical and chemical agents that can affect its function. Nucleotide excision repair (NER) is one of the most known and flexible mechanisms of DNA repair. This mechanism can recognize and remove damages causing DNA double-helix distortion, including the cyclobutane pyrimidine dimers (CPDs) and the pyrimidine-pyrimidone (6-4) photoproducts, promoted by ultraviolet light (UV). The human syndrome xeroderma pigmentosum (XP) is clinically characterized chiefly by the early onset of severe photosensitivity of the exposed regions of the skin, a very high incidence of skin cancers and frequent neurological abnormalities. The xpa gene seems to be involved during UV damage recognition, in both global genome repair (GGR) and transcription-coupled repair (TCR). The modulation of xpa expression may modify the DNA repair rate in the cell genome, providing a valuable contribution to an understanding of the NER process. The controlled expression of the cDNA xpa in XP12RO deficient cells was achieved through the transfection of a muristerone-A inducible vector, pINXA. The INXA15 clone shows good induction of the XPA protein and total complementation of XP12RO cell deficiency. Overexpression of this protein resulted in UV cell survival comparable to normal control human cells. Moreover, low expression of the XPA protein in these cells is sufficient for total complementation in cellular UV sensitivity and DNA repair activity. These data demonstrate that XPA protein concentration is not a limiting factor for DNA repair.