Existence of Prophenoloxidase in Wing Discs: A Source of Plasma Prophenoloxidase in the Silkworm, Bombyx mori

Diao, Yupu; Lü, Aijun; Yang, Bing; Hu, W. Z.; Peng, Qing; Ling, Qing; Beerntsen, Brenda T.; Söderhäll, Kenneth; Ling, Erjun

doi:10.1371/journal.pone.0041416

Cited by 12 publications

(8 citation statements)

References 28 publications

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“…For example, wing discs dissected from B. mori larvae can release PPO into the culture medium. However, PPO-positive cells in wing disc cavities might derive from the attached hematopoietic organ (Diao et al, 2012 ). Since wing discs are physically connected with the hematopoietic organ via many small tubes (Ling et al, 2006 ), some hemocytes may be accidentally released into the wing discs when PPO is released.…”

Section: Distribution Of Ppomentioning

confidence: 99%

“…Ethanol can activate PPO even within cells and tissues, and PPO-positive cells appear if the substrates are subsequently replaced (Ling et al, 2005 ). Using this method, new types of PPO-positive hemocytes and tissues have been identified without using the immunostaining method (Ling and Yu, 2005 ; Ling et al, 2005 ; Diao et al, 2012 ; Shao et al, 2012 ). This method can also be used to detect PPO in native gels; for example, DmPPO1 and DmPPO2 appear as different bands on the same native gel (Asano and Takebuchi, 2009 ).…”

Section: Ppo Detectionmentioning

confidence: 99%

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Insect prophenoloxidase: the view beyond immunity

et al. 2014

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Insect prophenoloxidase (PPO) is an important innate immunity protein due to its involvement in cellular and humoral defense. It belongs to a group of type-3 copper-containing proteins that occurs in almost all organisms. Insect PPO has been studied for over a century, and the PPO activation cascade is becoming clearer. The insect PPO activation pathway incorporates several important proteins, including pattern-recognition receptors (PGRP, β GRP, and C-type lectins), serine proteases, and serine protease inhibitors (serpins). Due to their complexity, PPO activation mechanisms vary among insect species. Activated phenoloxidase (PO) oxidizes phenolic molecules to produce melanin around invading pathogens and wounds. The crystal structure of Manduca sexta PPO shows that a conserved amino acid, phenylalanine (F), can block the active site pocket. During activation, this blocker must be dislodged or even cleaved at the N-terminal sequence to expose the active site pockets and allow substrates to enter. Thanks to the crystal structure of M. sexta PPO, some domains and specific amino acids that affect PPO activities have been identified. Further studies of the relationship between PPO structure and enzyme activities will provide an opportunity to examine other type-3 copper proteins, and trace when and why their various physiological functions evolved. Recent researches show that insect PPO has a relationship with neuron activity, longevity, feces melanization (phytophagous insects) and development, which suggests that it is time for us to look back on insect PPO beyond the view of immunity in this review.

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Section: Distribution Of Ppomentioning

confidence: 99%

Section: Ppo Detectionmentioning

confidence: 99%

Insect prophenoloxidase: the view beyond immunity

et al. 2014

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“…2), supporting the idea that BmproPO1 may have sticky properties (Diao et al, 2012). However, it is still unclear whether this binding occurs in the hemolymph or nodule.…”

Section: Bmsphs In Plasma Are Concentrated In Nodules By B Mori Ctypmentioning

confidence: 71%

Mechanisms of nodule-specific melanization in the hemocoel of the silkworm, Bombyx mori

Shi¹,

Mang²,

Fu³

et al. 2016

Insect Biochemistry and Molecular Biology

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“…Larvae on days 1 or 3 of the fifth larval stage (V‐1 or V‐3) were used for experiments. Larval age is reported in days as previously described (Diao et al., ).…”

Section: Methodsmentioning

confidence: 99%

Thermolysin Damages Animal Life Through Degradation of Plasma Proteins Enhanced by Rapid Cleavage of Serpins and Activation of Proteases

Kong

Lü

Guan

et al. 2014

Arch Insect Biochem Physiol

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Thermolysin, a metallopeptidase secreted by pathogenic microbes, is concluded as an important virulence factor due to cleaving purified host proteins in vitro. Using the silkworm Bombyx mori as a model system, we found that thermolysin injection into larvae induces the destruction of the coagulation response and the activation of hemolymph melanization, which results in larval death. Thermolysin triggers the rapid degradation of insect and mammalian plasma proteins at a level that is considerably greater than expected in vitro and/or in vivo. To more specifically explore the mechanism, thermolysin-induced changes to key proteins belonging to the insect melanization pathway were assessed as a window for observing plasma protein cleavage. The application of thermolysin induced the rapid cleavage of the melanization negative regulator serpin-3, but did not directly activate the melanization rate-limiting enzyme prophenoloxidase (PPO) or the terminal serine proteases responsible for PPO activation. Terminal serine proteases of melanization are activated indirectly after thermolysin exposure. We hypothesize that thermolysin induces the rapid degradation of serpins and the activation of proteases directly or indirectly, boosting uncontrolled plasma protein degradation in insects and mammalians.

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Existence of Prophenoloxidase in Wing Discs: A Source of Plasma Prophenoloxidase in the Silkworm, Bombyx mori

Cited by 12 publications

References 28 publications

Insect prophenoloxidase: the view beyond immunity

Insect prophenoloxidase: the view beyond immunity

Mechanisms of nodule-specific melanization in the hemocoel of the silkworm, Bombyx mori

Thermolysin Damages Animal Life Through Degradation of Plasma Proteins Enhanced by Rapid Cleavage of Serpins and Activation of Proteases

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