Technique and Application of Single-molecule Fluorescence in situ Hybridization / 生物化学与生物物理进展

ABSTRACT

Single molecule fluorescence in situ hybridization (smFISH) is a method for imaging single mRNA molecule in fixed cell or tissue using oligonucleotide probes coupled with fluorophores. It can realize real-time study of interested transcripts by RNA localization and quantification. smFISH is widely suitable for many types of biological samples such as cell and tissue sections. It was invented in 1982 which opened up the application of visualizing single molecules. However, due to its shortcomings such as poor binding specificity, Raj et al. optimized this technique in 2008, using 48 independent probes that were separately coupled with fluorophores to locate transcripts. In contrast, methods using multiple labeled probes can distinguish false positive or false negative results due to a single probe misbinding or unbinding event. However, with the continuous application of the technique, it was found that the scheme still has many technical defects, such as low probe specificity, weak fluorescence intensity, low hybridization efficiency, and high background fluorescence. Since then, a series of derivative technologies have been developed. For example, HCR-FISH is a multi-fluorescence in situ hybridization method based on orthogonal amplification and hybridization chain reaction, which significantly improves the problem of weak signal. SeqFISH amplifies the signal and reduces nonspecific binding by continuously hybridizing the mRNA in the cell, imaging it, and stripping the probe in order to barcode RNA. MERFISH utilizes combination labeling, continuous imaging and other technologies to increase detection throughput, and uses binary barcodes to offset single-molecule labeling and detection errors, with more advanced built-in error correction functions to effectively improve the accuracy of results. ClampFISH uses biological orthogonal click chemistry to effectively lock the probe around the target and prevent the probe from disengaging in amplification microscopy. RNAscope amplifies its own signal while simultaneously suppressing the background by using novel probe design strategy and hybridization-based signal amplification system. Split-FISH uses splitting probes for signal enhancement to accurately detect single RNA molecule in complex tissue environments. AmpFISH achieves imaging of short RNA molecules by preparing long single-strand DNA concatemers through controlled rolling circle amplification. CircFISH uses two unique sets of probes (PC probes and PL probes) to distinguish between linear and circular RNAs. π-FISH rainbow enables simultaneous detection of DNA, RNA, and proteins at the single-molecule level with π-FISH target probes. HT-smFISH is more suitable for large or high throughput form of systematic experiments. With the development of technology, the subsequent data analysis process is particularly important. Different analysis software, such as dotdotdot and FISH-quant v2, also improve the process of smFISH. The excellent ability of smFISH to visualize single molecule of RNA makes that it is widely used in basic biological disciplines such as tumor biology, developmental biology, neurobiology, botany, virology. In this paper, we reviewed the basic principle of smFISH technology, its development process and improvement, limitations of smFISH technology and how to avoid them, its derivative technologies include HCR-FISH, SeqFISH, MERFISH, ClampFISH, RNAscope, Split-FISH, AmpFISH, CircFISH, π-FISH rainbow and HT-smFISH. The application progress of smFISH in different biological disciplines, such as developmental biology, tumor biology, neurobiology. Finally, the development prospect of smFISH technology is prospected.