Cellular internalization

Mangold SL, Carpenter RT, Kiessling LL (2008) Synthesis of fluorogenic polymers for visualizing cellular internalization. Org Lett 10 2997-3000... 

Figure 13.9 represents the TEM image of LDH particles and their cellular internalization. As expected, LDH particles are internalized by endocytosis. Figure 13.9(A) shows the cellular uptake process of LDHs after 3h of treatment, and demonstrates a successive entry of LDH by endocytosis first the LDH particles were located around the cell membrane due to their positive charge ( ), then they migrate to the membrane ruffles which are considered as endocytic bodies ( ), finally the coated intracellular vesicles were formed as early endosomes ( ). Figure 13.9(B)...

LDH-FITC is well overlapped with red fluorescent clathrin-TR, but not with caveolin-1-TR (Figure 13.10). This is dear evidence that clathrin-mediated endocytosis is the prindpal mechanism for the cellular internalization of LDH particles. Caveolae-mediated endocytosis, if any, seems not to be responsible for LDH uptake. 

Antigen binding by a complementary immunoglobulin molecule on the surface of B cells starts a process of cellular internalization of the foreign substance by pinocytosis. Once internalized by endosomes, systematic processing of the antigen takes place which breaks it down into smaller components. 

Machova Z, Muhle C, Krauss U, Trehin R, Koch A, Merkle HP, Beck-Sickinger AG (2002) Cellular internalization of enhanced green fluorescent protein ligated to a human calcitonin-based carrier peptide. Chem Biochem 3 672-677. 

In summary, the binding of oxLDL and/or lipids to several SC receptors (SRAI/II, CD36, CD68) has been clearly demonstrated. Most of other receptors may potentially bind oxLDL or lipids. Consequently, the cellular internalization of oxidized lipids by the SC receptor pathways may be involved in the biological effect of oxLDL, such as apoptosis induction. As a likely major ligand and because of their oxidized lipid contents, oxLDL may have many putative effects on different cells, such as alteration of cell signaling and gene expression. 

Cellular uptake is a diverse set of processes used by the cell. Often, the cell utilizes a variety of processes and not just a single mechanism. Therefore, different approaches should be taken to investigate. In this review, we have focused on several aspects of cellular internalization mechanisms to study the initial mode of internalization, and aspects of intracellular trafficking and metabolic activity. These aspects should not be regarded individually but should be considered together because often one aspect depends on the other. 

Nechers, L.M. (1993) Cellular internalization of oligodeoxynucleotides. In S.T.Crooke and B.Lebleu (eds) Antisense Research and Applications, CRC Press, Inc., Boca Raton, FL, pp. 451M60. 

Soon after the discovery of the ability of SPG to complex homopolynucleotides, it was demonstrated that schizophyllan complexes with poly(A) or poly(C) will dissociate at pH 4—6 [45]. This property is important as SPG polyplexes could potentially release their polynucleotide cargo in the acidic pH environment of endosomes and/or lysosomes. However, since these polyplexes possess a net negative charge and lack targeting groups, they are inefficient in terms of cellular internalization. 

Fig. 19 Cellular internalization, transgene expression, and relative cell viability of Tr4. Cellular uptake in (a) serum-free and (b) serum-containing media. Transgene expression and cell viability in (c) HeLa and (d) H9c2(2-1) cells. Figure adapted with permission from [155]. 2007 American Chemical Society...

Liu Y, Reineke TM (2007) Poly(glycoamidoamine)s for gene delivery, structural effects on cellular internalization, buffering capacity, and gene expression. Bioconjug Chem... 

Cellular internalization of macromolecules by endocytosis is an important biological process for their transcellular transport. Endocytosis can be categorized into adsorptive and receptor-mediated endocytosis (RME). RME involves specific binding of ligand to the receptor on the apical cell... 

More recently, phages that display known integrin-binding proteins have been shown not only to bind to mammalian cells but also to mediate cellular internalization through a mechanism of receptor-mediated endocytosis [87],... 

FIGURE 1 Mechanisms of cellular internalization of biodegradable nanoparticles. 

Kilk, K., Magzoub, M., Pooga, M., Eriksson, L. E., Langel, U., and Graslund, A. (2001) Cellular internalization of a cargo complex with a novel peptide derived from the third helix of the islet-1 homeodomain. Comparison with the penetratin peptide. Bioconjug. Chem. 12, 911-916. 

Perez F, Joliot A, Bloch-Gallego E, Zahraoui A, Triller A, Prochiantz A. Antennapedia homeobox as a signal for the cellular internalization and nuclear addressing of a small exogenous peptide. J Cell Sci 1992 102 717-22. 

In conclusion, cellular internalization of the toxins is required for intoxication. This is consistent with the molecular mode of intracellular cytotoxic action of both toxins described below. 

Henriques B, Florin I, Thelestam M (1987) Cellular internalization of Clostridium difficile toxin A. In Microb. Pathogen. 2 455—463. 

Lleres D, Weibel JM, Heissler D, Zuber G, Duportail G, Mely Y (2004) Dependence of the cellular internalization and transfection efficiency on the structure and physicochemical properties of cationic detergent/DNA/ liposomes. J Gene Med 6 415 28... 

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