Evidence for a compensatory increase in synthesis of brush border enzymes in the jejunum of Irish Setters with gluten-sensitive enteropathy.
OBJECTIVE
To determine whether biosynthesis of aminopeptidase N (ApN), alkaline phosphatase (AP), and total microvillus membrane protein is altered in Irish Setters with gluten-sensitive enteropathy (GSE).


METHODS
A litter of 6 Irish Setters with GSE and 3 healthy Greyhounds.


METHODS
Explants obtained from affected dogs at 4 and 12 months were maintained in vitro and were compared with material from healthy control dogs. Biosynthesis of ApN and AP was monitored by incorporation of [35S]methionine and immunoprecipitation of these enzymes.


RESULTS
Jejunal explants from affected Irish Setters had significantly higher rates of biosynthesis of total protein, microvillus membrane protein, AP, and ApN, compared with control tissue. Two forms of ApN with apparent molecular mass of 155 and 135 kd and 4 forms of AP with apparent molecular mass of 210 to 260, 150, 130, and 105 kd were identified in total membrane fractions from control and affected dogs.


CONCLUSIONS
Reduced activities of ApN and AP in dogs with GSE are not attributable to decreased synthesis of these proteins and document enhanced synthesis of microvillar membrane proteins, which may be a compensatory response to enterocyte damage. The 150-kd form of AP was most prominent in tissue from the most affected dogs, probably representing an early form of this enzyme. In contrast, the 105-kd form was most intense in tissue from controls and less intense in tissue of affected dogs.
Manners
H K
HK
Department of Small Animal Medicine and Surgery, The Royal Veterinary College, University of London, Hatfield, Herts, United Kingdom.
Sørensen
S H
SH
Embaye
H
H
Odedra
R M
RM
Batt
R M
RM
D000469:Alkaline Phosphatase / Q000096:biosynthesis*; D000818:Animals; D018826:CD13 Antigens / Q000096:biosynthesis*; D002446:Celiac Disease / Q000201:enzymology / Q000662:veterinary*; D004283:Dog Diseases / Q000201:enzymology*; D004285:Dogs; D005260:Female; D007413:Intestinal Mucosa / Q000201:enzymology / Q000648:ultrastructure; D007583:Jejunum / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis; D008871:Microvilli / Q000201:enzymology; D009924:Organ Culture Techniques
D008565:Membrane Proteins; D000469:Alkaline Phosphatase; D018826:CD13 Antigens