Schumacher J, Bacic T, Staritzbichler R, Daneschdar M, Klamp T, Arnold P, Jägle S, Türeci Ö, Markl J, Sahin U (2018) Enhanced stability of a chimeric hepatitis B core antigen virus-like-particle (HBcAg-VLP) by a C-terminal linker-hexahistidine-peptide. J Nanobiotechnology. Apr 13;16(1):39.
The effects of a carboxy-terminal polyhistidine-peptide and an intradimer disulfide-bridge on the stability of preclinically approved chimeric HBcAg-VLPs were assessed. We purified recombinant chimeric HBcAg-VLPs bearing different modified C-termini and compared their physical and chemical particle stability by quantitative protein-biochemical and biophysical techniques. We observed lower chemical resistance of T = 3- compared to T = 4-VLP (triangulation number) capsids and profound impairment of accessibility of hexahistidine-peptides in assembled VLPs. Histidines attached to the C-terminus were associated with superior mechanical and/or chemical particle stability depending on the number of histidine moieties. A molecular modeling approach based on cryo-electron microscopy and biolayer interferometry revealed the underlying structural mechanism for the strengthening of the integrity of VLPs. Interactions triggering capsid stabilization occur on a highly conserved residue on the basis of HBcAg-monomers as well as on hexahistidine-peptides of adjacent monomers. This new stabilization mechanism appears to mimic an evolutionary conserved stabilization concept for hepadnavirus core proteins.
These findings establish the genetically simply transferable C-terminal polyhistidine-peptide as a general stabilizing element for chimeric HBcAg-VLPs to increase their suitability.
Bidmon N, Kind S, Welters MJP, Joseph-Pietras D, Laske K, Maurer D, Hadrup SR, Schreibelt G, Rae R, Sahin U, Gouttefangeas C, Britten CM, van der Burg SH (2018) Development of an RNA-based kit for easy generation of TCR-engineered lymphocytes to control T-cell assay performance. J Immunol Methods. Apr 20. pii: S0022-1759(18)30025-5
Boegel S, Löwer M, Bukur T, Sorn P, Castle J, Sahin U. (2018) HLA and proteasome expression body map. BMC Medical Genomics 2018; 11:36
Methods: Here we applied a tailored gene quantification pipeline to 4323 publicly available RNA-Seq datasets representing 55 normal tissues and cell types to examine expression profiles of (classical and non-classical) HLA class I, class II and proteasomal genes.
Results: We generated the first comprehensive expression atlas of antigen presenting-related genes across 56 normal tissues and cell types, including immune cells, pancreatic islets, platelets and hematopoietic stem cells. We found a surprisingly heterogeneous HLA expression pattern with up to 100-fold difference in intra-tissue median HLA abundances. Cells of the immune system and lymphatic organs expressed the highest levels of classical HLA class I (HLA-A,-B,-C), class II (HLA-DQA1,-DQB1,-DPA1,-DPB1,-DRA,-DRB1) and non-classical HLA class I (HLA-E,-F) molecules, whereas retina, brain, muscle, megakaryocytes and erythroblasts showed the lowest abundance. In contrast, we identified a distinct and highly tissue-restricted expression pattern of the non-classical class I gene HLA-G in placenta, pancreatic islets, pituitary gland and testis. While the constitutive proteasome showed relatively constant expression across all tissues, we found the immunoproteasome to be enriched in lymphatic organs and almost absent in immune privileged tissues.
Conclusions: Here, we not only provide a reference catalog of tissue and cell type specific HLA expression, but also highlight extremely variable expression of the basic components of antigen processing and presentation in different cell types. Our findings indicate that low expression of classical HLA class I molecules together with lack of immunoproteasome components as well as upregulation of HLA-G may be of key relevance to maintain tolerance in immune privileged tissues.
Sahin U, Türeci Ö: Personalized vaccines for cancer immunotherapy. Science. 2018 Mar 23; 359(6382):1355-1360.
Diken M, Chu KK, Brodsky AN. (2018) Translating Science into Survival: Report on the Third International Cancer Immunotherapy Conference. Cancer Immunol Res. 2018 Jan;6(1):10-13. doi: 10.1158/2326-6066.CIR-17-0656.