Mechanisms of IRF2BPL-related disorders and identification of a potential therapeutic strategy

The recently discovered neurological disorder NEDAMSS is caused by heterozygous truncations in the transcriptional regulator IRF2BPL. Here, we reprogram patient skin fibroblasts to astrocytes and neurons to study mechanisms of this newly described disease. While full-length IRF2BPL primarily localizes to the nucleus, truncated patient variants sequester the wild-type protein to the cytoplasm and cause aggregation. Moreover, patient astrocytes fail to support neuronal survival in coculture and exhibit aberrant mitochondria and respiratory dysfunction. Treatment with the small molecule copper ATSM (CuATSM) rescues neuronal survival and restores mitochondrial function. Importantly, the in vitro findings are recapitulated in vivo, where co-expression of full-length and truncated IRF2BPL in Drosophila results in cytoplasmic accumulation of full-length IRF2BPL. Moreover, flies harboring heterozygous truncations of the IRF2BPL ortholog (Pits) display progressive motor defects that are ameliorated by CuATSM treatment. Our findings provide insights into mechanisms involved in NEDAMSS and reveal a promising treatment for this severe disorder.

Identification and Functional Characterization of a Novel Androgen Receptor Coregulator, EAP1

The androgen receptor (AR) plays an essential role in the development of prostate cancer, and androgen-deprivation therapy is used as a first-line treatment for prostate cancer. However, under androgen-deprivation therapy, castration-resistant prostate cancer inevitably arises, suggesting that the interacting transcriptional coregulators of AR are promising targets for developing novel therapeutics. In this study, we used novel proteomic techniques to evaluate the AR interactome, including biochemically labile binding proteins, which might go undetected by conventional purification methods. Using rapid immunoprecipitation mass spectrometry of endogenous proteins, we identified enhanced at puberty 1 (EAP1) as a novel AR coregulator, whereas its interaction with AR could not be detected under standard biochemical conditions. EAP1 enhanced the transcriptional activity of AR via the E3 ubiquitin ligase activity, and its ubiquitination substrate proteins included AR and HDAC1. Furthermore, in prostate cancer specimens, EAP1 expression was significantly correlated with AR expression as well as a poor prognosis of prostate cancer. Together, these results suggest that EAP1 is a novel AR coregulator that promotes AR activity and potentially plays a role in prostate cancer progression.

albicans Growth and EAP1 and HWP1 Gene Expression

Increasing resistance and changes in the spectrum of Candida infections have generated considerable interest in the development of new antifungal molecules. The use of antimicrobial peptides (AMPs) appears to be a promising approach. Frog skin AMPs (such as dermaseptins) have shown antimicrobial activity against several pathogens. In this study, we aimed to test the antimicrobial efficacy of dermaseptin S4 (DS4) against C. albicans. We determined the minimal inhibitory concentration (MIC) of DS4, and investigated the effects of the DS4 at low concentrations on human primary gingival fibroblasts. Additionally, we evaluated the effect of DS4 on C. albicans growth, form changes, and biofilm formation, as well as the expression of certain virulent genes. Our data show that DS4 completely inhibits C. albicans growth at a concentration of 32 μg/mL referring to the MIC of DS4. It should be noted that even with low concentrations (below 16 μg/mL), DS4 still have significant growth reduction of C. albicans, but were not toxic to human gingival fibroblasts. DS4 inhibited the transition from yeast to hyphae, and decreased the biofilm formation by reducing the biofilm mass weight. Surface morphological changes in the yeast cell membrane were observed following exposure to DS4. The gene expression analyses revealed that DS4 significantly decreased the expression of EAP1 and HWP1 genes. Overall results suggest the potential use of DS4 as an antifungal therapy to prevent C. albicans pathogenesis.

Genetic regulation in pubertal delay

Delayed puberty represents the clinical presentation of a final common pathway for many different pathological mechanisms. In the majority of patients presenting with significantly delayed puberty, there is a clear family history of delayed or disturbed puberty, and pubertal timing is known to be a trait with strong heritability. Thus, genetic factors clearly play a key role in determining the timing of puberty, and mutations in certain genes are recognised as responsible for delayed or absent puberty in a minority of patients. Through the identification of causal genetic defects such as these we have been able to learn a great deal about the pathogenesis of disrupted puberty and its genetic regulation. Firstly, deficiency in key genes that govern the development of the gonadotropin-releasing hormone system during fetal development may result in a spectrum of conditions ranging from isolated delayed puberty to absent puberty with anosmia. Secondly, a balance of inhibitory and excitatory signals, acting upstream of GnRH secretion, are vital for the correct timing of puberty. These act to repress the hypothalamic-pituitary-gonadal axis during mid-childhood and allow it to reactivate at puberty, and alterations in this equilibrium can cause delayed (or precocious) puberty. Thirdly, disturbances of energy metabolism inputs to the kisspeptin-GnRH system may also lead to late onset of puberty associated with changes in body mass.

