Probing the effect of matrix stiffness in endocytic signalling pathway of corneal epithelium.

Matrix stiffness regulates the physiology of the cells and plays an important role in maintaining its homeostasis. It has been reported to regulate cell division, proliferation, migration, extracellular uptake and various other physiological processes. The alteration in matrix stiffness has also been well reported in various disease pathologies. However, in ocular system, Keratoconus (KC) is an ideal model to study the effect of matrix stiffness on endocytosis since the progression of the disease is controlled by increasing the stromal elasticity. Our study using corneal epithelial and retinal pigment epithelial cell lines showed that ocular cells do respond to matrix stiffness by altering their morphology and endocytic uptake of FITC-Dextran 20 kDa. Further, by using KC epithelium as a clinical model, we hypothesize that change in stromal elasticity may also affect the endocytosis of KC epithelium. Our results clearly showed alteration in the expression of actin binding proteins such as Phosphorylated Cofilin, Profilin, Focal adhesion kinase, and Vinculin. Apart from cytoskeletal rearrangement proteins, we also observed endocytic proteins such as Clathrin, Caveolin1 and Rab 11 to be affected by matrix stiffness. Our study thus establishes connecting role between endocytosis and matrix stiffness which could be used to understand the pathophysiology of keratoconus that it is influenced by both mechanical and biochemical factors.

Probing the biophysical interaction between Neocarzinostatin toxin and EpCAM RNA aptamer.

Neocarzinostatin (NCS) a potent DNA-damaging, anti-tumor toxin extracted from Streptomyces carzinostaticus that recognizes double-stranded DNA bulge and induces DNA damage. 2 Fluoro (2F) Modified EpCAM RNA aptamer is a 23-mer that targets EpCAM protein, expressed on the surface of epithelial tumor cells. Understanding the interaction between NCS and the ligand is important for carrying out the targeted tumor therapy. In this study, we have investigated the biophysical interactions between NCS and 2-fluro Modified EpCAM RNA aptamer using Circular Dichroism (CD) and Infra-Red (IR) spectroscopy. The aromatic amino acid residues spanning the ß sheets of NCS are found to participate in intermolecular interactions with 2 F Modified EpCAM RNA aptamer. In-silico modeling and simulation studies corroborate with CD spectra data. Furthermore, it reinforces the involvement of C and D1 strand of NCS in intermolecular interactions with EpCAM RNA aptamer. This the first report on interactions involved in the stabilization of NCS-EpCAM aptamer complex and will aid in the development of therapeutic modalities towards targeted cancer therapy.

Protocol to produce plant-based hybrid nanovesicles from fresh turmeric and pepper using polyethylene glycol.

In addition to proteins, microRNAs, and lipids, plant-derived exosome-like nanovesicles (ENVs) are also enriched with host plant bioactives. Both curcumin and piperine are water insoluble, lack bioavailability, and are extracted by non-ecofriendly solvents. Herein, we present an eco-friendly protocol for co-isolating both curcumin and piperine in the form of hybrid ENVs. We describe steps for sample pre-processing, combined homogenization of plant materials, filtration, and differential centrifugation. We then detail procedures for polyethylene glycol-based fusion and precipitation of hybrid ENVs. For complete details on the use and execution of this protocol, please refer to Kumar et al.1.

Elucidating the Therapeutic Potential of Cell-Penetrating Peptides in Human Tenon Fibroblast Cells.

Cell-penetrating peptides (CPPs) have been widely used as vehicles for delivering therapeutic molecules to the site of action. Apart from their delivering potential, the biological effects of CPPs have not been explored in detail. JTS-1 is a CPP that has been reported to have gene delivery functions, although its biological role is yet to be determined. Hence, in this study, we revealed the biological mechanism such as its uptake mechanism and immunogenic potential and function using primary human tenon fibroblast (TF) cells collected from patients undergoing glaucoma trabeculectomy surgery. Our results showed that the JTS-1 peptide has an α-helical structure and is nontoxic up to 1 µM concentration. It was found to be colocalized with early endosome (Rab5), recycling endosome (Rab7), and Rab11 and interacted with major histocompatibility complex (MHC) class I and II. The peptide also affected actin polymerization, which is regulated by cofilin phosphorylation and ROCK1 localization. It also inhibited TF cell proliferation. Therefore, the JTS-1 peptide could be used as a possible therapeutic agent for modifying the fibrosis process, where TF proliferation is a key cause of surgery failure.

Deciphering the mechanoresponsive role of ß-catenin in keratoconus epithelium.

