Differential expression and cellular distribution of centrin isoforms during human ciliated cell differentiation in vitro.
Centrin protein is an ubiquitously expressed cytoskeletal component and is a member of the EF-hand superfamily of calcium-binding proteins. It was first discovered in the flagellar apparatus of unicellular green algae where it is involved in contraction of Ca(2+)-sensitive structures. Centrin protein is associated with centrosome-related structures such as spindle pole body in yeast, and centriole/basal bodies in flagellar and ciliated cells. Three centrin genes have been cloned in human cells. In this work, we have performed a comparative biochemical and functional analysis of centrin isoforms using a primary culture of human nasal epithelial cells which provides an efficient way to obtain a complete ciliated cell differentiation process. RT-PCR experiments show that the expression of the three human centrin genes increases during cell differentiation, and that only centrin 2 and 3 are expressed during cell proliferation. Using polyclonal antibodies raised against recombinant human centrin 2 and 3, we show a specific pattern of protein expression. Ultrastructural immunolocalization suggests that centrin proteins are involved in the early process of centriole assembly, as they are concentrated within the precursor structures of centriole/basal bodies. It also shows a differential localisation of centrin proteins in mature centriole/basal bodies, suggesting different functions for centrins 1/2 and centrin 3. This is also supported by functional analyses showing that centrin 1 and/or centrin 2 are involved in ciliary beating.
Laoukili
J
J
Laboratoire de Cytophysiologie et Toxicologie Cellulaire, Université Paris 7, France.
Perret
E
E
Middendorp
S
S
Houcine
O
O
Guennou
C
C
Marano
F
F
Bornens
M
M
Tournier
F
F
D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002454:Cell Differentiation; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D002923:Cilia / Q000378:metabolism / Q000648:ultrastructure; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D020033:Protein Isoforms / Q000378:metabolism
C472752:CETN2 protein, human; C107745:CETN3 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D020033:Protein Isoforms; C056608:caltractin