Split-Cas9-based targeted gene editing and nanobody-mediated proteolysis-targeting chimeras optogenetically coordinated regulation of Survivin to control the fate of cancer cells

POT, an optogenetics-based endogenous protein degradation system

Precise regulation of protein abundance is critical for cellular homeostasis, whose dysfunction may directly lead to human diseases. Optogenetics allows rapid and reversible control of precisely defined cellular processes, which has the potential to be utilized for regulation of protein dynamics at various scales. Here, we developed a novel optogenetics-based protein degradation system, namely Peptide-mediated OptoTrim-Away (POT) which employs expressed small peptides to effectively target endogenous and unmodified proteins. By engineering the light-induced oligomerization of the E3 ligase TRIM21, POT can rapidly trigger protein degradation via the proteasomal pathway. Our results showed that the developed POT-PI3K and POT-GPX4 modules, which used the iSH2 and FUNDC1 domains to specifically target phosphoinositide 3-kinase (PI3K) and glutathione peroxidase 4 (GPX4) respectively, were able to potently induce the degradation of these endogenous proteins by light. Both live-cell imaging and biochemical experiments validated the potency of these tools in downregulating cancer cell migration, proliferation, and even promotion of cell apoptosis. Therefore, we believe the POT offers an alternative and practical solution for rapid manipulation of endogenous protein levels, and it could potentially be employed to dissect complex signaling pathways in cell and for targeted cellular therapies.

Targeting intracellular cancer proteins with tumor-microenvironment-responsive bispecific nanobody-PROTACs for enhanced therapeutic efficacy

Proteolysis targeting chimeras (PROTACs) are pivotal in cancer therapy for their ability to degrade specific proteins. However, their non-specificity can lead to systemic toxicity due to protein degradation in normal cells. To address this, we have integrated a nanobody into the PROTACs framework and leveraged the tumor microenvironment to enhance drug specificity. In this study, we engineered BumPeD, a novel bispecific nanobody-targeted PROTACs-like platform, by fusing two nanobodies with a Furin protease cleavage site (RVRR) and a degron sequence (ALAPYIP or KIGLGRQKPPKATK), enabling the tumor microenvironment to direct the degradation of intracellular proteins. We utilized KN035 and Nb4A to target PD-L1 (programmed death ligand 1) on the cell surface and intracellular Survivin, respectively. In vitro experiments showed that BumPeD triggers Survivin degradation via the ubiquitin-proteasome pathway, inducing tumor apoptosis and suppressing bladder tumor cell proliferation and migration. In vivo experiments further confirmed BumPeD's robust anti-tumor efficacy, underscoring its potential as a precise protein degradation strategy for cancer therapy. Our platform provides a systematic approach to developing effective and practical protein degraders, offering a targeted theoretical basis and experimental support for the development of novel degradative drugs, as well as new directions for cancer therapy.

Discovery of nanobodies: a comprehensive review of their applications and potential over the past five years

Nanobodies (Nbs) are antibody fragments derived from heavy-chain-only IgG antibodies found in the Camelidae family as well as cartilaginous fish. Their unique structural and functional properties, such as their small size, the ability to be engineered for high antigen-binding affinity, stability under extreme conditions, and ease of production, have made them promising tools for diagnostics and therapeutics. This potential was realized in 2018 with the approval of caplacizumab, the world's first Nb-based drug. Currently, Nbs are being investigated in clinical trials for a broad range of treatments, including targeted therapies against PDL1 and Epidermal Growth Factor Receptor (EGFR), cardiovascular diseases, inflammatory conditions, and neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. They are also being studied for their potential for detecting and imaging autoimmune conditions and infectious diseases such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A variety of methods are now available to generate target-specific Nbs quickly and efficiently at low costs, increasing their accessibility. This article examines these diverse applications of Nbs and their promising roles. Only the most recent articles published in the last five years have been used to summarize the most advanced developments in the field.

Split Proteins and Reassembly Modules for Biological Applications

Split systems, modular entities enabling controlled biological processes, have become instrumental in biological research. This review highlights their utility across applications like gene regulation, protein interaction identification, and biosensor development. Covering significant progress over the last decade, it revisits traditional split proteins such as GFP, luciferase, and inteins, and explores advancements in technologies like Cas proteins and base editors. We also examine reassembly modules and their applications in diverse fields, from gene regulation to therapeutic innovation. This review offers a comprehensive perspective on the recent evolution of split systems in biological research.