The POU Transcription Factor POU-M2 Regulates <i>Vitellogenin Receptor</i> Gene Expression in the Silkworm, <i>Bombyx mori</i>

• Main Authors: Guanwang Shen, Enxiang Chen, Xiaocun Ji, Lina Liu, Jianqiu Liu, Xiaoting Hua, Dan Li, Yingdan Xiao, Qingyou Xia
• Format: Article
• Language: English
• Published: MDPI AG 2020-04-01
• Series: Genes
• Subjects: POU transcription factor; <i>Vitellogenin receptor</i>; transcriptional regulation; Oogenesis; <i>Bombyx mori</i>
• Online Access: https://www.mdpi.com/2073-4425/11/4/394

Vitellogenin receptors (VgRs) play critical roles in egg formation by transporting vitellogenin (Vg) into oocytes in insects. Although the function of VgR in insects is well studied, the transcriptional regulation of this gene is still unclear. Here, we cloned the promoter of the <i>VgR</i> gene from <i>Bombyx mori</i> (<i>BmVgR</i>), and predicted many POU cis-response elements (CREs) in its promoter. Electrophoretic mobility shift and chromatin immunoprecipitation assays showed that the POU transcription factor POU-M2 bound directly to the CREs of the promoter. Overexpression of POU-M2 in an ovarian cell line (BmNs) enhanced <i>BmVgR</i> transcription and promoter activity detected by quantitative reverse transcription PCR and luciferase reporter assays. Analyses of expression patterns indicated that <i>POU-M2</i> was expressed in ovary at day two of wandering stage initially, followed by <i>BmVgR</i>. RNA interference of <i>POU-M2</i> significantly reduced the transcription of <i>BmVgR</i> in ovary and egg-laying rate. Our results suggest a novel function for the POU factor in silkworm oogenesis by its involvement in <i>BmVgR</i> regulation and expands the understanding of POU factors in insect <i>VgR</i> expression.