Increasing expression of calcium permeable TRPC3 and TRPC7 channels enhances constitutive secretion

Verna Lavender , Setareh Chong , Katherine Ralphs , Adrian J Wolstenholme , Barbara J. Reaves (1)

1 Biology & Biochemistry

The hTRPC (human transient receptor potential canonical) family of non-selective cation channels are proposed to mediate calcium influx across the plasma membrane via PLC-coupled receptors. Heterologously expressed hTRPC3 and hTRPC7 have been localised at the cell surface, however, a large intracellular component has also been noted but not characterised. In this study we have investigated the intracellular pool in COS-7 cells and have shown co-localisation with markers for both the trans-Golgi network (TGN) and the cis-Golgi cisternae by immunofluorescence microscopy. Addition of Brefeldin A to cells expressing hTRPC3 or hTRPC7 resulted in the redistribution of the Golgi component to the endoplasmic reticulum indicating this pool is present in both the Golgi stack and the TGN. Expression of either TRPC3 or TRPC7, but not TRPC1 or the cell surface marker CD8, resulted in a 2-4 fold increase of secreted alkaline phosphatase in the extracellular media. Based on these data, we propose that an additional function of these members of the hTRPC family may be to enhance secretion either by affecting transport through the Golgi stack or increasing fusion at the plasma membrane.

Mots clés: Life Sciences

Verna Lavender, Setareh Chong, Katherine Ralphs, Adrian J Wolstenholme, Barbara J. Reaves. Increasing expression of calcium permeable TRPC3 and TRPC7 channels enhances constitutive secretion. Biochemical Journal, 2008, 413 (3), pp.437-446. ⟨10.1042/BJ20071488⟩. ⟨hal-00478907⟩