Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 28 April 2020 doi:10.20944/preprints202004.0172.v2 Title: Trends in symbiont-induced host cellular differentiation Authors: Shelbi L Russell1 and Jennie Ruelas Castillo2 Affiliations: 1. Department of Molecular Cell and Developmental Biology; University of California, Santa Cruz; Santa Cruz, California, 95064; United States of America. 2. Johns Hopkins University School of Medicine, Baltimore, Maryland, 21218. *Correspondence:
[email protected] Keywords: Wolbachia, Drosophila, Symbiosis, Cellular microbiology, Cellular differentiation, Epigenetics, Transcription, Translation, Proteolysis, 1 © 2020 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 28 April 2020 doi:10.20944/preprints202004.0172.v2 Abstract: Bacteria participate in a wide diversity of symbiotic associations with eukaryotic hosts that require precise interactions for bacterial recognition and persistence. Most commonly, host- associated bacteria interfere with host gene expression to modulate the immune response to the infection. However, many of these bacteria also interfere with host cellular differentiation pathways to create a hospitable niche, resulting in the formation of novel cell types, tissues, and organs. In both of these situations, bacterial symbionts must interact with eukaryotic regulatory pathways. Here, we detail what is known about how bacterial symbionts, from pathogens to mutualists, control host cellular differentiation across the central dogma, from epigenetic chromatin modifications, to transcription and mRNA processing, to translation and protein modifications. We identify four main trends from this survey. First, mechanisms for controlling host gene expression appear to evolve from symbionts co-opting cross-talk between host signalling pathways. Second, symbiont regulatory capacity is constrained by the processes that drive reductive genome evolution in host-associated bacteria.