Scientists at the Department of Genetics, Blavatnik Institute at Harvard Medical School have made a groundbreaking discovery during their study of phosphate transport in fruit fly intestines. Their findings, published in the journal Nature, reveal the existence of a previously unknown organelle. This discovery challenges the assumption that all organelles within animal cells had already been identified.
Organelles are specialized structures within cells that perform specific functions. Well-known organelles include the nucleus, which houses DNA and facilitates its transcription into RNA, the endoplasmic reticulum, involved in protein synthesis, the Golgi apparatus, responsible for protein processing, and the mitochondrion, which generates cellular energy and participates in cell regulation and communication.
In their research, the team sought to demonstrate the effects of inorganic phosphate starvation on the fruit fly midgut’s digestive epithelium. They observed hyperproliferation and enterocyte differentiation as a response to phosphate depletion. This phenomenon could be a survival mechanism aimed at increasing the production of enterocytes capable of absorbing phosphate.
Furthermore, the researchers noticed a decrease in the expression of the PXo gene (CG10483) during phosphate depletion. Intrigued by the role of the PXo protein, they conducted additional experiments, inhibiting PXo expression and completely removing the gene. Interestingly, these manipulations resulted in effects similar to those observed during inorganic phosphate starvation. This suggests that PXo plays a crucial role in phosphate transport.
The researchers then employed immunostaining and ultrastructural analyses, which revealed the presence of PXo within a previously unidentified organelle characterized by multilamellar membranes. They named this newly discovered organelle “PXo bodies.” Remarkably, PXo bodies functioned as storage sites for phosphate. When PXo expression was suppressed or the gene was absent, the PXo bodies degraded, releasing the stored phosphate into the cell.
While this study significantly enhances our understanding of phosphate metabolism and cellular signaling, further research is necessary to fully elucidate the functions and interactions of this newly discovered organelle. Additionally, investigating the presence of PXo bodies in other organisms could provide valuable insights into their evolutionary significance.