Paperclip RNA Structure for Insect Cell Uptake
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Solution Overview
Problem
Current dsRNA-based insecticides are ineffective against lepidopteran pests due to reduced dsRNA uptake, leading to insecticide resistance, as these insects are refractory to dsRNA delivery, with gut cells failing to deliver ingested dsRNA to target mRNA molecules, necessitating improved delivery methods.
Innovation Solution
Development of a synthetic RNA molecule that folds into a 'paperclip' structure with a double-stranded region and single-stranded hairpin loops, allowing for clathrin-independent entry into insect cells, overcoming resistance mechanisms and enhancing RNAi efficacy in refractory insects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dsRNA is used to control insect pests, then it can effectively kill RNAi-sensitive insects, but it fails to work against lepidopteran pests due to reduced uptake
Solution Approach 1:
The patent changes the structural parameters of dsRNA by creating a hairpin configuration with specific stem and loop regions, and by controlling the length of the dsRNA molecule. This structural modification enables the RNA to be taken up by lepidopteran insects through clathrin-mediated endocytosis while maintaining RNAi activity, thus resolving the contradiction between efficacy and broad-spectrum activity
Solution Approach 2:
The patent introduces clathrin as an intermediary mechanism for dsRNA uptake. By designing the hairpin structure to be recognized and internalized via clathrin-mediated endocytosis, the invention creates a new delivery pathway that bypasses the uptake resistance in lepidopteran pests, enabling the insecticide to work across multiple insect orders
2Reliability
If dsRNA dosage is increased to overcome resistance in lepidopteran pests, then uptake may be improved, but toxicity to non-target species increases
Solution Approach 1:
The patent optimizes the length parameter of the dsRNA molecule (specifically the stem and loop regions) to create a structure that is selectively taken up by insect cells via clathrin-mediated endocytosis. This size optimization ensures effective uptake in target pests at lower doses while reducing non-specific uptake and toxicity in non-target species
Solution Approach 2:
The hairpin structure creates local structural features (stem region for RNAi activity, loop region for stability and recognition) that enhance selective uptake by insect cells. This localized structural optimization improves efficacy in target species without proportionally increasing harm to non-target organisms
3Reliability
If lab-bred resistant strains are developed through selection pressure, then dsRNA uptake is reduced, but this creates resistance that compromises long-term insecticide effectiveness
Solution Approach 1:
The patent introduces clathrin-mediated endocytosis as an alternative intermediary pathway for dsRNA uptake, bypassing the resistant uptake mechanism that has been selected against in lab strains. This alternative pathway remains functional in resistant populations, preserving long-term insecticide effectiveness
Solution Approach 2:
The invention segments the uptake mechanism into distinct pathways (clathrin-mediated vs. other pathways). By targeting the clathrin-mediated pathway with the hairpin structure, the patent creates a differentiated uptake route that is not compromised by resistance developed against other uptake mechanisms, ensuring durable control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The paperclip RNA structure facilitates efficient processing by Dicer and entry into insect cells, including lepidopteran species, effectively inducing RNAi and reducing feeding damage or killing target pests, thereby overcoming resistance and refractory issues.
Implementation Method 1
allowing for clathrin-independent entry into insect cells
Implementation Method 2
Delivery of double-stranded RNA to an organism will result in sequence-specific mRNA degradation in a process known as RNA interference (RNAi)
Implementation Method 3
efficient processing by Dicer
Data Source
AI summary
Described herein is a “paperclip” structured dsRNA (pcRNA) that has two closed ends (FIG. 1), and was developed and tested for its ability to enter insect cells and induce RNAi. While conventional dsRNAs, with their two collinear RNA strands, enter insect cells by clathrin-mediated endocytosis, the pcRNAs can enter cells by a clathrin-independent mechanism. The new structured dsRNA can be used to deliver dsRNA to insects that either develop resistance through alterations to their conventional uptake mechanisms and to insects that are naturally refractory to dsRNAs, including lepidopteran pests.