Dual peptides-modified cationic liposomes for enhanced Lung cancer gene therapy by a gap junction regulating strategy.

BACKGROUND: Gene therapy for lung cancer has emerged as a novel tumor-combating strategy for its superior tumor specificity, low systematical toxicity and huge clinical translation potential. Especially, the applications of microRNA shed led on effective tumor ablation by directly interfering with the crucial gene expression, making it one of the most promising gene therapy agents. However, for lung cancer therapy, the microRNA treatment confronted three bottlenecks, the poor tumor tissue penetration effect, the insufficient lung drug accumulation and unsatisfied gene transfection efficiency. To address these issues, an inhalable RGD-TAT dual peptides-modified cationic liposomes loaded with microRNA miR-34a and gap junction (GJ) regulation agent all-trans retinoic acid (ATRA) was proposed, which was further engineered into dry powder inhalers (DPIs). RESULTS: Equipped with a rough particle surface and appropriate aerodynamic size, the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs were expected to deposit into the deep lung and reach lung tumor lesions guided by targeting peptide RGD. Assisted by cellular transmembrane peptides TAT, the RGD-TAT-CLPs/ARTA@miR-34a was proven to be effectively internalized by cancer cells, enhancing gene transfection efficiency. Then, the GJ between tumor cells was upregulated by ARTA, facilitating the intercellular transport of miR-34a and boosting the gene expression in the deep tumor. CONCLUSION: Overall, the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs could enhance tumor tissue penetration, elevate lung drug accumulation and boost gene transfection efficiency, breaking the three bottlenecks to enhancing tumor elimination in vitro and in vivo. We believe that the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs could serve as a promising pulmonary gene delivery platform for multiple lung local disease treatments.

Junction Mapper is a novel computer vision tool to decipher cell-cell contact phenotypes.

Stable cell-cell contacts underpin tissue architecture and organization. Quantification of junctions of mammalian epithelia requires laborious manual measurements that are a major roadblock for mechanistic studies. We designed Junction Mapper as an open access, semi-automated software that defines the status of adhesiveness via the simultaneous measurement of pre-defined parameters at cell-cell contacts. It identifies contacting interfaces and corners with minimal user input and quantifies length, area and intensity of junction markers. Its ability to measure fragmented junctions is unique. Importantly, junctions that considerably deviate from the contiguous staining and straight contact phenotype seen in epithelia are also successfully quantified (i.e. cardiomyocytes or endothelia). Distinct phenotypes of junction disruption can be clearly differentiated among various oncogenes, depletion of actin regulators or stimulation with other agents. Junction Mapper is thus a powerful, unbiased and highly applicable software for profiling cell-cell adhesion phenotypes and facilitate studies on junction dynamics in health and disease.

Attaching-and-Effacing Pathogens Exploit Junction Regulatory Activities of N-WASP and SNX9 to Disrupt the Intestinal Barrier.

BACKGROUND & AIMS: Neural Wiskott-Aldrich Syndrome protein (N-WASP) is a key regulator of the actin cytoskeleton in epithelial tissues and is poised to mediate cytoskeletal-dependent aspects of apical junction complex (AJC) homeostasis. Attaching-and-effacing (AE) pathogens disrupt this homeostasis through translocation of the effector molecule early secreted antigenic target-6 (ESX)-1 secretion-associated protein F (EspF). Although the mechanisms underlying AJC disruption by EspF are unknown, EspF contains putative binding sites for N-WASP and the endocytic regulator sorting nexin 9 (SNX9). We hypothesized that N-WASP regulates AJC integrity and AE pathogens use EspF to induce junction disassembly through an N-WASP- and SNX9-dependent pathway. METHODS: We analyzed mice with intestine-specific N-WASP deletion and generated cell lines with N-WASP and SNX9 depletion for dynamic functional assays. We generated EPEC and Citrobacter rodentium strains complemented with EspF bearing point mutations abolishing N-WASP and SNX9 binding to investigate the requirement for these interactions. RESULTS: Mice lacking N-WASP in the intestinal epithelium showed spontaneously increased permeability, abnormal AJC morphology, and mislocalization of occludin. N-WASP depletion in epithelial cell lines led to impaired assembly and disassembly of tight junctions in response to changes in extracellular calcium. Cells lacking N-WASP or SNX9 supported actin pedestals and type III secretion, but were resistant to EPEC-induced AJC disassembly and loss of transepithelial resistance. We found that during in vivo infection with AE pathogens, EspF must bind both N-WASP and SNX9 to disrupt AJCs and induce intestinal barrier dysfunction. CONCLUSIONS: Overall, these studies show that N-WASP critically regulates AJC homeostasis, and the AE pathogen effector EspF specifically exploits both N-WASP and SNX9 to disrupt intestinal barrier integrity during infection.

Gap junction regulation by calmodulin.

Intracellular Ca(2+) activated calmodulin (CaM) inhibits gap junction channels in the low nanomolar to high micromolar range of [Ca(2+)]i. This regulation plays an essential role in numerous cellular processes that include hearing, lens transparency, and synchronized contractions of the heart. Previous studies have indicated that gap junction mediated cell-to-cell communication was inhibited by CaM antagonists. More recent evidence indicates a direct role of CaM in regulating several members of the connexin family. Since the intracellular loop and carboxyl termini of connexins are largely "invisible" in electron microscopy and X-ray crystallographic structures due to disorder in these domains, peptide models encompassing the putative CaM binding sites of several intracellular domains of connexins have been used to identify the Ca(2+)-dependent CaM binding sites of these proteins. This approach has been used to determine the CaM binding affinities of peptides derived from a number of different connexin-subfamilies.