Biology subjects

Royo, M.

Publications and source records attributed to Royo, M..

5 recordsLinked to original sources

bioRxiv2026

Preimplantation factor (PIF) links embryo-derived signaling to maternal pancreatic β-cell adaptation through an ERα-dependent pathway

Pregnancy requires maternal pancreatic {beta}-cells adaptations to increased insulin demand, yet the embryo-derived signals contributing to this response remain poorly defined. Here we identify preimplantation factor (PIF), an embryo-derived peptide present in maternal circulation from early gestation, as a regulator of {beta}-cell adaptation. In a murine model of gestational diabetes mellitus (GDM), circulating PIF levels were reduced during mid-gestation, indicating that this endogenous signal is altered under gestational metabolic dysfunction. Conversely, chronic exposure of non-pregnant female mice to synthetic PIF (sPIF) recapitulated key temporal features of gestational {beta}-cell adaptation, including early {beta}-cell proliferation, increased glucose-stimulated circulating C-peptide, expansion of {beta}-cell mass and sustained enhancement of ex vivo glucose-stimulated insulin secretion (GSIS). Mechanistically, sPIF activated rapid ERK-, AKT- and PKA-dependent signaling that converged on estrogen receptor alpha (ER) phosphorylation and nuclear translocation. Pharmacological inhibition and genetic silencing demonstrated that ER is required for full propagation of the functional and kinase responses. This kinase-ER axis was conserved in human islets, where sPIF enhanced insulin secretion in an ER-dependent manner. These findings identify PIF as an embryo-derived metabolic signal supporting maternal {beta}-cell compensation and suggest that reduced PIF availability may contribute to inadequate {beta}-cell adaptation in GDM.

physiology↗

bioRxiv2026

cis-gamma-Amino-L-proline peptides as chemical probes of amyloidogenic processing in neurons and APP/PS1 mice

Alzheimers disease (AD) is characterized by the accumulation of amyloid-{beta} (A{beta}) peptides, which are a key factor in its pathogenesis. In this study, we present the design and evaluation of {gamma}-amino-L-proline peptides as metabolically stable, cell-penetrating molecules that can modulate amyloidogenic processing. We screened a library of {gamma}-peptides in primary neuronal cultures to determine their effects on endogenous A{beta}1-42 production, cytotoxicity, and {beta}-secretase (BACE1) activity. Comparative analysis of structurally related analogues enabled the identification of molecular features associated with A{beta}-lowering activity, establishing a qualitative structure-activity relationship. Peptide 33 (P33) emerged as a lead candidate, selectively reducing BACE1 activity without significantly inhibiting the homologous enzyme, BACE2. In vitro blood-brain barrier (BBB) assays revealed that P33 exhibits favorable transendothelial permeability. Intraperitoneal administration of P33 in APP/PS1 mice decreased A{beta} levels, reduced amyloid plaque burden, and improved performance in a behavioral recognition task without inducing cytotoxicity or systemic toxicity. These results define cis-{gamma}-amino-L-proline peptides as a bioorganically distinct and modular scaffold for the development of intracellular modulators of A{beta} production. HighlightsO_LI{gamma}LJAminoLJLLJproline peptides as metabolically stable modulators of A{beta} production. C_LIO_LIP33 showed BBB permeability and BACE1 inhibition in primary cortical neurons. C_LIO_LIIn APP/PS1 mice, P33 lowers amyloid burden and improves cognition. C_LIO_LIP33 shows good biocompatibility, supporting its therapeutic potential in AD C_LI

neuroscience↗

bioRxiv2026

Dysfunctional synaptic competition at dendritic spines in Fragile X syndrome

Dendritic spines are highly dynamic structures whose morphology and lifespan are modified in response to synaptic efficacy changes. Structural modifications following activity support the long-term encoding of information and could allow for the remodeling of neural circuits. Long-term depression (LTD) is a key mechanism for synaptic weight regulation, yet its structural correlates -- particularly for long-lasting, protein synthesis dependent forms -- remain poorly understood. Furthermore, in humans, this type of plasticity is often disrupted in neurodevelopmental disorders, correlating with cognitive dysfunction and structural abnormalities. Fragile X Syndrome (FXS) is the most common inherited form of intellectual disability and is characterized by excessive metabotropic receptor-mediated synaptic depression, excessive protein synthesis, and spine abnormalities. Here, we investigate the relationship between long lasting synaptic depression and structural plasticity, as well as the role of protein availability in determining how many spines can simultaneously undergo structural changes during LTD in both healthy and FXS mutant neurons. Using high resolution optical methods, we developed and tested a method for inducing metabotropic glutamate receptor (mGluR)-dependent depression at single spines via glutamate uncaging in mouse hippocampal neurons. We found that this form of activity leads to robust spine shrinkage, which requires new protein synthesis. However, when we induced this depression at multiple spines, they competed for structural changes and only one spine shrank. We hypothesized that this was due to limited resources, in the form of newly made proteins, and therefore, we decided to test if spine competition would be altered in the mouse model of FXS, where protein levels are abnormally elevated. Indeed, we found that competition was absent in FXS mutant neurons, and all of the stimulated spines underwent shrinkage following LTD induction. Importantly, we found that single spine structural plasticity in FXS was expressed to the same degree as in WT controls. Taken together, these findings suggest that the hallmark phenotype of excess mGluR LTD in FXS may result from a greater number of inputs undergoing synaptic depression, rather than excessive LTD at individual synapses. By probing plasticity at the level of individual inputs, our findings highlight the importance of evaluating activity across groups of synapses, in order to uncover plasticity interactions that are critical for learning. Understanding how these mechanisms are disrupted in neurodevelopmental disorders such as FXS can inform the development of effective therapeutic strategies.

