Biology subjects

Horner, K.

Publications and source records attributed to Horner, K..

3 recordsLinked to original sources

bioRxiv2026

Pathogenicity of autoreactive TH17 cells is modulated by the TRPM7 kinase

The melastatin-like transient receptor potential channel, TRPM7, is crucial for signaling in leukocytes. It harbors a channel domain, permeable to divalent cations as well as a serine/threonine -kinase, phosphorylating inter alia SMAD2. TRPM7 kinase activity is essential for the differentiation of non-pathogenic T helper 17 (TH17) cells as well as for T cell colonization and alloreactivity in the gut. As pathogenic TH17 (pTH17) cells drive autoimmune diseases, we studied TRPM7 kinase involvement in pTH17 polarization and function as well as in the development of multiple sclerosis (MS), using human T cells and established murine experimental autoimmune encephalomyelitis (EAE) models. Our results reveal an elevated TRPM7 activity in T effector cells derived from the cerebrospinal fluid (CSF) of MS patients, in line with higher functional TRPM7 expression on human TH17 cells. Utilizing a mouse line with disrupted kinase activity (Trpm7R/R), we uncovered both impaired differentiation of pathogenic TH17 cells as well as a significantly milder course of TH17-mediated transfer EAE in Trpm7R/R mice compared to Trpm7+/+ controls. In the CNS of Trpm7R/R mice, the number of FOXP3+ T cells (Tregs) was increased, while fewer TH17 cells infiltrated the CNS due to a migration defect of transferred pTH17 cells in the Trpm7R/R hosts and a failure to reactivate in the intestine, due to reduced MHCII signaling. Thus, inactivation of TRPM7 kinase may represent a promising therapeutic strategy targeting both differentiation and reactivation of pTH17 cells while preserving Tregs function and thereby dampening CNS inflammation in MS.

immunology↗

bioRxiv2025

A new subgenome of the Camelina genus reveals genome dominance is controlled by chromosomal proximity

Camelina sativa is an oilseed of the Brassicaceae, whose close relatives vary in ploidy number, providing a novel platform for studying plant genome evolution. The availability of diploid, tetraploid and hexaploid species of Camelina allow the evolutionary trajectory and fate of duplicated genes in the neopolyploid Camelina species to be elucidated. Here we report an improved assembly of the widely used C. sativa reference DH55 and three new genome assemblies of Camelina microcarpa; one tetraploid CN119243 (2n = 26), and two hexaploids with divergent chromosome numbers, Type 1 - CN119205 (2n=40) and Type 2 - CN120025 (2n=38). The tetraploid represents the first step in the evolutionary path to form C. sativa, while the hexaploids suggest three divergent lineages in the formation of higher ploidy Camelina species. The previously uncharacterized fourth subgenome found in C. microcarpa Type 2, although showing some homology to the C. sativa diploid progenitor genome, C. neglecta, showed numerous unique chromosomal rearrangements differentiating it from other subgenomes present in known Camelina species. Although this species was recently formed, the second subgenome showed gene expression dominance, which was in contrast to both 2n=40 Camelina species where the third subgenome was dominant. The expression dominance in Type 2 C. microcarpa contradicted the accepted two-step evolutionary process which led to the generation of related Brassicaceae species. However, the observed genome dominance in all Camelina species was negatively correlated with inter-subgenome chromatin interaction frequencies, suggesting that chromosome confirmation and proximity in the nucleus contributes to this mechanism of genome evolution. Despite the differences in genome structure, successful inter-specific hybridization provided evidence of chromosomal exchange between the divergent third sub-genomes of C. sativa and C. microcarpa Type 2, opening up a novel avenue to new diversity in the established oilseed. Key pointsO_LIAn improved genomic understanding of Camelina species and identification of distinct subgenome structures and relationships, which will facilitate strategies to increase the genetic diversity in C. sativa. C_LIO_LISubgenome evolution and subgenome dominance in polyploids is associated with chromosomal architecture and proximity in the nucleus. C_LIO_LIGenome assemblies representing all ploidy levels in the Camelina genus provide a unique and valuable platform for polyploid research. C_LI

genomics↗

bioRxiv2023

IQGAP2 regulates blood-brain barrier immune dynamics

Brain endothelial cells (BECs) play an important role in maintaining central nervous system (CNS) homeostasis through blood-brain barrier (BBB) functions. BECs express low baseline levels of adhesion receptors, which limits entry of leukocytes. However, the molecular mediators governing this phenotype remain mostly unclear. Here, we explored how infiltration of immune cells across the BBB is influenced by the scaffold protein IQ motif containing GTPase activating protein 2 (IQGAP2). In mice and zebrafish, we demonstrate that loss of Iqgap2 increases infiltration of peripheral leukocytes into the CNS under homeostatic and inflammatory conditions. Using single-cell RNA sequencing and immunohistology, we further show that BECs from mice lacking Iqgap2 exhibit a profound inflammatory signature, including extensive upregulation of adhesion receptors and antigen-processing machinery. Human tissue analyses also reveal that Alzheimers disease is associated with reduced hippocampal IQGAP2. Overall, our results implicate IQGAP2 as an essential regulator of BBB immune privilege and immune cell entry into the CNS.

neuroscience↗