Action-Related Thoughts and Beliefs Regulate the Effect of Age Stereotypes on Aging Preparation

Thinking about old age stereotypically affects one’s engagement in age-related behaviors and developmental regulation. We hypothesized that positive or negative aging stereotype (AS) would be associated with more or less aging preparation, while action-related thoughts and beliefs might exert influence thereon. We used the AAF online-study dataset consisting of 591 German, 348 Chinese, and 139 American adults (aged 18−93 and 55% female). Using a count measure of 15-preparatory-activities, we first explored the role of AS measured by a bipolar scale and how perceived utility and risk of aging preparation differentiate this association. Findings revealed that perceiving more utility buffered the impact of negative AS, which suggests that one’s action-related thoughts are more proximal and self-relevant predictor of aging preparation. Besides, Chinese and Americans were more susceptible to the presence of AS than Germans, implying that cultural background or societal conditions might also shape one’s belief system and thereby regulate behaviors.

Co-option of immune effectors by the hormonal signalling system triggering metamorphosis in Drosophila melanogaster

Insect metamorphosis is triggered by the production, secretion and degradation of 20-hydroxyecdysone (ecdysone). In addition to its role in developmental regulation, increasing evidence suggests that ecdysone is involved in innate immunity processes, such as phagocytosis and the induction of antimicrobial peptide (AMP) production. AMP regulation includes systemic responses as well as local responses at surface epithelia that contact with the external environment. At pupariation, Drosophila melanogaster increases dramatically the expression of three AMP genes, drosomycin (drs), drosomycin-like 2 (drsl2) and drosomycin-like 5 (drsl5). We show that the systemic action of drs at pupariation is dependent on ecdysone signalling in the fat body and operates via the ecdysone downstream target, Broad. In parallel, ecdysone also regulates local responses, specifically through the activation of drsl2 expression in the gut. Finally, we confirm the relevance of this ecdysone dependent AMP expression for the control of bacterial load by showing that flies lacking drs expression in the fat body have higher bacterial persistence over metamorphosis. In contrast, local responses may be redundant with the systemic effect of drs since reduction of ecdysone signalling or of drsl2 expression has no measurable negative effect on bacterial load control in the pupa. Together, our data emphasize the importance of the association between ecdysone signalling and immunity using in vivo studies and establish a new role for ecdysone at pupariation, which impacts developmental success by regulating the immune system in a stage-dependent manner. We speculate that this co-option of immune effectors by the hormonal system may constitute an anticipatory mechanism to control bacterial numbers in the pupa, at the core of metamorphosis evolution.

Several different sequences are implicated in bloodstream-form-specific gene expression in Trypanosoma brucei

The parasite Trypanosoma brucei grows as bloodstream forms in mammalian hosts, and as procyclic forms in tsetse flies. In trypanosomes, gene expression regulation depends heavily on post-transcriptional mechanisms. Both the RNA-binding protein RBP10 and glycosomal phosphoglycerate kinase PGKC are expressed only in mammalian-infective forms. RBP10 targets procyclic-specific mRNAs for destruction, while PGKC is required for bloodstream-form glycolysis. Developmental regulation of both is essential: expression of either RBP10 or PGKC in procyclic forms inhibits their proliferation. We show that the 3′-untranslated region of the RBP10 mRNA is extraordinarily long - 7.3kb - and were able to identify six different sequences, scattered across the untranslated region, which can independently cause bloodstream-form-specific expression. The 3′-untranslated region of the PGKC mRNA, although much shorter, still contains two different regions, of 125 and 153nt, that independently gave developmental regulation. No short consensus sequences were identified that were enriched either within these regulatory regions, or when compared with other mRNAs with similar regulation, suggesting that more than one regulatory RNA-binding protein is important for repression of mRNAs in procyclic forms. We also identified regions, including an AT repeat, that increased expression in bloodstream forms, or suppressed it in both forms. Trypanosome mRNAs that encode RNA-binding proteins often have extremely extended 3′-untranslated regions. We suggest that one function of this might be to act as a fail-safe mechanism to ensure correct regulation even if mRNA processing or expression of trans regulators is defective.

Developmental regulation of lupulin gland-associated genes in aromatic and bitter hops (Humulus lupulus L.)

Background Hop (Humulus lupulus L.) bitter acids are valuable metabolites for the brewing industry. They are biosynthesized and accumulate in glandular trichomes of the female inflorescence (hop cone). The content of alpha bitter acids, such as humulones, in hop cones can differentiate aromatic from bitter hop cultivars. These contents are subject to genetic and environmental control but significantly correlate with the number and size of glandular trichomes (lupulin glands). Results We evaluated the expression levels of 37 genes involved in bitter acid biosynthesis and morphological and developmental differentiation of glandular trichomes to identify key regulatory factors involved in bitter acid content differences. For bitter acid biosynthesis genes, upregulation of humulone synthase genes, which are important for the biosynthesis of alpha bitter acids in lupulin glands, could explain the higher accumulation of alpha bitter acids in bitter hops. Several transcription factors, including HlETC1, HlMYB61 and HlMYB5 from the MYB family, as well as HlGLABRA2, HlCYCB2–4, HlZFP8 and HlYABBY1, were also more highly expressed in the bitter hop cultivars; therefore, these factors may be important for the higher density of lupulin glands also seen in the bitter hop cultivars. Conclusions Gene expression analyses enabled us to investigate the differences between aromatic and bitter hops. This study confirmed that the bitter acid content in glandular trichomes (lupulin glands) is dependent on the last step of alpha bitter acid biosynthesis and glandular trichome density.

