Tetracyclines Modify Translation By Targeting Key Human rRNA Substructures

Abstract

SUMMARYApart from their antimicrobial properties, tetracyclines demonstrate clinically validated effects in the amelioration of pathological inflammation and human cancer. Delineation of the target(s) and mechanism(s) responsible for these effects, however, has remained elusive. Here, employing quantitative mass spectrometry-based proteomics, we identified human 80S ribosomes as targets of the tetracyclines Col-3 and doxycycline. We then developed in cell click selective crosslinking with RNA sequence profiling (icCL-Seq) to map binding sites for these tetracyclines on key human rRNA substructures at nucleotide resolution. Importantly, we found that structurally and phenotypically variant tetracycline analogs could chemically discriminate these rRNA binding sites. We also found that tetracyclines both subtly modify human ribosomal translation and selectively activate the cellular integrated stress response (ISR). Together, the peer-reviewed)

Translation attenuation by minocycline enhances longevity and proteostasis in old post-stress-responsive organisms

“…Strains carrying mutations in ncl-1 express twice as much 18S rRNA and produce 22% more protein than wild-type animals. As our and the Mortison data ( Mortison et al, 2018 ) suggest that minocycline directly binds to the C. elegans 18S rRNA, a two-fold increase in the 18S rRNA level and the associated increase in translation should shift the dose-response curve to the right and diminish minocycline’s effect on lifespan ( Figure 5B ).…”

“…Notably, this MOA also provides a unifying explanation for the many other seemingly unrelated effects of minocycline observed in preclinical and clinical studies, including its ability to reduce tumor growth, inflammation, and improve symptoms of fragile X. In fact, Mortison et al arrived at the same MOA studying the effects of doxycycline on inflammation and tumor growth ( Garrido-Mesa et al, 2013 ; Mortison et al, 2018 ).…”

“…Comparing the bacterial 16S rRNA to the cytoplasmic 18S rRNA of C. elegans and H. sapiens revealed a conserved tetracycline binding site in helix 34 (h34) ( Figure 4—figure supplement 1F ) ( Brodersen et al, 2000 ). A recent paper by the Meyers group identified doxycycline to directly bind to key 18S rRNA substructures of the cytoplasmic ribosome and showed different tetracyclines to discriminate between different 18S rRNA binding sites ( Caballero et al, 2011 ; Mortison et al, 2018 ). Thus, we concluded that minocycline directly targets the 18S rRNA, leading to the observed stalled ribosomes (80S peak) and attenuation of translation ( Figure 4A,B ).…”

CMT-3 targets different α-synuclein aggregates mitigating their toxic and inflammogenic effects

“…CMT-3 has also been shown to decrease lipopolysaccharide-induced microglial activation and cytokine release in the brain, which has been attributed to an inhibitory effect on protein translation 27 . Recently, a molecular mechanism has been provided for the effect of tetracyclines (including CMT-3) at attenuating eukaryotic protein synthesis 59 . This effect also seems to be responsible for enhancing longevity and proteostasis in a C. elegans- ageing model 59 – 61 .…”

“…Recently, a molecular mechanism has been provided for the effect of tetracyclines (including CMT-3) at attenuating eukaryotic protein synthesis 59 . This effect also seems to be responsible for enhancing longevity and proteostasis in a C. elegans- ageing model 59 – 61 . Therefore, while the effects we describe for CMT-3 on α-synuclein amyloid aggregation result purely from ex vivo and in vitro assays, this additional mechanism could indirectly help prevent protein aggregation in vivo.…”