p180 and SF3b4 Proteins Enhance mRNA Localization for Protein Secretion
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Solution Overview
Problem
Current methods for protein production in recombinant cells, such as CHO cells, face inefficiencies in protein synthesis and secretion due to low mRNA localization to the endoplasmic reticulum, leading to suboptimal production of glycoproteins like antibodies, which require post-translational modifications and have specific solubility and biological activity dependencies.
Innovation Solution
Development of recombinant cells with enhanced expression of p180 protein and SF3b4 protein, which promote mRNA localization to the endoplasmic reticulum, combined with the use of cis-elements in expression vectors to improve polysome formation and protein secretion capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CHO cells or HEK293 cells are used for protein production, then post-translational modifications can be achieved, but the rough endoplasmic reticulum is present only in a very small amount and is inferior in secretory activity
Solution Approach 1:
The invention changes the parameters of the expression system by introducing specific proteins (p180 and SF3b4) that alter the functional state of the endoplasmic reticulum, transforming it from a low-secretory state to a high-secretory state comparable to professional secretory cells
Solution Approach 2:
The invention uses p180 and SF3b4 proteins as intermediaries to enhance mRNA localization to the endoplasmic reticulum, thereby indirectly improving secretory activity without changing the cell type itself
2Quantity of substance
If mRNA is provided at high levels in expression vectors, then transcription activity is high, but mRNA localization to the endoplasmic reticulum is low and translation efficiency is poor
Solution Approach 1:
The invention introduces p180 and SF3b4 proteins as intermediaries that specifically bind to and facilitate mRNA localization to the endoplasmic reticulum, bridging the gap between high mRNA levels and efficient translation
Solution Approach 2:
The invention creates a feedback mechanism where increased p180 and SF3b4 expression leads to improved mRNA localization, which in turn enhances translation efficiency and protein secretion, creating a self-reinforcing system
3Ease of manufacture
If conventional expression vectors are used, then protein expression can be achieved, but secretory capacity is limited due to insufficient mRNA localization to the endoplasmic reticulum
Solution Approach 1:
The invention creates a composite expression system that combines conventional expression vectors with additional functional elements (p180 and SF3b4 expression cassettes), resulting in a hybrid system that maintains ease of manufacture while dramatically improving secretory capacity
Data Source
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AI summary
It has been believed that promoting the assembly of polysomes composed of many ribosomes attached to mRNA is very effective for highly efficient protein synthesis. However, the mechanism for p 180 protein's capability of promoting polysome formation has been yet to be elucidated. The inventors of the present application newly discovered SF3b4 protein as a protein that specifically interacts with the coiled-coil domain of p 180 protein, a responsible region for its capability of promoting polysome formation, and which is capable of promoting mRNA localization to an endoplasmic reticulum (ER). The inventors also found that, in cells capable of highly expressing both p180 protein and a protein promoting mRNA localization to an endoplasmic reticulum (ER) (e.g., SF3b4 protein), the mRNA localization to the endoplasmic reticulum can be significantly elevated so that the secretory capacity in cultured cells can be enhanced. Further, the inventors demonstrated that when a particular nucleotide sequence is inserted into an expression plasmid, SF3b4 protein exhibiting protein expression enhancing ability can be localized onto the endoplasmic reticulum membrane, and the mRNA distribution in polysomes can be shifted towards heavier fractions, whereby the secretory capacity in cells can be enhanced.