Biochemical properties of gastrokine-1 purified from chicken gizzard smooth muscle.
The potential role and function of gastrokine-1 (GNK1) in smooth muscle cells is investigated in this work by first establishing a preparative protocol to obtain this native protein from freshly dissected chicken gizzard. Some unexpected biochemical properties of gastrokine-1 were deduced by producing specific polyclonal antibody against the purified protein. We focused on the F-actin interaction with gastrokine-1 and the potential role and function in smooth muscle contractile properties.


BACKGROUND
GNK1 is thought to provide mucosal protection in the superficial gastric epithelium. However, the actual role of gastrokine-1 with regards to its known decreased expression in gastric cancer is still unknown. Recently, trefoil factors (TFF) were reported to have important roles in gastric epithelial regeneration and cell turnover, and could be involved in GNK1 interactions. The aim of this study was to evaluate the role and function of GNK1 in smooth muscle cells.


RESULTS
From fresh chicken gizzard smooth muscle, an original purification procedure was used to purify a heat soluble 20 kDa protein that was sequenced and found to correspond to the gastrokine-1 protein sequence containing one BRICHOS domain and at least two or possibly three transmembrane regions. The purified protein was used to produce polyclonal antibody and highlighted the smooth muscle cell distribution and F-actin association of GNK1 through a few different methods.


CONCLUSIONS
Altogether our data illustrate a broader distribution of gastrokine-1 in smooth muscle than only in the gastrointestinal epithelium, and the specific interaction with F-actin highlights and suggests a new role and function of GNK1 within smooth muscle cells. A potential role via TFF interaction in cell-cell adhesion and assembly of actin stress fibres is discussed.
Hnia
Karim
K
INSERM ERI 25 Muscle et Pathologies, Université Montpellier 1, EA 4202, CHU Arnaud de Villeneuve, Montpellier, France.
Notarnicola
Cécile
C
de Santa Barbara
Pascal
P
Hugon
Gérald
G
Rivier
François
F
Laoudj-Chenivesse
Dalila
D
Mornet
Dominique
D
D000199:Actins / Q000378:metabolism; D000818:Animals; D030161:Avian Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002645:Chickens / Q000378:metabolism*; D005895:Gizzard, Avian / Q000737:chemistry* / Q000378:metabolism; D007150:Immunohistochemistry; D009124:Muscle Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D009130:Muscle, Smooth / Q000737:chemistry* / Q000378:metabolism*; D014335:Tropomyosin / Q000378:metabolism
D000199:Actins; D030161:Avian Proteins; D009124:Muscle Proteins; D014335:Tropomyosin