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Michela Zamboni, Georgios Strimpakos, Eleonora Poggiogalle, Lorenzo M Donini, and Donato Civitareale

Obesity affects thyroid gland function. Hypothyroidism, thyroid nodules, goiter, and thyroid cancer are more frequent in patients with higher BMI values. Although these data are supported by many clinical and epidemiological studies, our knowledge is very scarce at the molecular level. In this study, we present the first experimental evidence that adipocyte signaling downregulates the expression of thyroid-specific transcription factor 2 (TTF-2/FoxE1). It plays a crucial role in thyroid development and thyroid homeostasis and it is strictly connected to thyroid cancer as well. We provide in vivo and in vitro evidence that inhibition of TTF-2/FoxE1 gene expression is mediated by adipocyte signaling.

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Sara Carmo-Silva, Marisa Ferreira-Marques, Clévio Nóbrega, Mariana Botelho, Daniela Costa, Célia A Aveleira, Stefan M Pulst, Luís Pereira de Almeida, and Claudia Cavadas

ATXN2 gene, encoding for ataxin-2, is located in a trait locus for obesity. Atxn2 knockout (KO) mice are obese and insulin resistant; however, the cause for this phenotype is still unknown. Moreover, several findings suggest ataxin-2 as a metabolic regulator, but the role of this protein in the hypothalamus was never studied before. The aim of this work was to understand if ataxin-2 modulation in the hypothalamus could play a role in metabolic regulation. Ataxin-2 was overexpressed/re-established in the hypothalamus of C57Bl6/Atxn2 KO mice fed either a chow or a high-fat diet (HFD). This delivery was achieved through stereotaxic injection of lentiviral vectors encoding for ataxin-2. We show, for the first time, that HFD decreases ataxin-2 levels in mouse hypothalamus and liver. Specific hypothalamic ataxin-2 overexpression prevents HFD-induced obesity and insulin resistance. Ataxin-2 re-establishment in Atxn2 KO mice improved metabolic dysfunction without changing body weight. Furthermore, we observed altered clock gene expression in Atxn2 KO that might be causative of metabolic dysfunction. Interestingly, ataxin-2 hypothalamic re-establishment rescued these circadian alterations. Thus, ataxin-2 in the hypothalamus is a determinant for weight, insulin sensitivity and clock gene expression. Ataxin-2’s potential role in the circadian clock, through the regulation of clock genes, might be a relevant mechanism to regulate metabolism. Overall, this work shows hypothalamic ataxin-2 as a new player in metabolism regulation, which might contribute to the development of new strategies for metabolic disorders.

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Tijana Mitić

Leading a research group as an early career researcher (ECR) in academia presents many challenges. First, it imposes many additional pressures on individuals, causing fear of missing out on a great opportunity that could advance your career. Together, the unsettling nature of short-term or temporary contracts, lack of guidance and the imposter syndrome can trigger a crisis in future leadership. Most leadership positions at universities are held by senior colleagues. ECRs have modest input in decision-making, due to a requirement for specific leadership training and experience with oversight that precedes suitable decision-making. The turbulence of the unprecedented world COVID-19 crisis has been felt disproportionally by many researchers, intensely by those with caring responsibilities. In the current academic climate, navigating either between your postdoctoral or fellowship project, leading others, taking strategic project directions, mentoring or networking may feel like too much. This editorial expresses views on the current state of the matter in academia with suggestions for helpful strategies to employ to meet research endpoints. It also addresses some challenges that new principal investigators and academic leaders may face due to external or institutional change, and provides some tangible advice with action points.

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Luca Clemente and Ian M Bird

The epidermal growth factor receptor (EGFR) is expressed robustly in the placenta, and critical processes of pregnancy such as placental growth and trophoblast fusion are dependent on EGFR function. However, the role that aberrant EGFR signaling might play in the etiology and/or maintenance of preeclampsia (PE) remains largely unexplored. Recently, we have shown that overexpression of EGFR in cultured uterine artery endothelial cells (UAEC), which express little endogenous EGFR, remaps responsiveness away from vascular endothelial growth factor receptor (VEGFR) signaling and toward EGFR, suggesting that endothelial EGFR expression may be kept low to preserve VEGFR control of angiogenesis. Here we will consider the evidence for the possibility that the endothelial dysfunction observed in PE might in some cases result from elevation of endothelial EGFR. During pregnancy, trophoblasts are known to synthesize large amounts of EGFR protein, and the placenta regularly releases syncytiotrophoblast-derived exosomes and microparticles into the maternal circulation. Although there are no reports of elevated EGFR gene expression in preeclamptic endothelial cells, the ongoing shedding of placental vesicles into the vascular system raises the possibility that EGFR-rich vesicles might fuse with endothelium, thereby contributing to the symptoms of PE by interrupting angiogenesis and blocking pregnancy-adapted vasodilatory function.

