GREB1: An evolutionarily conserved protein with a glycosyltransferase domain links ERα glycosylation and stability to cancer

A GREB1-steroid receptor feedforward mechanism governs differential GREB1 action in endometrial function and endometriosis

Cellular responses to the steroid hormones, estrogen (E2), and progesterone (P4) are governed by their cognate receptor's transcriptional output. However, the feed-forward mechanisms that shape cell-type-specific transcriptional fulcrums for steroid receptors are unidentified. Herein, we found that a common feed-forward mechanism between GREB1 and steroid receptors regulates the differential effect of GREB1 on steroid hormones in a physiological or pathological context. In physiological (receptive) endometrium, GREB1 controls P4-responses in uterine stroma, affecting endometrial receptivity and decidualization, while not affecting E2-mediated epithelial proliferation. Of mechanism, progesterone-induced GREB1 physically interacts with the progesterone receptor, acting as a cofactor in a positive feedback mechanism to regulate P4-responsive genes. Conversely, in endometrial pathology (endometriosis), E2-induced GREB1 modulates E2-dependent gene expression to promote the growth of endometriotic lesions in mice. This differential action of GREB1 exerted by a common feed-forward mechanism with steroid receptors advances our understanding of mechanisms that underlie cell- and tissue-specific steroid hormone actions.

The expanded spectrum of human disease associated with GREB1L likely includes complex congenital heart disease

OBJECTIVE

GREB1L has been linked prenatally to Potter's sequence, as well as less severe anomalies of the kidney, uterus, inner ear, and heart. The full phenotypic spectrum is unknown. The purpose of this study was to characterize known and novel pre- and postnatal phenotypes associated with GREB1L.

METHODS

We solicited cases from the Fetal Sequencing Consortium, screened a population-based genomic database, and conducted a comprehensive literature search to identify disease cases associated with GREB1L. We present a detailed phenotypic spectrum and molecular changes.

RESULTS

One hundred twenty-seven individuals with 51 unique pathogenic or likely pathogenic GREB1L variants were identified. 24 (47%) variants were associated with isolated kidney anomalies, 19 (37%) with anomalies of multiple systems, including one case of hypoplastic left heart syndrome, five (10%) with isolated sensorineural hearing loss, two (4%) with isolated uterine agenesis; and one (2%) with isolated tetralogy of Fallot.

CONCLUSION

GREB1L may cause complex congenital heart disease (CHD) in humans. Clinicians should consider GREB1L testing in the setting of CHD, and cardiac screening in the setting of GREB1L variants.

Molecular mechanisms of hypothalamic-pituitary-ovarian/thyroid axis regulating age at first egg in geese

Age at first egg (AFE) has consistently garnered interest as a crucial reproductive indicator within poultry production. Previous studies have elucidated the involvement of the hypothalamic-pituitary-ovarian (HPO) and hypothalamic-pituitary-thyroid (HPT) axes in regulating poultry sexual maturity. Concurrently, there was evidence suggesting a potential co-regulatory relationship between these 2 axes. However, as of now, no comprehensive exploration of the key pathways and genes responsible for the crosstalk between the HPO and HPT axes in the regulation of AFE has been reported. In this study, we conducted a comparative analysis of morphological differences and performed transcriptomic analysis on the hypothalamus, pituitary, thyroid, and ovarian stroma between normal laying group (NG) and abnormal laying group (AG). Morphological results showed that the thyroid index difference (D-) value (thyroid index D-value=right thyroid index-left thyroid index) was significantly (P < 0.05) lower in the NG than in the AG, while the ovarian index was significantly (P < 0.01) higher in the NG than in the AG. Furthermore, between NG and AG, we identified 99, 415, 167, and 1182 differentially expressed genes (DEGs) in the hypothalamus, pituitary, thyroid, and ovarian stroma, respectively. Gene ontology (GO) analysis highlighted that DEGs from 4 tissues were predominantly enriched in the "biological processes" category. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that 16, 14, 3, and 26 KEGG pathways were significantly enriched (P < 0.05) in the hypothalamus, pituitary, thyroid, and ovarian stroma. The MAPK signaling pathway emerged as the sole enriched pathway across all 4 tissues. Employing an integrated analysis of the protein-protein interaction (PPI) network and correlation analysis, we found GREB1 emerged as a pivotal component within the HPO axis to regulate estrogen-related signaling in the HPT axis, meanwhile, the HPT axis influenced ovarian development by regulating thyroid hormone-related signaling mainly through OPN5. Then, 10 potential candidate genes were identified, namely IGF1, JUN, ERBB4, KDR, PGF, FGFR1, GREB1, OPN5, DIO3, and THRB. These findings establish a foundation for elucidating the physiological and genetic mechanisms by which the HPO and HPT axes co-regulate goose AFE.

