The steroid receptor coactivator SRC-3 (p/CIP/RAC3/AIB1/ACTR/TRAM-1) is required for normal growth, puberty, female reproductive function, and mammary gland development

Lead Compound Development of SRC-3 Inhibitors with Improved Pharmacokinetic Properties and Anticancer Efficacy

Steroid receptor coactivator 3 (SRC-3) is a critical mediator of many intracellular signaling pathways that are crucial for cancer proliferation and metastasis. In this study, we performed structure-activity relationship exploration and drug-like optimization of the hit compound SI-2, guided by in vitro/in vivo metabolism studies and cytotoxicity assays. Our efforts led to the discovery of two lead compounds, SI-10 and SI-12. Both compounds exhibit potent cytotoxicity against a panel of human cancer cell lines and demonstrate acceptable pharmacokinetic properties. A biotinylated estrogen response element pull-down assay demonstrated that SI-12 could disrupt the recruitment of SRC-3 and p300 in the estrogen receptor complex. Importantly, SI-10 and SI-12 significantly inhibited tumor growth and metastasis in vivo without appreciable acute toxicity. These results demonstrate the potential of SI-10 and SI-12 as drug candidates for cancer therapy, given their potent SRC-3 inhibition and promising pharmacokinetic and toxicity profiles.

Critical Roles of SRC-3 in the Development and Progression of Breast Cancer, Rendering It a Prospective Clinical Target

Breast cancer (BCa) is the most frequently diagnosed malignant tumor in women and is also one of the leading causes of cancer-related death. Most breast tumors are hormone-dependent and estrogen signaling plays a critical role in promoting the survival and malignant behaviors of these cells. Estrogen signaling involves ligand-activated cytoplasmic estrogen receptors that translocate to the nucleus with various co-regulators, such as steroid receptor co-activator (SRC) family members, and bind to the promoters of target genes and regulate their expression. SRC-3 is a member of this family that interacts with, and enhances, the transcriptional activity of the ligand activated estrogen receptor. Although SRC-3 has important roles in normal homeostasis and developmental processes, it has been shown to be amplified and overexpressed in breast cancer and to promote malignancy. The malignancy-promoting potential of SRC-3 is diverse and involves both promoting malignant behavior of tumor cells and creating a tumor microenvironment that has an immunosuppressive phenotype. SRC-3 also inhibits the recruitment of tumor-infiltrating lymphocytes with effector function and promotes stemness. Furthermore, SRC-3 is also involved in the development of resistance to hormone therapy and immunotherapy during breast cancer treatment. The versatility of SRC-3 in promoting breast cancer malignancy in this way makes it a good target, and methodical targeting of SRC-3 probably will be important for the success of breast cancer treatment.

AIB1/SRC-3/NCOA3 function in estrogen receptor alpha positive breast cancer

The estrogen receptor alpha (ERα) is a steroid receptor that is pivotal in the initiation and progression of most breast cancers. ERα regulates gene transcription through recruitment of essential coregulators, including the steroid receptor coactivator AIB1 (Amplified in Breast Cancer 1). AIB1 itself is an oncogene that is overexpressed in a subset of breast cancers and is known to play a role in tumor progression and resistance to endocrine therapy through multiple mechanisms. Here we review the normal and pathological functions of AIB1 in regard to its ERα-dependent and ERα-independent actions, as well as its genomic conservation and protein evolution. We also outline the efforts to target AIB1 in the treatment of breast cancer.

Cancer invasion and metastasis: Insights from murine pubertal mammary gland morphogenesis

Cancer invasion and metastasis accounts for the majority of cancer related mortality. A better understanding of the players that drive the aberrant invasion and migration of tumors cells will provide critical targets to inhibit metastasis. Postnatal pubertal mammary gland morphogenesis is characterized by highly proliferative, invasive, and migratory normal epithelial cells. Identifying the molecular regulators of pubertal gland development is a promising strategy since tumorigenesis and metastasis is postulated to be a consequence of aberrant reactivation of developmental stages. In this review, we summarize the pubertal morphogenesis regulators that are involved in cancer metastasis and revisit pubertal mammary gland transcriptome profiling to uncover both known and unknown metastasis genes. Our updated list of pubertal morphogenesis regulators shows that most are implicated in invasion and metastasis. This review highlights molecular linkages between development and metastasis and provides a guide for exploring novel metastatic drivers.

Steroid-receptor coactivator complexes in thyroid hormone-regulation of Xenopus metamorphosis

Anuran metamorphosis is perhaps the most drastic developmental change regulated by thyroid hormone (T3) in vertebrate. It mimics the postembryonic development in mammals when many organs/tissues mature into adult forms and plasma T3 level peaks. T3 functions by regulating target gene transcription through T3 receptors (TRs), which can recruit corepressor or coactivator complexes to target genes in the absence or presence of T3, respectively. By using molecular and genetic approaches, we and others have investigated the role of corepressor or coactivator complexes in TR function during the development of two highly related anuran species, the pseudo-tetraploid Xenopus laevis and diploid Xenopus tropicalis. Here we will review some of these studies that demonstrate a critical role of coactivator complexes, particularly those containing steroid receptor coactivator (SRC) 3, in regulating metamorphic rate and ensuring the completion of metamorphosis.

Steroid receptor coactivators - their role in immunity

Steroid Receptor Coactivators (SRCs) are essential regulators of transcription with a wide range of impact on human physiology and pathology. In immunology, SRCs play multiple roles; they are involved in the regulation of nuclear factor-κB (NF-κB), macrophage (MΦ) activity, lymphoid cells proliferation, development and function, to name just a few. The three SRC family members, SRC-1, SRC-2 and SRC-3, can exert their immunological function either in an independent manner or act in synergy with each other. In certain biological contexts, one SRC family member can compensate for lack of activity of another member, while in other cases one SRC can exert a biological function that competes against the function of another family counterpart. In this review we illustrate the diverse biological functionality of the SRCs with regard to their role in immunity. In the light of recent development of SRC small molecule inhibitors and stimulators, we discuss their potential relevance as modulators of the immunological activity of the SRCs for therapeutic purposes.

Extracellular Adenosine (eAdo) - A2B Receptor Axis Inhibits in Nlrp3 Inflammasome-dependent Manner Trafficking of Hematopoietic Stem/progenitor Cells

We postulated that mobilization, homing, and engraftment of hematopoietic stem/progenitor cells (HSCPs) is facilitated by a state of sterile inflammation induced in bone marrow (BM) after administration of pro-mobilizing drugs or in response to pre-transplant myeloablative conditioning. An important role in this phenomenon plays purinergic signaling that by the release of extracellular adenosine triphosphate (eATP) activates in HSPCs and in cells in the hematopoietic microenvironment an intracellular pattern recognition receptor (PPR) known as Nlrp3 inflammasome. We reported recently that its deficiency results in defective trafficking of HSPCs. Moreover, it is known that eATP after release into extracellular space is processed by cell surface expressed ectonucleotidases CD39 and CD73 to extracellular adenosine (eAdo) that in contrast to eATP shows an anti-inflammatory effect. Based on data that the state of sterile inflammation promotes trafficking of HSPCs, and since eAdo is endowed with anti-inflammatory properties we become interested in how eAdo will affect the mobilization, homing, and engraftment of HSPCs and which of eAdo receptors are involved in these processes. As expected, eAdo impaired HSPCs trafficking and this occurred in autocrine- and paracrine-dependent manner by direct stimulation of these cells or by affecting cells in the BM microenvironment. We report herein for the first time that this defect is mediated by activation of the A2B receptor and a specific inhibitor of this receptor improves eAdo-aggravated trafficking of HSPCs. To explain this at the molecular level eAdo-A2B receptor interaction upregulates in HSPCs in NF-kB-, NRF2- and cAMP-dependent manner heme oxygenase-1 (HO-1), that is Nlrp3 inflammasome inhibitor. This corroborated with our analysis of proteomics signature in murine HSPCs exposed to eAdo that revealed that A2B inhibition promotes cell migration and proliferation. Based on this we postulate that blockage of A2B receptor may accelerate the mobilization of HSPCs as well as their hematopoietic reconstitution and this approach could be potentially considered in the future to be tested in the clinic.

