Biology subjects

Urbanczyk, S.

Publications and source records attributed to Urbanczyk, S..

3 recordsLinked to original sources

bioRxiv2022

Quantitative proteomics and lipidomics of TFG-deficient B cells provide insights into mechanisms of autophagic flux and plasma cell biology

The autophagy-flux-promoting protein TFG (Trk-fused gene) is up-regulated during B cell differentiation into plasma cells and supports survival of CH12 B cells. We hypothesized that quantitative proteomics analysis of CH12tfgKO B cells with intact or blocked autophagy-lysosome flux (via NH4Cl) will identify mechanisms of TFG-dependent autophagy, plasma cell biology and B cell survival. Analysis of CH12WT B cells in the presence of NH4Cl will identify proteins whose presence is continuously regulated by lysosomes independent of TFG. We determined hundreds of proteins to be controlled by TFG and/or NH4Cl. Notably, NH4Cl treatment alone increased the abundance of a cluster of cytosolic and mitochondrial translational proteins while it also reduced a number of proteins. Within the B cell relevant protein pool, BCL10 was reduced, while JCHAIN was increased in CH12tfgKO B cells. Furthermore, TFG regulated the abundance of transcription factors, such as JUNB, metabolic enzymes, such as the short-chain fatty acid activating enzyme ACOT9 or the glycolytic enzyme ALDOC. Gene ontology enrichment analysis revealed that TFG-regulated proteins localized to mitochondria and membrane-bounded organelles. Due to these findings we performed shotgun lipidomics of glycerophospholipids, uncovering that a particular phosphatidylethanolamine (PE) species, 32:0 PE, which lipidates LC3 most efficiently, was less abundant while phosphatidylglycerol (PG) was more abundant in CH12tfgKO B cells. In line with the role of PG as precursor for Cardiolipin (CL), the CL content was higher in CH12tfgKO B cells and addition of PG liposomes to B cells increased the amount of CL. We propose a role for TFG in B cell activation and plasma cell biology via regulation of proteins involved in germinal center and plasma cell development, such as BCL10 or JCHAIN, as well as in lipid homeostasis, mitochondria and metabolism.

immunology↗

bioRxiv2021

Metabolic breakdown of non-small cell lung cancers by mitochondrial HSPD1 targeting

The identification of novel targets is of paramount importance to develop more effective drugs and improve the treatment of non-small cell lung cancer (NSCLC), the leading cause of cancer-related deaths worldwide. Since cells alter their metabolic rewiring during tumorigenesis and along cancer progression, targeting key metabolic players and metabolism-associated proteins represents a valuable approach with a high therapeutic potential. Metabolic fitness relies on the functionality of heat shock proteins (HSPs), molecular chaperones that facilitate the correct folding of metabolism enzymes and their assembly in macromolecular structures. Here, we show HSPD1 (HSP60) as a survival gene ubiquitously expressed in NSCLC and associated with poor patients prognosis. HSPD1 knockdown or its chemical disruption by the small molecule KHS101 induces a drastic breakdown of oxidative phosphorylation, and suppresses cell proliferation both in vitro and in vivo. By combining drug profiling with transcriptomics and through a whole-genome CRISPR/Cas9 screen, we demonstrate that HSPD1-targeted anti-cancer effects are dependent on OXPHOS and validated molecular determinants of KHS101 sensitivity, in particular, the creatine-transporter SLC6A8 and the subunit of the cytochrome c oxidase complex COX5B. These results highlight mitochondrial metabolism as an attractive target and HSPD1 as a potential theranostic marker for developing therapies to combat NCSLC. SignificanceHSPD1 elimination or disruption interferes with NSCLC metabolic activity causing a strong OXPHOS-dependent energetic breakdown, which the cancer cells fail to overcome, highlighting HSPD1 as a potential theranostic marker for improving lung cancer therapy.

cancer biology↗

bioRxiv2021

Mitochondrial function is essential for humoral immunity by controlling flux of the TCA cycle, phosphatidic acid and mTOR activity in B cells

The function of mitochondrial respiration during B cell fate decisions and differentiation remains equivocal. This study reveals that selection for mitochondrial fitness occurs during B cell activation and is essential for subsequent plasma cell differentiation. By expressing a mutated mitochondrial helicase in transitional B cells, we depleted mitochondrial DNA during B cell maturation, resulting in reduced oxidative phosphorylation. Although no changes in follicular B cell development were evident, germinal centers, class switch recombination to IgG, plasma cell generation and humoral immunity were diminished. Defective oxidative phosphorylation led to aberrant flux of the tricarboxylic acid cycle and lowered the amount of saturated phosphatidic acid. Consequently, MTOR activity and BLIMP-1 induction were curtailed whereas HIF1, glycolysis and AMPK activity were amplified. Exogenous phosphatidic acid increased mTOR activity in activated B cells. Hence, mitochondrial function is required and selected for in activated B cells for the successful generation of functional plasma cells.

immunology↗