The evolution of S100A7: an unusual gene expansion in Myotis bats

Evolution of guanylate binding protein genes shows a remarkable variability within bats (Chiroptera)

Background

GBPs (guanylate binding proteins), an evolutionary ancient protein family, play a key role in the host's innate immune response against bacterial, parasitic and viral infections. In Humans, seven GBP genes have been described (GBP1-7). Despite the interest these proteins have received over the last years, evolutionary studies have only been performed in primates, Tupaia and rodents. These have shown a pattern of gene gain and loss in each family, indicative of the birth-and-death evolution process.

Results

In this study, we analysed the evolution of this gene cluster in several bat species, belonging to the Yangochiroptera and Yinpterochiroptera sub-orders. Detailed analysis shows a conserved synteny and a gene expansion and loss history. Phylogenetic analysis showed that bats have GBPs 1,2 and 4-6. GBP2 has been lost in several bat families, being present only in Hipposideidae and Pteropodidae. GBPs1, 4 and 5 are present mostly as single-copy genes in all families but have suffered duplication events, particularly in Myotis myotis and Eptesicus fuscus. Most interestingly, we demonstrate that GBP6 duplicated in a Chiroptera ancestor species originating two genes, which we named GBP6a and GBP6b, with different subsequent evolutionary histories. GBP6a underwent several duplication events in all families while GBP6b is present as a single copy gene and has been lost in Pteropodidae, Miniopteridae and Desmodus rotundus, a Phyllostomidae. With 14 and 15 GBP genes, Myotis myotis and Eptesicus fuscus stand out as having far more copies than all other studied bat species. Antagonistically, Pteropodidae have the lowest number of GBP genes in bats.

Conclusion

Bats are important reservoirs of viruses, many of which have become zoonotic diseases in the last decades. Further functional studies on bats GBPs will help elucidate their function, evolutionary history, and the role of bats as virus reservoirs.

Comparative analysis of the physical properties of murine and human S100A7: Insight into why zinc piracy is mediated by human but not murine S100A7

S100 proteins are a subfamily of EF-hand calcium-binding proteins found primarily in vertebrate animals. They are distinguished by binding of transition metals and functioning in both the intracellular and extracellular milieu. S100A7 functions in the protection of the skin and mucous membranes and is a biomarker in inflammatory skin disease. A recent study of Neisseria gonorrhoeae infection revealed that human but not murine S100A7 could be used to evade host nutritional immunity. To understand the molecular basis for this difference, we carried out a comparative analysis of the physical and structural properties of human and murine S100A7. The X-ray crystal structure of Ca2+-loaded mouse S100A7 (mS100A7) was determined to 1.69 Å resolution, and Ca2+-induced conformational changes were assessed by NMR. Unlike human S100A7 (hS100A7), which exhibits conformational changes in response to binding of Ca2+, no significant changes in mS100A7 were detected. Dynamic light scattering, circular dichroism, and a competition chelator assay were used to compare the Zn2+ affinity and the effects of ion binding on mS100A7 versus hS100A7. Alignment of their sequences revealed a substantial difference in the C-terminal region, which is an important mediator of protein-protein interactions, suggesting a rationale for the specificity of N. gonorrhoeae for hS100A7. These data, along with more detailed analysis of S100A7 sequence conservation across different species, support the proposal that, although hS100A7 is highly conserved in many mammals, the murine protein is a distinct ortholog. Our results highlight the potential limitations of using mouse models for studying bacterial infections in humans.

