Ancient Function of Teneurins in Tissue Organization and Neuronal Guidance in the Nematode Caenorhabditis elegans

The nematode Caenorhabditis elegans expresses the ten-1 gene that encodes teneurin. TEN-1 protein is expressed throughout the life of C. elegans. The loss of ten-1 function results in embryonic and larval lethality, highlighting its importance for fundamental processes during development. TEN-1 is expressed in the epidermis and neurons. Defects in neuronal pathfinding and epidermal closure are characteristic of ten-1 loss-of-function mutations. The molecular mechanisms of TEN-1 function in neurite outgrowth, neuronal pathfinding, and dendritic morphology in C. elegans are largely unknown. Its genetic redundancy with the extracellular matrix receptors integrin and dystroglycan and genetic interactions with several basement membrane components suggest a role for TEN-1 in the maintenance of basement membrane integrity, which is essential for neuronal guidance. Identification of the lat-1 gene in C. elegans, which encodes latrophilin, as an interaction partner of ten-1 provides further mechanistic insights into TEN-1 function in neuronal development. However, receptor-ligand interactions between LAT-1 and TEN-1 remain to be experimentally proven. The present review discusses the function of teneurin in C. elegans, with a focus on its involvement in the formation of receptor signaling complexes and neuronal networks

Diketopiperazine-Based, Flexible Tadalafil Analogues: Synthesis, Crystal Structures and Biological Activity Profile

Phosphodiesterase 5 (PDE5) is one of the most extensively studied phosphodiesterases that is highly specific for cyclic-GMP hydrolysis. PDE5 became a target for drug development based on its efficacy for treatment of erectile dysfunction. In the present study, we synthesized four novel analogues of the phosphodiesterase type 5 (PDE5) inhibitor—tadalafil, which differs in (i) ligand flexibility (rigid structure of tadalafil vs. conformational flexibility of newly synthesized compounds), (ii) stereochemistry associated with applied amino acid building blocks, and (iii) substitution with bromine atom in the piperonyl moiety. For both the intermediate and final compounds as well as for the parent molecule, we have established the crystal structures and performed a detailed analysis of their structural features. The initial screening of the cytotoxic effect on 16 different human cancer and non-cancer derived cell lines revealed that in most cases, the parent compound exhibited a stronger cytotoxic effect than new derivatives, except for two cell lines: HEK 293T (derived from a normal embryonic kidney, that expresses a mutant version of SV40 large T antigen) and MCF7 (breast adenocarcinoma). Two independent studies on the inhibition of PDE5 activity, based on both pure enzyme assay and modulation of the release of nitric oxide from platelets under the influence of tadalafil and its analogues revealed that, unlike a reference compound that showed strong PDE5 inhibitory activity, the newly obtained compounds did not have a noticeable effect on PDE5 activity in the range of concentrations tested. Finally, we performed an investigation of the toxicological effect of synthesized compounds on Caenorhabditis elegans in the highest applied concentration of 6a,b and 7a,b (160 μM) and did not find any effect that would suggest disturbance to the life cycle of Caenorhabditis elegans. The lack of toxicity observed in Caenorhabditis elegans and enhanced, strengthened selectivity and activity toward the MCF7 cell line made 7a,b good leading structures for further structure activity optimization and makes 7a,b a reasonable starting point for the search of new, selective cytotoxic agents

Proteasome activity contributes to prosurvival response upon mild mitochondrial stress in Caenorhabditis elegans

Defects in mitochondrial function activate compensatory responses in the cell. Mitochondrial stress that is caused by unfolded proteins inside the organelle induces a transcriptional response (termed the “mitochondrial unfolded protein response” [UPRmt]) that is mediated by activating transcription factor associated with stress 1 (ATFS-1). The UPRmt increases mitochondrial protein quality control. Mitochondrial dysfunction frequently causes defects in the import of proteins, resulting in the accumulation of mitochondrial proteins outside the organelle. In yeast, cells respond to mistargeted mitochondrial proteins by increasing activity of the proteasome in the cytosol (termed the “unfolded protein response activated by mistargeting of proteins” [UPRam]). The presence and relevance of this response in higher eukaryotes is unclear. Here, we demonstrate that defects in mitochondrial protein import in Caenorhabditis elegans lead to proteasome activation and life span extension. Both proteasome activation and life span prolongation partially depend on ATFS-1, despite its lack of influence on proteasomal gene transcription. Importantly, life span prolongation depends on the fully assembled proteasome. Our data provide a link between mitochondrial dysfunction and proteasomal activity and demonstrate its direct relevance to mechanisms that promote longevity

