Τετάρτη, 8 Μαΐου 2019

Molecular and Cellular Endocrinology

The impact of Catechol-O-methyl transferase knockdown on the cell proliferation of hormone-responsive cancers

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Mai F. Tolba, Hany A. Omar, Fatima Hersi, Ane C.F. Nunes, Ayman M. Noreddin

Abstract

Estrogen (E2) plays a central role in the development and progression of hormone-responsive cancers. Estrogen metabolites exhibit either stimulatory or inhibitory roles on breast and prostate cells. The catechol metabolite 4-hydroxyestradiol (4-OHE2) enhances cell proliferation, while 2-methoxyestradiol (2 ME) possesses anticancer activity. The major metabolizing enzyme responsible for detoxifying the deleterious metabolite 4-OHE2 and forming the anticancer metabolite 2 ME is Catechol-O-Methyl Transferase (COMT). The current work investigated the relationship between the expression level of COMT and the cell proliferation of hormone-responsive cancers. The results showed that COMT silencing enhanced the cell proliferation of ER-α positive cancer cells MCF-7 and PC-3 but not the cells that lack ER-α expression as MDA-MB231 and DU-145. The data generated from our study provides a better understanding of the effect of COMT on critical signaling pathways involved in the development and progression of breast cancer (BC) and prostate cancer (PC) including ER-α, p21cip1, p27kip1, NF-κB (P65) and CYP19A1. These findings suggest that COMT enzyme plays a tumor suppressor role in hormone receptor-positive tumors which opens the door for future studies to validate COMT expression as a novel biomarker for the prediction of cancer aggressiveness and treatment efficacy.

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SEIPIN overexpression in the liver may alleviate hepatic steatosis by influencing the intracellular calcium level

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Qiang Li, Yixing Li, Zhiwang Zhang, Huifang Kang, Lifang Zhang, Yuxiang Zhang, Lei Zhou

Abstract

SEIPIN deficiency leads to a severe lipodystrophic phenotype with loss of fat tissue. Interestingly, SEIPIN knockout in non-adipocytes is reported to promote intracellular triacylglycerol (TG) accumulation. However, the underlying mechanisms remain unclear at present. Here, we have shown that SEIPIN knockdown and overexpression exert opposite effects on hepatic lipometabolism. Our experimental data suggest that depletion of SEIPIN induces an increase in intracellular TG via activation of ER stress while its overexpression triggers a decrease in the intracellular TG content via increasing PGC-1α, which drives increased mitochondrial activity. Adeno-associated virus-mediated SEIPIN overexpression alleviated high fat diet-induced hepatosteatosis in mice. The collective results indicate that the effects of SEIPIN on TG and PGC-1α are dependent on calcium concentrations, signifying regulatory activity on hepatic lipometabolism through alterations in the intracellular calcium level, and support the potential utility of modulating intracellular SEIPIN and calcium levels as novel therapeutic strategies for fatty liver.



GPCR photopharmacology

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Maria Ricart-Ortega, Joan Font, Amadeu Llebaria

Abstract

New technologies for spatial and temporal remote control of G protein-coupled receptors (GPCRs) are necessary to unravel the complexity of GPCR signalling in cells, tissues and living organisms. An effective approach, recently developed, consists on the design of light-operated ligands whereby light-dependent GPCR activity regulation can be achieved. In this context, the use of light provides an advantage as it combines safety, easy delivery, high resolution and it does not interfere with most cellular processes. In this review we summarize the most relevant successful achievements in GPCR photopharmacology. These recent findings constitute a significant advance in research studies on the molecular dynamics of receptor activation and their physiological roles in vivo. Moreover, these molecules hold potential toward clinical uses as light-operated drugs, which can overcome some of the problems of conventional pharmacology.



CXCL12-regulated miR-370–3p functions as a tumor suppressor gene by targeting HMGA2 in nonfunctional pituitary adenomas

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Feng Cai, Congxin Dai, Shasha Chen, Qun Wu, Xiaohai Liu, Yuan Hong, Zhen Wang, Li Li, Wei Yan, Renzhi Wang, Jianmin Zhang

Abstract

Silencing of noncoding genes within the imprinted DLK1-MEG3 locus is exclusive to human nonfunctional pituitary adenomas (NFPAs), but the exact mechanism is still unclear. This study was designed to demonstrate the impact of CXCL12 on the expression of miRNAs within this locus and phenotypic alterations of NFPAs. Human NFPA samples were collected for screening differentially expressed miRNAs by CXCL12. Target mRNAs of the miRNAs were predicted and verified in vitro. Tumor phenotypic alterations were also tested. Another 51 NFPA samples were enrolled to examine the correlation and clinical features. The expression of miR-370 was decreased by CXCL12 treatment in NFPAs. miR-370–3p was predicted and verified to target HMGA2 as a tumor suppressor gene. Overexpression of HMGA2 inhibited its antitumor function. miR-370–3p was downregulated and HMGA2 was upregulated significantly in High grade NFPAs. In conclusion, the CXCL12/miR-370–3p/HMGA2 signaling pathway is involved in tumor growth and invasiveness of NFPAs.