Keratoconus (KC) is a corneal dystrophy characterized by progressive ectasia that leads to severe visual impairment and remains one of the leading indications for corneal transplantation. The etiology is believed to be multifactorial and alterations have been documented in the biomechanical, biochemical and ultrastructural characteristics of the cornea. While the exact site of disease origin is still debated, changes in the corneal epithelium are believed to occur even before the disease is clinically manifested. In this study we investigate the possible role of ß-catenin as mechanotransducer in KC corneal epithelium. The sheets of corneal epithelium removed from keratoconic eyes when they underwent collagen crosslinking as a therapeutic procedure were used for this study. The healthy corneal epithelium of patients undergoing Laser Refractive Surgery for the correction of their refractive error, served as controls. Immunoblotting and tissue immunofluorescence studies were performed on KC epithelium to analyse the expression and localization of ß-catenin, E-cadherin, ZO1, α-catenin, Cyclin D1, α-actinin, RhoA, and Rac123. Co-immunoprecipitation of ß-catenin followed by mass spectrometry of KC epithelium was performed to identify its interacting partners. This was further validated by using epithelial tissues grown on scaffolds of different stiffness. Histology data reported breaks in the Bowman's layer in KC patients. We hypothesize that these breaks expose the epithelium to the keratoconic corneal stroma, which, is known to have a decreased elastic modulus and that ß-catenin acts as a mechanotransducer that induces structural changes such as loss of polarity (Syntaxin3) and barrier function (ZO1) through membrane delocalization. The results of our study strongly suggest that ß-catenin could be a putative mechanotransducer in KC epithelium, thus supporting our hypothesis.

Synthesis of saporin-antibody conjugates for targeting EpCAM positive tumour cells.

Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein involved in cell proliferation and differentiation. Ribosomal inactivating proteins derived from plants specifically target ribosomes and irreversibly inhibit protein synthesis. EpCAM antibody and saporin were conjugated using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide chemistry. The mass of the conjugates were characterised using matrix-assisted laser desorption ionisation (MALDI). The saporin-EpCAM (SAP-EpAB) conjugates were tested in-vitro against MCF-7 (breast cancer cells), WERI-Rb1 (retinoblastoma) cells. The flow cytometry and fluorescence microscopy were performed to show the binding efficiency of SAP-EpAB conjugate. Whole transcriptome changes of sap-conjugate treated cells were studied using affymetrix microarrays. MALDI-TOF analysis and polyacrylamide gel electrophoresis confirmed the conjugation of SAP with EpCAM antibody. Flow cytometry and fluorescent microscopy analysis revealed the binding of SAP-EpAB conjugates to the MCF-7, WERI-Rb1 cells. Apoptosis assay by annexin-V has shown an increased apoptotic and necrotic population in conjugate treated cells. MTT assay confirmed the tumour cell death and had shown the IC50 value of 0.8 µg for conjugate in MCF-7 (breast cancer cells), and 1 µg for WERI-Rb1 (retinoblastoma) cells. The microarray analysis revealed downregulation of the tumourigenic genes and upregulation of pro-apoptotic genes leading to apoptosis of tumour cells.

Designing and enhancing the antifungal activity of corneal specific cell penetrating peptide using gelatin hydrogel delivery system.

BACKGROUND: Fungal keratitis is a major cause of corneal blindness accounting for more than one-third of microbiologically proven cases. The management of fungal keratitis is through topical or systemic antifungal medications alone or in combination with surgical treatment. Topical medications such as natamycin and voriconazole pose major challenges due to poor penetration across the corneal epithelium. To address the issue various carrier molecules like nanoparticles, lipid vesicles, and cell penetrating peptides were explored. But the major drawback such as non-specificity and lack of bioavailability remains. PURPOSE: In this study, we have attempted to design corneal specific cell penetrating peptide using subtractive proteomic approach from the published literature and tried to improve its bioavailability through gelatin hydrogel delivery system. MATERIAL AND METHODS: Using subtractive proteomic approach two peptides VRF005 and VRF007 were identified on the basis of solubility, cell permeability and amphipathicity. The peptides were modeled for three-dimensional structure and simulated for membrane penetration. The peptides were characterized using circular dichroism spectroscopy, dynamic light scattering and native polyacrylamide gel electrophoresis. Further uptake studies were performed on primary corneal epithelial cells and the stability was analyzed in corneal epithelial tissue lysates. Insilico prediction of peptides showed it to have antifungal activity which was further validated using colony forming assay and time killing kinetics. The duration of antifungal activity of peptide was improved using gelatin hydrogel through sustained delivery. RESULTS: VRF005 and VRF007 showed α-helical structure and was within the allowed region of Ramachandran plot. The simulation study showed their membrane penetration. The peptide uptake was found to be specific to corneal epithelial cells and also showed intracellular localization in Candida albicans and Fusarium solani. Peptides were found to be stable up to 2 hours when incubated with corneal epithelial tissue lysate. Dynamic light scattering, and native polyacrylamide gel electrophoresis revealed aggregation of peptides. VRF007 showed antifungal activity up to 24 hour whereas VRF005 showed activity up to 4 hours. Hence gelatin hydrogel-based delivery system was used to improve the activity. Actin staining of corneal epithelial cells showed that the cells were attached on gelatin hydrogel. CONCLUSION: We have designed corneal specific cell penetrating peptides using subtractive proteomic approach. Bioavailability and delivery of peptide was enhanced using gelatin hydrogel system.

