Biology subjects

Patzke, S.

Publications and source records attributed to Patzke, S..

5 recordsLinked to original sources

bioRxiv2024

Comprehensive Analysis of 177Lu-lilotomab Satetraxetan in Lymphoma Cell Lines: Implications for Precision Radioimmunotherapy and Combination Schemes

177Lu-lilotomab satetraxetan (Betalutin) is an anti-CD37 radioimmunoconjugate evaluated as single administration therapy for the treatment of patients with relapsed/refractory follicular lymphoma or diffuse large B-cell lymphoma (DLBCL). 177Lu-lilotomab satetraxetan treatment is well-tolerated and shows consistent activity in most of the patients evaluated so far. Herein, we investigated the activity of 177Lu-lilotomab satetraxetan in a panel of 55 lymphoma cell lines of B and T cell origin. CD37-targeted radioimmunotherapy was more effective in CD37-positive B-cell lymphomas (n=46) than negative CD37 negative T-cell lymphomas (n=9). Focusing on DLBCL cell lines, mutations such as BCL2 or MYC translocations were not correlated to sensitivity. However, BCL2 expression was higher in resistant than sensitive GCB-DLBCL cell lines, and the addition of the BCL2 inhibitor venetoclax showed synergism when added to the radioimmunoconjugate. Finally, the pattern of activity of 177Lu-lilotomab satetraxetan differed from what was achieved with a CD37-targeting antibody-drug conjugate or with R-CHOP, indicating the potential benefit of the beta-emitter payload. In conclusion, this systematic analysis of the responsiveness of lymphoma cell lines to CD37-targeting radioimmunotherapy consolidated 177Lu-lilotomab satetraxetan as a promising compound for the treatment of CD37 positive malignancies and identified candidate biomarkers and co-targets to detect and overcome cancer cell-intrinsic resistance mechanisms.

cancer biology↗

bioRxiv2022

CSPP1 stabilizes growing microtubule ends and damaged lattices from the luminal side.

Microtubules are dynamic cytoskeletal polymers, and their organization and stability are tightly regulated by numerous cellular factors. While regulatory proteins controlling formation of interphase microtubule arrays and mitotic spindles have been extensively studied, the biochemical mechanisms responsible for generating stable microtubule cores of centrioles and cilia are poorly understood. Here, we used in vitro reconstitution assays to investigate microtubule-stabilizing properties of CSPP1, a centrosome and cilia-associated protein mutated in the neurodevelopmental ciliopathy Joubert syndrome. We found that CSPP1 preferentially binds to polymerizing microtubule ends that grow slowly or undergo growth perturbations and, in this way, resembles microtubule-stabilizing compounds such as taxanes. Fluorescence microscopy and cryo-electron tomography showed that CSPP1 is deposited in the microtubule lumen and inhibits microtubule growth and shortening through two separate domains. CSPP1 also specifically recognizes and stabilizes damaged microtubule lattices. These data help to explain how CSPP1 regulates elongation and stability of ciliary axonemes and other microtubule-based structures.

cell biology↗

bioRxiv2022

CCDC66 regulates primary cilium length and signaling competence via multi-site interactions with transition zone and axonemal proteins

The primary cilium is a conserved microtubule-based organelle that serves as a hub for many signaling pathways. It functions as part of the centrosome/cilium complex, which also contains the basal body and the centriolar satellites. Little is known about the mechanisms by which the microtubule-based axoneme of the cilium is assembled with proper length and structure, particularly in terms of the activity of microtubule-associated proteins (MAPs) and the crosstalk between the different compartments of the centrosome/cilium complex. Here, we analyzed CCDC66, a MAP implicated in cilium biogenesis and ciliopathies affecting eye and brain. Live-cell imaging revealed that CCDC66 compartmentalizes between centrosomes, centriolar satellites, and the ciliary axoneme and tip during cilium assembly and disassembly. CCDC66 loss-of-function in human cells causes defects in cilium assembly, length and morphology. Notably, CCDC66 interacts with the MAPs and ciliopathy proteins CEP104 and CSPP1 and cooperates with them during axonemal length regulation. Moreover, CCDC66 interacts with the transition zone protein CEP290 selectively at the centriolar satellites. Its loss disrupts basal body recruitment of transition zone proteins and IFT-B machinery and causes defective Hedgehog signaling. Overall, our results establish CCDC66 as a multifaceted regulator of the primary cilium, and propose a mechanistic insight into how the cooperation of ciliary MAPs as well as subcompartments ensures assembly of a functional cilium.

cell biology↗

bioRxiv2020

CEP78 functions downstream of CEP350 to control biogenesis of primary cilia by negatively regulating CP110 levels

CEP78 is a centrosomal protein implicated in ciliogenesis and ciliary length control, and mutations in the CEP78 gene cause retinal cone-rod dystrophy associated with hearing loss. However, the mechanism by which CEP78 affects cilia formation is unknown. Based on a recently discovered disease-causing CEP78 p.L150S mutation, we identified the disease-relevant interactome of CEP78. We confirmed that CEP78 interacts with the EDD1-DYRK2-DDB1VPRBP E3 ubiquitin ligase complex, which is involved in CP110 ubiquitination and degradation, and identified a novel interaction between CEP78 and CEP350 that is weakened by the CEP78L150S mutation. We show that CEP350 promotes centrosomal recruitment and stability of CEP78, which in turn leads to centrosomal recruitment of EDD1. Consistently, cells lacking CEP78 display significantly increased cellular and centrosomal levels of CP110, and depletion of CP110 in CEP78-deficient cells restored ciliation frequency to normal. We propose that CEP78 functions downstream of CEP350 to promote ciliogenesis by negatively regulating CP110 levels via an EDD1-dependent mechanism.

cell biology↗

bioRxiv2016

The E3 ubiquitin ligase UBR5 regulates centriolar satellite stability and primary cilia formation via ubiquitylation of CSPP-L.

Primary cilia are crucial for signal transduction in a variety of pathways, including Hedgehog and Wnt. Disruption of primary cilia formation (ciliogenesis) is linked to numerous developmental disorders (known as ciliopathies) and diseases, including cancer. The Ubiquitin-Proteasome System (UPS) component UBR5 was previously identified as a putative modulator of ciliogenesis in a functional genomics screen. UBR5 is an E3 Ubiquitin ligase that is frequently deregulated in tumours, but its biological role in cancer is largely uncharacterised, partly due to a lack of understanding of interacting proteins and pathways. We validated the effect of UBR5 depletion on primary cilia formation using a robust model of ciliogenesis, and identified CSPP1, a centrosomal and ciliary protein required for cilia formation, as a UBR5-interacting protein. We show that UBR5 ubiquitylates CSPP1, and that UBR5 is required for cytoplasmic organization of CSPP1-comprising centriolar satellites in centrosomal periphery. Hence, we have established a key role for UBR5 in ciliogenesis that may have important implications in understanding cancer pathophysiology.

cell biology↗