Decidualization of human endometrial stromal cells requires steroid receptor coactivator-3

Steroid receptor coactivator-3 (SRC-3; also known as NCOA3 or AIB1) is a member of the multifunctional p160/SRC family of coactivators, which also includes SRC-1 and SRC-2. Clinical and cell-based studies as well as investigations on mice have demonstrated pivotal roles for each SRC in numerous physiological and pathophysiological contexts, underscoring their functional pleiotropy. We previously demonstrated the critical involvement of SRC-2 in murine embryo implantation as well as in human endometrial stromal cell (HESC) decidualization, a cellular transformation process required for trophoblast invasion and ultimately placentation. We show here that, like SRC-2, SRC-3 is expressed in the epithelial and stromal cellular compartments of the human endometrium during the proliferative and secretory phase of the menstrual cycle as well as in cultured HESCs. We also found that SRC-3 depletion in cultured HESCs results in a significant attenuation in the induction of a wide-range of established biomarkers of decidualization, despite exposure of these cells to a deciduogenic stimulus and normal progesterone receptor expression. These molecular findings are supported at the cellular level by the inability of HESCs to morphologically transform from a stromal fibroblastoid cell to an epithelioid decidual cell when endogenous SRC-3 levels are markedly reduced. To identify genes, signaling pathways and networks that are controlled by SRC-3 and potentially important for hormone-dependent decidualization, we performed RNA-sequencing on HESCs in which SRC-3 levels were significantly reduced at the time of administering the deciduogenic stimulus. Comparing HESC controls with HESCs deficient in SRC-3, gene enrichment analysis of the differentially expressed gene set revealed an overrepresentation of genes involved in chromatin remodeling, cell proliferation/motility, and programmed cell death. These predictive bioanalytic results were confirmed by the demonstration that SRC-3 is required for the expansion, migratory and invasive activities of the HESC population, cellular properties that are required in vivo in the formation or functioning of the decidua. Collectively, our results support SRC-3 as an important coregulator in HESC decidualization. Since perturbation of normal homeostatic levels of SRC-3 is linked with common gynecological disorders diagnosed in reproductive age women, this endometrial coregulator-along with its new molecular targets described here-may open novel clinical avenues in the diagnosis and/or treatment of a non-receptive endometrium, particularly in patients presenting non-aneuploid early pregnancy loss.

SRC-3 deficiency prevents atherosclerosis development by decreasing endothelial ICAM-1 expression to attenuate macrophage recruitment

Steroid receptor coactivator 3 (SRC-3) is a member of the p160 SRC family. This factor can interact with multiple nuclear hormone receptors and transcription factors to regulate the expression of their target genes. Although many physiological roles of SRC-3 have been revealed, its role in atherosclerosis is not clear. In this study, we found that SRC-3^-/-ApoE^-/- mice have reduced atherosclerotic lesions and necrotic areas in their aortas and aortic roots compared with SRC-3^+/+ApoE^-/- mice after Western diet (WD) feeding for 12 weeks. RNA-Seq and Western blot analyses of the aorta revealed that SRC-3 was required for maintaining the expression of ICAM-1, which was required for macrophage recruitment and atherosclerosis development. siRNA-mediated knockdown of SRC-3 in endothelial cells significantly reduced WD-induced atherosclerotic plaque formation. Additionally, treatment of ApoE^-/- mice with SRC-3 inhibitor bufalin prevented atherosclerotic plaque development. SRC-3 deficiency reduced aortic macrophage recruitment. Accordingly, ICAM-1 expression was markedly decreased in the aortas of SRC-3^-/-ApoE^-/- mice and ApoE^-/- mice with endothelial SRC-3 knockdown mediated by AAV9-shSRC-3 virus. Mechanistically, SRC-3 coactivated NF-κB p65 to increase ICAM-1 transcription in endothelial cells. Collectively, these findings demonstrate that inhibiting SRC-3 ameliorates atherosclerosis development, at least in part through suppressing endothelial activation by decreasing endothelial ICAM-1 expression via reducing NF-κB signaling.

SRC3 deficiency exacerbates lipopolysaccharide-induced acute respiratory distress syndrome in mice

Acute respiratory distress syndrome (ARDS) is a severe disease. Inflammation is the key element implicated in ARDS. Steroid receptor coactivator 3 (SRC3), a coactivator protein for transcription, is involved in regulation of inflammatory response. Here we explored the potential roles of SRC3 in ARDS. We utilized the SRC3 deficient (SRC3^-/-) mice and established the lipopolysaccharides (LPS)-induced ARDS model. The mortality, lung injury, leucocytes infiltration and inflammatory cytokine production were compared between wild type (WT) and SRC3^-/- mice. The NF-κB activation in lung of WT and SRC3^-/- mice was measured. After LPS treatment, SRC3^-/- mice had higher mortality and more severe lung damage than WT mice. LPS-treated SRC3^-/- mice had more leucocytes infiltration and upregulated inflammatory cytokine production. LPS-treated SRC3^-/- mice had elevated NF-κB activation. SRC3^-/- mice had exacerbated ARDS in LPS-treated mice.

Aib1 deficiency exacerbates inflammatory responses in acute myocardial infarction mice

Acute myocardial infarction (AMI) is one of the major causes of death throughout the world, while inflammation has been known as a major contributor to the pathophysiology of AMI. Inhibition of inflammation is shown to protect from AMI. Amplified in breast 1 (Aib1) is a transcriptional coactivator protein which can suppress inflammation. The anti-inflammatory activities of Aib1 imply its potential effects against AMI; however, to date the role of Aib1 in AMI has not been described yet. Here we explored the potential functions of Aib1 in AMI. We induced AMI in both wild-type (WT) and Aib1^-/- mice. The expression levels of Aib1 and inflammatory cytokines in the AMI WT mice were measured by RT-PCR and Western blot. The heart infarction area and cardiac functions were compared between the AMI WT and Aib1^-/- mice. The expression levels of inflammatory cytokines including IL-6, IL-1β, TNF-α, and MCP-1 in heart tissues were compared between the AMI WT and Aib1^-/- mice by ELISA and RT-PCR. AMI induced the production of inflammatory cytokines whereas suppressed the expression of Aib1 in WT mice. AMI Aib1^-/- mice displayed increased infarct area and aggravated heart dysfunction, as well as upregulated levels of Il-6, Il-1β, Tnf-α, and Mcp-1 in heart tissues. Aib1 deficiency exacerbates inflammation in AMI mice. KEY MESSAGES: AMI induced inflammation in the heart tissue of mice. Aib1 knockout exacerbated infarction in AMI mice. Aib1 knockout exacerbated cardiac dysfunction in AMI mice. Aib1 knockout exacerbated inflammation in AMI mice.

Defining the mammalian coactivation of hepatic 12-h clock and lipid metabolism

The 12-h clock coordinates lipid homeostasis, energy metabolism, and stress rhythms via the transcriptional regulator XBP1. However, the biochemical and physiological bases for integrated control of the 12-h clock and diverse metabolic pathways remain unclear. Here, we show that steroid receptor coactivator SRC-3 coactivates XBP1 transcription and regulates hepatic 12-h cistrome and gene rhythmicity. Mice lacking SRC-3 show abnormal 12-h rhythms in hepatic transcription, metabolic functions, systemic energetics, and rate-limiting lipid metabolic processes, including triglyceride, phospholipid, and cardiolipin pathways. Notably, 12-h clock coactivation is not only preserved, with its cistromic activation priming ahead of the zeitgeber cue of light, but concomitant with rhythmic remodeling in the absence of food. These findings reveal that SRC-3 integrates the mammalian 12-h clock, energy metabolism, and membrane and lipid homeostasis and demonstrates a role for the 12-h clock machinery as an active transcriptional mechanism in anticipating physiological and metabolic energy needs and stresses.

