The Mitochondrial Phosphatase PTPMT1 is Required for the Proper Growth Rate in the Red Flour Beetle, .

Protein tyrosine phosphatase, mitochondrial 1 (PTPMT1) is a mitochondrial phosphatase that is highly conserved in animals. Functional analyses using knockout animals have revealed a variety of physiological roles of PTPMT1 in vertebrates and insects. However, because of the high lethality of knockout in these animals, the roles of PTPMT1 in the later postembryonic development remain relatively obscure. In the present study, using the RNA interference technique, we analyzed functions in later larval stages of the red flour beetle, . was expressed in both anterior and posterior parts of the body constitutively without obvious fluctuations from the middle larval instar through pupation. The -knockdown larvae injected with double-stranded RNA at the middle instar showed a prolonged larval period, which was mainly caused by an extra larval molt. On the other hand, the increase in adult body length was subtle in the -knockdown , and the head capsule width was smaller than that of the control animals at the same larval instar. The expression levels of genes encoded by the mitochondrial genome were reduced in -knockdown larvae, indicating that PTPMT1 plays an important role in mitochondrial function in , like in other species. By contrast, the expression levels of a juvenile hormone (JH)-biosynthetic gene and a JH-signaling gene were rather increased in the -knockdown larvae, which may have been caused indirectly by the reduction of larval growth rate. Altogether, these findings indicate that is required for the proper growth rate via some mitochondrial physiological role in larvae.