Adaptable, turn-on maturation (ATOM) fluorescent biosensors for multiplexed detection in cells.

A grand challenge in biosensor design is to develop a single-molecule, fluorescent protein-based platform that can be easily adapted to recognize targets of choice. Here, we created a family of adaptable, turn-on maturation (ATOM) biosensors consisting of a monobody (circularly permuted at one of two positions) or a nanobody (circularly permuted at one of three positions) inserted into a fluorescent protein at one of three surface loops. Multiplexed imaging of live human cells coexpressing cyan, yellow and red ATOM sensors detected biosensor targets that were specifically localized to various subcellular compartments. Fluorescence activation involved ligand-dependent chromophore maturation with turn-on ratios of up to 62-fold in cells and 100-fold in vitro. Endoplasmic reticulum- and mitochondria-localized ATOM sensors detected ligands that were targeted to those organelles. The ATOM design was validated with three monobodies and one nanobody inserted into distinct fluorescent proteins, suggesting that customized ATOM sensors can be generated quickly.

Adaptable, Turn-On Monobody (ATOM) Fluorescent Biosensors for Multiplexed Detection in Cells.

A grand challenge in biosensor design is to develop a single molecule, fluorescent protein-based platform that can be easily adapted to recognize targets of choice. Conceptually, this can be achieved by fusing a small, antibody-like binding domain to a fluorescent protein in such a way that target binding activates fluorescence. Although this design is simple to envision, its execution is not obvious. Here, we created a family of adaptable, turn-on monobody (ATOM) biosensors consisting of a monobody, circularly permuted at one of two positions, inserted into a fluorescent protein at one of three surface loops. Multiplexed imaging of live human cells co-expressing cyan, yellow, and red ATOM sensors detected the biosensor targets (WDR5, SH2, and hRAS proteins) that were localized to the nucleus, cytoplasm, and plasma membrane, respectively, with high specificity. ER- and mitochondria-localized ATOM sensors also detected ligands that were targeted to those organelles. Fluorescence activation involved ligand-dependent chromophore maturation with fluorescence turn-on ratios of >20-fold in cells and up to 100-fold in vitro . The sensing mechanism was validated with three arbitrarily chosen monobodies inserted into jellyfish as well as anemone lineages of fluorescent proteins, suggesting that ATOM sensors with different binding specificities and additional colors can be generated relatively quickly.

Screening asymptomatic men for prostate cancer: A comparison of international guidelines on prostate-specific antigen testing.

OBJECTIVE: To summarise and compare the key recommendations on prostate-specific antigen (PSA)-based screening for prostate cancer, and so highlight where more evidence is required to facilitate consistent recommendations. METHODS: The Medline database and websites of 18 national screening organisations and professional associations were searched between January 2010 and November 2020 to identify screening guidelines published in English, considering recent clinical trials. RESULTS: Population-based PSA testing of asymptomatic men is not widely recommended. Guidelines emphasize shared patient-clinician decision making. For 'average-risk' men choosing to be screened, the recommended age varies from 50-55 to 70 years, alongside consideration of life expectancy (ranging from 7-15 years). Screening intervals, when specified, are biennial (most common), annual, or determined from baseline PSA. The earliest age for screening high-risk men (frequently defined as of African descent or with a family history of prostate cancer) is 40 years, but recommendations often defer to clinical judgement. CONCLUSIONS: Population screening of asymptomatic men is not widely recommended. Instead, balancing the potential harms and benefits of PSA testing is endorsed. Variation between guidelines stems from differing interpretations of key trials and could lead to clinician-dependent screening views. The development of clinical decision aids and international consensus on guidelines may help reduce national and international variation on how men are counselled.