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Coats plus (CP) can be caused by mutations in the CTC1 component of CST, which promotes polymerase a (pola)/primase- dependent fill-in throughout the genome and at telomeres. The cellular pathology relating to CP has not been established. We identified a homozygous POT1 S322L substitution (POT1(CP)) in two siblings with CP. POT1(CP) induced a proliferative arrest that could be bypassed by telomerase. POT1CP was expressed at normal levels, bound TPP1 and telomeres, and blocked ATR signaling. POT1(CP) was defective in regulating telomerase, leading to telomere elongation rather than the telomere shortening observed in other telomeropathies. POT1(CP) was also defective in the maintenance of the telomeric C strand, causing extended 3' overhangs and stochastic telomere truncations that could be healed by telomerase. Consistent with shortening of the telomeric C strand, metaphase chromosomes showed loss of telomeres synthesized by leading strand DNA synthesis. We propose that CP is caused by a defect in POT1/CST-dependent telomere fill-in. We further propose that deficiency in the fill-in step generates truncated telomeres that halt proliferation in cells lacking telomerase, whereas, in tissues expressing telomerase (e.g., bone marrow), the truncations are healed. The proposed etiology can explain why CP presents with features distinct from those associated with telomerase defects (e.g., dyskeratosis congenita).

Phosphorus (P) is an essential element to all living cells, yet fluctuations in P concentrations are recurrent in the marine environment. Diatoms are amongst the most successful phytoplankton groups, adapting to and surviving periods of suboptimal conditions and resuming growth as soon as nutrient concentrations permit. A knowledge of the molecular underpinnings of diatom ecological success is, however, still very incomplete. By strand-specific RNA sequencing, we analyzed the global transcriptome changes of the diatom Phaeodactylum tricornutum in response to P fluctuations over a course of 8d, defining five distinct physiological states. This study reports previously unidentified genes highly responsive to P stress in P.tricornutum. Our data also uncover the complexity of the P.tricornutum P-responsive sensory and signaling system that combines bacterial two-component systems with more complex pathways reminiscent of metazoans. Finally, we identify a multitude of novel long intergenic nonprotein coding RNAs (lincRNAs) specifically responsive to P depletion, suggesting putative regulatory roles in the regulation of P homeostasis. Our work provides additional molecular insights into the resilience of diatoms and their ecological success, and opens up novel routes to address and explore the function and regulatory roles of P.tricornutum lincRNAs in the context of nutrient stress.

Recently discovered histone lysine acylation marks increase the functional diversity of nucleosomes well beyond acetylation. Here, we focus on histone butyrylation in the context of sperm cell differentiation. Specifically, we investigate the butyrylation of histone H4 lysine 5 and 8 at gene promoters where acetylation guides the binding of Brdt, a bromodomain-containing protein, thereby mediating stagespecific gene expression programs and post-meiotic chromatin reorganization. Genome-wide mapping data show that highly active Brdt-bound gene promoters systematically harbor competing histone acetylation and butyrylation marks at H4 K5 and H4 K8. Despite acting as a direct stimulator of transcription, histone butyrylation competes with acetylation, especially at H4 K5, to prevent Brdt binding. Additionally, H4 K5K8 butyrylation also marks retarded histone removal during late spermatogenesis. Hence, alternating H4 acetylation and butyrylation, while sustaining direct gene activation and dynamic bromodomain binding, could impact the final male epigenome features.

Testosterone has in recent years been proven essential for normal growth and maturation of small growing follicles. Concomitantly, low functional ovarian reserve (LFOR), characterized by a small growing follicle pool, has been associated with low testosterone levels, which can be of ovarian and/or adrenal origin. In this study we, therefore, investigated whether peripheral sex steroid precursors and testosterone levels potentially reflect on adrenal function. In a retrospective cohort study of 355 consecutive infertile women, who presented to an academically affiliated fertility center in New York City, we investigated in a series of statistical models whether low peripheral sex steroid precursors and testosterone are associated with peripheral cortisol (C) levels, reflecting adrenal function. To determine potential correlations, we investigated the dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), androstenedione (AD), total testosterone (TT), free testosterone (FT); sex hormone binding globulin (SHBG), anti-Mullerian hormone (AMH), thyroid stimulating hormone (TSH) and C in a series of multivariate and logistic regression analyses, utilizing C either as a continuous variable or with cut off <5.0 mu g/dL, and TT only as a continuous variable. Practically all models demonstrated significant predictability of peripheral sex hormone precursors for C levels, with DHEA demonstrating the strongest and most consistent predictability as an individual parameter and as part of the DHEAS/DHEA ratio. We conclude that in infertile women peripheral sex hormone precursors, especially DHEA, reflect C levels and, therefore, adrenal function. In infertile women, at all ages low levels of sex hormone precursors, therefore, should be considered indications for further adrenal assessments. (C) 2016 Elsevier Ltd. All rights reserved.

