Loss of Hsp67Bc leads to autolysosome enlargement in the Drosophila brain

Abstract

Hsp67Bc is a small heat shock protein found in Drosophila melanogaster. Apart from performing a function (common for all small heat shock proteins) of preventing aggregation of misfolded proteins, it is involved in macroautophagy regulation alongside the Starvin protein. Overexpression of the D. melanogaster Hsp67Bc gene has been shown to stimulate macroautophagy in S2 cell culture. Nonetheless, it has been unknown how the absence of the Hsp67Bc gene may affect it. Here, we studied the effect of Hsp67Bc gene deletion on the macroautophagy induced by the pathogenic Wolbachia wMelPop strain in D. melanogaster. We detected Wolbachia inside autophagic vacuoles in fly neurons, thereby proving that these endosymbionts were being eliminated via macroautophagy. Nevertheless, we did not register any difference in brain bacterial load between Hsp67Bc-null and control flies at all tested stages of ontogenesis. Moreover, the abundance of autophagic vacuoles was similar between neurons of the mutant and control flies, yet the cross-sectional area of autolysosomes on ultrathin sections was more than 1.5-fold larger in Hsp67Bc-null fly brains than in the control line. Our findings suggest that the product of the Hsp67Bc gene does not participate in the initiation of endosymbiont-induced macroautophagy but may mediate autophagosome maturation: the deletion of the Hsp67Bc gene leads to the increase in autolysosome size.

Wolbachia -Driven Memory Loss in a Parasitic Wasp Increases Superparasitism to Enhance Horizontal Transmission

“…Min and Benzer ( 48 ) found that Wolbachia can cause a widespread degeneration of tissues, including the brain and retina. Malkeyeva et al ( 49 ) reported that Wolbachia- induced a macro-autophagy in the neurons of D. melanogaster . However, without another probe for the CNS demonstrating co-localization of nervous tissue and Wolbachia , it is still unclear if there is a direct interaction.…”

Wolbachia‐infected Trichogramma dendrolimi is outcompeted by its uninfected counterpart in superparasitism but does not have developmental delay

“…52,53 Wolbachia can cause degeneration of the retina and brain, and induce macro-autophagy in the neurons of D. melanogaster. 54,55 Some studies have shown that the memory retention of Trichogramma wasps is induced by Wolbachia infection. For example, memory duration is significantly shorter in Wolbachiainfected T. brassicae than in their uninfected counterparts.…”

“…Some studies have detected Wolbachia colonization in the central nervous system of host insects, including Folsomia candida , 47 Spalangia endius , 48 Drosophila melanogaster , 49,50 and Eurema hecabe , 51 and this may account for the effects of Wolbachia on host behaviors, including locomotion, sleep, feeding, mating preference and frequency, learning, and memory capacity 52,53 . Wolbachia can cause degeneration of the retina and brain, and induce macro‐autophagy in the neurons of D. melanogaster 54,55 . Some studies have shown that the memory retention of Trichogramma wasps is induced by Wolbachia infection.…”