Progesterone Actions and Resistance in Gynecological Disorders

Estrogen and progesterone and their signaling mechanisms are tightly regulated to maintain a normal menstrual cycle and to support a successful pregnancy. The imbalance of estrogen and progesterone disrupts their complex regulatory mechanisms, leading to estrogen dominance and progesterone resistance. Gynecological diseases are heavily associated with dysregulated steroid hormones and can induce chronic pelvic pain, dysmenorrhea, dyspareunia, heavy bleeding, and infertility, which substantially impact the quality of women's lives. Because the menstrual cycle repeatably occurs during reproductive ages with dynamic changes and remodeling of reproductive-related tissues, these alterations can accumulate and induce chronic and recurrent conditions. This review focuses on faulty progesterone signaling mechanisms and cellular responses to progesterone in endometriosis, adenomyosis, leiomyoma (uterine fibroids), polycystic ovary syndrome (PCOS), and endometrial hyperplasia. We also summarize the association with gene mutations and steroid hormone regulation in disease progression as well as current hormonal therapies and the clinical consequences of progesterone resistance.

The non-LTR retrotransposons of Entamoeba histolytica: genomic organization and biology

Genome sequence analysis of Entamoeba species revealed various classes of transposable elements. While E. histolytica and E. dispar are rich in non-long terminal repeat (LTR) retrotransposons, E. invadens contains predominantly DNA transposons. Non-LTR retrotransposons of E. histolytica constitute three families of long interspersed nuclear elements (LINEs), and their short, nonautonomous partners, SINEs. They occupy ~ 11% of the genome. The EhLINE1/EhSINE1 family is the most abundant and best studied. EhLINE1 is 4.8 kb, with two ORFs that encode functions needed for retrotransposition. ORF1 codes for the nucleic acid-binding protein, and ORF2 has domains for reverse transcriptase (RT) and endonuclease (EN). Most copies of EhLINEs lack complete ORFs. ORF1p is expressed constitutively, but ORF2p is not detected. Retrotransposition could be demonstrated upon ectopic over expression of ORF2p, showing that retrotransposition machinery is functional. The newly retrotransposed sequences showed a high degree of recombination. In transcriptomic analysis, RNA-Seq reads were mapped to individual EhLINE1 copies. Although full-length copies were transcribed, no full-length 4.8 kb transcripts were seen. Rather, sense transcripts mapped to ORF1, RT and EN domains. Intriguingly, there was strong antisense transcription almost exclusively from the RT domain. These unique features of EhLINE1 could serve to attenuate retrotransposition in E. histolytica.

SRC3 Promotes the Protective Effects of Bone Marrow Mesenchymal Stem Cell Transplantation on Cerebral Ischemia in a Mouse Model

Mesenchymal stem cells (MSCs) derived from the bone marrow (BM) are reported to protect against ischemic brain injury. This study aimed to investigate whether the steroid receptor cofactor 3 (SRC3) was involved in MSC-induced neuroprotection. BM-MSCs were isolated from wild-type (WT) and SRC3 knockout (SRC3^-/-) mice and transplanted into mice with middle cerebral artery occlusion (MCAO). The MSC identification and differentiation were determined by flow cytometry and Alizarin Red S staining after osteogenic and adipogenic stimulations. The effects of MSCs on brain injury were assessed by brain water content, modified neurological severity score (mNSS), Morris water maze test, and open field test. Finally, the effects of MSCs on MCAO-induced oxidative stress were assessed by measuring the levels of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) and mRNA levels of SOD1, SOD2, and CAT. We found that SRC3 deficiency did not impact the MSC identification or osteogenic and adipogenic differentiation. MSC-SRC3^-/- transplantation in mice that underwent the MCAO procedure exhibited diminished effects on suppression of brain edema, neurological deficits, cognitive disruption, locomotor impairment, and anxiety compared to comparable levels of MSC-WT. Finally, MSC-WT transplantation inhibited MCAO-induced oxidative stress, and the effects were significantly attenuated in MCAO mice transplanted with MSC-SRC3^-/-. MSCs suppressed the MCAO-induced upregulation of MDA activity and the inhibition of SOD, GSH, SOD1, SOD2, and CAT levels, and SRC3-deficient MSCs showed significantly reduced effects. Our results indicate that SRC3 plays an important role in mediating the neuroprotective effects of MSCs in mice that experienced ischemic stroke.

SRC-3 Knockout Attenuates Myocardial Injury Induced by Chronic Intermittent Hypoxia in Mice

This study investigated the effects of chronic intermittent hypoxia (CIH), a model of sleep apnea syndrome (SAS), on cardiac function. SRC-3 was extremely lowly expressed in the adult mouse heart tissue, while SRC-3 was highly expressed in the adult mouse heart tissue after CIH, suggesting that SRC-3 is involved in CIH model. We further studied the role of SRC-3 in CIH-induced myocardial injury in mice. Twenty-four healthy Balb/c male mice (n = 16, wild type; n = 8, SRC-3 knockout (SRC3-KO)) were randomly divided into three groups: air control (Ctrl), CIH, and CIH+SRC3-KO. Mice were exposed to CIH for 12 weeks. qRT-PCR was used to evaluate cardiac expression of the following genes: 11HSD1, 11HSD2, GR, MR, COX-2, OPN, NOX2, HIF-1-α, IL-1β, IL-6, iNOS, TNF-α, PC-1, and TGF-β. Enzymatic levels of SOD, CAT, MDA, NOS, and NO in the mouse hearts were determined using commercially available kits. Immunohistochemistry (IHC) was used to evaluate NF-κB expression in cardiac tissues. A transmission electron microscope (TEM) was used to evaluate myocardial ultrastructure. TUNEL staining was used to assess myocardial cell apoptosis. CIH induced cardiac damage, which was ameliorated in the SRC-3 KO mice. CIH significantly increased the heart-to-body weight ratio, expression of all aforementioned genes except 11HSD1, GR, and MR, and increased the levels of MDA, NOS, NO, and NF-κB, which were attenuated in the SRC-3 KO mice. The CIH group had the lowest SOD and CAT levels, which were partially recovered in the CIH+SRC3-KO group. 11HSD2 gene expression was elevated in both the CIH and CIH+SRC3-KO groups compared to the Ctrl group. The CIH group had severe myocardial cell apoptosis and mitochondrial dysfunction, which were alleviated in the CIH+SRC3-KO group. CIH causes cardiac damage through inducing oxidative stress and inflammation. Knockout of SRC-3 ameliorates CIH-induced cardiac damage through antagonizing CIH-triggered molecular changes in cardiac tissue.

17β-Estradiol Attenuates Intracerebral Hemorrhage-Induced Blood-Brain Barrier Injury and Oxidative Stress Through SRC3-Mediated PI3K/Akt Signaling Pathway in a Mouse Model

Estrogen is neuroprotective in brain injury models, and steroid receptor cofactor 3 (SRC3) mediates estrogen signaling. We aimed to investigate whether and how SRC3 is involved in the neuroprotective effects of 17ß-estradiol (E2) in a mouse model of intracerebral hemorrhage (ICH). Ovariectomized female mice were treated with E2 after autologous blood injection-induced ICH. Brain damage was assessed by neurological deficit score, brain water content, and oxidative stress levels. Blood–brain barrier (BBB) integrity was evaluated by Evan's blue extravasation and claudin-5, ZO-1, and occludin levels. SRC3 expression and PI3K/Akt signaling pathway were examined in ICH mice treated with E2. The effect of SRC3 on E2-mediated neuroprotection was determined by examining neurological outcomes in SRC3-deficient mice undergone ICH and E2 treatment. We found that E2 alleviated ICH-induced brain edema and neurological deficits, protected BBB integrity, and suppressed oxidative stress. E2 enhanced SRC3 expression and PI3K-/Akt signaling pathway. SRC3 deficiency abolished the protective effects of E2 on ICH-induced neurological deficits, brain edema, and BBB integrity. Our results suggest that E2 suppresses ICH-induced brain injury and SRC3 plays a critical role in E2-mediated neuroprotection.

