Transgenic Mammals Secreting Proteins in Milk
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Solution Overview
Problem
Current methods for producing desired proteins in transgenic animals are inefficient and costly, with proteins often being difficult to purify from blood or culture media, which can be toxic or carcinogenic, and do not allow for efficient transmission to offspring.
Innovation Solution
A DNA sequence is developed using a mammalian milk protein promoter, such as whey acid protein, to control the transcription and secretion of proteins, allowing for their production in mammalian milk, facilitating purification and enabling transmission to female offspring, using techniques like microinjection and retrovirus vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If foreign genes are inserted into vertebrate embryos using mechanical microinjection or retrovirus vectors, then transgenic animals can be produced with foreign gene expression, but the proteins are difficult to purify from blood or culture media and the process is inefficient and costly
Solution Approach 1:
The patent introduces milk as an intermediary medium for protein secretion and purification. By directing foreign gene expression to the mammary gland through tissue-specific promoters, the protein of interest is secreted into milk rather than being produced in blood or culture media. This intermediary system simplifies purification since milk is a natural, non-toxic medium that can be easily collected and processed, avoiding the complexity of purifying from blood or culture media while maintaining high production efficiency.
Solution Approach 2:
The patent applies local quality by using tissue-specific promoters (such as casein or whey acid protein promoters) that direct gene expression specifically to the mammary gland tissue. This localized expression ensures that the foreign protein is produced only in the milk-producing tissue, allowing for targeted secretion into milk while avoiding expression in other tissues where purification would be more difficult. This spatial specificity resolves the contradiction between production efficiency and purification ease.
2Object-affected harmful factors
If proteins are produced in transgenic animals using conventional methods, then protein production is achieved, but the culture media additives can be toxic or carcinogenic and purification is difficult
Solution Approach 1:
The patent converts the natural biological system of milk production into a beneficial purification system. Instead of using toxic culture media additives that complicate purification, the invention utilizes milk—a natural, non-toxic biological fluid—as the secretion medium. The mammary gland's natural protein secretion machinery is harnessed to direct the foreign protein into milk, transforming a physiological process into a benefit that simultaneously achieves high protein yield and simplifies purification by eliminating toxic contaminants.
Solution Approach 2:
The transgenic animal's mammary gland performs self-service by naturally secreting the foreign protein into milk along with its own milk proteins. The animal's own physiological systems are utilized to produce and secrete the recombinant protein, eliminating the need for external culture media and toxic additives. This self-service approach maintains high productivity while avoiding harmful substances, as the animal's body naturally handles protein synthesis and secretion without requiring toxic external agents.
3Productivity
If milk protein promoters are used to control gene transcription, then protein secretion into milk is achieved with high yield and ease of purification, but the promoter must be from a mammalian source to ensure proper transcriptional control
Solution Approach 1:
The patent employs universal mammalian milk protein promoters (such as casein or whey acid protein promoters) that can drive expression of diverse foreign genes across different mammalian species. These promoters serve multiple functions: they are recognized by the host animal's transcriptional machinery, they direct tissue-specific expression to the mammary gland, and they enable high-level protein secretion into milk regardless of the foreign gene's origin. This universality simplifies DNA construction compared to developing species-specific promoters for each target organism, as the same promoter framework can be used across different mammalian hosts.
Data Source
AI summary
A DNA sequence containing a gene encoding a protein, the gene being under the transcriptional control in the DNA sequence of a mammalian milk protein promoter which does not naturally control the transcription of the gene, such DNA sequence including DNA enabling secretion of the protein.