HSFA1a modulates plant heat stress responses and alters the 3D chromatin organization of enhancer-promoter interactions

The complex and dynamic three-dimensional organization of chromatin within the nucleus makes understanding the control of gene expression challenging, but also opens up possible ways to epigenetically modulate gene expression. Because plants are sessile, they evolved sophisticated ways to rapidly modulate gene expression in response to environmental stress, that are thought to be coordinated by changes in chromatin conformation to mediate specific cellular and physiological responses. However, to what extent and how stress induces dynamic changes in chromatin reorganization remains poorly understood. Here, we comprehensively investigated genome-wide chromatin changes associated with transcriptional reprogramming response to heat stress in tomato. Our data show that heat stress induces rapid changes in chromatin architecture, leading to the transient formation of promoter-enhancer contacts, likely driving the expression of heat-stress responsive genes. Furthermore, we demonstrate that chromatin spatial reorganization requires HSFA1a, a transcription factor (TF) essential for heat stress tolerance in tomato. In light of our findings, we propose that TFs play a key role in controlling dynamic transcriptional responses through 3D reconfiguration of promoter-enhancer contacts

Histone deacetylase activities are required for innate immune cell control of Th1 but not Th2 effector cell function.

Histone deacetylases (HDACs) play a critical role in regulating gene expression and key biological processes. However, how HDACs are involved in innate immunity is little understood. Here, in this first systematic investigation of the role of HDACs in immunity, we show that HDAC inhibition by a small-molecule HDAC inhibitor (HDACi), LAQ824, alters Toll-like receptor 4 (TLR4)-dependent activation and function of macrophages and dendritic cells (DCs). Surprisingly, pan-HDAC inhibition modulates only a limited set of genes involved in distinct arms of immune responses. Specifically, it inhibited DC-controlled T helper 1 (Th1) effector but not Th2 effector cell activation and migration. It also inhibited macrophage- and DC-mediated monocyte but not neutrophil chemotaxis. These unexpected findings demonstrate the high specificity of HDAC inhibition in modulating innate and adaptive immune responses, and highlight the potential for HDACi to alter the Th1 and Th2 balance in therapeutic settings

Wolbachia Has Two Different Localization Patterns in Whitefly Bemisia tabaci AsiaII7 Species.

The whitefly Bemisia tabaci is a cosmopolitan insect species complex that harbors the obligate primary symbiont Portiera aleyrodidarum and several facultative secondary symbionts including Wolbachia, which have diverse influences on the host biology. Here, for the first time, we revealed two different localization patterns of Wolbachia present in the immature and adult stages of B. tabaci AsiaII7 cryptic species. In the confined pattern, Wolbachia was restricted to the bacteriocytes, while in the scattered pattern Wolbachia localized in the bacteriocytes, haemolymph and other organs simultaneously. Our results further indicated that, the proportion of B. tabaci AsiaII7 individuals with scattered Wolbachia were significantly lower than that of confined Wolbachia, and the distribution patterns of Wolbachia were not associated with the developmental stage or sex of whitefly host. This study will provide a new insight into the various transmission routes of Wolbachia in different whitefly species

Genome-wide CRISPR screen identifies protein pathways modulating tau protein levels in neurons

Aggregates of hyperphosphorylated tau protein are a pathological hallmark of more than 20 distinct neurodegenerative diseases, including Alzheimer's disease, progressive supranuclear palsy, and frontotemporal dementia. While the exact mechanism of tau aggregation is unknown, the accumulation of aggregates correlates with disease progression. Here we report a genome-wide CRISPR screen to identify modulators of endogenous tau protein for the first time. Primary screens performed in SH-SY5Y cells, identified positive and negative regulators of tau protein levels. Hit validation of the top 43 candidate genes was performed using Ngn2-induced human cortical excitatory neurons. Using this approach, genes and pathways involved in modulation of endogenous tau levels were identified, including chromatin modifying enzymes, neddylation and ubiquitin pathway members, and components of the mTOR pathway. TSC1, a critical component of the mTOR pathway, was further validated in vivo, demonstrating the relevance of this screening strategy. These findings may have implications for treating neurodegenerative diseases in the future

The percentage of <i>Wolbachia</i> location patterns in different stages of AsiaII7 <i>Bemisia tabaci</i>.

<p>For egg, nymph, male and female adults, 56, 46, 47 and 57 individuals (three repeats in total) were successfully visualized by FISH respectively. The differences between the percentages of scattered and confined <i>Wolbachia</i> were compared using t-test, the “***” over the bars mean significantly differences between the percentages at α = 0.01 level. T = -24.30, P = 0.0017 for egg; T = -27.89, P = 0.0013 for nymph; T = -16.09, P = 0.0038 for male and T = -22.02, P = 0.0021 for female adults.</p

FISH visualization of <i>Wolbachia</i> in the female adults of AsiaII7 <i>B</i>. <i>tabaci</i>.

<p>Panel a-b: confined and scattered <i>Wolbachia</i> in female adults; panel c: the negative control whitefly female hybridization without specific probe Left panels: fluorescence in dark field; right panels: fluorescence in bright field. B: bacteriome in whitefly host, H: haemolymph tissue of whitefly host.</p

The infection of <i>Wolbachia</i> in the different stages of AsiaII7 <i>Bemisia tabaci</i>.

<p><i>Wolbachia</i> was detected by PCR with the specific <i>wsp</i> primers, an expected DNA band of approximately 610 bp positively appeared in all the samples. M: DNA marker; Lanes 1–6 are positive control (<i>Portiera</i>, ~1000 bp), negative control (ddH₂O), egg, nymph, male and female adults of AsiaII7 respectively.</p

<i>Wolbachia</i> Has Two Different Localization Patterns in Whitefly <i>Bemisia tabaci</i> AsiaII7 Species

<div><p>The whitefly <i>Bemisia tabaci</i> is a cosmopolitan insect species complex that harbors the obligate primary symbiont <i>Portiera aleyrodidarum</i> and several facultative secondary symbionts including <i>Wolbachia</i>, which have diverse influences on the host biology. Here, for the first time, we revealed two different localization patterns of <i>Wolbachia</i> present in the immature and adult stages of <i>B</i>. <i>tabaci</i> AsiaII7 cryptic species. In the confined pattern, <i>Wolbachia</i> was restricted to the bacteriocytes, while in the scattered pattern <i>Wolbachia</i> localized in the bacteriocytes, haemolymph and other organs simultaneously. Our results further indicated that, the proportion of <i>B</i>. <i>tabaci</i> AsiaII7 individuals with scattered <i>Wolbachia</i> were significantly lower than that of confined <i>Wolbachia</i>, and the distribution patterns of <i>Wolbachia</i> were not associated with the developmental stage or sex of whitefly host. This study will provide a new insight into the various transmission routes of <i>Wolbachia</i> in different whitefly species.</p></div