Anthocyanins inhibit tumor necrosis alpha-induced loss of Caco-2 cell barrier integrity.

An increased permeability of the intestinal barrier is proposed as a major event in the pathophysiology of conditions characterized by chronic gut inflammation. This study investigated the capacity of pure anthocyanins (AC), and berry and rice extracts containing different types and amounts of AC, to inhibit tumor necrosis alpha (TNFα)-induced permeabilization of Caco-2 cell monolayers. Caco-2 cells differentiated into intestinal epithelial cell monolayers were incubated in the absence/presence of TNFα, with or without the addition of AC or AC-rich plant extracts (ACRE). AC and ACRE inhibited TNFα-induced loss of monolayer permeability as assessed by changes in transepithelial electrical resistance (TEER) and paracellular transport of FITC-dextran. In the range of concentrations tested (0.25-1 µM), O-glucosides of cyanidin, and delphinidin, but not those of malvidin, peonidin and petunidin protected the monolayer from TNFα-induced decrease of TEER and increase of FITC-dextran permeability. Cyanidin and delphinidin acted by mitigating TNFα-triggered activation of transcription factor NF-κB, and downstream phosphorylation of myosin light chain (MLC). The protective actions of the ACRE on TNFα-induced TEER increase was positively correlated with the sum of cyanidins and delphinidins (r2 = 0.83) content in the ACRE. However, no correlation was observed between TEER and ACRE total AC, malvidin, or peonidin content. Results support a particular capacity of cyanidins and delphinidins in the protection of the intestinal barrier against inflammation-induced permeabilization, in part through the inhibition of the NF-κB pathway.

Nonuniform distribution of myosin light chains within the thick filaments of lobster slow muscle: Immunocytochemical study.

The in situ distribution of the alpha and beta myosin light chains was investigated at the subsarcomeric and subfilament levels in individual fibers of the superficial flexor muscle (SFM) of the lobster, Homarus americanus. Polyclonal antibodies were produced against the two classes of myosin light chains and used for subsequent immunolocalization on thin sections of sarcomeres and on isolated filaments from both the medial and lateral fiber bundles of the SFM. The beta myosin light chains were uniformly distributed within the crossbridge region of sarcomeres of both medial and lateral bundles. The alpha myosin light chains were uniformly distributed within the crossbridge region of sarcomeres from the medial bundle, but were nonuniformly distributed over the crossbridge region of lateral bundle sarcomeres. In the latter, the number of alpha myosin light chains was highest toward the center of the thick filaments, diminishing towards the ends. Similar distributions of alpha light chains were found in isolated myosin filaments. These data demonstrate that heterogeneity in protein composition extends to the level of the myosin filament and suggest that the myosin filament substructure in lobster may be different than that found in vertebrate skeletal muscle.

Function of myosin-V in filopodial extension of neuronal growth cones.

The molecular mechanisms underlying directed motility of growth cones have not been determined. The role of myosin-V, an unconventional myosin, in growth cone dynamics was examined by chromophore-assisted laser inactivation (CALI). CALI of purified chick brain myosin-V absorbed onto nitrocellulose-coated cover slips inhibited the ability of myosin-V to translocate actin filaments. CALI of myosin-V in growth cones of chick dorsal root ganglion neurons resulted in rapid filopodial retraction. The rate of filopodial extension was significantly decreased, whereas the rate of filopodial retraction was not affected, which suggests a specific role for myosin-V in filopodial extension.