Chromatin Structure and Function in Mosquitoes

Abstract

The principles and function of chromatin and nuclear architecture have been extensively studied in model organisms, such as Drosophila melanogaster. However, little is known about the role of these epigenetic processes in transcriptional regulation in other insects including mosquitoes, which are major disease vectors and a worldwide threat for human health. Some of these life-threatening diseases are malaria, which is caused by protozoan parasites of the genus Plasmodium and transmitted by Anopheles mosquitoes; dengue fever, which is caused by an arbovirus mainly transmitted by Aedes aegypti; and West Nile fever, which is caused by an arbovirus transmitted by Culex spp. In this contribution, we review what is known about chromatin-associated mechanisms and the 3D genome structure in various mosquito vectors, including Anopheles, Aedes, and Culex spp. We also discuss the similarities between epigenetic mechanisms in mosquitoes and the model organism Drosophila melanogaster, and advocate that the field could benefit from the cross-application of state-of-the-art functional genomic technologies that are well-developed in the fruit fly. Uncovering the mosquito regulatory genome can lead to the discovery of unique regulatory networks associated with the parasitic life-style of these insects. It is also critical to understand the molecular interactions between the vectors and the pathogens that they transmit, which could hold the key to major breakthroughs on the fight against mosquito-borne diseases. Finally, it is clear that epigenetic mechanisms controlling mosquito environmental plasticity and evolvability are also of utmost importance, particularly in the current context of globalization and climate change.

Anopheles mosquitoes reveal new principles of 3D genome organization in insects

“…We found that several properties of chromatin organization, identified previously in Drosophila , are shared by Anopheles species. In particular, Anopheles genomes are divided into distinct compartments, characterized by different gene density and expression levels, and that loci belonging to different compartments are insulated from each other by TAD boundaries, as previously shown by Rowley et al 16 and reviewed in Lezcano et al 58 . However, our data suggest that there are more than two types of compartments in the nucleus.…”

Phenotypic Plasticity: What Has DNA Methylation Got to Do with It?

“…Epigenetic mechanisms encapsulate any heritable change of an organism's phenotype that does not change its DNA sequence. Epigenetic mechanisms include cytosine methylation (commonly referred to as DNA methylation, Figure 2), histone tail post-translational modifications (PTMs), non-coding RNAs and potentially the way that chromatin is organised within the nucleus of the cell [22][23][24][25]. Epigenetic mechanisms regulate gene expression patterns and can define and alter cell and organism phenotypes.…”

Comprehensive Genomic Discovery of Non-Coding Transcriptional Enhancers in the African Malaria Vector Anopheles coluzzii

“…The subset of enhancers that are biologically active in a given cell can only be detected by indirect means in nuclei isolated from a pure sample of the target cell type or stage. Previous work on mosquito non-coding regulatory elements has employed chromatin-based approaches ( Behura et al, 2016 ; Perez-Zamorano et al, 2017 ; Mysore et al, 2018 ; Ruiz et al, 2019 ; Lezcano et al, 2020 ; Nowling et al, 2021 ; Ruiz et al, 2021 ). However, for phenotypic studies, pure samples of the relevant cell type may not be feasible to obtain.…”