Endocytosis temperature dependency

Serial optical sections of tumor cells incubated with diO-LCM for 20 min at RT gave an identical staining pattern as seen in the brain tumor in situ (cf. Fig. 13.1 (bottom right panel)), and showed that LCM became internalized. The process was temperature dependent. When incubated at 37°C, LCM were taken up by C6 tumor cells at the rate of 7 LCM/5 min, while the rate was 4 LCM/5 min at RT. Little uptake by the tumor cells took place at 4°C. These results are illustrated in Fig. 13.5, and are consistent with endocytosis being the main mechanism of LCM uptake by tumor cells (ref. 531). 

P. H. Weigel and J. A. Oka, Temperature dependence of endocytosis mediated by the asialoglycoprotein receptor in isolated rat hepatocytes. Evidence for two potentially rate-limiting steps. J. Biol. Chem. 256 2615-2617 (1981). 

Fig. 1 Proposed model for the internalization of PTD-conjugated macromolecules into cells. Interaction of positively charged PTDs with negatively charged proteoglycans and glycosa-minoglycans plays an important role in the internalization. The electrostatic interaction is followed by energy- and temperature-dependent endocytotic pathways. This involves phago-cytotic and pinocytotic pathways clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis...

Fig. 1. (A) Diagram of an in vitro assay for CCV formation from PMs. LSP low-speed pellet. LSS low-speed supernatant. HSP high-speed pellet. HSS high-speed supernatant. (B) Temperature-dependent recruitment of endocytic receptors from LSPs to HSPs in the presence of ATP, GTP, and cytosol. Scavenger receptor class B, t5ipe I (SR-BI) is a PM marker that is independent of clathrin-mediated endocytosis. (Figures reproduced from Miwako et al, 2003.)...

Wolkers, W.F. et al.. Temperature dependence of fluid phase endocytosis coincides with membrane properties of pig platelets, Biochem. Biophys. Acta — Biomembr., 1612,154,2003. 

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