Biology subjects

Pajonczyk, D.

Publications and source records attributed to Pajonczyk, D..

4 recordsLinked to original sources

bioRxiv2026

Modulation of the agonist and antagonist activity of peptidic FPR1 ligands through N-terminal modifications: A structural and functional analysis

Formyl peptide receptor 1 (FPR1) is a promising therapeutic target for the treatment of inflammatory and infectious diseases. Although multiple classes of peptides are known to modulate FPR1 activity, comprehensive studies systematically linking N-terminal modifications to binding, mechanism of action and functional outcomes remain limited. In this study, we aimed to rationalise the binding and activity of three peptide series (MLF, FLFLF, and MLFYLA) featuring diverse N-terminal modifications from a structural point of view. A combined in silico and in vitro approach was employed to evaluate the activity of newly designed peptide agonists and to generate mechanistic binding hypotheses. Our findings led to the identification of a transmembrane binding pocket in FPR1, which provides a structural basis for the observed antagonist and partial agonist behaviours and leads to a generalisable strategy for tuning the functional outcome of peptidic ligands.

pharmacology and toxicology↗

bioRxiv2024

Physiological bias governs neutrophil inflammatory threat perception

Background and PurposeThe functional G protein-coupled receptor (GPCR) signalling unit consists of an agonist acting on a receptor that is coupled to a G protein that transduces the signals to effectors within a complex cellular environment. While much attention is given to GPCR-agonist or GPCR-transducer relationships, the contribution of the cellular environment remains significantly unexplored. Experimental ApproachHere, we juxtaposed the signalling responses triggered by the activation of two GPCR pattern recognition receptors, Formyl peptide receptor 1 and Formyl peptide receptor 2, in a recombinant cell system against their signalling dynamics in the native neutrophilic environment. Key resultsWe observed that agonist activation leads to cell context-dependent substantial differences in the receptor signalling texture. While the impact of receptor activation on de novo cAMP formation varied depending on the cell type, MAPK activation was similar in both systems. This physiological bias was conserved across species. Expression analysis unveiled the absence of the Gi-sensitive adenylyl cyclases ADCY5 and ADCY6 in neutrophils, implying that cAMP de novo synthesis cannot be inhibited by Gi-coupled receptors. The signalling behaviour of the Gi-coupled LTB4 high-affinity receptor BLT1 in neutrophils corroborated our findings. Conclusion and ImplicationsOur data underscore the profound impact of the specific cellular environment on GPCR signalling, causing physiological bias in GPCR signalling, thereby affecting drug efficacy and therapeutic targeting.

systems biology↗

bioRxiv2024

Comparative analysis of Formyl peptide receptor 1 and Formyl peptide receptor 2 reveals shared and preserved signaling profiles

Pattern Recognition Receptors are key in identifying pathogenic or damaged cell-related patterns or molecules. Among these, the closely linked formyl peptide receptors FPR1 and FPR2 are believed to hold pivotal yet differing functions in immune regulation. To address the intriguing question of how these highly related receptors with a shared agonist spectrum play differing roles in modulating inflammation, we analyzed the signaling profile for a panel of FPR agonists in vivo and ex vivo settings. Our analysis uncovered a shared core signature for both FPRs across signaling pathways. Whereas formylated peptides generally acted as potent agonists at FPR1, FPR2 agonists, irrespective of N-terminal formylation, displayed consistently low activity ratios, suggesting an underutilized signaling potential of this receptor. Signaling outcomes were defined by specific agonist-receptor pairings and no receptor-specific signaling texture was identified. Activation of the FPR signaling axis by fMLF in human neutrophils did impact neutrophil survival. Overall, the distinct characteristics underlying inflammatory, anti-inflammatory, or pro-resolving profiles could not be attributed to a specific receptor isoform, signaling pattern, or a particular class of agonists, challenging assumptions about distinct inflammatory profiles linked to specific receptors, signaling patterns, or agonist classes.

pharmacology and toxicology↗

bioRxiv2021

A novel adhesive complex at the base of intestinal microcilli

Intestinal epithelial cells form dense arrays of microvilli at the apical membrane to enhance their functional capacity. Microvilli contain a protocadherin-based intermicrovillar adhesion complex localized at their tips which regulates microvillar length and packaging. Here, we identify a second adhesive complex in microvilli of intestinal epithelial cells. This complex is localized at the basal region of microvilli and consists of the adhesion molecule TMIGD1, the phosphoprotein EBP50 and the F-actin - plasma membrane cross-linking protein ezrin. Ternary complex formation requires unmasking of the EBP50 PDZ domains by ezrin binding and is strongly enhanced upon mutating Ser162 located in PDZ domain 2 of EBP50. Dephosphorylation of EBP50 at S162 is mediated by PP1, a serine/threonine phosphatase localized at the microvillar base and involved in ezrin phosphocycling. Importantly, the binding of EBP50 to TMIGD1 enhances the dynamic turnover of EBP50 at microvilli in a Ser162 phosphorylation-dependent manner. We identify an adhesive complex at the microvillar base and propose a potential mechanism that regulates microvillar dynamics in enterocytes.

cell biology↗