Biology subjects

Ochoa, J. C.

Publications and source records attributed to Ochoa, J. C..

4 recordsLinked to original sources

bioRxiv2025

Dynamic Rysto receptor remodeling controls its ability to confer extreme resistance

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) mediate effector-triggered immunity (ETI), often accompanied by a hypersensitive response (HR). Conversely, extreme resistance (ER) provides exceptionally rapid and effective antiviral protection without visible cell death, yet the molecular and physiological mechanisms underlying ER remain poorly defined. The TIR-NLR receptor Rysto recognizes the coat protein (CP) of potato virus Y (PVY) and can trigger either ER or HR depending on the context. Here, we demonstrate that the efficacy of Rysto-mediated ER relies on the orchestration of various defense mechanisms. These involve transcriptional priming, and spatial redistribution of the receptor and a subset of chaperones. Rysto-expressing lines exhibit a preactivated immune state, including increased expression of genes encoding glycine-rich proteins associated with the cell wall interface and thickness. Upon PVY infection, Rysto plants undergo rapid transcriptome reprogramming, including redox- and defense-related pathways. At the protein level, Rysto initially forms a pre-active complex with Hsp70 and CP-interacting cochaperonins (CPIPs) which is remodeled upon PVY CP binding. PVY CP competes for Hsp70, enabling Rysto to oligomerize into an active resistosome. This process is further accompanied by relocalization of a subpool of the receptor toward an interface of plasma membrane, cell wall. Our research reveals a chaperone-mediated activation mechanism and spatial immune repositioning that differentiate ER responses from traditional HR, offering a detailed system for achieving durable antiviral resistance in plants.

plant biology↗

bioRxiv2025

FAK inhibitor treatment systemically regulates the glioblastoma immune environment via blocking monocyte trafficking

Glioblastoma (GBM) is the most common primary malignant brain tumour in adults with dismal survival rates, and current therapies, including most immunotherapies, are not efficacious due to the highly immunosuppressive microenvironment. Studies in other solid cancers report that impairment of the integrin effector pathway involving focal adhesion kinase (FAK) can promote anti-tumour immune responses. Therefore, we set out to address whether, and if so how, suppressing FAK function may influence GBM by using both tumour cell-specific FAK gene deletion and systemic delivery of a clinically relevant FAK kinase inhibitor (FAKi) VS-4718 in an orthotopic murine stem cell model of GBM. We found that treatment with the FAKi, but not tumour cell-specific FAK gene deletion, resulted in GBM clearance and improved survival. This was dependent on adaptive immunity, and tumour-infiltrating T cells in FAKi-treated tumours displayed increased cytotoxic potential and reduced exhaustion. We also found a significant reduction in immuno-suppressive peripherally-derived macrophages and FAKi treatment caused sequestration of inflammatory monocytes within the bone marrow, resulting in impaired monocyte trafficking to tumours as judged by adoptive transfer. This is due to suppression of key adhesion and migration signalling through 4{beta}1 integrin and CX3CR1 in peripheral monocytes. Our work here describes a previously unidentified role for FAK in trafficking of peripheral suppressive macrophages to GBM tumours, reducing T cell exhaustion and promoting anti-tumour immunity. This highlights a new way in which systemic FAK inhibitors can be used to provide a beneficial immune modulatory strategy for the treatment of GBM.

immunology↗

bioRxiv2025

The NLR immune receptor Roq1 recognizes the Pseudomonas syringae HopAG1 effector via its Nudix domain

O_LIPlant nucleotide-binding leucine-rich repeat receptors (NLRs) sense directly or indirectly effectors - proteins employed by pathogens during infection. While indirect recognition can be initiated by unrelated effectors targeting the same cellular component, direct recognition is restricted by conformational constraints of the pathogen protein and corresponding receptor. C_LIO_LIRecognition of XopQ (Roq1) receptor confers resistance to bacteria expressing members of the highly conserved effector family comprising XopQ/HopQ1/RipB. The structure of the activated Roq1 was solved previously, revealing that LRR and C-JID domains of Roq1 are involved in XopQ binding. C_LIO_LIIn this study, we found that Roq1 detects HopAG1, a member of a structurally different effector family. Presence of HopAG1 in Pseudomonas syringae reduced bacterial growth and symptoms development in wild-type but not in roq1 Nicotiana benthamiana plants. Moreover, HopAG1 co-immunoprecipitated with Roq1 indicating that both proteins associate. Based on deletion and structural analyses, we postulate that this interaction occurs via the Nudix domain of HopAG1 that binds to a similar receptor interface like XopQ. C_LIO_LINudix fold is predicted in multiple pathogen effectors suggesting that Roq1 may recognize effector families other than XopQ and HopAG1. Accordingly, it is also conceivable that other TNLs may detect a broader range of effector families than supposed. C_LI

plant biology↗

bioRxiv2022

Natural variation in Arabidopsis responses to Plasmodiophora brassicae reveals an essential role for RPB1

Despite the identification of clubroot resistance genes in various Brassica crops our understanding of the genetic basis of immunity to Plasmodiophora brassicae infection in the model plant Arabidopsis thaliana remains limited. To address this issue we performed a screen of 142 natural accessions and identified 11 clubroot resistant Arabidopsis lines. Genome wide association analysis identified several genetic loci significantly linked with resistance. Three genes from two of these loci were targeted for deletion by CRISPR/Cas9 mutation in resistant accessions Est-1 and Uod-1. Deletion of Resistance to Plasmodiophora brassicae 1 (RPB1) rendered both lines susceptible to the P. brassicae pathotype P1+. Further analysis of rpb1 knock-out Est-1 and Uod-1 lines showed that the RPB1 protein is required for activation of downstream defence responses, such as the expression of phytoalexin biosynthesis gene CYP71A13. RPB1 has no known functional domains or homology to previously characterised proteins. The clubroot susceptible Arabidopsis accession Col-0 lacks a functional RPB1 gene; when Col-0 is transformed with RPB1 expression driven by its native promoter it is capable of activating RPB1 expression in response to infection but this is not sufficient to confer resistance. Constitutive over-expression of RPB1 in Col-0 leads to drastically reduced growth and activation of stress-responsive genes. Furthermore, we found that transient expression of RPB1 in Nicotiana tabacum induced programmed cell death in leaves. We conclude that RPB1 is a critical component of the defence response to P. brassicae infection in Arabidopsis, acting downstream of pathogen recognition but required for the elaboration of effective resistance.

plant biology↗