Specific involvement of glycogen synthase kinase-3 in the function and activity of sex steroid hormone receptors reveals the complexity of their regulation

Estrogen Receptor α Agonist is Beneficial for Young Female Rats Against Chronic Unpredicted Mild Stress-Induced Depressive Behavior and Cognitive Deficits

BACKGROUND

Women are reported more likely to develop depression and dementia. However, the involved mechanism is poorly understood.

OBJECTIVE

Here, we clarified the role of estrogen receptor α (ERα) in depression and cognitive deficit in young female rats.

METHODS

After being exposed to 7-weeks' chronic unpredicted mild stress (CUMS), the depression resilient rats (Res rats) and depressed rats (Dep rats) were selected according to their records in sucrose preference test, forced swimming test, and open field test. Their cognition abilities were tested by Morris water maze. Proteomic assay, immunoprecipitation, western blotting, immunohistochemical, and Nissl staining were also used to understand the involved mechanism.

RESULTS

Compared with control rats and Res rats, Dep rats showed cognitive deficits and hippocampal impairments revealed by proteomic data, neuron losses, increased cleaved caspase-3, β-catenin phosphorylation, and glycogen synthase kinase3β (GSK3β) activation. As ERα, but not ERβ, was found declined in hippocampi of Dep rats, 4,4k,4a-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT, an ERα agonist, 1 mg/kg/day), was used to treat Dep rats (Dep + PPT). Twenty days later, the depressive behaviors, cognition deficits, and hippocampal neuron loss were rescued in Dep + PPT rats. Furthermore, Res and Dep + PPT rats had higher levels of β-catenin combined with ERα and lower levels of β-catenin combined with GSK3β than Dep rats in hippocampi.

CONCLUSION

These results demonstrated hippocampal ERα is an important pro-resilient factor in CUMS-induced depressive behaviors and cognitive deficits. It was also given that the neuroprotection afforded by hippocampal ERα/Wnt interactions have significant implications for cognition and emotion in young females.

Effect of the acute and chronic administration of Lupinus albus β-conglutin on glycaemia, circulating cholesterol, and genes potentially involved

Constituents of lupin seeds, like γ-conglutin and lupanine, have gained attention as potential complementary treatments for dysglycaemia management. Notwithstanding, the effect of other lupin components on carbohydrate metabolism, including β-conglutin protein, has received little attention. Here, we investigated the influence of the acute and chronic administration of β-conglutin on glycaemia modulation in normal and streptozotocin induced-to-diabetes rats. We analysed the liver transcriptome modulation exerted by β-conglutin in diabetes-induced rats using DNA microarrays to scout for potential molecular targets and pathways involved in this biological response. The acute administration of β-conglutin reduced the incremental area under the curve of glycaemia in normal and diabetes-induced animals. In a seven-day study with diabetic animals, glycaemia increased significantly in non-treated animals but remained unchanged in animals treated with a daily dose of β-conglutin. Total cholesterol was significantly lower at the end of the experimental period (-21.8 %, p = 0.039). The microarray and gene ontology analyses revealed several targets and pathways potentially modulated by β-conglutin treatment, including a possible down-regulation of Jun kinase activity. Moreover, our data indicate that targets related to oxidative stress, inflammation, and estrogenic activity might orchestrate these metabolic effects. In conclusion, our findings show that β-conglutin may help manage postprandial glycaemia and reduce cholesterol levels under the dysglycaemia stage. We identified and proposed new potential molecular targets for further research related to the mechanism of action of β-conglutin.

Candidate Genes and MiRNAs Linked to the Inverse Relationship Between Cancer and Alzheimer's Disease: Insights From Data Mining and Enrichment Analysis

The incidence of cancer and Alzheimer’s disease (AD) increases exponentially with age. A growing body of epidemiological evidence and molecular investigations inspired the hypothesis of an inverse relationship between these two pathologies. It has been proposed that the two diseases might utilize the same proteins and pathways that are, however, modulated differently and sometimes in opposite directions. Investigation of the common processes underlying these diseases may enhance the understanding of their pathogenesis and may also guide novel therapeutic strategies. Starting from a text-mining approach, our in silico study integrated the dispersed biological evidence by combining data mining, gene set enrichment, and protein-protein interaction (PPI) analyses while searching for common biological hallmarks linked to AD and cancer. We retrieved 138 genes (ALZCAN gene set), computed a significant number of enriched gene ontology clusters, and identified four PPI modules. The investigation confirmed the relevance of autophagy, ubiquitin proteasome system, and cell death as common biological hallmarks shared by cancer and AD. Then, from a closer investigation of the PPI modules and of the miRNAs enrichment data, several genes (SQSTM1, UCHL1, STUB1, BECN1, CDKN2A, TP53, EGFR, GSK3B, and HSPA9) and miRNAs (miR-146a-5p, MiR-34a-5p, miR-21-5p, miR-9-5p, and miR-16-5p) emerged as promising candidates. The integrative approach uncovered novel miRNA-gene networks (e.g., miR-146 and miR-34 regulating p62 and Beclin1 in autophagy) that might give new insights into the complex regulatory mechanisms of gene expression in AD and cancer.