Exploring the Spatial Landscape of the Estrogen Receptor Proximal Proteome With Antibody-Based Proximity Labeling

Estrogen receptor α (ERα) drives the transcription of genes involved in breast cancer (BC) progression, relying on coregulatory protein recruitment for its transcriptional and biological activities. Mutation of ERα as well as aberrant recruitment of its regulatory proteins contribute to tumor adaptation and drug resistance. Therefore, understanding the dynamic changes in ERα protein interaction networks is crucial for elucidating drug resistance mechanisms in BC. Despite progress in studying ERα-associated proteins, capturing subcellular transient interactions remains challenging and, as a result, significant number of important interactions remain undiscovered. In this study, we employed biotinylation by antibody recognition (BAR), an innovative antibody-based proximity labeling (PL) approach, coupled with mass spectrometry to investigate the ERα proximal proteome and its changes associated with resistance to aromatase inhibition, a key therapy used in the treatment of ERα-positive BC. We show that BAR successfully detected most of the known ERα interactors and mainly identified nuclear proteins, using either an epitope tag or endogenous antibody to target ERα. We further describe the ERα proximal proteome rewiring associated with resistance applying BAR to a panel of isogenic cell lines modeling tumor adaptation in the clinic. Interestingly, we find that ERα associates with some of the canonical cofactors in resistant cells and several proximal proteome changes are due to increased expression of ERα. Resistant models also show decreased levels of estrogen-regulated genes. Sensitive and resistant cells harboring a mutation in the ERα (Y537C) revealed a similar proximal proteome. We provide an ERα proximal protein network covering several novel ERα-proximal partners. These include proteins involved in highly dynamic processes such as sumoylation and ubiquitination difficult to detect with traditional protein interaction approaches. Overall, we present BAR as an effective approach to investigate the ERα proximal proteome in a spatial context and demonstrate its application in different experimental conditions.

The O-GlcNAc dichotomy: when does adaptation become pathological?

O-Linked attachment of β-N-acetylglucosamine (O-GlcNAc) on serine and threonine residues of nuclear, cytoplasmic, and mitochondrial proteins is a highly dynamic and ubiquitous post-translational modification that impacts the function, activity, subcellular localization, and stability of target proteins. Physiologically, acute O-GlcNAcylation serves primarily to modulate cellular signaling and transcription regulatory pathways in response to nutrients and stress. To date, thousands of proteins have been revealed to be O-GlcNAcylated and this number continues to grow as the technology for the detection of O-GlcNAc improves. The attachment of a single O-GlcNAc is catalyzed by the enzyme O-GlcNAc transferase (OGT), and their removal is catalyzed by O-GlcNAcase (OGA). O-GlcNAcylation is regulated by the metabolism of glucose via the hexosamine biosynthesis pathway, and the metabolic abnormalities associated with pathophysiological conditions are all associated with increased flux through this pathway and elevate O-GlcNAc levels. While chronic O-GlcNAcylation is well associated with cardiovascular dysfunction, only until recently, and with genetically modified animals, has O-GlcNAcylation as a contributing mechanism of cardiovascular disease emerged. This review will address and critically evaluate the current literature on the role of O-GlcNAcylation in vascular physiology, with a view that this pathway can offer novel targets for the treatment and prevention of cardiovascular diseases.

