The role of the trithorax group TnaA isoforms in Hox gene expression, and in Drosophila late development

Abstract

Regulation of developmental gene expression in eukaryotes involves several levels. One of them is the maintenance of gene expression along the life of the animal once it is started by different triggers early in development. One of the questions in the field is when in developmental time, the animal start to use the different maintenance mechanisms. The trithorax group (TrxG) of genes was first characterized as essential for maintaining homeotic gene expression. The TrxG gene tonalli interacts genetically and physically with genes and subunits of the BRAHMA BAP chromatin remodeling complex and encodes TnaA proteins with putative E3 SUMO-ligase activity. In contrast to the phenocritic lethal phase of animals with mutations in other TrxG genes, tna mutant individuals die late in development. In this study we determined the requirements of TnaA for survival at pupal and adult stages, in different tna mutant genotypes where we corroborate the lack of TnaA proteins, and the presence of adult homeotic loss-of-function phenotypes. We also investigated whether the absence of TnaA in haltere and leg larval imaginal discs affects the presence of the homeotic proteins Ultrabithorax and Sex combs reduced respectively by using some of the characterized genotypes and more finely by generating TnaA defective clones induced at different stages of development. We found that, tna is not required for growth or survival of imaginal disc cells and that it is a fine modulator of homeotic gene expression.

Regulated inositol synthesis is critical for balanced metabolism and development in Drosophila melanogaster

“…Pupal lethality has also been reported in D melanogaster strains harboring mutations in numerous other pathways, with a consensus that the arrests often appear to be caused by events that occurred earlier in development ( Shearn et al, 1971 ; Engels et al, 1987 ; Gildea et al, 2000 ; Yoshida et al, 2016 ; Kowalewski-Nimmerfall et al, 2014 ; Rosales-Vega et al, 2018 ; Syed et al, 2019 ; Drelon et al, 2019 ; Ray and Lakhotia, 2019 ; Wang et al, 2019 ; Yusuff et al, 2020 ). Having established that inositol is causing developmental defects, some next steps would be to determine if this is due inositol's role in membrane biogenesis, signal transduction, osmoregulation, as a carbon/energy source, as an insulin mimetic, or in some other component of maintenance of homeostasis and/or metabolism.…”

TnaA, a trithorax group protein, modulates wingless expression in different regions of the Drosophila wing imaginal disc

“…We previously established that tna genetically interacts with the Notch pathway to control the level of Wingless protein at the D/V boundary. Next, we knocked-down TnaA (a decrease of approximately 70% with respect to the wild-type level), by expressing a tna RNAi ( tna JF02536 , 13 , 21 ) in the anterior compartment of the wing disc (Sup. Fig.…”

“…tna EY22929 is a hypomorphic P{EPgy2} element insertion-derived allele 44 . These three alleles are described in 13 . tna MI01482 is a MiMIC element insertion-derived allele 45 .…”

“…SUMO ligases favor the SUMOylation of specific target proteins. tonalli ( tna ) is a trithorax-group gene that is essential during larval and pupal development 12 , 13 . It encodes several TnaA isoforms with putative E3 SUMO ligase activity in the subunits of the BRAHMA complex, Osa and Brahma 13 , 14 and probably in other nuclear proteins in imaginal discs.…”

SUMOylation in development and neurodegeneration

“…TnaA interacts with Osa, a subunit of the Drosophila SWI/SNF chromatin remodeling complexes and a possible SUMOylation target (Monribot-Villanueva et al, 2013;Nie et al, 2009). Although TnaA is not required for normal Ubx expression, it may nonetheless play a role in fine-tuning this expression as ectopic Ubx expression resulting from Pc mutations is significantly decreased in tna mutants (Rosales-Vega et al, 2018).…”