TNF-alpha inhibits pregnancy-adapted Ca2+ signaling in uterine artery endothelial cells

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Amanda C. Ampey, Derek S. Boeldt, Luca Clemente, Mary A. Grummer, FuXian Yi, Ronald R. Magness, Ian M. Bird

Abstract

Enhancement of vasodilation of uterine arteries during pregnancy occurs through increased connexin (Cx)43 gap junction (GJ) communication supporting more frequent and sustained Ca2+ 'bursts'. Such adaptation is lacking in subjects with preeclampsia (PE). Here we show TNF-alpha, commonly increased in PE subjects, inhibits Cx43 function and Ca2+ bursts in pregnancy-derived ovine uterine artery endothelial cells (P-UAEC) via Src and MEK/ERK phosphorylation of Cx43, and this can be reversed by PP2 or U0126. Of relevance to humans: (1) the nutraceutical Src antagonist t10, c12 CLA also recovers Ca2+ bursting in P-UAEC. (2) TNF-alpha can reduce and PP2 rescue Ca2+ bursting and NO output in human umbilical vein endothelium (HUV Endo) preparations. (3) Treatment of HUV Endo from PE subjects with PP2 alone can rescue bursting and NO output. We conclude TNF-alpha acts via Src more than MEK/ERK to inhibit GJ Cx43 function in PE subjects, and CLA may offer a potential therapy.



Cryo-EM structures of GPCRs coupled to Gs, Gi and Go

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Javier García-Nafría, Christopher G. Tate

Abstract

Advances in electron cryo-microscopy (cryo-EM) now permit the structure determination of G protein-coupled receptors (GPCRs) coupled to heterotrimeric G proteins by single-particle imaging. A combination of G protein engineering and the development of antibodies that stabilise the heterotrimeric G protein facilitate the formation of stable GPCR-G protein complexes suitable for structural biology. Structures have been determined of GPCRs coupled to either heterotrimeric G proteins (Gs, Gi or Go) or mini-G proteins (mini-Gs or mini-Go) by single-particle cryo-EM and X-ray crystallography, respectively. This review describes the technical breakthroughs allowing their structure determination and compares the different techniques. In addition, we compare the structures of GPCRs coupled either to Gs, Gi or Go and analyse the contributions of amino acid residues to the GPCR-G protein interface. There is no unique set of interactions that specifies coupling either to Gs, Gi or Go. Instead, there is a common core of interactions between the C-terminal α-helix of the G protein α-subunit and helices H3, H5 and H6 of the receptor. In addition, there are varying degrees of interaction between all the other GPCR helices and intracellular loops to five regions of the α-subunit and four regions of the β-subunit. These data support the contention that there is not a simple linear barcode that defines the specificity of G protein coupling and thus how a G protein couples to a GPCR cannot currently be determined from simply analysing amino acid sequences. Although the overall architecture of GPCR-G protein complexes is conserved, there are significant differences in the molecular details. The number and type of molecular interactions between amino acid residues at the interfaces varies, resulting in subtly different orientation and position of the G protein with respect to the GPCR. This in turn affects the interface surface area that varies between 845 Å2 and 1490 Å2, which could impact upon the lifetime of signalling complexes in the cell.

Graphical abstract

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Editorial Board

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s):



Characterizing the complexity of Australian marsupial insulin-like growth factor 1 genes

Publication date: 15 May 2019

Source: Molecular and Cellular Endocrinology, Volume 488

Author(s): Peter Rotwein

Abstract

Insulin-like growth factor 1 (IGF1) actions are essential for somatic growth and tissue repair. IGF1 gene regulation is controlled by many inputs, with growth hormone playing a major role. In most mammals, the 6-exon IGF1/Igf1 gene produces multiple transcripts via independent activity of its promoters plus alternative RNA splicing and differential polyadenylation. Here, by analyzing public genomic and RNA-sequencing repositories, I have characterized three Australian marsupial IGF1 genes. Koala, Tasmanian devil, and wallaby IGF1 are more complicated than other mammals, as they contain up to 11 exons, and encode multiple mRNAs and predicted protein precursors, including potentially novel isoforms. Moreover, just two of multiple growth hormone-stimulated transcriptional enhancers found in other IGF1/Igf1 loci are detected in these species. These observations define Australian marsupial IGF1 genes and demonstrate that comprehensive interrogation of genomic and RNA-sequencing resources is an effective strategy for characterizing genes and gene expression in otherwise experimentally intractable organisms.



