Differential Requirement of Cd8 Enhancers E8I and E8VI in Cytotoxic Lineage T Cells and in Intestinal Intraepithelial Lymphocytes

CD8 expression in T lymphocytes is tightly regulated by the activity of at least six Cd8 enhancers (E8I-E8VI), however their complex developmental stage-, subset-, and lineage-specific interplays are incompletely understood. Here we analyzed ATAC-seq data on the Immunological Genome Project database and identified a similar developmental regulation of chromatin accessibility of a subregion of E8I, designated E8I-core, and of E8VI. Loss of E8I-core led to a similar reduction in CD8 expression in naïve CD8+ T cells and in IELs as observed in E8I−/− mice, demonstrating that we identified the core enhancer region of E8I. While E8VI−/− mice displayed a mild reduction in CD8 expression levels on CD8SP thymocytes and peripheral CD8+ T cells, CD8 levels were further reduced upon combined deletion of E8I-core and E8VI. Moreover, activated E8I-core−/−E8VI−/− CD8+ T cells lost CD8 expression to a greater degree than E8I-core−/− and E8VI−/− CD8+ T cells, suggesting that the combined activity of both enhancers is required for establishment and maintenance of CD8 expression before and after TCR activation. Finally, we observed a severe reduction of CD4 CTLs among the TCRβ+CD4+ IEL population in E8I-core−/− but not E8VI−/− mice. Such a reduction was not observed in Cd8a−/− mice, indicating that E8I-core controls the generation of CD4 CTLs independently of its role in Cd8a gene regulation. Further, the combined deletion of E8I-core and E8VI restored CD4 CTL subsets, suggesting an antagonistic function of E8VI in the generation of CD4 CTLs. Together, our study demonstrates a complex utilization and interplay of E8I-core and E8VI in regulating CD8 expression in cytotoxic lineage T cells and in IELs. Moreover, we revealed a novel E8I-mediated regulatory mechanism controlling the generation of intestinal CD4 CTLs

Histone deacetylase 1 controls CD4+ T cell trafficking in autoinflammatory diseases.

CD4+ T cell trafficking is a fundamental property of adaptive immunity. In this study, we uncover a novel role for histone deacetylase 1 (HDAC1) in controlling effector CD4+ T cell migration, thereby providing mechanistic insight into why a T cell-specific deletion of HDAC1 protects against experimental autoimmune encephalomyelitis (EAE). HDAC1-deficient CD4+ T cells downregulated genes associated with leukocyte extravasation. In vitro, HDAC1-deficient CD4+ T cells displayed aberrant morphology and migration on surfaces coated with integrin LFA-1 ligand ICAM-1 and showed an impaired ability to arrest on and to migrate across a monolayer of primary mouse brain microvascular endothelial cells under physiological flow. Moreover, HDAC1 deficiency reduced homing of CD4+ T cells into the intestinal epithelium and lamina propria preventing weight-loss, crypt damage and intestinal inflammation in adoptive CD4+ T cell transfer colitis. This correlated with reduced expression levels of LFA-1 integrin chains CD11a and CD18 as well as of selectin ligands CD43, CD44 and CD162 on transferred circulating HDAC1-deficient CD4+ T cells. Our data reveal that HDAC1 controls T cell-mediated autoimmunity via the regulation of CD4+ T cell trafficking into the CNS and intestinal tissues

The corepressor NCOR1 regulates the survival of single-positive thymocytes

Nuclear receptor corepressor 1 (NCOR1) is a transcriptional regulator bridging repressive chromatin modifying enzymes with transcription factors. NCOR1 regulates many biological processes, however its role in T cells is not known. Here we show that Cd4-Cre-mediated deletion of NCOR1 (NCOR1 cKOCd4) resulted in a reduction of peripheral T cell numbers due to a decrease in single-positive (SP) thymocytes. In contrast, double-positive (DP) thymocyte numbers were not affected in the absence of NCOR1. The reduction in SP cells was due to diminished survival of NCOR1-null postselection TCRhiCD69+ and mature TCRhiCD69 thymocytes. NCOR1-null thymocytes expressed elevated levels of the pro-apoptotic factor BIM and showed a higher fraction of cleaved caspase 3-positive cells upon TCR stimulation ex vivo. However, staphylococcal enterotoxin B (SEB)-mediated deletion of V8+ CD4SP thymocytes was normal, suggesting that negative selection is not altered in the absence of NCOR1. Finally, transgenic expression of the pro-survival protein BCL2 restored the population of CD69+ thymocytes in NCOR1 cKOCd4 mice to a similar percentage as observed in WT mice. Together, these data identify NCOR1 as a crucial regulator of the survival of SP thymocytes and revealed that NCOR1 is essential for the proper generation of the peripheral T cell pool.(VLID)463721

Correction: Alterations of Red Cell Membrane Properties in Neuroacanthocytosis.

Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington’s disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an “acanthocytic state” of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration

Separable Roles for a Caenorhabditis elegans RMI1 Homolog in Promoting and Antagonizing Meiotic Crossovers Ensure Faithful Chromosome Inheritance.

During the first meiotic division, crossovers (COs) between homologous chromosomes ensure their correct segregation. COs are produced by homologous recombination (HR)-mediated repair of programmed DNA double strand breaks (DSBs). As more DSBs are induced than COs, mechanisms are required to establish a regulated number of COs and to repair remaining intermediates as non-crossovers (NCOs). We show that the Caenorhabditis elegans RMI1 homolog-1 (RMH-1) functions during meiosis to promote both CO and NCO HR at appropriate chromosomal sites. RMH-1 accumulates at CO sites, dependent on known pro-CO factors, and acts to promote CO designation and enforce the CO outcome of HR-intermediate resolution. RMH-1 also localizes at NCO sites and functions in parallel with SMC-5 to antagonize excess HR-based connections between chromosomes. Moreover, RMH-1 also has a major role in channeling DSBs into an NCO HR outcome near the centers of chromosomes, thereby ensuring that COs form predominantly at off-center positions

RMH-1 and SMC-5 cooperate to prevent accumulation of aberrant interhomolog connections.

<p>(A) In <i>smc-5(ok2421)</i>, RMH-1 foci increase in mid pachytene nuclei (MP) (green square), while in late pachytene (LP) (yellow square), a zone with fewer foci is still present, as in WT. (B) Quantification of RMH-1 foci in MP nuclei in WT (<i>n</i> = 205) and <i>smc-5(ok2421)</i> (<i>n</i> = 203). In the mutant, we frequently observe nuclei with more than 25 foci, never seen in the WT. Distribution of mid pachytene GFP::RMH-1 foci is significantly different between WT and <i>smc-5</i> mutant (Mann Whitney test, **** <i>p</i> < 0.0001). (C) Quantification of RMH-1 foci in LP nuclei; data are represented as mean +/- SD with ns (not significant). Quantification of hatch rate (D), larval arrest (E), and DAPI bodies in diakinesis oocytes (F) for WT, <i>rmh-1(jf54)</i>, <i>smc-5(ok2421)</i>, and <i>rmh-1(jf54); smc-5</i> (<i>n</i> = 35–45 hermaphrodites per genotype). Data are represented as mean +/- SD with ns (not significant) and * <i>p</i> < 0.05, ** <i>p</i> < 0.01, *** <i>p</i> < 0.001, **** <i>p</i> < 0.0001. (G–J) Images of individual diakinesis bivalents stained for long arm and short arm markers. Both <i>rmh-1(jf54)</i> and <i>smc-5</i> single mutants exhibit abnormally structured bivalents at low frequency (H,I). In <i>rmh-1; smc-5</i>, all diakinesis nuclei contain bivalents with abnormal structures; typical of these abnormalities is a side-by-side organization of the long arms of the bivalents (J′), presumably reflecting the presence of persistent interhomolog associations at NCO sites. (K) Quantification of the frequencies of diakinesis nuclei (-2 and -1) containing at least one abnormal bivalent (<i>n</i> = 13–25 nuclei per genotype). Data are represented as percentage with ns (not significant) and ** <i>p</i> < 0.01, *** <i>p</i> < 0.001, and **** <i>p</i> < 0.0001 (Chi² test) (L–N) Images of chromosomes in diakinesis nuclei from <i>zhp-3; smc-5</i> and <i>rmh-1(jf54) zhp-3; smc-5</i> worms. Despite the absence of the canonical meiotic CO machinery component ZHP-3, fewer than 12 DAPI structures are observed in some <i>zhp-3; smc-5</i>–1 oocytes, indicating the presence of ectopic connections (L,M). Such ectopic connections occur at high frequency in the <i>rmh-1(jf54) zhp-3; smc-5</i> triple mutant (N–N′). The quantification is presented in (O) with <i>n</i> = 13–36 oocytes per genotype. Data are represented as mean +/- SD with ns (not significant), * <i>p</i> < 0.05 and **** <i>p</i> < 0.0001.</p