Apoptosis of posterior silk gland of Bombyx mori during spinning period and the role of PI3K/Akt pathway

Abstract

Bombyx mori is an economic insect of the Lepidoptera. Its posterior silk gland (PSG) is an important organ for fibroin synthesis. In order to study the occurrence of apoptosis in PSG and the role of PI3K/Akt signaling pathway during spinning period, changes in morphology of silk gland, expressions of fibroin components Fib-H, Fib-L and P25 and Akt, TOR2, P70S6K and S6 in PI3K/Akt pathway, expressions of apoptosis related genes caspase-3, caspase-9 and activity of caspase-3 were explored. The results showed that the morphology of silk gland dramatically degenerated; transcription of Fib-H, Fib-L, and P25 gradually declined with time; and Fib-L protein level reduced by 0.6-fold at 72 h. Moreover, the transcription levels of Akt, TOR2, P70S6K, and S6 also decreased by 0.3-, 0.8-, 0.7-, and 0.1-fold, respectively, indicating that the downregulation of PI3K/Akt signaling pathway could lead to reduction in fibroin synthesis. In addition, the transcription levels of caspase-3 and caspase-9 increased by 1.3- and 3.6-fold, respectively, and the enzyme activity of caspase-3 grew at a maximum of 1.6-fold. The results showed the occurrence of apoptosis in PSG during spinning period. In conclusion, the present study indicated that both the decline in fibroin components and the increase in apoptosis-related genes were regulated by PI3K/Akt signaling pathway during spinning period, which shed new light on the functions of PI3K/Akt signaling pathway.

Cell death during complete metamorphosis

“…This signalling pathway in fact represents the mediator that leads to the activation of autophagy at metamorphosis via nutrient signals and hormones, at least in the larval fat body [5]. Furthermore, a recent study has reported that the expression of apoptosisrelated genes, such as caspases, during the spinning period is regulated by PI3K/Akt, suggesting a possible role of this signalling pathway in activating apoptosis in the posterior silk gland of B. mori, too [80]. However, further investigation is needed to confirm this hypothesis for the PI3K/Akt pathway and, hopefully, to characterize the putative regulatory mechanism.…”

Silk Fibroin/Hydroxyapatite Coating Improved Osseointegration of Porous Titanium Implants under Diabetic Conditions via Activation of the PI3K/Akt Signaling Pathway

“…19,25 Apart from the above advantages, SF has a synergistic effect with HA on PI3K/Akt activation. 26,27 Some previous reports have shown the applications of SF 28 and HA 29 as a surface coating on TIs under normal culture conditions. However, to our knowledge, there have been no reports demonstrating the promotive effect of SF/HA hybrid coatings under diabetic conditions.…”

“…By contrast, hydroxyapatite (HA) as a component of natural bone tissue has excellent osteoinductivity and biodegradability, which could be slowly replaced as a bone repair and replacement material . It has been demonstrated that the incorporation of HA in SF scaffolds may promote bone regeneration through the osteoinductive effects of HA on osteogenic cells, exerting better osteoconductivity and osteoinductivity than SF alone. , Apart from the above advantages, SF has a synergistic effect with HA on PI3K/Akt activation. , Some previous reports have shown the applications of SF and HA as a surface coating on TIs under normal culture conditions. However, to our knowledge, there have been no reports demonstrating the promotive effect of SF/HA hybrid coatings under diabetic conditions.…”

MicroRNA bmo‐miR‐31‐5p inhibits apoptosis and promotes BmNPV proliferation by targeting the CYP9e2 gene of Bombyx mori

“…It also helps maintain body growth and development, organ remodeling and cellular immunity. [1][2][3] Apoptosis is also involved in resisting virus invasion and maintaining body stability. 4 For example, the human body protects against influenza A virus (IAV) infection by regulating apoptosis.…”