SRC3 acetylates calmodulin in the mouse brain to regulate synaptic plasticity and fear learning

Protein acetylation is a reversible posttranslational modification, which is regulated by lysine acetyltransferase (KAT) and lysine deacetyltransferase (KDAC). Although protein acetylation has been shown to regulate synaptic plasticity, this was mainly for histone protein acetylation. The function and regulation of nonhistone protein acetylation in synaptic plasticity and learning remain largely unknown. Calmodulin (CaM), a ubiquitous Ca²⁺ sensor, plays critical roles in synaptic plasticity such as long-term potentiation (LTP). During LTP induction, activation of NMDA receptor triggers Ca²⁺ influx, and the Ca²⁺ binds with CaM and activates calcium/calmodulin-dependent protein kinase IIα (CaMKIIα). In our previous study, we demonstrated that acetylation of CaM was important for synaptic plasticity and fear learning in mice. However, the KAT responsible for CaM acetylation is currently unknown. Here, following an HEK293 cell-based screen of candidate KATs, steroid receptor coactivator 3 (SRC3) is identified as the most active KAT for CaM. We further demonstrate that SRC3 interacts with and acetylates CaM in a Ca²⁺ and NMDA receptor-dependent manner. We also show that pharmacological inhibition or genetic downregulation of SRC3 impairs CaM acetylation, synaptic plasticity, and contextual fear learning in mice. Moreover, the effects of SRC3 inhibition on synaptic plasticity and fear learning could be rescued by 3KQ-CaM, a mutant form of CaM, which mimics acetylation. Together, these observations demonstrate that SRC3 acetylates CaM and regulates synaptic plasticity and learning in mice.

SRC-3 Deficiency Exacerbates Neurological Deficits in a Mouse Model of Intracerebral Hemorrhage: Role of Oxidative Stress

Intracerebral hemorrhage (ICH) causes long term neurological abnormality or death. Oxidative stress is closely involved in ICH mediated brain damage. Steroid receptor cofactor 3 (SRC-3), a p160 family member, is widely expressed in the brain and regulates transactivation of Nrf2, a key component of antioxidant response. Our study aims to test if SRC-3 is implicated in ICH mediated brain injury. We first examined levels of SRC-3 and oxidative stress in the brain of mice following ICH and analyzed their correlation. Then ICH was induced in wild type (WT) and SRC-3 knock out mice and how SRC-3 deletion affected ICH induced brain damage, oxidative stress and behavioral outcome was assessed. We found that SRC-3 mRNA and protein expression levels were reduced gradually after ICH induction in WT mice along with an increase in oxidative stress levels. Correlation analysis revealed that SRC-3 mRNA levels negatively correlated with oxidative stress. Deletion of SRC-3 further increased ICH induced brain edema, neurological deficit score and oxidative stress and exacerbated ICH induced behavioral abnormality including motor dysfunction and cognitive impairment. Our findings suggest that SRC-3 is involved in ICH induced brain injury, probably through modulation of oxidative stress.

Steroid Receptor Coactivator 3 Regulates Synaptic Plasticity and Hippocampus-dependent Memory

Steroid hormones play important roles in brain development and function. The signaling of steroid hormones depends on the interaction between steroid receptors and their coactivators. Although the function of steroid receptor coactivators has been extensively studied in other tissues, their functions in the central nervous system are less well investigated. In this study, we addressed the function of steroid receptor coactivator 3 (SRC3) - a member of the p160 SRC protein family that is expressed predominantly in the hippocampus. While hippocampal development was not altered in Src3^+/- mice, hippocampus-dependent functions such as short-term memory and spatial memory were impaired. We further demonstrated that the deficient learning and memory in Src3^+/- mice was strongly associated with the impairment of long-term potentiation (LTP) at Schaffer Collateral-CA1 synapses. Mechanistic studies indicated that Src3^+/- mutation altered the composition of N-methyl-D-aspartate receptor subunits in the postsynaptic densities of hippocampal neurons. Finally, we showed that SRC3 regulated synaptic plasticity and learning mainly dependent on its lysine acetyltransferase activity. Taken together, these results reveal previously unknown functions of SRC3 in the hippocampus and thus may provide insight into how steroid hormones regulate brain function.

SRC-3 deficiency protects host from Listeria monocytogenes infection through increasing ROS production and decreasing lymphocyte apoptosis

Listeria monocytogenes is the third major cause of death among food poisoning. Our previous studies have demonstrated that steroid receptor coactivator 3 (SRC-3) plays a critical protective role in host defense against extracellular bacterial pathogens such as Escherichia coli and Citrobacter rodentium. However, its role involved in intracellular bacterial pathogen infection remains unclear. Herein, we found that SRC-3-/- mice are more resistant to L. monocytogenes infection after tail intravenous injection with L. monocytogenes compared with wild-type mice. After infecting with L. monocytogenes, SRC-3-/- mice exhibited decreased mortality rate, decreased bacterial load, less body weight loss, less proinflammatory cytokines and less severe tissue damage compared with wild-type mice. SRC-3-/- mice produced more ROS and decreased L. monocytogenes-induced lymphocyte apoptosis. Mechanically, SRC-3-/- mice displayed decreased expressions of negative regulator of ROS (NRROS) and interferon (IFN)-β and its target genes such as Daxx, Mx1 and TRAIL associated with apoptosis. Taken together, SRC-3 deficiency can protect host from L. monocytogenes infection through increasing ROS production and decreasing lymphocyte apoptosis via affecting the expressions of NRROS and IFN-β.

Estrogen receptor-α signaling in post-natal mammary development and breast cancers

17β-estradiol controls post-natal mammary gland development and exerts its effects through Estrogen Receptor ERα, a member of the nuclear receptor family. ERα is also critical for breast cancer progression and remains a central therapeutic target for hormone-dependent breast cancers. In this review, we summarize the current understanding of the complex ERα signaling pathways that involve either classical nuclear “genomic” or membrane “non-genomic” actions and regulate in concert with other hormones the different stages of mammary development. We describe the cellular and molecular features of the luminal cell lineage expressing ERα and provide an overview of the transgenic mouse models impacting ERα signaling, highlighting the pivotal role of ERα in mammary gland morphogenesis and function and its implication in the tumorigenic processes. Finally, we describe the main features of the ERα-positive luminal breast cancers and their modeling in mice.

PELP1/SRC-3-dependent regulation of metabolic PFKFB kinases drives therapy resistant ER+ breast cancer

Recurrence of metastatic breast cancer stemming from acquired endocrine and chemotherapy resistance remains a health burden for women with luminal (ER+) breast cancer. Disseminated ER+ tumor cells can remain viable but quiescent for years to decades. Contributing factors to metastatic spread include the maintenance and expansion of breast cancer stem cells (CSCs). Breast CSCs frequently exist as a minority population in therapy resistant tumors. In this study, we show that cytoplasmic complexes composed of steroid receptor (SR) co-activators, PELP1 and SRC-3, modulate breast CSC expansion through upregulation of the HIF-activated metabolic target genes PFKFB3 and PFKFB4. Seahorse metabolic assays demonstrated that cytoplasmic PELP1 influences cellular metabolism by increasing both glycolysis and mitochondrial respiration. PELP1 interacts with PFKFB3 and PFKFB4 proteins, and inhibition of PFKFB3 and PFKFB4 kinase activity blocks PELP1-induced tumorspheres and protein-protein interactions with SRC-3. PFKFB4 knockdown inhibited in vivo emergence of circulating tumor cell (CTC) populations in mammary intraductal (MIND) models. Application of PFKFB inhibitors in combination with ER targeted therapies blocked tumorsphere formation in multiple models of advanced breast cancer including tamoxifen (TamR) and paclitaxel (TaxR) resistant models, murine tumor cells, and ER+ patient-derived organoids (PDxO). Together, our data suggest that PELP1, SRC-3, and PFKFBs cooperate to drive ER+ tumor cell populations that include CSCs and CTCs. Identifying non-ER pharmacological targets offers a useful approach to blocking metastatic escape from standard of care ER/estrogen (E2)-targeted strategies to overcome endocrine and chemotherapy resistance.

