Upon illumination, photosensitizer molecules produce reactive oxygen species (ROS) that can be utilized for functional manipulation of living cells, including protein inactivation, targeted damage introduction, and cellular ablation. Photosensitizers used to date have been either exogenous, resulting in delivery and removal challenges, or genetically encoded proteins that form or bind a native photosensitizing molecule, resulting in a constitutively active photosensitizer inside the cell. By binding a heavy-atom substituted fluorogenic dye with a genetically encoded Fluorogen Activating Protein (FAP), we demonstrate an ‘on-demand’ activated photosensitizer that produces singlet oxygen and fluorescence only when FAP-bound and activated with near infrared light. This Targeted and Activated Photosensitizer (TAPs) approach enables protein inactivation and targeted cell killing in cultured cells and rapid targeted lineage ablation in living larval and adult zebrafish. The near-infrared excitation and emission of this FAP-TAPs photosensitizer module provides a new spectral range for photosensitizer proteins, useful for imaging, manipulation and cellular ablation deep within living organisms.

The regulation of surface levels of protein is critical for proper cell function and influences properties including cell adhesion, ion channel contributions to current flux, and the sensitivity of surface receptors to ligands. Here we demonstrate a two-color labeling system in live cells using a single fluorogen activating peptide (FAP) based fusion tag, which enables the rapid and simultaneous quantification of surface and internal proteins. In the nervous system, BK channels can regulate neural excitability and neurotransmitter release, and the surface trafficking of BK channels can be modulated by signaling cascades and assembly with accessory proteins. Using this labeling approach, we examine the dynamics of BK channel surface expression in HEK293 cells. Surface pools of the pore-forming BKα subunit were stable, exhibiting a plasma membrane half-life of >10 h. Long-term activation of adenylyl cyclase by forskolin reduced BKα surface levels by 30%, an effect that could not be attributed to increased bulk endocytosis of plasma membrane proteins. This labeling approach is compatible with microscopic imaging and flow cytometry, providing a solid platform for examining protein trafficking in living cells.

BackgroundThe prognostic significance of FOXP3+ tumor-infiltrating lymphocytes (TILs) in patients with breast cancer remains controversial. The aims of our meta-analysis are to evaluate its association with clinicopathological characteristics and prognostic significance in patients with breast cancer.MethodsPubMed, Embase, Cochrane Database and the Ovid Database were systematically searched (up to April 2015). The meta-analysis was performed using hazard ratio (HR), odds ratio (OR) and 95 % confidence intervals (CI) as effect measures. Using the random-effects model, statistical analysis was performed using Stata software, version 12.0.ResultsSeventeen studies including 8277 patients with breast cancer were analyzed. The meta-analysis indicated that the incidence difference of FOXP3+ TILs was significant when comparing the lymph node positive group to negative group (OR = 1.305, 95 % CI [1.071, 1.590]), the histological grade III group to the I–II group (OR = 3.067, 95 % CI [2.288, 4.111]), the ER positive group to the negative group (OR = 0.435, 95 % CI [0.287, 0.660]), the PR positive group to the negative group (OR = 0.493, 95 % CI [0.296, 0.822]), the HER2 positive group to the negative group (OR = 1.896, 95 % CI [1.335, 2.692]), the TNBC group to the non TNBC group (OR = 2.456, 95 % CI [1.801, 3.348]). The detection of FOXP3+ TILs was significantly correlated with the recurrence-free survival (RFS) of patients (HR = 1.752, 95 % CI [1.188–2.584]) and the overall survival (OS) of patients (HR =1.447, 95 % CI [1.037–2.019]).ConclusionsOur meta-analysis demonstrates that the presence of high levels of FOXP3+ TILs is associated with prognosis for breast cancer patients and predicts lymph node metastasis, hormone receptor and HER-2 status.