Neocarzinostatin, Aptamer Conjugates for Targeting EpCAM-positive Tumor Cells.

BACKGROUND/AIM: The aim of this study was to investigate the role of Neocarzinostatin (NCS) conjugated with epithelial cell adhesion molecule (EpCAM) aptamer in EpCAM-positive cancer cells. NCS is an antitumor antibiotic protein chromophore that has the ability to cleave double stranded DNA and can be used as a potential drug for the treatment of EpCAM-positive cancers. EpCAM aptamer is an oligonucleotide ligand that binds specifically to EpCAM, a protein overexpressed in tumor cells. MATERIALS AND METHODS: NCS was conjugated with EpCAM aptamer using Sulfo-Succinimidyl 6-(3-(2-pyridyldithio) - propionamide hexanoate) LC-(SPDP) cross-linker to deliver it to EpCAM-positive tumor cells. The conjugates were characterized using polyacrylamide gel electrophoresis (PAGE) and high-performance liquid chromatography (HPLC). Flow cytometry was used to study the binding efficiency of the aptamer and the conjugates in cancer cells. The effect of the conjugate on cancer cells was studied using propidium iodide (PI) to analyze the cell cycle phase changes. The apoptosis assay was performed using the IC50 concentration of NCS. Microarrays were performed to study the gene level changes in cancer cells upon treatment with NCS and the conjugate. RESULTS: Flow cytometry revealed significant binding of aptamer and conjugate in the MCF-7 and WERI-Rb1 cell lines. Briefly, 62% in MCF and 30% in WERI-Rb1 cells with conjugate treated cells (p<0.005). The cell-cycle analysis indicated G2 phase arrest in MCF-7 cells and S phase arrest in WERI-Rb1 cells (p<0.005). Microarray analysis showed differentially expressed genes involved in cell cycle, DNA damage, and apoptosis. The BrDU assay and the apoptosis assay showed that the expression of BrDU was reduced in conjugate-treated cells and the PARP levels were increased confirming the double stranded DNA breaks (p<0.005). In MCF-7 and WERI-Rb1 cells, most of the cells underwent necrosis (p<0.005). CONCLUSION: The EpCAM aptamer conjugated NCS showed specificity to EpCAM-positive cells. The effect of the conjugates on cancer cells were impressive as the conjugate arrested the cell cycle and promoted apoptosis and necrosis. The high levels of PARP expression confirmed the DNA breaks upon conjugate treatment. Our study demonstrates that the NCS conjugated with EpCAM can be targeted to cancer cells sparing normal cells.

A comparative fluorescent beacon-based method for serum microRNA quantification.

Circulating serum microRNAs (miRNAs) are promising biomarkers for disease diagnosis. The quantification of the serum miRNA copy number is a challenge due to the presence of low levels in the serum. Here, we report on a direct measurement of the miRNA copy number from human serum using a locked nucleic acid (LNA) modified beacon probe with a single step using fluorescence spectroscopy and microscopy. We had used a minimum volume of 0.1 µL healthy human serum and retinoblastoma serum to show the biological variation of the miRNA copy number.

Antioxidant, Larvicidal, and Cytotoxic Studies on Asplenium aethiopicum (Burm. f.) Becherer.

The present study was intended to determine the antioxidant, larvicidal, and cytotoxic potential of various extracts of Asplenium aethiopicum (Burm. f.) Becherer. Antioxidant potential of the extracts was determined by the DPPH radical scavenging, phosphomolybdenum, and scavenging of H2O2. Larvicidal activity of Asplenium aethiopicum was performed against the fourth instar larvae Culex quinquefasciatus. Cytotoxic activity was analysed in terms of brine shrimp lethality bioassay. The best free radical scavenging activity was exerted by methanolic extract of Asplenium aethiopicum (IC50 91.4 µg/mL) followed by acetone extract (IC50 99.8 µg/mL). Highest larval mortality was observed in the crude acetone extracts of Asplenium aethiopicum against Culex quinquefasciatus (LC50 = 166.6 ppm) followed by methanolic extracts. Acetone extract of Asplenium aethiopicum was found to be most effective at which 50% and 90% mortality of brine shrimp nauplii that occurred were found to be 192.8 and 434.3 ppm, respectively. The results of the present study revealed the antioxidant, larvicidal, and cytotoxic potential of Asplenium aethiopicum.