Steroid Receptor Coactivator-3 Is Required for Inhibition of the Intestinal Muscularis Inflammatory Response of Postoperative Ileus in Mice

Inflammation theory has suggested that the pathogenesis of postoperative ileus (POI) involves the steroid receptor coactivator-3 (SRC-3). Therefore, we investigated the role of SRC-3 in the muscles of the small intestine using a mouse POI model. Here, we reported that intestinal manipulation (IM) significantly reduced the extent of phenol red migration in the entire gastrointestinal tract, and the calculated geometric center (GC) value in wild-type (WT) mice at 24 h after surgery was higher than that in the knockout (KO) mice and in the sham-operated control group. The expression of SRC-3 was upregulated in the mouse intestinal muscularis at 24 h after surgical manipulation, and the mRNA and protein levels of inflammatory cytokines were upregulated compared with those in the control group. At 24 h after IM, the number of neutrophils in the experimental group was significantly higher than that in the control group; in the IM group, the number of neutrophils in the SRC-3-/- mice was markedly higher than that in the WT mice. At 24 h after IM, the myeloperoxidase (MPO) activity in the experimental group was significantly higher than that in the control group. In the IM group, the MPO activity of the SRC-3-/- mice was markedly higher than that of the WT mice. In summary, proinflammatory cytokines, the number of neutrophils, and the MPO activity were significantly increased in the muscularis of the jejunum and ileum of KO mice after IM compared with those of the WT mice, indicating that SRC-3 might play a protective role in POI.

SRC-3, a Steroid Receptor Coactivator: Implication in Cancer

Steroid receptor coactivator-3 (SRC-3), also known as amplified in breast cancer 1 (AIB1), is a member of the SRC family. SRC-3 regulates not only the transcriptional activity of nuclear receptors but also many other transcription factors. Besides the essential role of SRC-3 in physiological functions, it also acts as an oncogene to promote multiple aspects of cancer. This review updates the important progress of SRC-3 in carcinogenesis and summarizes its mode of action, which provides clues for cancer therapy.

A Role of Endogenous Histone Acetyltransferase Steroid Hormone Receptor Coactivator 3 in Thyroid Hormone Signaling During Xenopus Intestinal Metamorphosis

Background: Thyroid hormone (triiodothyronine [T3]) plays an important role in regulating vertebrate developmental, cellular, and metabolic processes via T3 receptor (TR). Liganded TR recruit coactivator complexes that include steroid receptor coactivators (SRC1, SRC2 or SRC3), which are histone acetyltransferases, to T3-responsive promoters. The functions of endogenous coactivators during T3-dependent mammalian adult organ development remain largely unclear, in part, due to the difficulty to access and manipulate late-stage embryos and neonates. We use Xenopus metamorphosis as a model for postembryonic development in vertebrates. This process is controlled by T3, involves drastic changes in every organ/tissue, and can be easily manipulated. We have previously found that SRC3 was upregulated in the intestine during amphibian metamorphosis. Methods: To determine the function of endogenous SRC3 during intestinal remodeling, we have generated Xenopus tropicalis animals lacking a functional SRC3 gene and analyzed the resulting phenotype. Results: Although removing SRC3 had no apparent effect on external development and animal gross morphology, the SRC3 (-/-) tadpoles displayed a reduction in the acetylation of histone H4 in the intestine compared with that in wild-type animals. Further, the expression of TR target genes was also reduced in SRC3 (-/-) tadpoles during intestinal remodeling. Importantly, SRC3 (-/-) tadpoles had inhibited/delayed intestinal remodeling during natural and T3-induced metamorphosis, including reduced adult intestinal stem cell proliferation and apoptosis of larval epithelial cells. Conclusion: Our results, thus, demonstrate that SRC3 is a critical component of the TR-signaling pathway in vivo during intestinal remodeling.

The Biological Significance of Targeting Acetylation-Mediated Gene Regulation for Designing New Mechanistic Tools and Potential Therapeutics

The molecular interplay between nucleosomal packaging and the chromatin landscape regulates the transcriptional programming and biological outcomes of downstream genes. An array of epigenetic modifications plays a pivotal role in shaping the chromatin architecture, which controls DNA access to the transcriptional machinery. Acetylation of the amino acid lysine is a widespread epigenetic modification that serves as a marker for gene activation, which intertwines the maintenance of cellular homeostasis and the regulation of signaling during stress. The biochemical horizon of acetylation ranges from orchestrating the stability and cellular localization of proteins that engage in the cell cycle to DNA repair and metabolism. Furthermore, lysine acetyltransferases (KATs) modulate the functions of transcription factors that govern cellular response to microbial infections, genotoxic stress, and inflammation. Due to their central role in many biological processes, mutations in KATs cause developmental and intellectual challenges and metabolic disorders. Despite the availability of tools for detecting acetylation, the mechanistic knowledge of acetylation-mediated cellular processes remains limited. This review aims to integrate molecular and structural bases of KAT functions, which would help design highly selective tools for understanding the biology of KATs toward developing new disease treatments.

Wound Healing-related Functions of the p160 Steroid Receptor Coactivator Family

Multicellular organisms have evolved sophisticated mechanisms to recover and maintain original tissue functions following injury. Injury responses require a robust transcriptomic response associated with cellular reprogramming involving complex gene expression programs critical for effective tissue repair following injury. Steroid receptor coactivators (SRCs) are master transcriptional regulators of cell-cell signaling that is integral for embryogenesis, reproduction, normal physiological function, and tissue repair following injury. Effective therapeutic approaches for facilitating improved tissue regeneration and repair will likely involve temporal and combinatorial manipulation of cell-intrinsic and cell-extrinsic factors. Pleiotropic actions of SRCs that are critical for wound healing range from immune regulation and angiogenesis to maintenance of metabolic regulation in diverse organ systems. Recent evidence derived from studies of model organisms during different developmental stages indicates the importance of the interplay of immune cells and stromal cells to wound healing. With SRCs being the master regulators of cell-cell signaling integral to physiologic changes necessary for wound repair, it is becoming clear that therapeutic targeting of SRCs provides a unique opportunity for drug development in wound healing. This review will provide an overview of wound healing-related functions of SRCs with a special focus on cellular and molecular interactions important for limiting tissue damage after injury. Finally, we review recent findings showing stimulation of SRCs following cardiac injury with the SRC small molecule stimulator MCB-613 can promote cardiac protection and inhibit pathologic remodeling after myocardial infarction.

Steroid receptor coactivator 3 (SRC-3/AIB1) is enriched and functional in mouse and human Tregs

A subset of CD4 + lymphocytes, regulatory T cells (Tregs), are necessary for central tolerance and function as suppressors of autoimmunity against self-antigens. The SRC-3 coactivator is an oncogene in multiple cancers and is capable of potentiating numerous transcription factors in a wide variety of cell types. Src-3 knockout mice display broad lymphoproliferation and hypersensitivity to systemic inflammation. Using publicly available bioinformatics data and directed cellular approaches, we show that SRC-3 also is highly enriched in Tregs in mice and humans. Human Tregs lose phenotypic characteristics when SRC-3 is depleted or pharmacologically inhibited, including failure of induction from resting T cells and loss of the ability to suppress proliferation of stimulated T cells. These data support a model for SRC-3 as a coactivator that actively participates in protection from autoimmunity and may support immune evasion of cancers by contributing to the biology of Tregs.

