Transcriptional expression of m6A and m5C RNA methyltransferase genes in the brain and fat body of honey bee adult workers

Abstract

Honey bee (Apis mellifera) adult workers change behaviors and nutrition according to age progression. Young workers, such as nurses, perform in-hive tasks and consume protein-rich pollen, while older workers (foragers) leave the colony to search for food, and consume carbohydrate-rich nectar. These environmentally stimulated events involve transcriptional and DNA epigenetic marks alterations in worker tissues. However, post-transcriptional RNA modifications (epitranscriptomics) are still poorly explored in bees. We investigated the transcriptional profiles of m6A and m5C RNA methyltransferases in the brain and fat body of adult workers of 1) different ages and performing different tasks [nurses of 8 days-old (N-8D) and foragers of 29 days-old (F-29D), sampled from wild-type colonies], and 2) same-aged young workers caged in an incubator and treated with a pollen-rich [PR] or a pollen-deprived [PD] diet for 8 days. In the brain, METTL3, DNMT2, NOP2, NSUN2, NSUN5, and NSUN7 genes increased expression during adulthood (from N-8D to F-29D), while the opposite pattern was observed in the fat body for METTL3, DNMT2, and NSUN2 genes. Regarding diet treatments, high expression levels were observed in the brains of the pollen-deprived group (DNMT2, NOP2, and NSUN2 genes) and the fat bodies of the pollen-rich group (NOP2, NSUN4, and NSUN5 genes) compared to the brains of the PR group and the fat bodies of the PD group, respectively. Our data indicate that RNA epigenetics may be an important regulatory layer in the development of adult workers, presenting tissue-specific signatures of RNA methyltransferases expression in response to age, behavior, and diet content.

N6‐methyladenosine modification of RNA controls dopamine synthesis to influence labour division in ants

“…In a previous study, we found that labour division has an inherent genetic basis that can be controlled by Sifor or miR-279c-5p in red fire ants (Chen et al, 2022;. RNA epigenetics serve as an important manifestation of remodelled gene (Bataglia et al, 2021(Bataglia et al, , 2022, consistent with the results of this study. However, these reports are only descriptive in terms of the overall m 6 A levels of RNA, indicating a potential function, but not a described mechanism.…”

“…The components of the m 6 A writer complex are involved in mRNA methylation in humans; however, their role in social insects is not well understood. A previous study showed that METTL3, DNMT2, NOP2, NSUN2, NSUN5 and NSUN7 transcripts were expressed at higher levels in the brains of foragers than in younger honeybees (Bataglia et al., 2022). In our study, we found that foragers had significantly higher expression levels of Mettl3 , Mettl14 , Wtap , and Vir than nurses (Figure 2c).…”

“…An important characteristic of social insects is the presence of temporal polyethism, with younger workers staying in the nest and older workers feeding off the colony (Chen et al., 2022; Chen, Ma, et al., 2023). Foragers need more brain skills than nurses, such as adapting to the environment, seeking food resources and fighting other colonies (Bataglia et al., 2022). The behavioural transition from internal to external tasks is accompanied by precise modifications in the brain (Durst et al., 1994; Farris et al., 2001).…”

“…Worker larvae contain more m 6 A RNA peaks than queen-destined larvae, which are differentially altered by nutritional uptake (Bataglia et al, 2021;Wang et al, 2021). Moreover, the m 6 A methyltransferase gene and m 6 A levels differ significantly during the developmental stages of adult honeybee workers (Bataglia et al, 2021(Bataglia et al, , 2022. However, whether changes in RNA m 6 A levels functionally facilitate labour division in ants remains unknown.…”

ALKBH8 as a potential N6‐methyladenosine (m6A) eraser in insects

“…The studies further indicated that m 6 A methylation is involved in viral infection and sperm tail formation in the mosquitoes, respectively. In addition, existence of m 6 A machinery was demonstrated in the honey bee Apis mellifera with m 6 A levels significantly different between 4th larval instars of worker and queen bees (Bataglia, Simões, & Nunes, 2021;Bataglia, Simões, & Nunes, 2022;Wang et al, 2021). While m 6 A readers and writers have been reported from D. melanogaster, B. mori, A. mellifera, Ae.…”