Developmental stage-specific distribution and phosphorylation of Mblk-1, a transcription factor involved in ecdysteroid-signaling in the honey bee brain

Sci Rep. 2020 May 26;10(1):8735. doi: 10.1038/s41598-020-65327-z.

Abstract

In the honey bee, the mushroom bodies (MBs), a higher-order center in insect brain, comprise interneurons termed Kenyon cells (KCs). We previously reported that Mblk-1, which encodes a transcription factor involved in ecdysteroid-signaling, is expressed preferentially in the large-type KCs (lKCs) in the pupal and adult worker brain and that phosphorylation by the Ras/MAPK pathway enhances the transcriptional activity of Mblk-1 in vitro. In the present study, we performed immunoblotting and immunofluorescence studies using affinity-purified anti-Mblk-1 and anti-phosphorylated Mblk-1 antibodies to analyze the distribution and phosphorylation of Mblk-1 in the brains of pupal and adult workers. Mblk-1 was preferentially expressed in the lKCs in both pupal and adult worker brains. In contrast, some Mblk-1 was phosphorylated almost exclusively in the pupal stages, and phosphorylated Mblk-1 was preferentially expressed in the MB neuroblasts and lKCs in pupal brains. Immunofluorescence studies revealed that both Mblk-1 and phosphorylated Mblk-1 are located in both the cytoplasm and nuclei of the lKC somata in the pupal and adult worker brains. These findings suggest that Mblk-1 plays a role in the lKCs in both pupal and adult stages and that phosphorylated Mblk-1 has pupal stage-specific functions in the MB neuroblasts and lKCs in the honey bee brain.

MeSH terms

  • Animals
  • Bees / growth & development*
  • Bees / metabolism
  • Brain / metabolism*
  • Cell Nucleus / metabolism
  • Cytoplasm / metabolism
  • Ecdysteroids / metabolism*
  • Gene Expression Regulation, Developmental
  • Insect Proteins / metabolism
  • MAP Kinase Signaling System
  • Mushroom Bodies / growth & development
  • Mushroom Bodies / metabolism
  • Organ Specificity
  • Phosphorylation
  • Transcription Factors / metabolism*

Substances

  • Ecdysteroids
  • Insect Proteins
  • Transcription Factors