Antagonism versus cooperativity with TALE cofactors at the base of the functional diversification of Hox protein function

International audienceExtradenticle (Exd) and Homothorax (Hth) function as positive transcriptional cofactors of Hox proteins, helping them to bind specifically their direct targets. The posterior Hox protein Abdominal-B (Abd-B) does not require Exd/Hth to bind DNA; and, during embryogenesis, Abd-B represses hth and exd transcription. Here we show that this repression is necessary for Abd-B function, as maintained Exd/Hth expression results in transformations similar to those observed in loss-of-function Abd-B mutants. We characterize the cis regulatory module directly regulated by Abd-B in the empty spiracles gene and show that the Exd/Hth complex interferes with Abd-B binding to this enhancer. Our results suggest that this novel Exd/Hth function does not require the complex to bind DNA and may be mediated by direct Exd/Hth binding to the Abd-B homeodomain. Thus, in some instances, the main positive cofactor complex for anterior Hox proteins can act as a negative factor for the posterior Hox protein Abd-B. This antagonistic interaction uncovers an alternative way in which MEIS and PBC cofactors can modulate Abd-B like posterior Hox genes during development

Regulation of Fn14 Receptor and NF-κB Underlies Inflammation in Meniere’s Disease

Meniere’s disease (MD) is a rare disorder characterized by episodic vertigo, sensorineural hearing loss, tinnitus, and aural fullness. It is associated with a fluid imbalance between the secretion of endolymph in the cochlear duct and its reabsorption into the subarachnoid space, leading to an accumulation of endolymph in the inner ear. Epidemiological evidence, including familial aggregation, indicates a genetic contribution and a consistent association with autoimmune diseases (AD). We conducted a case–control study in two phases using an immune genotyping array in a total of 420 patients with bilateral MD and 1,630 controls. We have identified the first locus, at 6p21.33, suggesting an association with bilateral MD [meta-analysis leading signal rs4947296, OR = 2.089 (1.661–2.627); p = 1.39 × 10−09]. Gene expression profiles of homozygous genotype-selected peripheral blood mononuclear cells (PBMCs) demonstrated that this region is a trans-expression quantitative trait locus (eQTL) in PBMCs. Signaling analysis predicted several tumor necrosis factor-related pathways, the TWEAK/Fn14 pathway being the top candidate (p = 2.42 × 10−11). This pathway is involved in the modulation of inflammation in several human AD, including multiple sclerosis, systemic lupus erythematosus, or rheumatoid arthritis. In vitro studies with genotype-selected lymphoblastoid cells from patients with MD suggest that this trans-eQTL may regulate cellular proliferation in lymphoid cells through the TWEAK/Fn14 pathway by increasing the translation of NF-κB. Taken together; these findings suggest that the carriers of the risk genotype may develop an NF-κB-mediated inflammatory response in MD

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

In an international cohort of 279 patients with hypoxemic influenza pneumonia, we identified 13 patients (4.6%) with autoantibodies neutralizing IFN-alpha and/or -omega, which were previously reported to underlie 15% cases of life-threatening COVID-19 pneumonia and one third of severe adverse reactions to live-attenuated yellow fever vaccine. Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-alpha 2 alone (five patients) or with IFN-omega (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-alpha 2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-omega. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients 70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-alpha 2 and IFN-omega (OR = 11.7, P = 1.3 x 10(-5)), especially those <70 yr old (OR = 139.9, P = 3.1 x 10(-10)). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for similar to 5% of cases of life-threatening influenza pneumonia in patients <70 yr old

Engrailed anterior compartment expression and the evolution of pre-adaptive novelty

Trabajo presentado en la 27th European Drospophila Research Conference, celebrada en Lyon (Francia) del 20 al 23 de octubre de 2023.The re-use, or co-option, of developmental genes in new organs forms the base of many evolutionary novelties. Although there is abundant research on gene co-option, few studies have considered the functional consequences of full gene network co-option. One of the best-characterised co-option cases is the recruitment of the posterior spiracle gene-network to the posterior lobe of the Drosophila melanogaster male genitalia.Peer reviewe