Developmental regulation and functional prediction of microRNAs in an expanded Fasciola hepatica miRNome

The liver fluke, Fasciola hepatica, is a global burden on the wellbeing and productivity of farmed ruminants, and a zoonotic threat to human health. Despite the clear need for accelerated discovery of new drug and vaccine treatments for this pathogen, we still have a relatively limited understanding of liver fluke biology and host interactions. Noncoding RNAs, including micro (mi)RNAs, are key to transcriptional regulation in all eukaryotes, such that an understanding of miRNA biology can shed light on organismal function at a systems level. Four previous publications have reported up to 89 mature miRNA sequences from F. hepatica, but our data show that this does not represent a full account of this species miRNome. We have expanded on previous studies by sequencing, for the first time, miRNAs from multiple life stages (adult, newly excysted juvenile (NEJ), metacercariae and adult-derived extracellular vesicles (EVs)). These experiments detected an additional 61 high-confidence miRNAs, most of which have not been described in any other species, expanding the F. hepatica miRNome to 150 mature sequences. We used quantitative (q)PCR assays to provide the first developmental profile of miRNA expression across metacercariae, NEJ, adult and adult-derived Evs. The majority of miRNAs were expressed most highly in metacercariae, with at least six distinct expression clusters apparent across life stages. Intracellular miRNAs were functionally analysed to identify target mRNAs with inversely correlated expression in F. hepatica tissue transcriptomes, highlighting regulatory interactions with key virulence transcripts including cathepsin proteases, and neuromuscular genes that control parasite growth, development and motility. We also linked 28 adult-derived EV miRNAs with downregulation of 397 host genes in F. hepatica-infected transcriptomes from ruminant lymph node, peripheral blood mononuclear cell (PBMC) and liver tissue transcriptomes. These included genes involved in signal transduction, immune and metabolic pathways, adding to the evidence for miRNA-based immunosuppression during fasciolosis. These data expand our understanding of the F. hepatica miRNome, provide the first data on developmental miRNA regulation in this species, and provide a set of testable hypotheses for functional genomics interrogations of liver fluke miRNA biology.

HIC2 Controls Developmental Hemoglobin Switching By Repressing BCL11A Transcription

One of the oldest and most deeply studied problems in developmental gene expression is the switch from fetal to adult type hemoglobin production in red blood cell precursors. Interest in this question has been fueled by its relevance to genetic blood disorders such as sickle cell disease (SCD) and thalassemia. BCL11A is a transcriptional repressor that is thought to directly silence the fetal β-type globin (HBG1/2) genes in adult erythroid cells. Transcriptome and RNA polymerase II profiling indicate that the BCL11A gene is transcribed considerably more highly in adult erythroblasts compared to fetal cells, accounting in large part for corresponding changes in BCL11A protein levels. Yet, the mechanism governing BCL11A developmental regulation is still unclear. To identify novel regulators of the fetal-to-adult globin switch, we interrogated our recent CRISPR based genetic screens that employed single guide RNAs (sgRNAs) targeting transcription factors (Huang et al., Blood, 2020) and uncovered HIC2, a penta-dactyl zinc finger DNA binding protein bearing a BTB/POZ domain as a novel regulator of hemoglobin switching. HIC2 is expressed more highly in fetal erythroblasts compared to adult cells, a pattern inverse to that of BCL11A. Overexpression (OE) of HIC2 in the adult type erythroid HUDEP2 cell line stimulated the expression of 322 genes while impairing that of 224 genes (FDR < 0.01 and fold change ≥ 2). The most highly upregulated genes (>150-fold) were HBG1/2. Upregulation was accompanied by gains in chromatin accessibility and histone H3K27acetylation of HBG1/2, and increased chromatin contacts between the distal globin gene enhancer (LCR) and the HBG1/2 genes. Overexpression of HIC2 in primary human erythroblasts also significantly increased HBG1/2 mRNA and protein levels, sufficient to reduce cell sickling in SCD patient-derived erythroid cells. HIC2 OE lowered BCL11A mature and pre-mRNA production, indicating that HIC2 attenuates BCL11A transcription. Forced expression of BCL11A restored HBG1/2 silencing in HIC2 OE HUDEP2 cells, suggesting that BCL11A repression accounts for the effects of HIC2 on fetal globin genes. ChIP-seq revealed a strong HIC2 binding peak at the erythroid BCL11A +55 enhancer. HIC2 OE reduced chromatin accessibility and H3K27acetylation of the +55 enhancer, as well as the enhancer-promoter contacts, suggesting that HIC2 directly decommissions the enhancer to attenuate BCL11A transcription. The BCL11A +55 enhancer contains two consensus HIC2 binding motifs under the HIC2 peak adjacent to GATA:E-box and GATA motifs. CRISPR-mediated mutagenesis of both HIC2 motifs raised BCL11A basal level transcription and diminished the ability of overexpressed HIC2 to repress BCL11A transcription. Notably, HIC2 OE impaired binding of transcription factor GATA1 at the +55 enhancer, suggesting that this enhancer is under developmental control. Indeed, GATA1 binding and chromatin accessibility of +55 enhancer were virtually undetectable in HUDEP1 cells, which represent a more fetal-like state. CRISPR-mediated depletion of HIC2 in HUDEP1 cells reversed this pattern with gains in GATA1 binding, chromatin accessibility, and BCL11A transcription. In sum, HIC2 emerges as a critical regulator of hemoglobin switching that operates by imposing developmental stage-specific control onto a BCL11A transcriptional enhancer. Disclosures Blobel: Fulcrum therapeutics: Consultancy; Pfizer: Research Funding.