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Vaishnavi Venugopalan, Maren Rehders, Jonas Weber, Lisa Rodermund, Alaa Al-Hashimi, Tonia Bargmann, Janine Golchert, Vivien Reinecke, Georg Homuth, Uwe Völker, Francois Verrey, Janine Kirstein, Heike Heuer, Ulrich Schweizer, Doreen Braun, Eva K Wirth, and Klaudia Brix

Proteolytic cleavage of thyroglobulin (Tg) for thyroid hormone (TH) liberation is followed by TH release from thyroid follicles into the circulation, enabled by TH transporters. The existence of a functional link between Tg-processing cathepsin proteases and TH transporters has been shown to be independent of the hypothalamus–pituitary–thyroid axis. Thus, lack of cathepsin K, combined with genetic defects in the TH transporters Mct8 and Mct10, that is the Ctsk −/−/Mct8 −/y/Mct10 −/− genotype, results in persistent Tg proteolysis due to autophagy induction. Because amino acid transport by L-type amino acid transporter 2 (Lat2) has been described to regulate autophagy, we asked whether Lat2 availability is affected in Ctsk −/−/Mct8 −/y/Mct10 −/− thyroid glands. Our data revealed that while mRNA amounts and subcellular localization of Lat2 remained unaltered in thyroid tissue of Ctsk −/−/Mct8 −/y/Mct10 −/− mice in comparison to WT controls, the Lat2 protein amounts were significantly reduced. These data suggest a direct link between Lat2 function and autophagy induction in Ctsk −/−/Mct8 −/y/Mct10 −/− mice. Indeed, thyroid tissue of Lat2 −/− mice showed enhanced endo-lysosomal cathepsin activities, increased autophagosome formation, and enhanced autophagic flux. Collectively, these results suggest a mechanistic link between insufficient Lat2 protein function and autophagy induction in the thyroid gland of male mice.

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Liang Xu, Haoran Li, Ouyang Zhang, Fengming Zhang, Menghui Song, Mengchen Ma, Youjuan Zhao, Rongxiu Ding, Dandan Li, Zhixiong Dong, Shengnan Jin, Weiping Han, and Chunming Ding

The pathogenesis of nonalcoholic steatohepatitis (NASH), a severe stage of nonalcoholic fatty liver disease, is complex and implicates multiple cell interactions. However, therapies for NASH that target multiple cell interactions are still lacking. Melatonin (MEL) alleviates NASH with mechanisms not yet fully understood. Thus, we herein investigate the effects of MEL on key cell types involved in NASH, including hepatocytes, macrophages, and stellate cells. In a mouse NASH model with feeding of a methionine and choline-deficient (MCD) diet, MEL administration suppressed lipid accumulation and peroxidation, improved insulin sensitivity, and attenuated inflammation and fibrogenesis in the liver. Specifically, MEL reduced proinflammatory cytokine expression and inflammatory signal activation and attenuated CD11C+CD206 M1-like macrophage polarization in the liver of NASH mice. The reduction of proinflammatory response by MEL was also observed in the lipopolysaccharide-stimulated Raw264.7 cells. Additionally, MEL increased liver fatty acid β-oxidation, leading to reduced lipid accumulation, and restored the oleate-loaded primary hepatocytes. Finally, MEL attenuated hepatic stellate cell (HSC) activation and fibrogenesis in the liver of MCD-fed mice and in LX-2 human HSCs. In conclusion, MEL acts on multiple cell types in the liver to mitigate NASH-associated phenotypes, supporting MEL or its analog as potential treatment for NASH.

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Yefei Pang and Peter Thomas

Progesterone causes vascular smooth muscle cell relaxation through membrane progesterone receptors (mPRs), which are members of the progestin and adipoQ receptor (PAQR) family, and nuclear PRs (nPRs). However, beneficial vascular effects of progesterone in preventing pre-atherosclerosis and the involvement of mPRs and nPRs remain unclear. The results show short- to long-term treatments with 100 nM progesterone (P4) and specific agonists for mPRs, OD 02-0, and nPRs, R5020, inhibited pre-atherosclerotic events in human umbilical vein endothelial cells (HUVECs), decreasing focal adhesion (FA) by monocytes, FA signaling, HUVEC migration and invasion, and vinculin expression. Progesterone and OD 02-0, but not R5020, inhibited phosphorylation of Src and focal adhesion kinase, critical kinases of FA signaling, within 20 min and migration and invasion of HUVECs and monocyte adhesion after 3 h. These inhibitory P4 and 02-0 effects were attenuated with MAP kinase and Pi3k inhibitors, indicating involvement of these kinases in this mPR-mediated action. However, after 16 h, OD 02-0 was no longer effective in inhibiting FA signaling, while both progesterone and R5020 decreased the activity of the two kinases. Knockdown of receptor expression with siRNA confirmed that mPRα mediates short-term and nPR long-term inhibitory effects of progesterone on FA signaling. Thus, progesterone inhibition of FA signaling and pre-atherosclerosis is coordinated through mPRα and nPRs.

