Lack of integrin alpha-chain endoproteolytic cleavage in furin-deficient human colon adenocarcinoma cells LoVo.
In the present report the biosynthesis of the integrin alpha-chains endowed with constitutive endoproteolytic cleavage was evaluated in LoVo cells where furin, a subtilisin-like convertase involved in post-translational endoproteolytic processing, is not functional. It was found that cell-surface alpha 3, alpha 6 and alpha v subunits were not processed endoproteolytically into heavy and light chains as they were in HT29-D4 cells, a furin-competent cell line. Complete removal of N-linked oligosaccharides and pulse-chase experiments confirmed that the cleavage of the alpha 6 integrin subunit occurring 45 min after translation in HT29 cells did not take place in LoVo cells. Apart from cleavage deficiency, alpha 6 subunit glycosylation, association with beta 4 subunits and targeting to the plasma membrane seemed comparable in LoVo and HT29 cells. The pro-alpha 6 and the pro-alpha 3 subunits immunopurified from LoVo cells were highly sensitive to endoproteolysis by recombinant furin. Furin cleavage was calcium dependent and resulted in the conversion of the 140 kDa pro-alpha 6 into a 120 kDa heavy chain. These results suggest strongly that furin is involved in the endoproteolytic processing of cleavable integrin alpha subunits.
Lehmann
M
M
URA CNRS 1924, Laboratoire de Biologie Cellulaire, Université Aix-Marseille II, Faculté de Pharmacie, France.
Rigot
V
V
Seidah
N G
NG
Marvaldi
J
J
Lissitzky
J C
JC
D036002:ADP Ribose Transferases; D000230:Adenocarcinoma; D000581:Amidohydrolases / Q000378:metabolism; D001427:Bacterial Toxins; D003110:Colonic Neoplasms; D005098:Exotoxins / Q000633:toxicity; D045683:Furin; D006801:Humans; D006868:Hydrolysis; D016023:Integrins / Q000378:metabolism*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D013381:Subtilisins / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D000581:Amidohydrolases; D001427:Bacterial Toxins; D005098:Exotoxins; D045683:Furin; D016023:Integrins; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011994:Recombinant Proteins; D013381:Subtilisins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A