Identification of Greb1l as a genetic determinant of crisscross heart in mice showing torsion of the heart tube by shortage of progenitor cells

Despite their burden, most congenital defects remain poorly understood, due to lack of knowledge of embryological mechanisms. Here, we identify Greb1l mutants as a mouse model of crisscross heart. Based on 3D quantifications of shape changes, we demonstrate that torsion of the atrioventricular canal occurs together with supero-inferior ventricles at E10.5, after heart looping. Mutants phenocopy partial deficiency in retinoic acid signaling, which reflect overlapping pathways in cardiac precursors. Spatiotemporal gene mapping and cross-correlated transcriptomic analyses further reveal the role of Greb1l in maintaining a pool of dorsal pericardial wall precursor cells during heart tube elongation, likely by controlling ribosome biogenesis and cell differentiation. Consequently, we observe growth arrest and malposition of the outflow tract, which are predictive of abnormal tube remodeling in mutants. Our work on a rare cardiac malformation opens novel perspectives on the origin of a broader spectrum of congenital defects associated with GREB1L in humans.

A MYCN-independent mechanism mediating secretome reprogramming and metastasis in MYCN-amplified neuroblastoma

MYCN amplification (MNA) is a defining feature of high-risk neuroblastoma (NB) and predicts poor prognosis. However, whether genes within or in close proximity to the MYCN amplicon also contribute to MNA+ NB remains poorly understood. Here, we identify that GREB1, a transcription factor encoding gene neighboring the MYCN locus, is frequently coexpressed with MYCN and promotes cell survival in MNA+ NB. GREB1 controls gene expression independently of MYCN, among which we uncover myosin 1B (MYO1B) as being highly expressed in MNA+ NB and, using a chick chorioallantoic membrane (CAM) model, as a crucial regulator of invasion and metastasis. Global secretome and proteome profiling further delineates MYO1B in regulating secretome reprogramming in MNA+ NB cells, and the cytokine MIF as an important pro-invasive and pro-metastatic mediator of MYO1B activity. Together, we have identified a putative GREB1-MYO1B-MIF axis as an unconventional mechanism promoting aggressive behavior in MNA+ NB and independently of MYCN.

Long noncoding RNAs induced control of ferroptosis: Implications in cancer progression and treatment

A novel kind of nonapoptotic, iron-dependent cell death brought on by lipid peroxidation is known as ferroptosis. Numerous pathological processes, including neurotoxicity, neurological disorders, ischemia-reperfusion damage, and particularly cancer, have been demonstrated to be influenced by changes in the ferroptosis-regulating network. Recent studies have established the critical roles that ferroptosis can play in cancer development and the evolution of resistance to standard chemoradiotherapy, thus suggesting that ferroptosis may be a feasible therapeutic strategy for cancer management. Gene expression may be regulated at the transcriptional and posttranscriptional levels by long noncoding RNAs (lncRNAs). They have been implicated in tumorigenesis. Some lncRNAs participate in the biological process of ferroptosis, which represents an exciting alternative to regulate ferroptosis as a means of cancer therapy. Even though there is evidence that lncRNAs have a mechanistic role in the ferroptosis of cancer cells, research on the mechanism and potential treatments for these lncRNAs is still lacking. We elucidate the potential mechanisms by which lncRNAs modulate ferroptosis in cancer and examine the promise and challenges of employing lncRNAs as novel therapeutic targets in cancer.

Emerging regulatory mechanisms of noncoding RNAs in topologically associating domains

Topologically associating domains (TADs) are integral to spatial genome organization, instructing gene expression, and cell fate. Recently, several advances have uncovered roles for noncoding RNAs (ncRNAs) in the regulation of the form and function of mammalian TADs. Phase separation has also emerged as a potential arbiter of ncRNAs in the regulation of TADs. In this review we discuss the implications of these novel findings in relation to how ncRNAs might structurally and functionally regulate TADs from two perspectives: moderating loop extrusion through interactions with architectural proteins, and facilitating TAD phase separation. Additionally, we propose future studies and directions to investigate these phenomena.

