Staff member

Anna Seriola Petit

Senior Researcher
Bioengineering in Reproductive Health

Staff member publications

Hortigüela, Verónica, Larrañaga, Enara, Cutrale, Francesco, Seriola, Anna, García-Díaz, María, Lagunas, Anna, Andilla, Jordi, Loza-Alvarez, Pablo, Samitier, Josep, Ojosnegros, Samuel, Martinez, Elena, (2018). Nanopatterns of surface-bound ephrinB1 produce multivalent ligand-receptor interactions that tune EphB2 receptor clustering Nano Letters 18, (1), 629-637

Here we present a nanostructured surface able to produce multivalent interactions between surface-bound ephrinB1 ligands and membrane EphB2 receptors. We created ephrinB1 nanopatterns of regular size (<30 nm in diameter) by using self-assembled diblock copolymers. Next, we used a statistically enhanced version of the Number and Brightness technique, which can discriminate - with molecular sensitivity - the oligomeric states of diffusive species to quantitatively track the EphB2 receptor oligomerization process in real time. The results indicate that a stimulation using randomly distributed surface-bound ligands was not sufficient to fully induce receptor aggregation. Conversely, when nanopatterned onto our substrates, the ligands effectively induced a strong receptor oligomerization. This presentation of ligands improved the clustering efficiency of conventional ligand delivery systems, as it required a 9-fold lower ligand surface coverage and included faster receptor clustering kinetics compared to traditional crosslinked ligands. In conclusion, nanostructured diblock copolymers constitute a novel strategy to induce multivalent ligand-receptor interactions leading to a stronger, faster, and more efficient receptor activation, thus providing a useful strategy to precisely tune and potentiate receptor responses. The efficiency of these materials at inducing cell responses can benefit applications such as the design of new bioactive materials and drug-delivery systems.

Ojosnegros, Samuel, Cutrale, Francesco, Rodríguez, Daniel, Otterstrom, Jason J., Chiu, Chi Li, Hortigüela, Verónica, Tarantino, Carolina, Seriola, Anna, Mieruszynski, Stephen, Martínez, Elena, Lakadamyali, Melike, Raya, Angel, Fraser, Scott E., (2017). Eph-ephrin signaling modulated by polymerization and condensation of receptors Proceedings of the National Academy of Sciences of the United States of America 114, (50), 13188-13193

Eph receptor signaling plays key roles in vertebrate tissue boundary formation, axonal pathfinding, and stem cell regeneration by steering cells to positions defined by its ligand ephrin. Some of the key events in Eph-ephrin signaling are understood: ephrin binding triggers the clustering of the Eph receptor, fostering transphosphorylation and signal transduction into the cell. However, a quantitative and mechanistic understanding of how the signal is processed by the recipient cell into precise and proportional responses is largely lacking. Studying Eph activation kinetics requires spatiotemporal data on the number and distribution of receptor oligomers, which is beyond the quantitative power offered by prevalent imaging methods. Here we describe an enhanced fluorescence fluctuation imaging analysis, which employs statistical resampling to measure the Eph receptor aggregation distribution within each pixel of an image. By performing this analysis over time courses extending tens of minutes, the information-rich 4D space (x, y, oligomerization, time) results were coupled to straightforward biophysical models of protein aggregation. This analysis reveals that Eph clustering can be explained by the combined contribution of polymerization of receptors into clusters, followed by their condensation into far larger aggregates. The modeling reveals that these two competing oligomerization mechanisms play distinct roles: polymerization mediates the activation of the receptor by assembling monomers into 6- to 8-mer oligomers; condensation of the preassembled oligomers into large clusters containing hundreds of monomers dampens the signaling. We propose that the polymerization–condensation dynamics creates mechanistic explanation for how cells properly respond to variable ligand concentrations and gradients.

Keywords: Eph, Ephrin, Receptor tyrosine kinase, Gradients, Cell communication