Hedgehog promotes cell proliferation in the midgut of silkworm, Bombyx mori

Abstract

The Hedgehog (Hh) signaling pathway is one of the major regulators of embryonic development and tissue homeostasis in multicellular organisms. However, the role of this pathway in the silkworm, especially in the silkworm midgut, remains poorly understood. Here, we report that Bombyx mori Hedgehog (BmHh) is expressed in most tissues of silkworm larvae and that its functions are well-conserved throughout evolution. We further demonstrate that the messenger RNA of four Hh signaling components, BmHh ligand, BmPtch receptor, signal transducer BmSmo and transcription factor BmCi, are all upregulated following Escherichia coli or Bacillus thuringiensis infection, indicating the activation of the Hh pathway. Simultaneously, midgut cell proliferation is strongly promoted. Conversely, the repression of Hh signal transduction with double-stranded RNA or cyclopamine inhibits the expression of BmHh and BmCi and reduces cell proliferation. Overall, these findings provide new insights into the Hh signaling pathway in the silkworm, B. mori.

De Novo Sequencing and High-Contiguity Genome Assembly of Moniezia expansa Reveals Its Specific Fatty Acid Metabolism and Reproductive Stem Cell Regulatory Network

“…Generally, compared to those without active cell differentiation, cells and tissues with active cell differentiation, such as osteoblasts, kidney, bone marrow, and fetal liver hematopoietic cells, often contain higher levels of TGF-β signals, and TGF-β signals can be detected in almost all tumor cells. The Hedgehog signaling pathway is one of the major regulators of embryonic development and tissue homeostasis in multicellular organisms ( Zhu et al., 2020 ). The Hippo pathway is an evolutionarily conserved signaling cascade that controls organ size during development by regulating cell proliferation and apoptosis and stem cell self-renewal ability ( Yin et al., 2020 ).…”

Insights into midgut cell types and their crucial role in antiviral immunity in the lepidopteran model Bombyx mori

“…The secretion of the signaling protein Hedgehog has been well-documented in both Drosophila and B. mori ( 48 , 49 ). Following infection by Escherichia coli or Bacillus thuringiensis , a notable proliferation of midgut cells and upregulation of Hedgehog genes have been observed in the silkworm.…”

“…Following infection by Escherichia coli or Bacillus thuringiensis , a notable proliferation of midgut cells and upregulation of Hedgehog genes have been observed in the silkworm. When genes associated with the Hedgehog pathway were experimentally silenced, cell growth was suppressed, indicating the pathway’s regulatory role ( 49 ). These findings provide insights into the critical role of signaling proteins in immunity against pathogens.…”