neuroscience↗

bioRxiv2024

A CYCLIC PEPTIDE TARGETS GLIOBLASTOMA BY BINDING TO ABERRANTLY EXPOSED SNAP25

Disease-specific changes in tumors and other diseased tissues are an important target of research because they provide clues on the pathophysiology of the disease as well as uncovering potentially useful markers for diagnosis and treatment. Here, we report a new cyclic peptide, CESPLLSEC (CES), that specifically accumulated (homed) in intracranial U87MG and the WT-GBM model of glioblastoma from intravenous (IV) injection, associating with the vasculature. Affinity chromatography of U87MG tumor extracts on insolubilized CES peptide identified Synaptosomal Associated Protein 25 (SNAP25) as a candidate target molecule (receptor) for CES. Several results supported the identification of SNAP25 as the CES receptor. IV-injected FAM-CES colocalized with SNAP25 in the tumors, and direct binding studies showed specific CES peptide binding to recombinant human SNAP25. A CES peptide-drug conjugate designed for photodynamic therapy showed selective cytotoxicity to SNAP25+ glioblastoma cell lines. Specific accumulation of systemically injected anti-SNAP25 antibody in U87MG glioblastoma, and labeling of intact U87MG cells with anti-SNAP in flow cytometry showed that SNAP25 is available from the circulation but not in normal tissues and that it is present at the cell surface. Using an array of ECM proteins and surface plasmon resonance revealed that SNAP25 binds moderately to collagen V and strongly to collagen VI. Modeling studies suggested that CES and collagen VI compete for the same binding site on SNAP25. Our results introduce CES as a valuable targeting peptide for drug delivery, and its receptor SNAP25 as a possible molecular marker of interest for glioblastoma.

cancer biology↗

bioRxiv2024

Therapeutic Tumor Macrophage Reprogramming in Breast Cancer Through a Peptide-Drug Conjugate

In triple negative breast cancer (TNBC), pro-tumoral macrophages promote metastasis and suppress the immune response. To target these cells, we engineered a previously identified CD206 (mannose receptor)-binding peptide, mUNO, to enhance its affinity and proteolytic stability. The new rationally designed peptide, MACTIDE, includes a trypsin inhibitor loop, from the Sunflower Trypsin Inhibitor-I. Binding studies to recombinant CD206 revealed a 15-fold lower KD for MACTIDE compared to parental mUNO. Additionally, mass spectrometry showed a 5-fold increase in half-life in tumor lysate for MACTIDE compared to mUNO. Homing studies in TNBC-bearing mice showed that fluorescein (FAM)-MACTIDE precisely targeted CD206+ tumor-associated macrophages (TAMs) upon intravenous, intraperitoneal and even oral administration, with no significant accumulation in liver. We coupled MACTIDE to the FDA-approved drug Verteporfin, an established photosensitizer for photodynamic therapy and inhibitor of the YAP/TAZ pathway, to generate a conjugate here referred to as MACTIDE-V. In the orthotopic 4T1 TNBC mouse model, non-irradiated MACTIDE-V-treated mice unexpectedly showed a similar anti-tumoral effect and fewer signs of toxicity as irradiated MACTIDE-V-treated mice, leading to subsequent studies on the laser-independent activity of this conjugate. In vitro studies using bone-marrow derived mouse macrophages showed that MACTIDE-V excluded YAP from the nucleus, increased the phagocytic activity and upregulated several genes associated with cytotoxic anti-tumoral macrophages. In mouse models of TNBC, MACTIDE-V slowed primary tumor growth, suppressed lung metastases, increased markers of phagocytosis and antigen presentation in TAMs and monocytes, increasing the tumor infiltration of several lymphocyte subsets. We therefore propose MACTIDE-V as a useful peptide-drug conjugate to modulate macrophage function in the context of breast tumor immunotherapy.

cancer biology↗