Alopecia areata (AA) is a common inflammatory disease targeting the anagen-stage hair follicle. Different cytokines have been implicated in the disease profile, but their pathogenic role is not yet fully determined. We studied biopsies of pretreatment lesional and non-lesional (NL) scalp and post-treatment (intra-lesional steroid injection) lesional scalp of 6 patchy patients with AA using immunohistochemistry and gene expression analysis. Immunohistochemistry showed increases in CD3(+), CD8(+) T cells, CD11c(+) dendritic cells and CD1a(+) Langerhans cells within and around hair follicles of pretreatment lesional scalp, which decreased upon treatment. qRT-PCR showed in pretreatment lesional scalp (compared to NL) significant increases (P < 0.05) in expression of inflammatory markers (IL-2, IL-2RA, JAK3, IL-15), Th1 (CXCL10 and CXCL9), Th2 (IL-13, CCL17 and CCL18), IL-12/IL-23p40 and IL-32. Among these, we observed significant downregulation with treatment in IL-12/IL-23p40, CCL18 and IL-32. We also observed significant downregulation of several hair keratins in lesional scalp, with significant upregulation of KRT35, KRT75 and KRT86 in post-treatment lesional scalp. This study shows concurrent activation of Th1 and Th2 immune axes as well as IL-23 and IL-32 cytokine pathways in lesional AA scalp and defined a series of response biomarkers to corticosteroid injection. Clinical trials with selective antagonists coupled with cytokine-pathway biomarkers will be necessary to further dissect pathogenic immunity.

The signaling molecule cAMP regulates functions ranging from bacterial transcription to mammalian memory. In mammals, cAMP is synthesized by nine transmembrane adenylyl cyclases (ACs) and one soluble AC (sAC). Despite similarities in their catalytic domains, these ACs differ in regulation. Transmembrane ACs respond to G proteins, whereas sAC is uniquely activated by bicarbonate. Via bicarbonate regulation, sAC acts as a physiological sensor for pH/bicarbonate/CO2, and it has been implicated as a therapeutic target, e.g. for diabetes, glaucoma, and a male contraceptive. Here we identify the bisphenols bithionol and hexachlorophene as potent, sAC-specific inhibitors. Inhibition appears mostly non-competitive with the substrate ATP, indicating that they act via an allosteric site. To analyze the interaction details, we solved a crystal structure of an sAC.bithionol complex. The structure reveals that the compounds are selective for sAC because they bind to the sAC-specific, allosteric binding site for the physiological activator bicarbonate. Structural comparison of the bithionol complex with apo-sAC and other sAC.ligand complexes along with mutagenesis experiments reveals an allosteric mechanism of inhibition; the compound induces rearrangements of substrate binding residues and of Arg(176), a trigger between the active site and allosteric site. Our results thus provide 1) novel insights into the communication between allosteric regulatory and active sites, 2) a novel mechanism for sAC inhibition, and 3) pharmacological compounds targeting this allosteric site and utilizing this mode of inhibition. These studies provide support for the future development of sAC-modulating drugs.

