Domesticated gag Gene of Drosophila LTR Retrotransposons Is Involved in Response to Oxidative Stress

Abstract

Drosophila melanogaster is one of the most extensively used genetic model organisms for studying LTR retrotransposons that are represented by various groups in its genome. However, the phenomenon of molecular domestication of LTR retrotransposons has been insufficiently studied in Drosophila, as well as in other invertebrates. The present work is devoted to studying the role of the domesticated gag gene, Gagr, in the Drosophila genome. The Gagr gene has been shown to be involved in the response to stress caused by exposure to ammonium persulfate, but not in the stress response to oligomycin A, zeomycin, and cadmium chloride. Ammonium persulfate tissue specifically activates the expression of Gagr in the tissues of the carcass, but not in the gut. We found that the Gagr gene promoter contains one binding motif for the transcription factor kayak, a component of the JNK signaling pathway, and two binding motifs for the transcription factor Stat92E, a component of the Jak-STAT signaling pathway. Remarkably, Gagr orthologs contain the second binding motif for Stat92E only in D. melanogaster, D. simulans and D. sechellia, whereas in D. yakuba and D. erecta, Gagr orthologs contain a single motif, and there are no binding sites for Stat92E in the promoters of Gagr orthologs in D. ananassae and in species outside the melanogaster group. The data obtained indicate the formation of the protective function of the Gagr gene during evolution.

Nanopore RNA Sequencing Revealed Long Non-Coding and LTR Retrotransposon-Related RNAs Expressed at Early Stages of Triticale SEED Development

“…While further functional and evolutionary studies are required, we suggest that these GAG loci are intermediate products of RTE diversification or “domestication”. The “domestication” of GAG proteins has been documented in animals and insects [ 84 , 85 , 86 , 87 ]. Because of the short lengths of these GAG proteins, it can be also suggested that they may be involved in control of the activity of functional RTEs via incorporation into their virus-like particles.…”

Domesticated LTR-Retrotransposon gag-Related Gene (Gagr) as a Member of the Stress Response Network in Drosophila

“…According to our data, the Gagr gene in Drosophilidae evolved by acquiring binding sites for the transcription factors kayak and STAT, the activity of which is modulated by the JNK and JAK/Stat stress pathways [ 13 ]. As we have shown in the study, the Gagr gene is significantly activated by oxidative stress.…”

“…As we have shown [ 13 ], the binding motif for the JNK pathway transcription factor kayak is present in the promoter region of the Gagr homologs of Sophophora and Drosophila species. In addition, there is a binding motif for Stat92E in the melanogaster subgroup, but it is absent in D. ananassae .…”

“…Currently, the only domesticated retroelement gag gene, Gagr (homolog of the gag gene of the Gypsy group of LTR retroelements), is known, and its functions have been partially characterized [ 12 ]. The Gagr gene is possibly associated with the origin of new functions and the involvement in stress response in Drosophila species [ 13 ]. Gagr expression is activated in response to the induction by bacterial lipopolysaccharides in S2 cells, and this activation depends on the regulators of the MAPK/JNK stress signaling pathways Tak1 , hep and bsk [ 14 ].…”

“…In previous studies, we found that the stress-induced activation of the Gagr gene is controlled by potential regulators involved in endoplasmic reticulum (ER) stress. The Gagr gene is involved in a cellular oxidative stress response but is not activated under mitochondrial stress [ 13 ]. The product of the Gagr gene has membrane localization [ 12 ].…”