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Glycolipid-protein interaction in the mechanism of signal transduction: Studies with a photoactivable ganglioside analogue

100%

Masserini M., Pitto M., Ferraretto A., Brunne J., Palestini P.

Acta Biochimica Polonica

1998

tom 45

nr 2

An increasing body of evidence suggests that glycolipid domains are present on the plasma membrane surface of mammalian cells and play a key role in signal transduction. We have investigated the modulation of glycolipid-protein interaction consequent to a specific event occurring at the plasma membrane. For this purpose, a new photoactivable, radioactive derivative of GM1 ganglioside, carrying a phenyldiazirine fatty acid labelled with 125I, has been used with rat cerebellar granule cells in culture. Upon incubation of photoactivable GM1 with the cells followed by illumination, several proteins become radioactive and were detectable on the two dimensional-electrophoresis, which points to their interaction with the ganglioside. Upon addition of cytotoxic doses of glutamate, known to induce indirectly the activation of protein kinase C (PKC), one of the proteins crosslinked by photoactivable GM1 in control cells of molecular mass about 92 kDa and pI about 4, was not anymore detectable; this suggests its exclusion from the glycolipid domains. On the contrary, another protein, of about 15 kDa and pI 6.5, previously not crosslinked, was interacting with the ganglioside derivative after glutamate treatment. Comparable effects were exerted by phorbol-2-myristate-3-acetate, which directly induces the activation of PKC. These results show that PKC activation, a key step of inbound trans-membrane signalling, affects the interaction between glycolipids and proteins at the plasma membrane surface, possibly within a mixed domain. The dynamic modulation of ganglioside-protein interaction may affect the involvement of glycolipid domains in membrane-located events such as signal transmission and lipid/protein sorting.

Cellular uptake of coumarin-6 as a model drug loaded in solid lipid nanoparticles

72%

Rivolta I., Panariti A., Lettiero B., Sesana S., Gasco P., Gasco M. R., Masserini M., Miserocchi G.

Journal of Physiology and Pharmacology

2011

tom 62

nr 1

The aim of present work was to elucidate the interaction of solid lipid nanoparticles (SLNs) with cellular plasma-membrane to gain insight of intracellular drug delivery. To this aim we followed the uptake of coumarin-6 (a drug model) either free in the extracellular medium or loaded on SLN (c-SLN). Alveolar epithelial cells were exposed to a biocompatible concentration of c-SLN (0.01 mg/ml of tripalmitin) prepared by warm microemulsion whose lipid matrix was constituted by low melting point molecules (fatty acids, triglycerides). Intracellular fluorescence and preferential accumulation in the perinuclear region were increased by 54.8% on comparing c-SLN to the same amount of free coumarin-6 in the medium. Lowering temperature from 37° to 4°C decreased the intracellular signal intensity by about 48% equally for the free as well as for loaded drug, thus suggesting the inhibition of a similar non-endocytotic entrance pathway. No specific co-localization of the fluorescence with intracellular organelles was found. The c-SLN calorimetric profile obtained with differential scanning calorimetry (DSC), revealing transition within the range 58-62°C, altered remarkably upon incubation with cells, suggesting a change in SLN structure after association with cells membranes. We propose that the uptake of the model drug loaded on SLN is only partly related to the endocytotic pathway; it occurs despite the loss of integrity of the original SLN structure and it appears to be more efficient when the drug is vehicled rather than being free in the culture medium.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 Journal of Physiology and Pharmacology

2 Masserini M.

1 Brunne J.

1 Ferraretto A.

1 Gasco M. R.

1 Gasco P.

1 Lettiero B.

1 Miserocchi G.

1 Palestini P.

1 Panariti A.

1 Pitto M.

1 Rivolta I.

1 Sesana S.

1 2011

1 1998

Wyniki wyszukiwania

Glycolipid-protein interaction in the mechanism of signal transduction: Studies with a photoactivable ganglioside analogue

Cellular uptake of coumarin-6 as a model drug loaded in solid lipid nanoparticles