Estrogen signaling via estrogen receptor alpha and its implications for neurodegeneration associated with Alzheimer's disease in aging women

Estrogen receptor alpha (ERα) is a transcription factor activated by estrogenic hormones to regulate gene expression in certain organs, including the brain. In the brain, estrogen signaling pathways are central for maintaining cognitive functions. Herein, we review the neuroprotective effects of estrogens mediated by ERα. The estrogen/ERα pathways are affected by the reduction of estrogens in menopause, and this event may be a risk factor for neurodegeneration associated with Alzheimer's disease in women. Thus, developing a better understanding of estrogen/ERα signaling may be critical for defining new biomarkers and potential therapeutic targets for Alzheimer's disease in women.

Estrogen receptor α revised: Expression, structure, function, and stability

Estrogen receptor α (ERα) is a ligand-dependent transcription factor that regulates the expression of estrogen-responsive genes. Approximately 70% of patients with breast cancer are ERα positive. Estrogen stimulates cancer cell proliferation and contributes to tumor progression. Endocrine therapies, which suppress the ERα signaling pathway, significantly improve the prognosis of patients with breast cancer. However, the development of de novo or acquired endocrine therapy resistance remains a barrier to breast cancer treatment. Therefore, understanding the regulatory mechanisms of ERα is essential to overcome the resistance to treatment. This review focuses on the regulation of ERα expression, including copy number variation, epigenetic regulation, transcriptional regulation, and stability, as well as functions from the point of view post-translational modifications.

Demystifying the O-GlcNAc Code: A Systems View

Post-translational modification with O-linked β-N-acetylglucosamine (O-GlcNAc), a process referred to as O-GlcNAcylation, occurs on a vast variety of proteins. Mounting evidence in the past several decades has clearly demonstrated that O-GlcNAcylation is a unique and ubiquitous modification. Reminiscent of a code, protein O-GlcNAcylation functions as a crucial regulator of nearly all cellular processes studied. The primary aim of this review is to summarize the developments in our understanding of myriad protein substrates modified by O-GlcNAcylation from a systems perspective. Specifically, we provide a comprehensive survey of O-GlcNAcylation in multiple species studied, including eukaryotes (e.g., protists, fungi, plants, Caenorhabditis elegans, Drosophila melanogaster, murine, and human), prokaryotes, and some viruses. We evaluate features (e.g., structural properties and sequence motifs) of O-GlcNAc modification on proteins across species. Given that O-GlcNAcylation functions in a species-, tissue-/cell-, protein-, and site-specific manner, we discuss the functional roles of O-GlcNAcylation on human proteins. We focus particularly on several classes of relatively well-characterized human proteins (including transcription factors, protein kinases, protein phosphatases, and E3 ubiquitin-ligases), with representative O-GlcNAc site-specific functions presented. We hope the systems view of the great endeavor in the past 35 years will help demystify the O-GlcNAc code and lead to more fascinating studies in the years to come.

Decoding the Therapeutic Implications of the ERα Stability and Subcellular Distribution in Breast Cancer

Approximately 70% of all breast cancer cases are estrogen receptor-alpha positive (ERα+) and any ERα signaling pathways deregulation is critical for the progression of malignant mammary neoplasia. ERα acts as a transcription factor that promotes the expression of estrogen target genes associated with pro-tumor activity in breast cancer cells. Furthermore, ERα is also part of extranuclear signaling pathways related to endocrine resistance. The regulation of ERα subcellular distribution and protein stability is critical to regulate its functions and, consequently, influence the response to endocrine therapies and progression of this pathology. This minireview highlights studies that have deciphered the molecular mechanisms implicated in controlling ERα stability and nucleo-cytoplasmic transport. These mechanisms offer information about novel biomarkers, therapeutic targets, and promising strategies for breast cancer treatment.