Products of Bisphenol A Degradation Induce Cytotoxicity in Human Erythrocytes (In Vitro)

The aim of this work has been to study the possible degradation path of BPA under the Fenton reaction, namely to determine the energetically favorable intermediate products and to compare the cytotoxicity of BPA and its intermediate products of degradation. The DFT calculations of the Gibbs free energy at M06-2X/6-311G(d,p) level of theory showed that the formation of hydroquinone was the most energetically favorable path in a water environment. To explore the cytotoxicity the erythrocytes were incubated with BPA and three intermediate products of its degradation, i.e., phenol, hydroquinone and 4-isopropylphenol, in the concentrations 5–200 μg/mL, for 1, 4 and 24 h. BPA induced the strongest hemolytic changes in erythrocytes, followed by hydroquinone, phenol and 4-isopropylphenol. In the presence of hydroquinone, the highest level of RONS was observed, whereas BPA had the weakest effect on RONS generation. In addition, hydroquinone decreased the level of GSH the most. Generally, our results suggest that a preferable BPA degradation path under a Fenton reaction should be controlled in order to avoid the formation of hydroquinone. This is applicable to the degradation of BPA during waste water treatment and during chemical degradation in sea water

Comprehensive list of SUMO targets in Caenorhabditis elegans and its implication for evolutionary conservation of SUMO signaling

Abstract Post-translational modification by small ubiquitin-related modifier (SUMO) is a key regulator of cell physiology, modulating protein-protein and protein-DNA interactions. Recently, SUMO modifications were postulated to be involved in response to various stress stimuli. We aimed to identify the near complete set of proteins modified by SUMO and the dynamics of the modification in stress conditions in the higher eukaryote, Caenorhabditis elegans. We identified 874 proteins modified by SUMO in the worm. We have analyzed the SUMO modification in stress conditions including heat shock, DNA damage, arsenite induced cellular stress, ER and osmotic stress. In all these conditions the global levels of SUMOylation was significantly increased. These results show the evolutionary conservation of SUMO modifications in reaction to stress. Our analysis showed that SUMO targets are highly conserved throughout species. By comparing the SUMO targets among species, we approximated the total number of proteins modified in a given proteome to be at least 15–20%. We developed a web server designed for convenient prediction of potential SUMO modification based on experimental evidences in other species

TENT5 cytoplasmic noncanonical poly(A) polymerases regulate the innate immune response in animals

International audienceInnate immunity is the first line of host defense against pathogens. Here, through global transcriptome and proteome analyses, we uncover that newly described cytoplasmic poly(A) polymerase TENT-5 (terminal nucleotidyltransferase 5) enhances the expression of secreted innate immunity effector proteins in Caenorhabditis elegans. Direct RNA sequencing revealed that multiple mRNAs with signal peptide-encoding sequences have shorter poly(A) tails in tent-5-deficient worms. Those mRNAs are translated at the endoplasmic reticulum where a fraction of TENT-5 is present, implying that they represent its direct substrates. Loss of tent-5 makes worms more susceptible to bacterial infection. Notably, the role of TENT-5 in innate immunity is evolutionarily conserved. Its orthologs, TENT5A and TENT5C, are expressed in macrophages and induced during their activation. Analysis of macrophages devoid of TENT5A/C revealed their role in the regulation of secreted proteins involved in defense response. In summary, our study reveals cytoplasmic polyadenylation to be a previously unknown component of the posttranscriptional regulation of innate immunity in animals