Biology subjects

Jonak, C.

Publications and source records attributed to Jonak, C..

4 recordsLinked to original sources

bioRxiv2023

Cutaneous T cell lymphoma atlas reveals malignant Th2 cells supported by a B cell-rich microenvironment

Cutaneous T-cell lymphoma (CTCL) is a potentially fatal clonal malignancy of T cells primarily affecting the skin. The most common form of CTCL, mycosis fungoides (MF), can be difficult to diagnose resulting in treatment delay. The pathogenesis of CTCL is not fully understood due to limited data from patient studies. We performed single-cell RNA sequencing and spatial transcriptomics profiling of skin from patients with MF-type CTCL, and an integrated comparative analysis with human skin cell atlas datasets from healthy skin, atopic dermatitis and psoriasis. We reveal the co-optation of Th2-immune gene programmes by malignant CTCL cells and modelling of the tumour microenvironment to support their survival. We identify MHC-II+ fibroblast subsets reminiscent of lymph node T-zone reticular cells and monocyte-derived dendritic cells that can maintain Th2-like tumour cells. CTCL Th2-like tumour cells are spatially associated with B cells, forming aggregates reminiscent of tertiary lymphoid structures which are more prominent with progressive disease. Finally, we validated the enrichment of B cells in CTCL skin infiltrates and its association with disease progression across three independent patient cohorts. Our findings provide diagnostic aids, potential biomarkers for disease staging and therapeutic strategies for CTCL.

genomics↗

bioRxiv2022

Single-cell RNA sequencing analyses of primary cutaneous B-cell disorders reveal distinct molecular patterns consistent with clinical behavior

Primary cutaneous B-cell lymphomas comprise a heterogeneous group of extranodal non-Hodgkin lymphomas. While primary cutaneous diffuse large B-cell lymphoma leg type (pcDLBCL-LT) is highly aggressive, the two other subtypes, primary cutaneous follicle centre lymphoma (pcFCL) and primary cutaneous marginal zone lymphoma (pcMZL), usually follow an indolent course. To better understand the molecular landscape of these entities, we performed single-cell RNA sequencing of pcFCL, pcMZL, and pcDLBCL-LT skin lesions and compared them to B-cell rich lymphoid proliferation (rB-LP) lesions, gastric MALT lymphoma, nodal FCL, and nodal DLBCL. Our data show that these lymphomas can be clearly distinguished from each other on a transcriptomic level based on scRNA-seq. pcMZL, pcFCL, and rB-LP all exhibited a persistent germinal centre reaction as evidenced by the presence of required support cells and continuous somatic hypermutation within the expanded clone. By contrast, malignant clones of pcDLBCL-LT and gastric MALT lymphoma lesions lacked these features. Further, pcMZL top expanded clones were developing within lesions from naive and not post-germinal centre B cells as currently presumed. Therefore, pcMZL may represent a non-malignant reaction against a yet to be determined antigen. Conversely, in pcFCL, B cells showed a larger amount of clonal expansion. The lack of further differentiation of these B cells may explain its indolent clinical course. In contrast to pcDLCBL-LT, our data thus indicate that pcMZL and pcFCL, similar to rB-LP are characterised by a functional germinal centre reaction likely driven by (a yet unknown) antigen recognition, which supports the classification of pcMZL as a lymphoproliferative disease. Key pointsO_LIIndolent B cell neoplasms are uniquely characterised by ongoing, antigen-driven germinal centre reactions. C_LIO_LIPrimary cutaneous B cell lymphomas are distinct entities compared to their systemic counterparts. C_LI

cancer biology↗

bioRxiv2020

Arabidopsis Poly(ADP-ribose)-binding protein RCD1 interacts with Photoregulatory Protein Kinases in nuclear bodies

Continuous reprogramming of gene expression in response to environmental signals is required for plant survival in changing environment. One mechanism responsible for this is signaling through hub proteins that integrate external stimuli and transcriptional responses. RADICAL-INDUCED CELL DEATH1 (RCD1) functions as a nuclear hub protein, that interacts with a variety of transcription factors through its C-terminal RST domain and acts as a co-regulator of numerous stress responses in plants. Here, a previously unknown function for RCD1 as a novel plant poly(ADP-ribose) (PAR) reader protein is described. RCD1 localizes to specific locations inside the nucleus, in a PAR-dependent manner; its N-terminal WWE domain o binds PAR and together with the PARP-like domain determines its localization to nuclear bodies (NBs), which is prevented by inhibition of PAR synthesis. RCD1 also interacts with Photoregulatory Protein Kinases (PPKs) that co-localize with RCD1 in the NBs. The PPKs, that have been associated with circadian clock, abscisic acid, and light signaling pathways, phosphorylate RCD1 at multiple sites in the intrinsically disordered region between the WWE and PARP-like domains. This affects its stability and functions in the nucleus and1 provides a mechanism where the turnover of a PAR-binding transcriptional co-regulator is controlled by nuclear protein kinases.

plant biology↗

bioRxiv2019

DEK influences the trade-off between growth and arrest via H2A.Z-nucleosomes in Arabidopsis

The decision of whether to grow and proliferate or to restrict growth and develop resilience to stress is a key biological trade-off. In plants, constitutive growth results in increased sensitivity to environmental stress1,2. The underlying mechanisms controlling this decision are however not well understood. We used temperature as a cue to discover regulators of this process in plants, as it both enhances growth and development rates within a specific range and is also a stress at extremes. We found that the conserved chromatin-associated protein DEK plays a central role in balancing the response between growth and arrest in Arabidopsis, and it does this via H2A.Z-nucleosomes. DEK target genes show two distinct categories of chromatin architecture based on the distribution of H2A.Z in +1 nucleosome and gene body, and these predict induction or repression by DEK. We show that these chromatin signatures of DEK target genes are conserved in human cells, suggesting that DEK may act through an evolutionarily conserved mechanism to control the balance between growth and arrest in plants and animals.

plant biology↗