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Colin D Clyne, Kevin P Kusnadi, Alexander Cowcher, James Morgan, Jun Yang, Peter J Fuller, and Morag J Young

The mineralocorticoid receptor (MR) is a ligand-activated transcription factor that regulates cardiorenal physiology and disease. Ligand-dependent MR transactivation involves a conformational change in the MR and recruitment of coregulatory proteins to form a unique DNA-binding complex at the hormone response element in target gene promoters. Differences in the recruitment of coregulatory proteins can promote tissue-, ligand- or gene-specific transcriptional outputs. The goal of this study was to evaluate the circadian protein TIMELESS as a selective regulator of MR transactivation. TIMELESS has an established role in cell cycle regulation and DNA repair. TIMELESS may not be central to mammalian clock function and does not bind DNA; however, RNA and protein levels oscillate over 24 h. Co-expression of TIMELESS down-regulated MR transactivation of an MR-responsive reporter in HEK293 cells, yet enhanced transactivation mediated by other steroid receptors. TIMELESS markedly inhibited MR transactivation of synthetic and native gene promoters and expression of MR target genes in H9c2 cardiac myoblasts. Immunofluorescence showed aldosterone induces colocalisation of TIMELESS and MR, although a direct interaction was not confirmed by coimmunoprecipitation. Potential regulation of circadian clock targets cryptochrome 1 and 2 by TIMELESS was not detected. However, our data suggest that these effects may involve TIMELESS coactivation of oestrogen receptor alpha (ERα). Taken together, these data suggest that TIMELESS may contribute to MR transcriptional outputs via enhancing ERα inhibitory actions on MR transactivation. Given the variable expression of TIMELESS in different cell types, these data offer new opportunities for the development of MR modulators with selective actions.

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Wender do Nascimento Rouver, Nathalie Tristão Banhos Delgado, Leticia Tinoco Gonçalves, Jéssyca Aparecida Soares Giesen, Charles Santos da Costa, Eduardo Merlo, Eduardo Damasceno Costa, Virginia Soares Lemos, Jones Bernardes Graceli, and Roger Lyrio dos Santos

The role of androgens in vascular reactivity is controversial, particularly regarding their age-related actions. The objective of this study was to conduct a temporal evaluation of the vascular reactivity of resistance arteries of young male rats, as well as to understand how male sex hormones can influence the vascular function of these animals. Endothelium-mediated relaxation was characterized in third-order mesenteric arteries of 10-, 12-, 16-, and 18w (week-old) male rats. Concentration–response curves to acetylcholine (ACh, 0.1 nmol/L–10 µmol/L) were constructed in arteries previously contracted with phenylephrine (PE, 3 µmol/L), before and after the use of nitric oxide synthase or cyclooxygenase inhibitors. PE concentration–response curves (1 nmol/L–100 μmol/L) were also built. The levels of vascular nitric oxide, superoxide anion, and hydrogen peroxide were assessed and histomorphometry analysis was performed. The 18w group had impaired endothelium-dependent relaxation. All groups showed prostanoid-independent and nitric oxide-dependent vasodilatory response, although this dependence seems to be smaller in the 18w group. The 18w group had the lowest nitric oxide and hydrogen peroxide production, in addition to the highest superoxide anion levels. Besides functional impairment, 18w animals showed morphological differences in third-order mesenteric arteries compared with the other groups. Our data show that time-dependent exposure to male sex hormones appears to play an important role in the development of vascular changes that can lead to impaired vascular reactivity in mesenteric arteries, which could be related to the onset of age-related cardiovascular changes in males.

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Renjini A Padmanabhan, Damodaranpillai P Zyju, Anand G Subramaniam, Jaya Nautiyal, and Malini Laloraya

Estrogen accounts for several biological processes in the body; embryo implantation and pregnancy being one of the vital events. This manuscript aims to unearth the nuclear role of Son of sevenless1 (SOS1), its interaction with estrogen receptor alpha (ERα), and signal transducer and activator of transcription 3 (STAT3) in the uterine nucleus during embryo implantation. SOS1, a critical cytoplasmic linker between receptor tyrosine kinase and rat sarcoma virus signaling, translocates into the nucleus via its bipartite nuclear localization signal (NLS) during the ‘window of implantation’ in pregnant mice. SOS1 associates with chromatin, interacts with histones, and shows intrinsic histone acetyltransferase (HAT) activity specifically acetylating lysine 16 (K16) residue of histone H4. SOS1 is a coactivator of STAT3 and a co-repressor of ERα. SOS1 creates a partial mesenchymal–epithelial transition by acting as a transcriptional modulator. Finally, our phylogenetic tree reveals that the two bipartite NLS surface in reptiles and the second acetyl coenzymeA (CoA) (RDNGPG) important for HAT activity emerges in mammals. Thus, SOS1 has evolved into a moonlighting protein, the special class of multi-tasking proteins, by virtue of its newly identified nuclear functions in addition to its previously known cytoplasmic function.