Building proteomic pathways using Drosophila ventral furrow formation as a model

Abstract

Ventral furrow formation is the first morphogenetic movement to occur during Drosophila gastrulation causing the internalization of mesodermal precursors. A previous proteomic screen for ventral-specific proteome changes identified a set of about forty "difference-proteins" that spanned many cellular functions. To understand the connections between these disparate proteins, we initiated a pathway-building scheme using cycles of protein expression manipulation and proteome analysis. This pathway-building exercise started with the proteasomal subunit, Pros35, one of three proteasome subunits found to be ventral-specific difference-proteins. Here we show that Pros35 is a key regulator in ventral furrow formation. Altering the level of Pros35 led to ventral furrow defects. Proteome analysis of the changes induced by Pros35 RNAi showed extensive overlap with the original set of ventral-specific difference-proteins. One of the most prominent changes was in the extracellular iron carrier, Transferrin (Tsf1). Tsf1 is normally less abundant in ventral cells relative to lateral cells; however, RNAi of Pros35 in ventralized embryos negated this ventral-specific difference. Increasing Tsf1 in wild-type embryos blocked ventral furrow formation and caused proteome changes that were similar to the previously seen ventral-specific difference-proteins, including Pros35, which indicates the existence of an unprecedented regulatory loop between the proteasome and iron homeostasis. Additionally, we show that the iron regulatory protein, Irp-1A, also plays an important role in ventral furrow formation. Together these three proteins are part of a regulatory loop that coordinately controls a large number of ventral-specific protein changes.

Iron Sulfur and Molybdenum Cofactor Enzymes Regulate the Drosophila Life Cycle by Controlling Cell Metabolism

“…Furthermore, transcriptional regulation of ferritin upon iron sensing appears to dominate the Drosophila iron response (Georgieva et al, 1999 ; Missirlis et al, 2007 ; Rosas-Arellano et al, 2016 ), suggesting that an undiscovered transcription factor responds to varying cytosolic iron concentration in insects. Of note, Drosophila ferritin is loaded with iron in the endoplasmic reticulum (Xiao et al, 2014 ; Xiao and Zhou, 2018 ) and is an essential gene (González-Morales et al, 2015 ), as is also the case for IRP-1A (Puri et al, 2008 ). More work is needed to understand cellular iron homeostasis in Drosophila .…”

Shotgun and TMT-Labeled Proteomic Analysis of the Ovarian Proteins of an Insect Vector, Aedes aegypti (Diptera: Culicidae)

“…Although mosquito TF binds a single iron atom, it does not serve as a major transport protein in mosquitoes ( Geiser and Winzerling 2012 ). Available information indicates it is more likely involved in mosquito immunity ( Yoshiga et al 1997 , Harizanova et al 2005 ) and development ( Puri et al 2008 ). Ferritins can store up 4,500 atoms of iron ( Theil 2012 , Plays et al 2021 ).…”

Iron Absorption in Drosophila melanogaster

“…Whether it traffics iron between tissues remains unclear. Ventral furrow formation during the early development of the Drosophila embryo appears to require differential regulation of Tsf1 in ventral and lateral cells, but the mechanistic details of why this needs to be so, are not understood [77]. There is evidence that Tsf1 is an immune-responsive gene [64,78].…”