Biology subjects

Irie, Y.

Publications and source records attributed to Irie, Y..

4 recordsLinked to original sources

bioRxiv2022

Black Queen Hypothesis, partial privatization, andquorum sensing evolution

Microorganisms produce costly cooperative goods whose benefit is partially shared with nonproducers, called mixed goods. The Black Queen Hypothesis predicts that partially privatization of benefits from the mixed goods has two major evolutionary implications. First, to favor strains producing several mixed goods over nonproducing strains. Second, to favor the maintenance of cooperative traits through different strains instead of having all cooperative traits present in a single strain (metabolic specialization). Despite the importance of quorum sensing regulation of mixed goods, it is not clear how partial privatization of benefits affects quorum sensing evolution. Here, we studied the influence of partial privatization of benefits on the evolution of quorum sensing. We developed a mathematical population genetics model of an unstructured microbial population considering four strains that differ in their ability to produce an autoinducer (quorum sensing signaling molecule) and a mixed good. Our model assumes that the production of the autoinducers and the mixed goods is constitutive and/or depends on quorum sensing. Our results suggest that partially privatized benefits cannot foster quorum sensing. This result occurs because: (1) a strain that produces both autoinducer and good (fully producing strain) cannot persist in the population; (2) the strain only producing the autoinducer and the strain producing mixed goods in response to the autoinducers cannot coexist, i.e., metabolic specialization cannot be fostered.

evolutionary biology↗

bioRxiv2021

APOE ε4 allele advances the age-dependent decline of amyloid β clearance in the human cortex

IntroductionOur previous study indicated that the pericapillary clearance of amyloid {beta} (A{beta}) declines with age in APOE 3/3 subjects. Here, we examine whether the APOE {varepsilon}4 allele has an impact on this age-related decline. MethodsWe examined 69 autopsy brains of APOE {varepsilon}3/{varepsilon}4 or APOE {varepsilon}3/{varepsilon}3 individuals (30-65 years) for the immunohistochemical localization of intracellular, extracellular, and pericapillary A{beta} in the cerebral cortex. ResultsIn APOE {varepsilon}3/{varepsilon}4 individuals, the percentage of A{beta} positive pericapillary spaces began to decrease (p=0.030), and the number of extracellular A{beta} particles increased in the early 30s (p=0.0008). Those average values were significantly lower (p<0.0001) and higher (p<0.0001), respectively, compared to APOE {varepsilon}3/{varepsilon}3 individuals. DiscussionOur observations indicate that APOE {varepsilon}4 allele advances by one decade at the onset of age-related decline in A{beta} glymphatic clearance. This finding supports early clinical intervention and stratification by APOE genotype to prevent A{beta} deposition and AD progression.

pathology↗

bioRxiv2020

Pseudomonas aeruginosa biofilms display carbohydrate ligands for CD206 and CD209 that interfere with their receptor function

Bacterial biofilms represent a challenge to the healthcare system because of their resilience against antimicrobials and immune attack. Biofilms consist of bacterial aggregates embedded in an extracellular polymeric substance (EPS) composed of carbohydrate polymers, nucleic acids and proteins. Carbohydrates within P. aeruginosa biofilms include neutral and mannose-rich Psl, and cationic Pel composed of N-acetyl-galactosamine and N-acetyl-glucosamine. Here we show that P. aeruginosa biofilms display ligands for the C-type lectin receptors mannose receptor (MR, CD206) and Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209). Binding of MR and DC-SIGN to P. aeruginosa biofilms is carbohydrate-and calcium-dependent and extends to biofilms formed by clinical isolates. Confocal analysis of P. aeruginosa biofilms shows abundant DC-SIGN ligands among bacteria aggregates while MR ligands concentrate into discrete clusters. DC-SIGN ligands are also detected in planktonic P. aeruginosa cultures and depend on the presence of the common polysaccharide antigen. Carbohydrates purified from P. aeruginosa biofilms are recognised by DC-SIGN and MR; both receptors preferentially bind the high molecular weight fraction (HMW; >132,000Da) with KDs in the nM range. HMW preparations contain 74.9-80.9% mannose, display -mannan segments and alter the morphology of human dendritic cells without causing obvious changes in cytokine responses. Finally, HMW interferes with the endocytic activity of cell-associated MR and DC-SIGN. This work identifies MR and DC-SIGN as receptors for bacterial biofilms and highlights the potential for biofilm-associated carbohydrates as immunomodulators through engagement of C-type lectin receptors. Author SummarySelective engagement of pattern recognition receptors during infection guides the decision-making process during induction of immune responses. This work identifies mannose-rich carbohydrates within bacterial biofilms as novel molecular patterns associated with bacterial infections. P. aeruginosa biofilms and biofilm-derived carbohydrates bind two important lectin receptors, MR (CD206) and DC-SIGN (CD209), involved in recognition of self and immune evasion. Abundance of MR and DC-SIGN ligands in the context of P. aeruginosa biofilms could impact immune responses and promote chronic infection.

microbiology↗

bioRxiv2018

Hfq-assisted RsmA regulation is central to Pseudomonas aeruginosa biofilm and motility

Expression of biofilm-associated genes is controlled by multiple regulatory elements, allowing bacteria to appropriately switch between sessile and motile lifestyles. In Pseudomonas aeruginosa, the post-transcriptional regulator RsmA has been implicated in the control of various genes including those related to biofilms, but much of the evidence for these links is limited to transcriptomic and phenotypic studies. RsmA binds to target mRNAs to modulate translation by affecting ribosomal access and/or mRNA stability. Here we trace a global regulatory role of RsmA to the inhibition of Vfr - a transcription factor that controls a transcriptional regulator FleQ. FleQ directly controls biofilm-associated genes that encode the PEL polysaccharide biosynthesis machinery. Furthermore, we show that RsmA cannot bind vfr mRNA alone, but requires the RNA chaperone protein Hfq. This is the first example where a RsmA protein family member is demonstrated to require another protein for RNA binding.

microbiology↗