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Downregulation of NHP 2 promotes proper cyst formation in Drosophila ovary
Author(s) -
Morita Shumpei,
Ota Ryoma,
Kobayashi Satoru
Publication year - 2018
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/dgd.12539
Subject(s) - gene knockdown , biology , germline , nucleolus , microbiology and biotechnology , ribonucleoprotein , mitosis , downregulation and upregulation , cyst , cell growth , stem cell , cell , cell division , cell culture , genetics , gene , rna , pathology , cytoplasm , medicine
In Drosophila ovary, g ermline s tem c ells ( GSC s) divide to produce two daughter cells. One daughter is maintained as a GSC , whereas the other initiates cyst formation, a process involving four synchronous mitotic divisions that form 2‐, 4‐, 8‐, and 16‐cell cysts. In this study, we found that reduction in the level of NHP 2, a component of the H/ ACA small nucleolar ribonucleoprotein complex that catalyzes rRNA pseudouridylation, promotes progression to 8‐cell cysts. NHP 2 protein was concentrated in the nucleoli of germline cells during cyst formation. NHP 2 expression, as well as the nucleolar size, abruptly decreased during progression from 2‐cell to 4‐cell cysts. Reduction in NHP 2 activity in the germline caused accumulation of 4‐ and 8‐cell cysts and decreased the number of single cells. In addition, NHP 2 knockdown impaired the transition to 16‐cell cysts. Furthermore, a tumorous phenotype caused by Sex‐lethal ( Sxl ) knockdown, which is characterized by accumulation of single and two‐cell cysts, was partially rescued by NHP 2 knockdown. When Sxl and NHP 2 activities were concomitantly repressed, the numbers of four‐ and eight‐cell cysts were increased. In addition, Sxl protein physically interacted with NHP 2 mRNA in ovaries. Thus, it is reasonable to conclude that Sxl represses NHP 2 activity at the post‐transcriptional level to promote proper cyst formation. Because NHP 2 knockdown did not affect global protein synthesis in the germarium, we speculate that changes in NHP 2‐dependent pseudouridylation, which is involved in translation of specific mRNA s, must be intact in order to promote proper cyst formation.