Androgens and androgen receptor action in skin and hair follicles

Beyond sexual functions, androgens exert their action in skin physiology and pathophysiology. Skin cells are able to synthesize most active androgens from gonadal or adrenal precursors and the enzymes involved in skin steroidogenesis are implicated both in normal or pathological processes. Even when the role of androgens and androgen receptor (AR) in skin pathologies has been studied for decades, their molecular mechanisms in skin disorders remain largely unknown. Here, we analyze recent studies of androgens and AR roles in several skin-related disorders, focusing in the current understanding of their molecular mechanisms in androgenetic alopecia (AGA). We review the molecular pathophysiology of type 2 5α-reductase, AR coactivators, the paracrine factors deregulated in dermal papillae (such as TGF-β, IGF 1, WNTs and DKK-1) and the crosstalk between AR and Wnt signaling in order to shed some light on new promising treatments.

Epidermal stem cells and skin tissue engineering in hair follicle regeneration

The reconstitution of a fully organized and functional hair follicle from dissociated cells propagated under defined tissue culture conditions is a challenge still pending in tissue engineering. The loss of hair follicles caused by injuries or pathologies such as alopecia not only affects the patients' psychological well-being, but also endangers certain inherent functions of the skin. It is then of great interest to find different strategies aiming to regenerate or neogenerate the hair follicle under conditions proper of an adult individual. Based upon current knowledge on the epithelial and dermal cells and their interactions during the embryonic hair generation and adult hair cycling, many researchers have tried to obtain mature hair follicles using different strategies and approaches depending on the causes of hair loss. This review summarizes current advances in the different experimental strategies to regenerate or neogenerate hair follicles, with emphasis on those involving neogenesis of hair follicles in adult individuals using isolated cells and tissue engineering. Most of these experiments were performed using rodent cells, particularly from embryonic or newborn origin. However, no successful strategy to generate human hair follicles from adult cells has yet been reported. This review identifies several issues that should be considered to achieve this objective. Perhaps the most important challenge is to provide three-dimensional culture conditions mimicking the structure of living tissue. Improving culture conditions that allow the expansion of specific cells while protecting their inductive properties, as well as methods for selecting populations of epithelial stem cells, should give us the necessary tools to overcome the difficulties that constrain human hair follicle neogenesis. An analysis of patent trends shows that the number of patent applications aimed at hair follicle regeneration and neogenesis has been increasing during the last decade. This field is attractive not only to academic researchers but also to the companies that own almost half of the patents in this field.

Blockade of estrogen-stimulated proliferation by a constitutively-active prolactin receptor having lower expression in invasive ductal carcinoma

A comprehensive understanding of prolactin's (PRL's) role in breast cancer is complicated by disparate roles for alternatively-spliced PRL receptors (PRLR) and crosstalk between PRL and estrogen signaling. Among PRLRs, the short form 1b (SF1b) inhibits PRL-stimulated cell proliferation. In addition to ligand-dependent PRLRs, constitutively-active varieties, missing the S2 region of the extracellular domain (ΔS2), naturally occur. Expression analysis of the ΔS2 version of SF1b (ΔS2SF1b) showed higher expression in histologically-normal contiguous tissue versus invasive ductal carcinoma. To determine the function of ΔS2SF1b, a T47D breast cancer line with inducible expression was produced. Induction of ΔS2SF1b blocked estrogen-stimulated cell proliferation. Unlike intact SF1b, induction of ΔS2SF1b had no effect on PRL-mediated activation of Stat5a. However induction inhibited estrogen's stimulatory effects on serine-118 phosphorylation of estrogen receptor α, serine-473 phosphorylation of Akt, serine-9 phosphorylation of GSK3β, and c-myc expression. In addition, induction of ΔS2SF1b increased expression of the cell cycle-inhibiting protein, p21. Thus, increased expression of ΔS2SF1b, such as we demonstrate occurs with the selective PRLR modulator, S179D PRL, would create a physiological state in which estrogen-stimulated proliferation was inhibited, but differentiative responses to PRL were maintained.

