A serine protease in the midgut of the silkworm, Bombyx mori: Protein sequencing, identification of cDNA, demonstration of its synthesis as zymogen form and activation during midgut remodeling

Characterization of Kunitz-type protease inhibitor purified from hemolymph of Galleria mellonella larvae

“…Although there remains the possibility that the activity of the TLP in the midgut was regulated at the synthetic level in a stage-dependent fashion, it is conceivable that Gm KTPI may be associated with the inhibition of residual TLP activity in the prepupal midgut. As for insect midgut SPs occurring specifically in the larval and prepupal stages, it has been previously suggested that while the larval midgut SPs are associated primarily with the digestion of dietary proteins, SPs in the prepupal midgut may be more involved in midgut remodeling processes (Broehan et al, 2008;Kaji et al, 2009). Thus far, three types of SPs have been shown to be involved in midgut remodeling during larval-pupal development, including a TLP with a molecular mass of 37 kDa from B. mori (Kaji et al, 2009), a TLP with a molecular mass of 26 kDa from Sarcophaga peregrina (Nakajima et al, 1997) and a CTLP from Spodoptera exigua (Herrero et al, 2005).…”

“…As for the tissues to be remodeled in insect metamorphosis, the midgut has been recognized as an appropriate focus of interest, as it undergoes drastic changes in morphology and function. It has been suggested that specific SPs are responsible for the disintegration of the larval midgut during the larval-pupal transition (Herrero et al, 2005;Kaji et al, 2009). Several trypsin-and chymotrypsin-like proteases (TLP and CTLP, respectively) that contribute to metamorphosis were identified in a variety of insects, and their involvement in midgut remodeling was demonstrated on the basis of their localization and stage-dependent expression (Herrero et al, 2005;Kaji et al, 2009;Broehan et al, 2010).…”

“…It has been suggested that specific SPs are responsible for the disintegration of the larval midgut during the larval-pupal transition (Herrero et al, 2005;Kaji et al, 2009). Several trypsin-and chymotrypsin-like proteases (TLP and CTLP, respectively) that contribute to metamorphosis were identified in a variety of insects, and their involvement in midgut remodeling was demonstrated on the basis of their localization and stage-dependent expression (Herrero et al, 2005;Kaji et al, 2009;Broehan et al, 2010). It has been previously theorized that these TLP and CTLP may leak into the hemolymph from the midgut during tissue remodeling and exert a deleterious effect on other tissues (Eguchi and Kanbe, 1982).…”

Serina proteinases digestivas de insetos-modelo

“…A ativação de um tripsinogênio de Bombyx mori é causada pela presença de um fator desconhecido não protéico presente no intestino médio, e não pela presença de enzimas ativadoras das serina proteases, como verificado em mamíferos (Kaji et al, 2009). …”

“…Assim, a cromatografia em coluna aniônica realizada em pH 7,0 não liga essa tripsina à matriz, pois a enzima deveria estar positivamente carregada (de acordo com a determinação experimental do pI) ou praticamente sem carga (de acordo com o pI teórico), sendo eluído no "flow-through"; entretanto, quando a mesma enzima é aplicada na mesma coluna em pH 9,0 interage com a matriz, pois nesse pH ela se encontra negativamente carregada e interage com a matriz, sendo eluída durante mori (Kaji et al, 2009), a ativação de tripsinogênios de insetos poderia estar condicionada à presença desse fator presente no intestino médio, e não à presença de enzimas ativadoras das serina proteases, como visto em mamíferos.…”