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In humans and animal models, Cesarean section (C-section) has been associated with alterations in the taxonomic structure of the gut microbiome. These changes in microbiota populations are hypothesized to impact immune, metabolic, and behavioral/neurologic systems and others. It is not clear if birth mode inherently changes the microbiome, or if C-section effects are context-specific and involve interactions with environmental and other factors. To address this and control for potential confounders, cecal microbiota from ~3 week old mice born by C-section (n = 16) versus natural birth (n = 23) were compared under matched conditions for housing, cross-fostering, diet, sex, and genetic strain. A total of 601 unique species were detected across all samples. Alpha diversity richness (i.e., how many species within sample; Chao1) and evenness/dominance (i.e., Shannon, Simpson, Inverse Simpson) metrics revealed no significant differences by birth mode. Beta diversity (i.e., differences between samples), as estimated with Bray-Curtis dissimilarities and Aitchison distances (using log[x + 1]-transformed counts), was also not significantly different (Permutational Multivariate ANOVA [PERMANOVA]). Only the abundance of Lachnoclostridium [Clostridium] scindens was found to differ using a combination of statistical methods (ALDEx2, DESeq2), being significantly higher in C-section mice. This microbe has been implicated in secondary bile acid production and regulation of glucocorticoid metabolism to androgens. From our results and the extant literature we conclude that C-section does not inherently lead to large-scale shifts in gut microbiota populations, but birth mode could modulate select bacteria in a context-specific manner: For example, involving factors associated with pre-, peri-, and postpartum environments, diet or host genetics.

The adipokine leptin regulates energy homeostasis through ubiquitously expressed leptin receptors. Leptin has a number of major signaling targets in the brain, including cells of the anterior pituitary (AP). We have previously reported that mice lacking leptin receptors in AP somatotropes display growth hormone (GH) deficiency, metabolic dysfunction, and adult-onset obesity. Among other targets, leptin signaling promotes increased levels of the pituitary transcription factor POU1F1, which in turn regulates the specification of somatotrope, lactotrope, and thyrotrope cell lineages within the AP. Leptin's mechanism of action on somatotropes is sex dependent, with females demonstrating posttranscriptional control of Pou1f1 messenger RNA (mRNA) translation. Here, we report that the stem cell marker and mRNA translational control protein, Musashi1, exerts repression of the Pou1f1 mRNA. In female somatotropes, Msi1 mRNA and protein levels are increased in the mouse model that lacks leptin signaling (Gh -CRE Lepr -null), coincident with lack of POU1f1 protein, despite normal levels of Pou1f1 mRNA. Single-cell RNA sequencing of pituitary cells from control female animals indicates that both Msi1 and Pou1f1 mRNAs are expressed in Gh -expressing somatotropes, and immunocytochemistry confirms that Musashi1 protein is present in the somatotrope cell population. We demonstrate that Musashi interacts directly with the Pou1f1 mRNA 3′ untranslated region and exerts translational repression of a Pou1f1 mRNA translation reporter in a leptin-sensitive manner. Musashi immunoprecipitation from whole pituitary reveals coassociated Pou1f1 mRNA. These findings suggest a mechanism in which leptin stimulation is required to reverse Musashi-mediated Pou1f1 mRNA translational control to coordinate AP somatotrope function with metabolic status. [ABSTRACT FROM AUTHOR]

The field of gut microbiota is of growing interest, especially in the recent discoveries of its interaction with host immune responses, which when disrupted, can further alter immunity. It also plays a role in cancer development, its microenvironment and response to anticancer therapeutics. Several recently published experimental studies had explored the efficacy of modifying microbiota to enhance the response of checkpoint inhibitors, suggesting its beneficial function in cancer management and potential to be targeted as a therapeutic agent to enhance efficacy of checkpoint inhibitors. Here we review available evidence, mechanisms and hypotheses of its use to enhance cancer response. [ABSTRACT FROM AUTHOR]

Introduction: Arsenic is a widely distributed environmental toxicant that can cause multi-tissue pathologies. Proteomic assays allow for the identification of biological processes modulated by arsenic in diverse tissue types., Method: The altered abundance of proteins from HaCaT human keratinocyte cell line exposed to arsenic was quantified using a label-free LC-MS/MS mass spectrometry workflow. Selected proteomics results were validated using western blot and RT-PCR. A functional annotation analytics strategy that included visual analytical integration of heterogeneous data sets was developed to elucidate functional categories. The annotations integrated were mainly tissue localization, biological process and gene family., Result: The abundance of 173 proteins was altered in keratinocytes exposed to arsenic; in which 96 proteins had increased abundance while 77 proteins had decreased abundance. These proteins were also classified into 69 Gene Ontology biological process terms. The increased abundance of transferrin receptor protein (TFRC) was validated and also annotated to participate in response to hypoxia. A total of 33 proteins (11 increased abundance and 22 decreased abundance) were associated with 18 metabolic process terms. The Glutamate--cysteine ligase catalytic subunit (GCLC), the only protein annotated with the term sulfur amino acid metabolism process, had increased abundance while succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial precursor (SDHB), a tumor suppressor, had decreased abundance., Conclusion: A list of 173 differentially abundant proteins in response to arsenic trioxide was grouped using three major functional annotations covering tissue localization, biological process and protein families. A possible explanation for hyperpigmentation pathologies observed in arsenic toxicity is that arsenic exposure leads to increased iron uptake in the normally hypoxic human skin. The proteins mapped to metabolic process terms and differentially abundant are candidates for evaluating metabolic pathways perturbed by arsenicals.

Molecular pathways regulating melanoma initiation and progression are potential targets of therapeutic development for this aggressive cancer. Identification and molecular analysis of these pathways in patients has been primarily restricted to targeted studies on individual proteins. Here, we report the most comprehensive analysis of formalin-fixed paraffin-embedded human melanoma tissues using quantitative proteomics. From 61 patient samples, we identified 171 proteins varying in abundance among benign nevi, primary melanoma, and metastatic melanoma. Seventy-three percent of these proteins were validated by immunohistochemistry staining of malignant melanoma tissues from the Human Protein Atlas database. Our results reveal that molecular pathways involved with tumor cell proliferation, motility, and apoptosis are mis-regulated in melanoma. These data provide the most comprehensive proteome resource on patient melanoma and reveal insight into the molecular mechanisms driving melanoma progression.

In eukaryotes, DNA is wrapped around proteins called histones and is condensed into chromatin. Post-translational modification of histones can result in changes in gene expression. One of the most well-studied histone modifications is the methylation of lysine 4 on histone H3 (H3K4). This residue can be mono-, di- or tri-methylated and these varying methylation states have been associated with different levels of gene expression. Understanding exactly what the purpose of these methylation states is, in terms of gene expression, has been a topic of much research in recent years. Enzymes that can add (methyltransferases) and remove (demethylases) these modifications are of particular interest. The first demethylase discovered, LSD1, is the most well-classified and has been implicated in contributing to human cancers and to DNA damage response pathways. Currently, there are limited methods for accurately studying the activity of demethylases in vitro or in vivo. In this work, we present MassSQUIRM (mass spectrometric quantitation using isotopic reductive methylation), a quantitative method for studying the activity of demethylases capable of removing mono- and di-methyl marks from lysine residues. We focus specifically on LSD1 due to its potential as a prime therapeutic target for human disease. This quantitative approach will enable better characterization of the activity of LSD1 and other chromatin modifying enzymes in vitro, in vivo or in response to inhibitors.