Drosophila TRIM32 cooperates with glycolytic enzymes to promote cell growth

Abstract

Cell growth and/or proliferation may require the reprogramming of metabolic pathways, whereby a switch from oxidative to glycolytic metabolism diverts glycolytic intermediates towards anabolic pathways. Herein, we identify a novel role for TRIM32 in the maintenance of glycolytic flux mediated by biochemical interactions with the glycolytic enzymes Aldolase and Phosphoglycerate mutase. Loss of Drosophila TRIM32, encoded by thin (tn), shows reduced levels of glycolytic intermediates and amino acids. This altered metabolic profile correlates with a reduction in the size of glycolytic larval muscle and brain tissue. Consistent with a role for metabolic intermediates in glycolysis-driven biomass production, dietary amino acid supplementation in tn mutants improves muscle mass. Remarkably, TRIM32 is also required for ectopic growth - loss of TRIM32 in a wing disc-associated tumor model reduces glycolytic metabolism and restricts growth. Overall, our results reveal a novel role for TRIM32 for controlling glycolysis in the context of both normal development and tumor growth.

Analyzing muscle structure and function throughout the larval instars in live Drosophila

“…In control larvae, larval locomotion velocity increases as the larvae progress through the instars [ Figure 5 I, ( Balakrishnan et al., 2020 )]. This increase in locomotion velocity throughout larval stages is consistent with an increase in muscle size that occurs during the instars ( Balakrishnan et al., 2020 , Demontis and Perrimon, 2009 , Bawa et al., 2020 ). Mutations in genes affecting larval locomotion thus far have predominantly decreased locomotion, with very few mutations identified that increase locomotion of the larva ( Camuglia et al., 2018 ).…”

TRIM32 and Malin in Neurological and Neuromuscular Rare Diseases

“…Regarding the C-terminal NHL repeats, no structural data is available for either protein, but the high sequence similarity between TRIM32 and malin would suggest that the NHL domain presents a similar three-dimensional structure. The crystal structure of the NHL domain of the TRIM32 Drosophila orthologue, thin , was recently solved and shown to fold in the typical beta-barrel shape (PDB 6D69; 6XG7) [ 31 , 32 ]. Using the Swiss-Model homology modeling software ( , accessed on 1 January 2021) and the crystal structure of the C-terminal domain of Danio rerio TRIM71, another NHL-containing TRIM (PDB 6FPT), we modeled the C-terminal domain of both malin and TRIM32 ( Figure 3 C).…”

“…The role of malin, in complex with laforin, in glycogen catabolism has been extensively described above. Interestingly, in the D. melanogaster model, the TRIM32 orthologue thin was recently shown to be implicated in glucose metabolism through the positive regulation of glycolytic enzymes aldolase and phosphoglycerate mutase [ 31 ]. In addition, TRIM32 silencing in normal muscles increases PI3K-AKT-FOXO signaling and enhances glucose uptake, thus inducing fiber growth [ 98 ].…”

“…Of note, glycogen can contribute to the formation of protein–polysaccharide complexes in muscle. For example, sarcoglycans, linking the actin cytoskeleton with the extracellular matrix to anchor the sarcolemma during muscle contraction, are altered by TRIM32 ablation in both the fruitfly and C2C12 cell models [ 31 , 32 ]. Taken together, these findings indicate that common pathways controlled by malin and TRIM32, even in a contrasting manner, may deserve further investigation to potentially identify novel therapeutic targets for both LD and LGMDR8.…”

Metabolic reprogramming in cancer: mechanistic insights from Drosophila

“…2 C.2). A glycolysis-dependent amplification loop may exist in Pvr tumors too, as tripartite motif-containing protein 32 (TRIM32; encoded by thin ), an E3 ubiquitin ligase that maintains glycolytic flux, is required for LDH transcription in tumors ( Bawa et al, 2020 ). Nonetheless, how TRIM32 controls LDH at the transcriptional level in Pvr tumors warrants further investigation.…”