Gene network co-option and the evolution of pre-adaptive novelty

Trabajo presentado en EMBO Workshop The evolution of animal genomes, celebrado en Sevilla (España) del 18 al 21 de septiembre de 2023.The re-use of developmental genes in new organs forms the base of many evolutionary novelties. Although there is abundant research on gene co-option, few studies have considered the functional consequences of full gene network co-option. We found in Drosophila that a gene network required for the formation of the respiratory posterior spiracles organs has been co-opted to the testis mesoderm where is required for sperm liberation (spermiation). We observed that during embryogenesis, the posterior segment determinant engrailed is activated in the anterior A8 segment. This expression novelty appeared in the Drosophilids associated to the posterior spiracle gene network co-option event to the cells holding the sperm heads, the Head Cyst Cells (HCC). We discovered that the same cis and trans regulatory elements control engrailed expression in the anterior A8 cells and in the HCC. CRISPR deletion of the engrailed enhancer, shows that A8 anterior activation is not required for the spiracle¿s development but is required in the testis. Homozygous flies lacking the posterior spiracle en enhancer are completely sterile due to sperm degeneration. Our work presents an example of a bona fide pre-adaptive developmental expression novelty: the activation of the En transcription factor in the anterior compartment of the embryonic A8 segment where, despite having no specific function, opens the possibility of this important developmental factor acquiring one in the future. The expression of en in the anterior compartment of the A8 segment, was likely caused by the regulatory ¿interlocking¿ of the co-opted networks. We propose gene network interlocking occurs as the result of the use of the same gene network in several organs, so that any change to the network because of its functionality in one organ, will be mirrored in all organs even if it has no selective advantage in some of them.Peer reviewe

Direct regulation of <i>sna-rg</i> by STAT.

(A) Representation of the minimal sna-rg R2P2 subfragments indicating the location of the putative STAT (pink crosses) and Hox-Exd-Hth DNA binding sites (black boxes). Mutated STAT binding sites are represented with a red X over the pink cross. (B) sna-rg R2P2-GFP expression. (C) No GFP expression is observed in A1 nor in A2 constructs (D). Gland expression is observed when A1 is joined to the A2 proximal half (E) or when A1 is joined to the A2 distal half (F). (G) A1 fused to a 20bp from the vvl1+2 enhancer containing a functional STAT binding site. (H) A1 fused to the same 20bp fragment where the STAT binding site has been mutated. (I-K) Embryos carrying both the sna-rg-R2P2-GFP-PH (green) and the sna-rg-R2P2-STATmut Histone2B-RFP-GFP-PH (red and green) constructs. Red nuclear expression is not observed at early stage 11 (I) but can be detected later exclusively in the CA (J). Df(1)os1A embryos lacking all Upd ligands (K) do not express sna-rg-R2P2-STATmut mCherry-GFP-PH. Black arrows in (E-G) point to the CA/PG gland primordia, red arrows to ectopic expression outside the glands. Scale bars 50 μm.</p

Regulatory gene-network controlling CA and PG specification.

The regulation of the sna-rg enhancer in wild type embryos uncovers upstream factors mediating CA and PG specification. upd transcription is repressed directly or indirectly by both Ci and Arm-dTCF. Hh signalling from the posterior compartment releases the Ci repressive activity over upd transcription. Dfd and Scr proteins prevent the gland primordia from entering into apoptosis and also up-regulate Upd expression. Activated STAT induces sna transcription by direct binding to the sna-rg enhancer. Besides the Hox proteins, an additional factor (question mark) also contributes to upd expression in the maxilla and labium. This additional factor could be the activated form of the Ci protein or another factor still to be defined.</p

JAK/STAT pathway requirement for gland specification.

(A-B) Wild type embryos carrying the sna-rg-mCherry (red) and 10xSTAT-GFP (green) reporter genes. (A) At st10, embryos present patches of green staining in the maxillary and labial segments at the position where the gland primordia will become activated. Weak sna-rg expression starts to appear. (B) At st11, when sna-rg-mCherry is strongly activated, 10xSTAT-GFP expression has faded from the maxilla while is maintained in the labium. Note that 10xSTAT-GFP expression is also activated in the tracheal primordia. (C-I) upd mRNA in situ hybridization in st10-st11 embryos. (C) A wild type early st11 embryo showing upd mRNA in the maxillary and labial segments is restricted to two patches where the CA and the PG form. (D) At late st11, upd mRNA expression only remains in the PG (asterisk marks the position where the CA primordium is located). (E) hh null mutants lose maxillary and labial upd transcription (asterisks), which remains in the tracheal primordia. (F) In wg null mutants, upd transcription is extended in the maxillary and labial segments (arrows), as well as expanding around the tracheal primordia. (G) Dfd Scr mutants lose maxillary and labial upd transcription (asterisks). Embryos in (G) are also Abd-B homozygous mutant to allow distinguishing unambiguously the triple Dfd Scr Abd-B homozygous embryos by the absence of upd expression in the A8 posterior spiracle primordium. (H) upd expression in a control embryo at st10. (I) upd expression in an embryo expressing the activator isoform of Ci in a st10 embryo. Scale bars 50 μm.</p