Deficiency of mitochondrial HSP70mA1 causes energy shortage and cellular apoptosis in two Henosepilachna beetles

The mammal mitochondrial heat shock protein 70 (HSP70mA) exerts pleiotropic functions in maintenance of normal roles of mitochondrial proteins, mitochondrial biogenesis and the formation of mitochondrial F₁F₀-ATP synthase. However, the roles of HSP70mA in other animals have been scarcely explored. The hsp70ma1 genes encode a very similar pair of HSP70mA1 proteins in two Henosepilachna beetle species, H. vigintioctopunctata and H. vigintioctomaculata.

The hsp70ma1 transcripts were widely expressed in all developmental stages including the embryos, larvae, prepupae, pupae and adults, and in the tested tissues containing foregut, midgut, hindgut, fat body, malpighian tubules, epidermis and hemocytes in the 3^rd-instar larvae in the two Henosepilachna species. Knockdown of hsp70ma1 completely inhibited pupation irrespective of administration of dshsp70ma1 at the 3^rd- or 4^th-instar larval stages. All hsp70ma1 RNAi larvae ate less foliage, experienced developmental arrest and remained as stunted prepupae. Subsequently, they gradually turned black and eventually died. Depletion of hsp70ma1 repressed ATP production. The gene expression pattern (increased GLUT4 mRNA abundance, decreased SREBP1 mRNA abundance) is consistent with the activation of the AMPK pathway, a well-characterized cellular response to energy depletion, and suggests an increased capacity for glycolytic flux. However, the gene expression patterns suggest a metabolic shift towards anaerobic metabolism of pyruvate, rather than through tricarboxylic acid cycle and oxidative phosphorylation. Moreover, knockdown of hsp70ma1 disrupted oxidative homeostasis and led to cellular apoptosis.

Our findings established a critical role of HSP70mA1 on the maintenance of mitochondria function in the two Henosepilachna species. © 2026 Society of Chemical Industry.