Glycogen synthase kinase-3 (GSK3): regulation, actions, and diseases

Glycogen synthase kinase-3 (GSK3) may be the busiest kinase in most cells, with over 100 known substrates to deal with. How does GSK3 maintain control to selectively phosphorylate each substrate, and why was it evolutionarily favorable for GSK3 to assume such a large responsibility? GSK3 must be particularly adaptable for incorporating new substrates into its repertoire, and we discuss the distinct properties of GSK3 that may contribute to its capacity to fulfill its roles in multiple signaling pathways. The mechanisms regulating GSK3 (predominantly post-translational modifications, substrate priming, cellular trafficking, protein complexes) have been reviewed previously, so here we focus on newly identified complexities in these mechanisms, how each of these regulatory mechanism contributes to the ability of GSK3 to select which substrates to phosphorylate, and how these mechanisms may have contributed to its adaptability as new substrates evolved. The current understanding of the mechanisms regulating GSK3 is reviewed, as are emerging topics in the actions of GSK3, particularly its interactions with receptors and receptor-coupled signal transduction events, and differential actions and regulation of the two GSK3 isoforms, GSK3α and GSK3β. Another remarkable characteristic of GSK3 is its involvement in many prevalent disorders, including psychiatric and neurological diseases, inflammatory diseases, cancer, and others. We address the feasibility of targeting GSK3 therapeutically, and provide an update of its involvement in the etiology and treatment of several disorders.

Progesterone receptor A stability is mediated by glycogen synthase kinase-3β in the Brca1-deficient mammary gland

Germ line mutations of the BRCA1 gene increase the risk of breast and ovarian cancer, but the basis of this tissue-specific tumor predisposition is not fully understood. Previously, we reported that the progesterone receptors are stabilized in Brca1-deficient mammary epithelial cells, and treating with anti-progesterone delays mammary tumorigenesis in Brca1/p53 conditional knock-out mice, suggesting that the progesterone has a critical role in breast carcinogenesis. To further explore how the stability of progesterone receptor is modulated, here, we have found that glycogen synthase kinase (GSK)-3β phosphorylation of progesterone receptor-A (PR-A) facilitates its ubiquitination. GSK-3β-mediated phosphorylation of serine 390 in PR-A regulates its subsequent ubiquitination and protein stability. Expression of PR-A(S390A) mutant in the human breast epithelial cells, MCF-10A, results in enhanced proliferation and formation of aberrant acini structure in the three-dimensional culture. Consistently, reduction of phosphorylation of serine 390 of PR-A and GSK-3β activity is observed in the Brca1-deficient mammary gland. Taken together, these results provide important aspects of tissue specificity of BRCA1-mediated suppression of breast carcinogenesis.

Hair follicle stem cell differentiation is inhibited through cross-talk between Wnt/β-catenin and androgen signalling in dermal papilla cells from patients with androgenetic alopecia

BACKGROUND

Hair follicle (HF) regeneration begins when signals from the mesenchyme-derived dermal papilla cells (DPC) reach multipotent epidermal stem cells in the bulge region. Wnt/β-catenin signalling is known to affect mammalian hair growth positively. In androgenetic alopecia (AGA), androgens cause HF miniaturization through a mechanism that remains unclear. Circulating androgens act on DPC and alter paracrine factors that influence hair epithelial cells.

OBJECTIVES

To elucidate the role of androgens in dermal papilla-induced differentiation of HF stem cells.

METHODS

HF stem cell differentiation was evaluated in a coculture model with DPC or culturing with media conditioned by DPC after activation of androgen and Wnt/β-catenin signalling pathways. To study the molecular cross-talk between the androgen and Wnt signalling pathway in DPC, we analysed the expression and activation of downstream Wnt signalling molecules in the presence of androgens.

RESULTS

In a coculture model with human DPC from patients with AGA and HF stem cells, we observed that androgens abrogate hair differentiation evaluated by hair-specific keratin 6 expression. Wnt signalling activation restored the ability of androgen-treated DPC to induce differentiation. Androgen treatment revealed a significant decrease in the cytoplasmic/total β-catenin protein ratio and upregulation of the activity of glycogen synthase kinase-3β in DPC, indicative of canonical Wnt pathway inhibition.

CONCLUSIONS

These results suggest that androgens deregulate DPC-secreted factors involved in normal HF stem cell differentiation via the inhibition of the canonical Wnt signalling pathway.