Dynamic Evolution of Bacterial Ligand Recognition by Formyl Peptide Receptors

The detection of invasive pathogens is critical for host immune defense. Cell surface receptors play a key role in the recognition of diverse microbe-associated molecules, triggering leukocyte recruitment, phagocytosis, release of antimicrobial compounds, and cytokine production. The intense evolutionary forces acting on innate immune receptor genes have contributed to their rapid diversification across plants and animals. However, the functional consequences of immune receptor divergence are often unclear. Formyl peptide receptors (FPRs) comprise a family of animal G protein-coupled receptors which are activated in response to a variety of ligands including formylated bacterial peptides, pathogen virulence factors, and host-derived antimicrobial peptides. FPR activation in turn promotes inflammatory signaling and leukocyte migration to sites of infection. Here we investigate patterns of gene loss, diversification, and ligand recognition among FPRs in primates and carnivores. We find that FPR1, which plays a critical role in innate immune defense in humans, has been lost in New World primates. Amino acid variation in FPR1 and FPR2 among primates and carnivores is consistent with a history of repeated positive selection acting on extracellular domains involved in ligand recognition. To assess the consequences of FPR divergence on bacterial ligand interactions, we measured binding between primate FPRs and the FPR agonist Staphylococcus aureus enterotoxin B, as well as S. aureus FLIPr-like, an FPR inhibitor. We found that few rapidly evolving sites in primate FPRs are sufficient to modulate recognition of bacterial proteins, demonstrating how natural selection may serve to tune FPR activation in response to diverse microbial ligands.

Convergent Loss of the Necroptosis Pathway in Disparate Mammalian Lineages Shapes Viruses Countermeasures

Programmed cell death is a vital process in the life cycle of organisms. Necroptosis, an evolutionary form of programmed necrosis, contributes to the innate immune response by killing pathogen-infected cells. This virus-host interaction pathway is organized around two components: the receptor-interacting protein kinase 3 (RIPK3), which recruits and phosphorylates the mixed lineage kinase-like protein (MLKL), inducing cellular plasma membrane rupture and cell death. Critically, the presence of necroptotic inhibitors in viral genomes validates necroptosis as an important host defense mechanism. Here, we show, counterintuitively, that in different mammalian lineages, central components of necroptosis, such as RIPK3 and MLKL, are deleted or display inactivating mutations. Frameshifts or premature stop codons are observed in all the studied species of cetaceans and leporids. In carnivores’ genomes, the MLKL gene is deleted, while in a small number of species from afrotheria and rodentia premature stop codons are observed in RIPK3 and/or MLKL. Interestingly, we also found a strong correlation between the disruption of necroptosis in leporids and cetaceans and the absence of the N-terminal domain of E3-like homologs (responsible for necroptosis inhibition) in their naturally infecting poxviruses. Overall, our study provides the first comprehensive picture of the molecular evolution of necroptosis in mammals. The loss of necroptosis multiple times during mammalian evolution highlights the importance of gene/pathway loss for species adaptation and suggests that necroptosis is not required for normal mammalian development. Moreover, this study highlights a co-evolutionary relationship between poxviruses and their hosts, emphasizing the role of host adaptation in shaping virus evolution.

S100A7 promotes the development of human endometriosis by activating NF-κB signaling pathway in endometrial stromal cells

Endometriosis (EM) is a chronic inflammatory disease affecting women aged between 23 and 42 years with a prevalence of 6%-10%. S100A7, a member of the S100 protein family, has been implicated in promoting inflammation. However, the role of S100A7 in EM and its underlying mechanism remain to be elucidated. S100A7 was silenced or overexpressed in primary endometrial stromal cells (ESCs). Cell proliferation was determined using a Cell Counting Kit-8. Cell cycle/apoptosis was monitored using a flow cytometer. Cell invasion was studied by a Transwell assay. Quantitative RT-PCR and Western blot analyses were used to evaluate gene expression. S100A7 and NF-κB expression is increased in both endometriotic tissue and ESCs from women with EM. The expression of S100A7 is correlated with the expression of NF-κB. S100A7 knockdown inhibits ESCs proliferation, cell cycle progression, cell invasion, and inflammation, but promotes cell apoptosis in an NF-κB dependent manner. In contrast, S100A7 overexpression demonstrated an inverse effect. S100A7 is increased in both endometriotic tissue and ESCs from women with EM. S100A7 overexpression contributes to EM through increasing ESCs proliferation, cell cycle progression, cell invasion, and inflammation, and inhibiting cell apoptosis in the NF-κB dependent manner. These findings highlight the importance of S100A7/NF-κB signaling in EM and provide new insights into therapeutic strategies for EM.

Decoding Psoriasis: Integrated Bioinformatics Approach to Understand Hub Genes and Involved Pathways

BACKGROUND

Psoriasis is a chronic immune mediated skin disorder with global prevalence of 0.2- 11.4%. Despite rare mortality, the severity of the disease could be understood by the accompanying comorbidities, that has even led to psychological problems among several patients. The cause and the disease mechanism still remain elusive.

