Making human nasal cilia beat in the cold: a real time assay for cell signalling

Human nasal epithelium must adapt to cold climates, and yet, in vitro, human ciliary beat frequency (CBF) is zero at 4 degreesC. Similarly, hibernating mammals do not die of pneumonia despite a core body temperature as low as 6 degreesC, implying that cilia continue to beat. Here, we show that protein kinase C (PKC) and Ca2+/calmodulin-dependent kinase II (CaMKII) regulate the profile of human nasal CBF in response to rising temperature from 4 degreesC. Onset of ciliary beat was at 10 degreesC in Medium 199, 7 degreesC in the presence of the PKC activator phorbol 12-myristate 13-acetate (PMA), the calcium ionophore ionomycin, or the CAMKII blocker myristoylated autocamtide-2 related inhibitory peptide (MACI), and 6 degreesC for the myristoylated peptide PKC inhibitor EGF-R Fragment 651-658 (MyrPKCI). During cell warming to 32 degreesC, the thermal profile was sigmoid in all solutions except those containing MACI + PMA. Surprisingly, cilia continued to beat despite 4 degreesC and were significantly more responsive to rising temperature with either MACI + PMA, or MACI + MyrPKCI. Our data suggest that CaMKII and PKC regulate the thermal slope and profile of CBF in vitro, and that when these protein kinases are manipulated, cilia can continue to beat despite hypothermia. These findings may relate to adaptive responses to cold climates. (C) 2002 Elsevier Science Inc. All rights reserved.