The Genetic Basis of Delayed Puberty

Delayed pubertal onset has many etiologies, but on average two-thirds of patients presenting with late puberty have self-limited (or constitutional) delayed puberty. Self-limited delayed puberty often has a strong familial basis. Segregation analyses from previous studies show complex models of inheritance, most commonly autosomal dominant, but also including autosomal recessive, bilineal, and X-linked. Sporadic cases are also observed. Despite this, the neuroendocrine mechanisms and genetic regulation remain unclear in the majority of patients with self-limited delayed puberty. Only rarely have mutations in genes known to cause aberrations of the hypothalamic-pituitary-gonadal axis been identified in cases of delayed puberty, and the majority of these are in relatives of patients with congenital hypogonadotropic hypogonadism (CHH), for example in the FGFR1 and GNRHR genes. Using next generation sequencing in a large family with isolated self-limited delayed puberty, a pathogenic mutation in the CHH gene HS6ST1 was found as the likely cause for this phenotype. Additionally, a study comparing the frequency of mutations in genes that cause GnRH deficiency between probands with CHH and probands with isolated self-limited delayed puberty identified that a significantly higher proportion of mutations with a greater degree of oligogenicity were seen in the CHH group. Mutations in the gene IGSF10 have been implicated in the pathogenesis of familial late puberty in a large Finnish cohort. IGSF10 disruption represents a fetal origin of delayed puberty, with dysregulation of GnRH neuronal migration during embryonic development presenting for the first time in adolescence as late puberty. Some patients with self-limited delayed puberty have distinct constitutional features of growth and puberty. Deleterious variants in FTO have been found in families with delayed puberty with extremely low BMI and maturational delay in growth in early childhood. Recent exciting evidence highlights the importance of epigenetic up-regulation of GnRH transcription by a network of miRNAs and transcription factors, including EAP1, during puberty. Whilst a fascinating heterogeneity of genetic defects have been shown to result in delayed and disordered puberty, and many are yet to be discovered, genetic testing may become a realistic diagnostic tool for the differentiation of conditions of delayed puberty.

IRF2BPL Is Associated with Neurological Phenotypes

Interferon regulatory factor 2 binding protein-like (IRF2BPL) encodes a member of the IRF2BP family of transcriptional regulators. Currently the biological function of this gene is obscure, and the gene has not been associated with a Mendelian disease. Here we describe seven individuals who carry damaging heterozygous variants in IRF2BPL and are affected with neurological symptoms. Five individuals who carry IRF2BPL nonsense variants resulting in a premature stop codon display severe neurodevelopmental regression, hypotonia, progressive ataxia, seizures, and a lack of coordination. Two additional individuals, both with missense variants, display global developmental delay and seizures and a relatively milder phenotype than those with nonsense alleles. The IRF2BPL bioinformatics signature based on population genomics is consistent with a gene that is intolerant to variation. We show that the fruit-fly IRF2BPL ortholog, called pits (protein interacting with Ttk69 and Sin3A), is broadly detected, including in the nervous system. Complete loss of pits is lethal early in development, whereas partial knockdown with RNA interference in neurons leads to neurodegeneration, revealing a requirement for this gene in proper neuronal function and maintenance. The identified IRF2BPL nonsense variants behave as severe loss-of-function alleles in this model organism, and ectopic expression of the missense variants leads to a range of phenotypes. Taken together, our results show that IRF2BPL and pits are required in the nervous system in humans and flies, and their loss leads to a range of neurological phenotypes in both species.

Endocrine disrupting chemicals affect the gonadotropin releasing hormone neuronal network

Endocrine disrupting chemicals have been shown to alter the pubertal process. The controlling levels of the Gonadotropin releasing hormone (GnRH) network involve GnRH itself, KiSS1, and the transcriptional regulators enhanced at puberty 1 (EAP1), Thyroid Transcription Factor 1 (TTF1), and Yin Yang 1 (YY1). While Genistein and Bisphenol A (BPA) have been shown to advance the advent of puberty, exposure to Dioxin delayed pubertal onset. Utilizing in vitro approaches, we observed that Genistein and BPA suppress inhibitory and activate stimulatory components of the GnRH network, while Dioxin exhibit an inhibitory effect at all regulatory hierarchical levels of the GnRH network. It repressed KiSS1, Gnrh, Ttf1 and Yy1 transcription via the xenobiotic response element (XRE), while EAP1 was not affected. Therefore, EDCs alter the neuroendocrine GnRH regulatory network at all hierarchical levels.