OBJECTIVE

To identify potential therapeutic targets and affecting pathways for better insight of the disease pathogenesis.

METHOD

The gene expression profile GSE13355 and GSE14905 were retrieved from NCBI, Gene Expression Omnibus database. The GEO profiles were integrated and the DEGs of lesional and non-lesional psoriasis skin were identified using the affy package in R software. The Kyoto Encyclopaedia of Genes and Genomes pathways of the DEGs were analyzed using clusterProfiler. Cytoscape, V3.7.1 was utilized to construct protein interaction network and analyze the interactome map of candidate proteins encoded in DEGs. Functionally relevant clusters were detected through Cytohubba and MCODE.

RESULTS

A total of 1013 genes were differentially expressed in lesional skin of which 557 were upregulated and 456 were downregulated. Seven dysregulated genes were extracted in non-lesional skin. The disease gene network of these DEGs revealed 75 newly identified differentially expressed gene that might have a role in development and progression of the disease. GO analysis revealed keratinocyte differentiation and positive regulation of cytokine production to be the most enriched biological process and molecular function. Cytokines -cytokine receptor was the most enriched pathways. Among 1013 identified DEGs in lesional group, 36 DEGs were found to have altered genetic signature including IL1B and STAT3 which are also reported as hub genes. CCNB1, CCNA2, CDK1, IL1B, CXCL8, MKI 67, ESR1, UBE2C, STAT1 and STAT3 were top 10 hub gene.

CONCLUSION

The hub genes, genomic altered DEGs and other newly identified differentially dysregulated genes would improve our understanding of psoriasis pathogenesis, moreover, the hub genes could be explored as potential therapeutic targets for psoriasis.

Antimicrobial peptides as an argument for the involvement of innate immunity in psoriasis (Review)

Antimicrobial peptides (AMPs) are a group of oligopeptides found in most multicellular organisms with a capacity for rapid and nonspecific destruction of pathogens. The action of destroying pathogens is associated with a strong proinflammatory activity, stimulating the secretion of cytokines, chemokines, growth factors but also chemotaxis, the activation of dendritic cells and involving adaptive immunity also. The action of AMPs fits perfectly into the characteristics of innate immunity which makes these peptides candidates to be considered as an important element of this type of immunity. It has been shown that AMPs are involved in a number of cellular processes such as: differentiation, proliferation, maturation, thus widening the degree of involvement of these peptides in the pathogenesis of chronic inflammatory diseases. In psoriasis, AMPs act both as a pro-inflammatory and chemotaxis factor and through the cathelicidin (LL-37)/dc DNA complex as a possible autoantigen for T cells, triggering an autoimmune response, activating the Th17/IL23 axis and maintaining the inflammatory process. Thus, many arguments are accumulated to consider that innate immunity through AMPs is an important link in the pathogenesis of psoriasis. Moreover, the action of antimicrobial peptides in psoriasis is almost entirely characteristic for the general mode of action of innate immunity.

S100A7/Ran-binding protein 9 coevolution in mammals

S100A7 has been suggested to interact with Ran-binding protein 9. Both proteins are nowadays considered key effectors in immune response. Functional interaction between proteins is ensured by coevolution. The mechanisms of vertebrate coevolution between S100A7 and RanBP9 remain unclear. Several approaches for studying coevolution have been developed. Protein coevolution was inferred by calculating the linear correlation coefficients between inter-protein distance matrices using Mirrortree. We found an overall moderate correlation value (R = 0.53, p < 1e-06). Moreover, owing to the high conservation of RanBP9 protein among vertebrates, we chose to utilize a recent version of Blocks in Sequences (BIS2) algorithm implemented in BIS2Analyzer webserver. A coevolution cluster was identified between the two proteins (p < 8.10e-05). In conclusion, our coevolutionary analysis suggests that amino acid variations may modulate S100A7/RanBP9 interaction with potential pathogenic effects. Such findings could guide further analysis to better elucidate the function of S100A7 and RanBP9 and to design drugs targeting for these molecules in diseases.