NCOA3 identified as a new candidate to explain autosomal dominant progressive hearing loss

Hearing loss is a frequent sensory impairment in humans and genetic factors account for an elevated fraction of the cases. We have investigated a large family of five generations, with 15 reported individuals presenting non-syndromic, sensorineural, bilateral and progressive hearing loss, segregating as an autosomal dominant condition. Linkage analysis, using SNP-array and selected microsatellites, identified a region of near 13 cM in chromosome 20 as the best candidate to harbour the causative mutation. After exome sequencing and filtering of variants, only one predicted deleterious variant in the NCOA3 gene (NM_181659, c.2810C > G; p.Ser937Cys) fit in with our linkage data. RT-PCR, immunostaining and in situ hybridization showed expression of ncoa3 in the inner ear of mice and zebrafish. We generated a stable homozygous zebrafish mutant line using the CRISPR/Cas9 system. ncoa3-/- did not display any major morphological abnormalities in the ear, however, anterior macular hair cells showed altered orientation. Surprisingly, chondrocytes forming the ear cartilage showed abnormal behaviour in ncoa3-/-, detaching from their location, invading the ear canal and blocking the cristae. Adult mutants displayed accumulation of denser material wrapping the otoliths of ncoa3-/- and increased bone mineral density. Altered zebrafish swimming behaviour corroborates a potential role of ncoa3 in hearing loss. In conclusion, we identified a potential candidate gene to explain hereditary hearing loss, and our functional analyses suggest subtle and abnormal skeletal behaviour as mechanisms involved in the pathogenesis of progressive sensory function impairment.

A steroid receptor coactivator stimulator (MCB-613) attenuates adverse remodeling after myocardial infarction

We are at an exciting era of identification of the cell and molecular processes necessary for tissue remodeling and repair. Unlike current systemic therapeutics, our studies reveal pharmacologic stimulation of SRCs modulates macrophage and fibrotic reparative cell responses to promote more effective repair and lasting beneficial remodeling after myocardial infarction.

Progressive remodeling of the heart, resulting in cardiomyocyte (CM) loss and increased inflammation, fibrosis, and a progressive decrease in cardiac function, are hallmarks of myocardial infarction (MI)-induced heart failure. We show that MCB-613, a potent small molecule stimulator of steroid receptor coactivators (SRCs) attenuates pathological remodeling post-MI. MCB-613 decreases infarct size, apoptosis, hypertrophy, and fibrosis while maintaining significant cardiac function. MCB-613, when given within hours post MI, induces lasting protection from adverse remodeling concomitant with: 1) inhibition of macrophage inflammatory signaling and interleukin 1 (IL-1) signaling, which attenuates the acute inflammatory response, 2) attenuation of fibroblast differentiation, and 3) promotion of Tsc22d3-expressing macrophages—all of which may limit inflammatory damage. SRC stimulation with MCB-613 (and derivatives) is a potential therapeutic approach for inhibiting cardiac dysfunction after MI.

Thyroid Hormone Signaling and the Liver

Thyroid hormone (TH) plays a critical role in maintaining metabolic homeostasis throughout life. It is well known that the liver and thyroid are intimately linked, with TH playing important roles in de novo lipogenesis, beta-oxidation (fatty acid oxidation), cholesterol metabolism, and carbohydrate metabolism. Indeed, patients with hypothyroidism have abnormal lipid panels with higher levels of low-density lipoprotein levels, triglycerides (triacylglycerol; TAG), and apolipoprotein B levels. Even in euthyroid patients, lower serum-free thyroxine levels are associated with higher total cholesterol levels, LDL, and TAG levels. In addition to abnormal serum lipids, the risk of nonalcoholic fatty liver disease (NAFLD) increases with lower free thyroxine levels. As free thyroxine rises, the risk of NAFLD is reduced. This has led to numerous animal studies and clinical trials investigating TH analogs and TH receptor agonists as potential therapies for NAFLD and hyperlipidemia. Thus, TH plays an important role in maintaining hepatic homeostasis, and this continues to be an important area of study. A review of TH action and TH actions on the liver will be presented here.

The Expression and Contribution of SRCs with Preeclampsia Placenta

The steroid hormones act by binding to their receptors and subsequently interacting with coactivators. Several classes of coactivators have been identified and shown to be essential in estradiol (E2) responsiveness. The major coregulators are the p160 steroid receptor coactivator (SRC) family. Although the function of SRCs in other organs has been well studied, it has not been thoroughly studied in the placenta. In addition, the correlation between preeclampsia (PE) and SRCs has not been examined previously. Therefore, we compared the expression patterns of SRCs in normal and PE placentas. In human PE placental tissues, SRC-1 mRNA, and protein levels were downregulated in the PE group. In addition, to assess the expression of SRCs in a PE environment, we used Reduced Uterine Perfusion Pressure (RUPP) model and placental cells were cultured in hypoxia condition. SRC-1 proteins were reduced in the placenta of PE-like rat RUPP model. Furthermore, SRCs proteins were significantly downregulated in hypoxia-grown placental cells. To examine the interaction between estrogen receptors (ERs) and SRC-1 protein, we performed co-immunoprecipitation. The interaction of SRC-1 with ERα was significantly stronger than that with ERβ. In PE placenta, the interaction of both ERα and ERβ with SRC-1 was stronger than that in normal placenta. In summary, our results demonstrate that expression levels of SRC-1, not SRC-2 and SRC-3, were decreased in hypoxia-induced PE placenta, which may further reduce the signaling of sex steroid hormones such as E2. The dysregulated signaling of E2 by SRC-1 expression could be associated with the PE placental symptoms of patients.

Intrinsically Disordered SRC-3/AIB1 Protein Undergoes Homeostatic Nuclear Extrusion by Nuclear Budding While Ectopic Expression Induces Nucleophagy

SRC-3/AIB1 (Amplified in Breast Cancer-1) is a nuclear receptor coactivator for the estrogen receptor in breast cancer cells. It is also an intrinsically disordered protein when not engaged with transcriptional binding partners and degraded upon transcriptional coactivation. Given the amplified expression of SRC-3 in breast cancers, the objective of this study was to determine how increasing SRC-3 protein levels are regulated in MCF-7 breast cancer cells. We found that endogenous SRC-3 was expelled from the nucleus in vesicle-like spheres under normal growth conditions suggesting that this form of nuclear exclusion of SRC-3 is a homeostatic mechanism for regulating nuclear SRC-3 protein. Only SRC-3 not associated with CREB-binding protein (CBP) was extruded from the nucleus. We found that overexpression in MCF-7 cells results in aneuploid senescence and cell death with frequent formation of nuclear aggregates which were consistently juxtaposed to perinuclear microtubules. Transfected SRC-3 was SUMOylated and caused redistribution of nuclear promyelocytic leukemia (PML) bodies and perturbation of the nuclear membrane lamin B1, hallmarks of nucleophagy. Increased SRC-3 protein-induced autophagy and resulted in SUMO-1 localization to the nuclear membrane and formation of protrusions variously containing SRC-3 and chromatin. Aspects of SRC-3 overexpression and toxicity were recapitulated following treatment with clinically relevant agents that stabilize SRC-3 in breast cancer cells. We conclude that amplified SRC-3 levels have major impacts on nuclear protein quality control pathways and may mark cancer cells for sensitivity to protein stabilizing therapeutics.

New concepts in the study of the sexual differentiation and activation of reproductive behavior, a personal view

Since the beginning of this century, research methods in neuroendocrinology enjoyed extensive refinements and innovation. These advances allowed collection of huge amounts of new data and the development of new ideas but have not led to this point, with a few exceptions, to the development of new conceptual advances. Conceptual advances that took place largely resulted from the ingenious insights of several investigators. I summarize here some of these new ideas as they relate to the sexual differentiation and activation by sex steroids of reproductive behaviors and I discuss how our research contributed to the general picture. This selective review clearly demonstrates the importance of conceptual changes that have taken place in this field since beginning of the 21st century. The recent technological advances suggest that our understanding of hormones, brain and behavior relationships will continue to improve in a very fundamental manner over the coming years.

Progesterone and Estrogen Signaling in the Endometrium: What Goes Wrong in Endometriosis?

In the healthy endometrium, progesterone and estrogen signaling coordinate in a tightly regulated, dynamic interplay to drive a normal menstrual cycle and promote an embryo-receptive state to allow implantation during the window of receptivity. It is well-established that progesterone and estrogen act primarily through their cognate receptors to set off cascades of signaling pathways and enact large-scale gene expression programs. In endometriosis, when endometrial tissue grows outside the uterine cavity, progesterone and estrogen signaling are disrupted, commonly resulting in progesterone resistance and estrogen dominance. This hormone imbalance leads to heightened inflammation and may also increase the pelvic pain of the disease and decrease endometrial receptivity to embryo implantation. This review focuses on the molecular mechanisms governing progesterone and estrogen signaling supporting endometrial function and how they become dysregulated in endometriosis. Understanding how these mechanisms contribute to the pelvic pain and infertility associated with endometriosis will open new avenues of targeted medical therapies to give relief to the millions of women suffering its effects.

