Biology subjects

Gamsjaeger, R.

Publications and source records attributed to Gamsjaeger, R..

3 recordsLinked to original sources

bioRxiv2026

Defining the Immunomodulatory Determinants of 3-mer Oligonucleotides on TLR7 and TLR8 sensing

Chemical modifications such as 2'-O-methyl (2'-OMe) are central to the efficacy and tolerability of RNA therapeutics. We recently identified that 2'-OMe RNA fragments as short as three nucleotides can exert opposing effects on Toll-like receptor 8 (TLR8) sensing in a motif-dependent manner. This discovery raises important considerations for degradation products of chemically modified RNA therapeutics, which may generate such immunologically active fragments. Here, leveraging their short length, we systematically map how base and sugar modifications within 3-mer oligonucleotides regulate TLR7 and TLR8 responses, and we resolve the structural basis for both TLR8 potentiation and TLR7/8 antagonism by RNA fragments. Building on these insights, we report the development of a dual TLR7/8 inhibitory oligonucleotide with therapeutic potential in autoimmune disease. Together, these findings provide unprecedented resolution of the immunomodulatory properties of oligonucleotide modifications on TLR7/8 and establish 3-mer oligonucleotides as the shortest functional class of RNA therapeutics described to date.

immunology↗

bioRxiv2024

2'-O-Methyl-guanosine 3-base RNA fragments mediate essential natural TLR7/8 antagonism

Recognition of RNA fragments by Toll-like receptors (TLR) 7 and 8 is a key contributor to the initiation of a protective innate immune response against pathogens. A long-standing enigma is how degradation products of host RNAs, generated by the daily phagocytic clearance of billions of apoptotic cells, fail to activate TLR7 and TLR8 signalling1. Here, we report that select 2-O-methyl (2-Ome) guanosine RNA fragments as short as 3 bases, including those derived from host-RNAs, are potent TLR7 and TLR8 antagonists that reduce TLR7 sensing in vivo. Mechanistically, antagonistic fragments are directed towards a distinct binding site on these proteins by 5-end 2-Ome guanosine. Our results indicate that host-RNAs evade detection by TLR7/8 due to a pool of abundant host ribosomal 2-Ome-modified RNA fragments that naturally antagonize TLR7 and TLR8 sensing to avoid auto-immunity. Crucially, rare TLR7 and TLR8 mutations located at this antagonistic site decrease the inhibitory activity of 2-Ome guanosine RNA fragments and lead to auto-immunity in patients. Our findings also establish that select chemically synthesised 3-base oligonucleotides can harness the protective anti-inflammatory activity of this natural immune checkpoint for therapeutic targeting of TLR7-driven diseases. One Sentence SummaryShort 2-O-Methyl RNA fragments are natural TLR7/8 antagonists

immunology↗

bioRxiv2020

A biophysical and structural analysis of DNA binding by oligomeric hSSB1 (NABP2/OBFC2B)

The oxidative modification of DNA can result in the loss of genome integrity and must be repaired to maintain overall genomic stability. We have recently demonstrated that human single stranded DNA binding protein 1 (hSSB1/NABP2/OBFC2B) plays a crucial role in the removal of 8-oxo-7,8-dihydro- guanine (8-oxoG), the most common form of oxidative DNA damage. The ability of hSSB1 to form disulphide-bonded tetramers and higher oligomers in an oxidative environment is critical for this process. In this study, we have used nuclear magnetic resonance (NMR) spectroscopy and surface plasmon resonance (SPR) experiments to determine the molecular details of ssDNA binding by oligomeric hSSB1. We reveal that hSSB1 oligomers interact with single DNA strands containing damaged DNA bases; however, our data also show that oxidised bases are recognised in the same manner as undamaged DNA bases. We further demonstrate that oxidised hSSB1 interacts with ssDNA with a significantly higher affinity than its monomeric form confirming that oligomeric proteins such as tetramers can bind directly to ssDNA. NMR experiments provide evidence that oligomeric hSSB1 is able to bind longer ssDNA in both binding polarities using a distinct set of residues different to those of the related SSB from Escherichia coli.

biochemistry↗