Genomic regulation of Krüppel-like-factor family members by corticosteroid receptors in the rat brain.

Hippocampal mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) mediate glucocorticoid hormone (GC) action in the hippocampus. These receptors bind to glucocorticoid responsive elements (GREs) within target genes, eliciting transcriptional effects in response to stress and circadian variation. Until recently, little was known about the genome-wide targets of hippocampal MRs and GRs under physiological conditions. Following on from our genome-wide MR and GR ChIP-seq and Ribo-Zero RNA-seq studies on rat hippocampus, we investigated the Krüppel-like factors (KLFs) as targets of MRs and GRs throughout the brain under circadian variation and after acute stress. In particular, Klf2, Klf9 and Klf15 are known to be stress and/or GC responsive and play a role in neurobiological processes including synaptic plasticity and neuronal differentiation. We found increased binding of MR and GR to GREs within Klf2, Klf9 and Klf15 in the hippocampus, amygdala, prefrontal cortex, and neocortex after acute stress and resulting from circadian variation, which was accompanied by upregulation of corresponding hnRNA and mRNA levels. Adrenalectomy abolished transcriptional upregulation of specific Klf genes. These results show that MRs and GRs regulate Klf gene expression throughout the brain following exposure to acute stress or in response to circadian variation, likely alongside other transcription factors.

T-cell trans-synaptic vesicles are distinct and carry greater effector content than constitutive extracellular vesicles.

The immunological synapse is a molecular hub that facilitates the delivery of three activation signals, namely antigen, costimulation/corepression and cytokines, from antigen-presenting cells (APC) to T cells. T cells release a fourth class of signaling entities, trans-synaptic vesicles (tSV), to mediate bidirectional communication. Here we present bead-supported lipid bilayers (BSLB) as versatile synthetic APCs to capture, characterize and advance the understanding of tSV biogenesis. Specifically, the integration of juxtacrine signals, such as CD40 and antigen, results in the adaptive tailoring and release of tSV, which differ in size, yields and immune receptor cargo compared with steadily released extracellular vesicles (EVs). Focusing on CD40L+ tSV as model effectors, we show that PD-L1 trans-presentation together with TSG101, ADAM10 and CD81 are key in determining CD40L vesicular release. Lastly, we find greater RNA-binding protein and microRNA content in tSV compared with EVs, supporting the specialized role of tSV as intercellular messengers.

Distinct regulation of hippocampal neuroplasticity and ciliary genes by corticosteroid receptors.

Glucocorticoid hormones (GCs) - acting through hippocampal mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) - are critical to physiological regulation and behavioural adaptation. We conducted genome-wide MR and GR ChIP-seq and Ribo-Zero RNA-seq studies on rat hippocampus to elucidate MR- and GR-regulated genes under circadian variation or acute stress. In a subset of genes, these physiological conditions resulted in enhanced MR and/or GR binding to DNA sequences and associated transcriptional changes. Binding of MR at a substantial number of sites however remained unchanged. MR and GR binding occur at overlapping as well as distinct loci. Moreover, although the GC response element (GRE) was the predominant motif, the transcription factor recognition site composition within MR and GR binding peaks show marked differences. Pathway analysis uncovered that MR and GR regulate a substantial number of genes involved in synaptic/neuro-plasticity, cell morphology and development, behavior, and neuropsychiatric disorders. We find that MR, not GR, is the predominant receptor binding to >50 ciliary genes; and that MR function is linked to neuronal differentiation and ciliogenesis in human fetal neuronal progenitor cells. These results show that hippocampal MRs and GRs constitutively and dynamically regulate genomic activities underpinning neuronal plasticity and behavioral adaptation to changing environments.