Lean body mass accretion is elevated in response to dietary vitamin D: A dose-response study in female weanling rats

Vitamin D status positively relates to lean body mass in infants. This study tested the effect of vitamin D on body composition and growth-related hormones. It was hypothesized that low vitamin D status programs for higher fat mass accretion. Female weanling Sprague-Dawley rats (4 weeks; n = 6/diet) were randomized to AIN-93G diets with modified vitamin D contents for 8 weeks: group 1 (1 IU vitamin D₃/g diet), group 2 (2 IU vitamin D₃/g diet), and group 3 (4 IU vitamin D₃/g diet). At week 0, 4, and 8 of study, measurements included: serum 25(OH)D₃, IGF-1, IGFBP3, leptin, and whole body composition assessed with DXA. Differences among groups were tested using mixed model ANOVA with Tukey's post hoc t-tests. No differences were observed in baseline body composition and biomarkers, nor did body weight and food intake differ over the study. At week 8, serum 25(OH)D₃ in group 3 was higher (P < .0001) compared to groups 1 and 2. At 8 weeks, lean mass (P < .05) and lean mass accretion (P < .05) were significantly higher in groups 2 and 3 compared to group 1. Serum IGF-1 concentration declined over time (P < .001) with smaller declines at week 8 in group 3 (P < .05). Serum IGFBP3 concentration was lower at week 4 in group 2 compared to groups 1 and 3. Serum leptin concentration and fat mass were not affected by diet. These results suggested that the achievement of higher vitamin D status may support a lean body phenotype without altering weight gain.

Cellular and molecular mechanisms of the preovulatory follicle differenciation and ovulation: What do we know in the mare relative to other species

Terminal follicular differentiation and ovulation are essential steps of reproduction. They are induced by the increase in circulating LH, and lead to the expulsion from the ovary of oocytes ready to be fertilized. This review summarizes our current understanding of cellular and molecular pathways that control ovulation using a broad mammalian literature, with a specific focus to the mare, which is unique in some aspects of ovarian function in some cases. Essential steps and key factors are approached. The first part of this review concerns LH, receptors and signaling, addressing the description of the equine gonadotropin and cloning, signaling pathways that are activated following the binding of LH to its receptors, and implication of transcription factors which better known are CCAAT-enhancer-binding proteins (CEBP) and cAMP response element-binding protein (CREB). The second and major part is devoted to the cellular and molecular actors within follicular cells during preovulatory maturation. We relate to 1) molecules involved in vascular permeability and vasoconstriction, 2) involvement of neuropeptides, such as kisspeptin, neurotrophins and neuronal growth factor, neuropeptide Y (NPY), 3) the modification of steroidogenesis, steroids intrafollicular levels and enzymes activity, 4) the local inflammation, with the increase in prostaglandins synthesis, and implication of leukotrienes, cytokines and glucocorticoids, 5) extracellular matrix remodelling with involvement of proteases, antiproteases and inhibitors, as well as relaxin, and finaly 6) the implication of oxytocine, osteopontin, growth factors and reactive oxygen species. The third part describes our current knowledge on molecular aspect of in vivo cumulus-oocyte-complexe maturation, with a specific focus on signaling pathways, paracrine factors, and intracellular regulations that occur in cumulus cells during expansion, and in the oocyte during nuclear and cytoplasmic meiosis resumption. Our aim was to give an overall and comprehensive map of the regulatory mechanisms that intervene within the preovulatory follicle during differentiation and ovulation.

SRC3 Is a Cofactor for RORγt in Th17 Differentiation but Not Thymocyte Development

SRC3, a highly conserved member of the steroid receptor coactivator (SRC) family, is recruited by transcription factors to regulate cellular function. Previously, we demonstrated that SRC1, another highly conserved member of the SRC family, interacts with RORγt to regulate Th17 differentiation. However, the relationship between SRC1 and SRC3 in the regulation of Th17 cell function remains unknown. In this study, we demonstrate that mouse SRC3 interacts with RORγt in Th17 cells but not in thymocytes. In addition, Src3^-/- mice exhibited defective Th17 differentiation and induction of experimental autoimmune encephalomyelitis but normal thymocyte development. Furthermore, a K313 to arginine mutation of RORγt (RORγt-K313R), which disrupts the interaction of RORγt with SRC3 but not with SRC1, impairs Th17 differentiation but not thymocyte development. These data suggest that SRC3 works with SRC1 to regulate RORγt-dependent Th17 differentiation but is not essential for RORγt-dependent thymocyte development.

The AIB1siRNA-loaded hyaluronic acid-assembled PEI/heparin/Ca2+ nanocomplex as a novel therapeutic strategy in lung cancer treatment

In the present study, AIB1siRNA‑loaded polyethyleneimine (PEI)/heparin/Ca2+ nanoparticles (NPs) were successfully prepared and evaluated for their efficacy in lung cancer cells. The results demonstrated that the PEI and heparin complex reduced the toxic effect in cancer cells while maintaining its transfection efficiency. A nanosized particle of ~25 nm was formulated and siRNA was demonstrated to possess excellent binding efficiency in the particles. Confocal microscopy revealed that fluorescein‑labeled (FAM)‑small interfering (si)RNA dissociated from the HA‑PEI/heparin/Ca2+/siRNA (CPH‑siH) NPs and exhibited maximum fluorescence in the cytoplasm, which was important in elucidating its post‑transcriptional activity. CPH‑siH NPs exhibited a typical concentration‑dependent toxicity in cancer cells. Blank PEI/heparin/Ca2+ did not induce any toxicity in cancer cells, indicating its safety and lack of side effects. CPH‑siH (100 nm) induced the maximum apoptosis of cancer cells with nearly ~35% of cells in the early and late apoptosis stages. The expression of the nuclear receptor coactivator 3 (NCOA3, also known as AIB1) protein was knocked down in a concentration‑dependent manner, demonstrating the potent activity of AIB1siRNA in cancer cells. Together, these results indicated that HA‑PEI/heparin/Ca2+ NPs may be a promising carrier for the anticancer activity of AIB1siRNA in lung cancer cells.

SRC-3 protects intestine from DSS-induced colitis by inhibiting inflammation and promoting goblet cell differentiation through enhancement of KLF4 expression

Goblet cell loss, which leads to the reduction of mucin secretion, is a hallmark of ulcerative colitis (UC). We previously reported that steroid receptor coactivator 3 (SRC-3), a transcriptional coactivator, contributes to host defense against Citrobacter rodentium by recruiting neutrophils, suggesting a role of SRC-3 in intestine homeostasis. However, the biological role of SRC-3 in UC remains unclear. Here, we showed that SRC-3^-/- mice were more susceptible to dextran sulfate sodium (DSS)-induced colitis compared with wild-type mice after oral administration of 2% DSS dissolved in drinking water. After oral administration of 2% DSS, SRC-3^-/- mice displayed higher mortality rate, significant body weight loss, and higher clinical symptom scores compared to wild-type mice. SRC-3^-/- mice suffered a severe loss of mature colonic goblet cells, leading to more severe histopathology and more proinflammatory cytokine production. Mechanistically, SRC-3^-/- mice exhibited a decreased expression of transcription factor KLF4 in the colons, which is responsible for colonic goblet cell differentiation and maturation. At the molecular level, SRC-3 cooperated with c-Fos to promote KLF4 expression at the transcriptional level. These results demonstrate that SRC-3 can ameliorate DSS-induced colitis by inhibiting inflammation and promoting colonic goblet cell differentiation and maturation through enhancing the expression of transcriptional factor KLF4, which is responsible for colonic goblet cell differentiation and maturation.

