Clarification of the Mechanism by Which the Structural Components of Cocoons are Produced – Toward the Development of a Technology for Increasing the Production of Useful Proteins by Silkworms –

Research Press Release | March 07, 2016

<strong>(left)</strong> Normal silk gland, <strong>(right)</strong> Silk gland in which Antennapedia is strongly expressed <br /> <br />The white arrow is the middle silk gland, and the red arrow is the posterior silk gland. Blue shows the strength of genes that are normally induced in the middle silk gland, and the darker the blue, the more strongly are the genes induced.<br /> In the silk gland on the right, as the result of making Antennapedia act strongly, genes that are normally induced only in the middle silk gland are now even being induced in the posterior silk gland. <br />The lengths of the black lines at the bottom right of the photographs are each 0.3 cm.
(left) Normal silk gland, (right) Silk gland in which Antennapedia is strongly expressed
 
The white arrow is the middle silk gland, and the red arrow is the posterior silk gland. Blue shows the strength of genes that are normally induced in the middle silk gland, and the darker the blue, the more strongly are the genes induced.
In the silk gland on the right, as the result of making Antennapedia act strongly, genes that are normally induced only in the middle silk gland are now even being induced in the posterior silk gland.
The lengths of the black lines at the bottom right of the photographs are each 0.3 cm.


Key Points

・Among the proteins that form the cocoons of silkworms, we clarified the mechanism of the local production of large quantities of a protein that helps to produce other useful proteins such as collagen.


・The use of this mechanism will help to increase the production of such useful proteins by silkworms.

Outline

Among the two types of silk proteins, namely, water-soluble and water-insoluble, the National Institute of Agrobiological Sciences (NIAS), with Hokkaido University, has clarified the mechanism of the local production of sericin, which is a water-soluble protein. We demonstrated that Antennapedia* (Antp), a protein that activates the sericin gene, is produced in large quantities and strongly acts during cocoon production.


We indicated that, by making Antp act, it is possible to produce sericin in regions where sericin is not normally produced.


In addition, we showed that Antp also activates the genes of several other proteins that are produced in such locations, and we found common base sequences among the genes on which Antp acts, including the sericin gene.


Transgenic silkworms have already been used in practical technology for producing useful proteins such as human collagen in a highly pure, water-soluble form, to be used as raw materials such as for cosmetics. However, it is crucial for such technology to produce useful proteins in large quantities together with water-soluble silk proteins (sericin).


In the future, by using this newly discovered mechanism to strongly express the genes for useful proteins via Antp, it will be possible to increase the production of useful proteins by silkworms.

Terms

* Antennapedia (Antp)

One of a group of genes (homeotic genes) that identify the regions (such as segments) along the anteroposterior axis of the body during the embryonic development of an organism. It had first been discovered as a gene that is expressed to form structures such as legs and wings during embryogenesis in Drosophila, and later it was found to be a gene that determines the identity of thoracic segment and is common to many insects, including silkworms. The present research has clarified that this homeotic gene whose expression is important at the embryonic stage also has a completely different, important function in the silk gland, after that organ has differentiated.

Inquiries

Shigeharu TAKIYA, Associate Professor

Cell Structure and Function Group

Department of Biological Sciences

Faculty of Science

takiya[at]sci.hokudai.ac.jp

Japanese Link

マユの構成成分が生産される仕組みを解明 -カイコによる有用タンパク質生産を向上させる技術の開発へ- (02.12.2016)

Publications

A Hox Gene Antennapedia Regulates Expression of Multiple Major Silk Protein Genes in the Silkworm Bombyx moriThe Journal of Biological Chemistry (01.26.2016)

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