Transcriptome profiling reveals the developmental regulation of NaCl-treated Forcipomyia taiwana eggs

Background The biting midge, Forcipomyia taiwana, is one of the most annoying blood-sucking pests in Taiwan. Current chemical control methods only target the adult, not the immature stages (egg to pupa), of F. taiwana. Discovering new or alternative tactics to enhance or replace existing methods are urgently needed to improve the effectiveness of F. taiwana control. The egg is the least understood life stage in this pest species but may offer a novel point of control as addition of NaCl to the egg environment inhibits development. Thus, the objective of this study was to use RNA profiling to better understand the developmental differences between wild-type melanized (black) and NaCl-induced un-melanized (pink), infertile F. taiwana eggs. Results After de novo assembly with Trinity, 87,415 non-redundant transcripts (Ft-nr) with an N50 of 1099 were obtained. Of these, 26,247 (30%) transcripts were predicted to have long open reading frames (ORFs, defined here as ≥300 nt) and 15,270 (17.5%) transcripts have at least one predicted functional domain. A comparison between two biological replicates each of black and pink egg samples, although limited in sample size, revealed 5898 differentially expressed genes (DEGs; 40.9% of the transcripts with long ORFs) with ≥2-fold difference. Of these, 2030 were annotated to a Gene Ontology biological process and along with gene expression patterns can be separated into 5 clusters. KEGG pathway analysis revealed that 1589 transcripts could be assigned to 18 significantly enriched pathways in 2 main categories (metabolism and environmental information processing). As expected, most (88.32%) of these DEGs were down-regulated in the pink eggs. Surprisingly, the majority of genes associated with the pigmentation GO term were up-regulated in the pink egg samples. However, the two key terminal genes of the melanin synthesis pathway, laccase2 and DCE/yellow, were significantly down-regulated, and further verified by qRT-PCR. Conclusion We have assembled and annotated the first egg transcriptome for F. taiwana, a biting midge. Our results suggest that down-regulation of the laccase2 and DCE/yellow genes might be the mechanism responsible for the NaCl-induced inhibition of melanization of F. taiwana eggs.

The birth of piRNAs: how mammalian piRNAs are produced, originated, and evolved

PIWI-interacting RNAs (piRNAs), small noncoding RNAs 24–35 nucleotides long, are essential for animal fertility. They play critical roles in a range of functions, including transposable element suppression, gene expression regulation, imprinting, and viral defense. In mammals, piRNAs are the most abundant small RNAs in adult testes and the only small RNAs that direct epigenetic modification of chromatin in the nucleus. The production of piRNAs is a complex process from transcription to post-transcription, requiring unique machinery often distinct from the biogenesis of other RNAs. In mice, piRNA biogenesis occurs in specialized subcellular locations, involves dynamic developmental regulation, and displays sexual dimorphism. Furthermore, the genomic loci and sequences of piRNAs evolve much more rapidly than most of the genomic regions. Understanding piRNA biogenesis should reveal novel RNA regulations recognizing and processing piRNA precursors and the forces driving the gain and loss of piRNAs during animal evolution. Such findings may provide the basis for the development of engineered piRNAs capable of modulating epigenetic regulation, thereby offering possible single-dose RNA therapy without changing the genomic DNA. In this review, we focus on the biogenesis of piRNAs in mammalian adult testes that are derived from long non-coding RNAs. Although piRNA biogenesis is believed to be evolutionarily conserved from fruit flies to humans, recent studies argue for the existence of diverse, mammalian-specific RNA-processing pathways that convert precursor RNAs into piRNAs, perhaps associated with the unique features of mammalian piRNAs or germ cell development. We end with the discussion of major questions in the field, including substrate recognition and the birth of new piRNAs.