Background:The present study was focused on structural relationship between intracellular calcium stores and plasma membrane store-operated calcium channels in cultured normal and NF1 keratinocytes.Material/Methods:Calcium mobilization induced by thapsigargin or extracellular ATP was studied in control and cytochalasin D-treated human keratinocytes.Results:Treatment of keratinocytes with cytochalasin D disrupted the actin cytoskeleton and changed the cells from a planar, extended morphology, to a rounded shape. In normal control keratinocytes, thapsigargin induced a marked increase in intracellular calcium concentration ([Ca2+]i). The capacitative calcium influx of cytochalasin D-treated normal keratinocytes was significantly weaker compared to normal control cells. In normal keratinocytes, ATP induced a rapid and transient increase in [Ca2+]i. Thus disruption of the cytoskeleton blocked thapsigargin-induced calcium mobilization, but had no effect on ATP-induced [Ca2+]i mobilization in keratinocytes. The results suggest that microfilaments play crucial role for functional capacitative Ca2+ entry in cultured keratinocytes. The cytoskeleton and calcium mediated cell signaling have been demonstrated to be abnormal in keratinocytes cultured from patients with neurofibromatosis type 1 (NF1). In NF1 keratinocytes, thapsigargin induced a slow and moderate increase in [Ca2+]i. The effect of cytochalasin D on NF1 keratinocytes was less pronounced compared to normal keratinocytes. In NF1 keratinocytes, ATP induced a rapid and transient increase in [Ca2+]i.Conclusions:The actin microfilaments play a crucial role for functional capacitative Ca2+ entry in cultured keratinocytes, and that aberrant organization of cytoskeleton may partly explain altered calcium-mediated cell signaling in NF1.

Keywords: Actins - physiology, Adenosine Triphosphate - pharmacology, Biological Transport, Calcium - metabolism, Calcium - pharmacology, Calcium - physiology, Cytochalasin D - pharmacology, Cytoskeleton - drug effects, Cytoskeleton - physiology, Cytoskeleton - ultrastructure, Keratinocytes - cytology, Keratinocytes - drug effects, Keratinocytes - physiology, Neurofibromatosis 1 - pathology, Signal Transduction - drug effects, Signal Transduction - physiology, Skin - cytology, Skin - drug effects, Thapsigargin - pharmacology