Non-coding RNA-based regulation of inflammation

Inflammation is a multifactorial process and various biological mechanisms and pathways participate in its development. The presence of inflammation is involved in pathogenesis of different diseases such as diabetes mellitus, cardiovascular diseases and even, cancer. Non-coding RNAs (ncRNAs) comprise large part of transcribed genome and their critical function in physiological and pathological conditions has been confirmed. The present review focuses on miRNAs, lncRNAs and circRNAs as ncRNAs and their potential functions in inflammation regulation and resolution. Pro-inflammatory and anti-inflammatory factors are regulated by miRNAs via binding to 3'-UTR or indirectly via affecting other pathways such as SIRT1 and NF-κB. LncRNAs display a similar function and they can also affect miRNAs via sponging in regulating levels of cytokines. CircRNAs mainly affect miRNAs and reduce their expression in regulating cytokine levels. Notably, exosomal ncRNAs have shown capacity in inflammation resolution. In addition to pre-clinical studies, clinical trials have examined role of ncRNAs in inflammation-mediated disease pathogenesis and cytokine regulation. The therapeutic targeting of ncRNAs using drugs and nucleic acids have been analyzed to reduce inflammation in disease therapy. Therefore, ncRNAs can serve as diagnostic, prognostic and therapeutic targets in inflammation-related diseases in pre-clinical and clinical backgrounds.

Analysis of the estrogen receptor-associated lncRNA landscape identifies a role for ERLC1 in breast cancer progression

Estrogen receptor alpha (ERα) plays a vital role in the development of normal breast tissue and in breast cancer. By cross-analyzing The Cancer Genome Atlas (TCGA) database, ERα-regulated long noncoding RNA 1 (ERLC1) was identified as a long noncoding RNA exhibiting a strong association with ERα signaling and high specificity of expression in breast tissue. ERLC1 was transcriptionally activated by ERα, and ERLC1 stabilized the ESR1 transcript by sequestering miR-129 and tethering FXR1 to maintain a positive feedback loop that potentiated ERα signaling. ERLC1 was elevated in tamoxifen-resistant breast cancer cells, where ERLC1 depletion restored sensitivity to tamoxifen and increased the efficacy of palbociclib or fulvestrant therapy. Collectively, these data warrant further investigation of ERLC1 as a modulator of therapeutic response and potential therapeutic target in ER+ breast cancer.

Mast cells: Therapeutic targets for COVID-19 and beyond

Mast cells (MCs) are innate immune cells that widely distribute throughout all tissues and express a variety of cell surface receptors. Upon activation, MCs can rapidly release a diverse array of preformed mediators residing within their secretory granules and newly synthesize a broad spectrum of inflammatory and immunomodulatory mediators. These unique features of MCs enable them to act as sentinels in response to rapid changes within their microenvironment. There is increasing evidence now that MCs play prominent roles in other pathophysiological processes besides allergic inflammation. In this review, we highlight the recent findings on the emerging roles of MCs in the pathogenesis of coronavirus disease-2019 (COVID-19) and discuss the potential of MCs as novel therapeutic targets for COVID-19 and other non-allergic inflammatory diseases.

Recent Advances in Exosome-Based Drug Delivery for Cancer Therapy

Simple Summary

Exosomes derived from various sources can deliver therapeutic agents such as small molecule drugs, nucleic acids, and proteins to cancer cells by passive or active targeting. These exosomes can encapsulate drugs inside the exosomes, extending drug half-life and increasing drug release stability. In addition, exosomes are highly biocompatible due to their endogenous origin and can be used as nanocarriers for tissue-specific targeted delivery. This review discusses recent advances in exosome-based drug delivery for cancer therapy.

Abstract

Exosomes are a class of extracellular vesicles, with a size of about 100 nm, secreted by most cells and carrying various bioactive molecules such as nucleic acids, proteins, and lipids, and reflect the biological status of parent cells. Exosomes have natural advantages such as high biocompatibility and low immunogenicity for efficient delivery of therapeutic agents such as chemotherapeutic drugs, nucleic acids, and proteins. In this review, we introduce the latest explorations of exosome-based drug delivery systems for cancer therapy, with particular focus on the targeted delivery of various types of cargoes.