In vivo imaging provides unprecedented access to the dynamic behavior of cellular and subcellular structures in their natural context. Performing such imaging experiments in higher vertebrates such as mammals generally requires surgical access to the system under study. The optical accessibility of embryonic and larval zebrafish allows such invasive procedures to be circumvented and permits imaging in the intact organism. Indeed the zebrafish is now a well-established model to visualize dynamic cellular behaviors using in vivo microscopy in a wide range of developmental contexts from proliferation to migration and differentiation. A more recent development is the increasing use of zebrafish to study subcellular events including mitochondrial trafficking and centrosome dynamics. The relative ease with which these subcellular structures can be genetically labeled by fluorescent proteins and the use of light microscopy techniques to image them is transforming the zebrafish into an in vivo model of cell biology. Here we describe methods to generate genetic constructs that fluorescently label organelles, highlighting mitochondria and centrosomes as specific examples. We use the bipartite Gal4-UAS system in multiple configurations to restrict expression to specific cell-types and provide protocols to generate transiently expressing and stable transgenic fish. Finally, we provide guidelines for choosing light microscopy methods that are most suitable for imaging subcellular dynamics.

Due to their central role in essential physiological processes, potassium channels are common targets for animal toxins. These toxins in turn are of great value as tools for studying channel function and as lead compounds for drug development. Here, we used a direct toxin pull-down assay with immobilised KcsA potassium channel to isolate a novel KcsA-binding toxin (called Tx7335) from eastern green mamba snake (Dendroaspis angusticeps) venom. Sequencing of the toxin by Edman degradation and mass spectrometry revealed a 63 amino acid residue peptide with 4 disulphide bonds that belongs to the three-finger toxin family, but with a unique modification of its disulphide-bridge scaffold. The toxin induces a dose-dependent increase in both open probabilities and mean open times on KcsA in artificial bilayers. Thus, it unexpectedly behaves as a channel activator rather than an inhibitor. A charybdotoxin-sensitive mutant of KcsA exhibits similar susceptibility to Tx7335 as wild-type, indicating that the binding site for Tx7335 is distinct from that of canonical pore-blocker toxins. Based on the extracellular location of the toxin binding site (far away from the intracellular pH gate), we propose that Tx7335 increases potassium flow through KcsA by allosterically reducing inactivation of the channel.

Sustained exposure to stress or corticosteroids is known to cause changes in brain endocannabinoid (eCB) signaling, such that tissue contents of the eCBs N-arachidonylethanolamine (AEA) are generally reduced while 2-arachidonoylglycerol (2-AG) levels increase. These changes in eCB signaling are important for many of the aspects of chronic stress, such as anxiety, reward sensitivity and stress adaptation, yet the mechanisms mediating these changes are not fully understood. We have recently found that the stress related neuropeptide corticotropin-releasing hormone (CRH), acting through the CRH type 1 receptor (CRHR1), can reduce AEA content by increasing its hydrolysis by the enzyme fatty acid amide hydrolase (FAAH) as well as increase 2-AG contents. As extra-hypothalamic CRH is upregulated by chronic corticosteroid or stress exposure, we hypothesized that increased CRH signaling through CRHR1 contributes to the effects of chronic corticosteroid exposure on the eCB system within the amygdala and prefrontal cortex. Male rats were exposed to 7 days of systemic corticosterone capsules, with or without concurrent exposure to a CRHR1 antagonist, after which we examined eCB content. Consistent with previous studies in the amygdala, sustained corticosterone exposure increases CRH mRNA in the prefrontal cortex. As was shown previously, FAAH activity was increased and AEA contents were reduced within the amygdala and prefrontal cortex following chronic corticosterone exposure. Chronic corticosterone exposure also elevated 2-AG content in the prefrontal cortex but not the amygdala. These corticosteroid-driven changes were all blocked by systemic CRHR1 antagonism. Consistent with these data indicating sustained increases in CRH signaling can mediate the effects of chronic elevations in corticosteroids, CRH overexpressing mice also exhibited increased FAAH-mediated AEA hydrolysis in the amygdala and prefrontal cortex compared to wild type. CRH overexpression increased 2-AG content in the amygdala, but not the prefrontal cortex. These data indicate that chronic elevations in CRH signaling, as is seen following exposure to chronic elevations in corticosterone or stress, drive persistent changes in eCB function. As reductions in AEA signaling mediate the effects of CRH and chronic stress on anxiety, these data provide a mechanism linking these processes. (C) 2016 Elsevier Ltd. All rights reserved.