Glycogen synthase kinase-3β is involved in ligand-dependent activation of transcription and cellular localization of the glucocorticoid receptor

Glucocorticoids (GC) induce cell cycle arrest and apoptosis in different cell types and therefore are widely used to treat a variety of diseases including autoimmune disorders and cancer. This effect is mediated by the GC receptor (GR), a ligand-activated transcription factor that translocates into the nucleus where it modulates transcription of target genes in a promoter-specific manner. Glycogen synthase kinase-3 (GSK3) regulates GR response by genomic and nongenomic mechanisms, although the specific role of each isoform is not well defined. We used GSK3 pharmacological inhibitors and isoform-specific small interfering RNA to evaluate the role of GSK3 in the genomic regulation induced by GC. GSK3 inhibition resulted in the reduction of GC-induced mRNA expression of GC-induced genes such as BIM, HIAP1, and GILZ. Knockdown of GSK3β but not GSK3α reduced endogenous GILZ induction in response to dexamethasone and GR-dependent reporter gene activity. Chromatin immunoprecipitation experiments revealed that GSK3 inhibition impaired the dexamethasone-mediated binding of GR and RNA polymerase II to endogenous GILZ promoter. These results indicate that GSK3β is important for GR transactivation activity and that GSK3β inhibition suppresses GC-stimulated gene expression. Furthermore, we show that genomic regulation by the GR is independent of known GSK3β phosphorylation sites. We propose that GC-dependent transcriptional activation requires functional GSK3β signaling and that altered GSK3β activity influences cell response to GC.

The Interactions between Insulin and Androgens in Progression to Castrate-Resistant Prostate Cancer

An association between the metabolic syndrome and reduced testosterone levels has been identified, and a specific inverse relationship between insulin and testosterone levels suggests that an important metabolic crosstalk exists between these two hormonal axes; however, the mechanisms by which insulin and androgens may be reciprocally regulated are not well described. Androgen-dependant gene pathways regulate the growth and maintenance of both normal and malignant prostate tissue, and androgen-deprivation therapy (ADT) in patients exploits this dependence when used to treat recurrent and metastatic prostate cancer resulting in tumour regression. A major systemic side effect of ADT includes induction of key features of the metabolic syndrome and the consistent feature of hyperinsulinaemia. Recent studies have specifically identified a correlation between elevated insulin and high-grade PCa and more rapid progression to castrate resistant disease. This paper examines the relationship between insulin and androgens in the context of prostate cancer progression. Prostate cancer patients present a promising cohort for the exploration of insulin stabilising agents as adjunct treatments for hormone deprivation or enhancers of chemosensitivity for treatment of advanced prostate cancer.

β-Catenin Is a Positive Regulator of Estrogen Receptor-α Function in Breast Cancer Cells

Estrogen receptor-alpha (ERα) is a key factor in the development of breast cancer in humans. The expression and activity of ERα is regulated by a multitude of intracellular and extracellular signals. Here we show a cross-talk between β-catenin and ERα in human breast cancer cells. Knockdown of β-catenin by RNAi resulted in significant reduction of ERα mRNA and/or protein levels in MCF-7, T-47D, and BT-474 breast cancer cells and in significant reduction of estradiol-induced expression of the ERα target genes pS2 and GREB1. In addition β-catenin silencing resulted in significant decrease of growth of MCF-7 cells both in the absence and presence of estradiol. β-catenin and ERα could not be co-immunoprecipitated by ERα antibodies from lysates of E2-treated or untreated cells suggesting lack of direct physical interaction. It is concluded that β-catenin is a positive regulator of ERα mRNA and protein expression.

Interaction of estrogen receptors with insulin-like growth factor-I and Wnt signaling in the nervous system

Estradiol signaling through estrogen receptors in the nervous system involves a variety of rapid membrane/cytoplasm-initiated events that are integrated with different mechanisms of transcriptional regulation. Here we review the role of glycogen synthase kinase 3 (GSK3) and beta-catenin in the coordination of membrane/cytoplasm-initiated and nuclear-initiated estrogen receptor signaling. Estradiol activates in vitro and in vivo the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway in neural cells. By activating this pathway through estrogen receptors, estradiol increases the levels of inactive GSK3beta (phosphorylated in serine 9). In turn, the inhibition of GSK3beta increases the stability of beta-catenin and its nuclear translocation. Then, beta-catenin exerts two different transcriptional effects: (i) regulates beta-catenin/T cell factor (TCF) mediated transcription in a similar but not identical way as Wnt ligands and (ii) regulates estrogen receptor mediated transcription after its association with estrogen receptor alpha. In addition, by the regulation of PI3K/Akt/GSK3/beta-catenin pathway, other factors such as insulin-like growth factor-I (IGF-I) regulate estrogen receptor mediated transcription. Therefore, GSK3 and beta-catenin allow the interaction of membrane/cytoplasm-initiated estrogen receptor signaling, IGF-I signaling, Wnt signaling and nuclear-initiated estrogen receptor signaling in the nervous system.