C-type natriuretic peptide signaling in human follicular environment and its relation with oocyte maturation

Publication date: Available online 7 May 2019

Source: Molecular and Cellular Endocrinology

Author(s): Maíra Casalechi, Júlia A. Dias, Lorena V. Pinto, Verônica N. Lobach, Maria T. Pereira, Ines K. Cavallo, Adelina M. Reis, Cynthia Dela Cruz, Fernando M. Reis

Abstract

Studies in mice have shown that C-type natriuretic peptide (CNP) is produced by granulosa cells and contributes to ovarian follicle growth and oocyte meiotic arrest until the preovulatory LH surge. In humans, the relationship between intraovarian CNP levels and oocyte meiotic resumption is unknown. The aim of this study was to investigate whether CNP and its receptor NPR2 are expressed in human ovarian follicles and if their levels change according to the meiotic phase of oocytes. We collected follicular fluid (FF) and luteinized granulosa cells (LGC) from follicle pools (n = 47), and FF, LGC and cumulus cells (CC) from individual follicles (n = 96) during oocyte pickup for in vitro fertilization. There was a positive linear correlation between CNP levels in FF pools and basal antral follicle counting (rs = 0.458; p = 0.002), number of preovulatory follicles >16 mm (rs = 0.361; p = 0.016) and number of oocytes retrieved (rs = 0,378; p = 0.011) and a negative correlation between CNP levels in FF pools and the percentage of mature (MII) oocytes retrieved (rs = -0.39; p = 0.033). FF CNP levels in follicles containing MII oocytes were significantly lower than in follicles containing immature (MI) oocytes (median = 0.44 vs. 0.57 ng/ml, p < 0.05). Accordingly, the CNP precursor gene NPPC was 50% less expressed in LGC from follicles containing MII oocytes than in follicles containing MI oocytes (p < 0.01). In addition, NPR2 mRNA was down-regulated in CC surrounding MII oocytes (60% reduction, p < 0.01). CNP signaling is downregulated in human ovarian follicles containing mature oocytes. Further studies should clarify whether CNP signaling is essential to keep oocyte meiotic arrest in humans.



Hypothalamic impairment underlying heat intolerance in pregnant mice

Publication date: Available online 6 May 2019

Source: Molecular and Cellular Endocrinology

Author(s): Cheng-Hsien Lin, Sheng-Hsien Chen, Chin-Ping Chang, Kao-Chang Lin

Abstract

Pregnant women are vulnerable to heat stroke reactions caused by high environmental temperatures. Heat intolerance is associated with hypothalamic impairment. Here, we aim to ascertain whether pregnancy causes heat intolerance by inducing hypothalamic impairment in mice. In the heated groups, mice were exposed to whole body heating (WBH; 41.2 °C for 1 h) in an environment-controlled chamber. Then, they were returned to normal room temperature (26 °C) immediately after WBH. In the hyperbaric oxygen therapy (HBO2T) groups, mice were exposed to 100% O2 at 2.0 atm absolute (ATA) for 4 h immediately post-WBH. Mice that survived after 4 h of WBH were considered survivors. Here, we show that when pregnant mice underwent non-HBO2T (21% O2 at 1.0 ATA for 4 h) after WBH, the survival rate was 4/20, and the core temperature at 4 h post-WBH was 31.2 ± 0.2 °C. Both the survival rate and core temperature of HBO2T pregnant mice (10/10 and 35.2 ± 0.3 °C, respectively) were significantly greater than those in non-HBO2T pregnant mice. Compared to non-HBO2T heated mice, the HBO2T heated mice exhibited lower neurological severity scores, reduced hypothalamic neuronal damage, fewer apoptotic cells, reduced multiorgan damage scores, and lower hypothalamic levels of proinflammatory cytokines and nitrogen and oxygen radical species. Compared to non-HBO2T heated mice, the HBO2T-treated heated mice had significantly higher hypothalamic-pituitary-adrenal axis activity (evidenced by higher serum levels of both adrenocorticotrophic hormone and corticosterone). In conclusion, pregnancy induces heat intolerance by inducing hypothalamic impairment in mice. Additionally, HBO2T protects against heat intolerance in pregnant mice by preserving hypothalamic integrity.



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