SRC-3 is involved in maintaining hematopoietic stem cell quiescence by regulation of mitochondrial metabolism in mice

Quiescence maintenance is an important property of hematopoietic stem cells (HSCs), whereas the regulatory factors and underlying mechanisms involved in HSC quiescence maintenance are not fully uncovered. Here, we show that steroid receptor coactivator 3 (SRC-3) is highly expressed in HSCs, and SRC-3-deficient HSCs are less quiescent and more proliferative, resulting in increased sensitivity to chemotherapy and irradiation. Moreover, the long-term reconstituting ability of HSCs is markedly impaired in the absence of SRC-3, and SRC-3 knockout (SRC-3^-/-) mice exhibit a significant disruption of hematopoietic stem and progenitor cell homeostasis. Further investigations show that SRC-3 deficiency leads to enhanced mitochondrial metabolism, accompanied by overproduction of reactive oxygen species (ROS) in HSCs. Notably, the downstream target genes of peroxisome proliferator-activated receptor-coactivators 1α (PGC-1α) involved in the regulation of mitochondrial metabolism are significantly upregulated in SRC-3-deficient HSCs. Meanwhile, a significant decrease in the expression of histone acetyltransferase GCN5 accompanied by downregulation of PGC-1α acetylation is observed in SRC-3-null HSCs. Conversely, overexpression of GCN5 can inhibit SRC-3 deficiency-induced mitochondrial metabolism enhancement and ROS overproduction, thereby evidently rescuing the impairment of HSCs in SRC-3^-/- mice. Collectively, our findings demonstrate that SRC-3 plays an important role in HSC quiescence maintenance by regulating mitochondrial metabolism.

Role of human oocyte-enriched factors in somatic cell reprograming

Cellular reprograming paves the way for creating functional patient-specific tissues to eliminate immune rejection responses by applying the same genetic profile. However, the epigenetic memory of a cell remains a challenge facing the current reprograming methods and does not allow transcription factors to bind properly. Because somatic cells can be reprogramed by transferring their nuclear contents into oocytes, introducing specific oocyte factors into differentiated cells is considered a promising approach for mimicking the reprograming process that occurs during fertilization. Mammalian metaphase II oocyte possesses a superior capacity to epigenetically reprogram somatic cell nuclei towards an embryonic stem cell-like state than the current factor-based reprograming approaches. This may be due to the presence of specific factors that are lacking in the current factor-based reprograming approaches. In this review, we focus on studies identifying human oocyte-enriched factors aiming to understand the molecular mechanisms mediating cellular reprograming. We describe the role of oocyte-enriched factors in metabolic switch, chromatin remodelling, and global epigenetic transformation. This is critical for improving the quality of resulting reprogramed cells, which is crucial for therapeutic applications.

Hyperactivation of nuclear receptor coactivators induces PERK-dependent cell death

Nuclear receptor coactivators (NCOAs) function as coactivators for nuclear receptors as well as several other transcription factors and potentiate their transcriptional activity. NCOAs play an important role in biology of hormone-dependent and -independent cancers. MCB-613 is a recently described, small molecule stimulator of NCOAs and anti-neoplastic compound that leads to the death of tumour cells due to increased cellular stress. In the present study we investigated the molecular mechanism of MCB-613-induced cell death. We report that absence of NCOA3 leads to compromised activation of PERK signalling pathway during unfolded protein response (UPR). We found that chemical and genetic inhibition of NCOA3 attenuated the expression of PERK at mRNA and protein level. We show that loss of NCOA3 renders cells hypersensitive to UPR induced cell death. Our results show that MCB-613 induced cell death is attenuated in NCOA3 knockout HeLa cells and MCB-613 leads to enhanced PERK signalling in wild-type HeLa cells. The knockdown of PERK provides resistance to MCB-613 mediated cell death while knockdown of XBP1 and ATF6 have no such effect. Our results suggest that hyperstimulation of NCOA3 by MCB-613 induces cell death by evoking constitutive PERK signalling. Taken together our results point to NCOA3 as an important determinant in regulating cell fate during ER stress, with too little and too much NCOA3 both producing deleterious effects.

Nuclear Shp2 directs normal embryo implantation via facilitating the ERα tyrosine phosphorylation by the Src kinase

Estrogen and progesterone coupled with locally produced signaling molecules are essential for embryo implantation. However, the hierarchical landscape of the molecular pathways that governs this process remains largely unexplored. Here we show that the protein tyrosine phosphatase Shp2, a positive transducer of RTK signaling, is predominately localized in the nuclei in the periimplantation mouse uterus. Uterine-specific deletion of Shp2 exhibits reduced progesterone receptor (PR) expression and progesterone resistance, which derails normal uterine receptivity, leading to complete implantation failure in mice. Notably, the PR expression defects are attributed to the limited estrogen receptor α (ERα) activation in uterine stroma. Further analysis reveals that nuclear Shp2, rather than cytosolic Shp2, promotes the ERα transcription activity. This function is achieved by enhancing the Src kinase-mediated ERα tyrosine phosphorylation, which facilitates ERα binding to Pgr promoter in an ERK-independent manner in periimplantation uteri. Besides uncovering a regulatory mechanism, this study could be clinically relevant to dysfunctional ERα-caused endometrial disorders in women.

Steroid Receptor Coactivator 3 Contributes to Host Defense against Enteric Bacteria by Recruiting Neutrophils via Upregulation of CXCL2 Expression

Steroid receptor coactivator 3 (SRC-3) is a transcriptional coactivator that interacts with nuclear receptors and some other transcription factors to enhance their effects on target gene transcription. We reported previously that SRC-3-deficient (SRC-3^-/-) mice are extremely susceptible to Escherichia coli-induced septic peritonitis as a result of uncontrolled inflammation and a defect in bacterial clearance. In this study, we observed significant upregulation of SRC-3 in colonic epithelial cells in response to Citrobacter rodentium infection. Based on these findings, we hypothesized that SRC-3 is involved in host defense against attaching and effacing bacterial infection. We compared the responses of SRC-3^-/- and wild-type mice to intestinal C. rodentium infection. We found that SRC-3^-/- mice exhibited delayed clearance of C. rodentium and more severe tissue pathology after oral infection with C. rodentium compared with wild-type mice. SRC-3^-/- mice expressed normal antimicrobial peptides in the colons but exhibited delayed recruitment of neutrophils into the colonic mucosa. Accordingly, SRC-3^-/- mice showed a delayed induction of CXCL2 and CXCL5 in colonic epithelial cells, which are responsible for neutrophil recruitment. At the molecular level, we found that SRC-3 can activate the NF-κB signaling pathway to promote CXCL2 expression at the transcriptional level. Collectively, we show that SRC-3 contributes to host defense against enteric bacteria, at least in part via upregulating CXCL2 expression to recruit neutrophils.

Pubertal Mammary Gland Development: Elucidation of In Vivo Morphogenesis Using Murine Models

During the past 25 years, the combination of increasingly sophisticated gene targeting technology with transplantation techniques has allowed researchers to address a wide array of questions about postnatal mammary gland development. These in turn have significantly contributed to our knowledge of other branched epithelial structures. This review chapter highlights a selection of the mouse models exhibiting a pubertal mammary gland phenotype with a focus on how they have contributed to our overall understanding of in vivo mammary morphogenesis. We discuss mouse models that have enabled us to assign functions to particular genes and proteins and, more importantly, have determined when and where these factors are required for completion of ductal outgrowth and branch patterning. The reason for the success of the mouse mammary gland model is undoubtedly the suitability of the postnatal mammary gland to experimental manipulation. The gland itself is very amenable to investigation and the combination of genetic modification with accessibility to the tissue has allowed an impressive number of studies to inform biology. Excision of the rudimentary epithelial structure postnatally allows genetically modified tissue to be readily transplanted into wild type stroma or vice versa, and has thus defined the contribution of each compartment to particular phenotypes. Similarly, whole gland transplantation has been used to definitively discern local effects from indirect systemic effects of various growth factors and hormones. While appreciative of the power of these tools and techniques, we are also cognizant of some of their limitations, and we discuss some shortcomings and future strategies that can overcome them.