Effects of malnutrition on expression and activity of lactase in children.
OBJECTIVE
Many malnourished infants have reduced lactase specific activity in the small intestine. The aim of this study was to test the hypothesis that the hypolactasia of malnourished infants results from transcriptional suppression of lactase expression.


METHODS
Biopsy specimens were studied from two groups of infants: 29 with malnutrition and 10 normally nourished controls with normal morphology and lactase activity.


RESULTS
In malnourished infants, lactase messenger RNA (mRNA) was reduced to 32% and sucrase to 61% of normal. Lactase and sucrase enzyme proteins and activities were lower in malnourished infants, and partial villus atrophy was present. The genotype of adult hypolactasia was not present.


CONCLUSIONS
Because the hypolactasia of malnourished children was associated with much lower lactase than sucrase mRNA abundance and because the epigenetic suppression, which accounted for the reduction of sucrase mRNA, was inadequate to explain the greater reduction of lactase mRNA, this study concludes that malnutrition suppresses lactase gene transcription or mRNA stability in infants. The reductions of lactase mRNA, distinct from those found in adults with genetic hypolactasia, explain the low lactase activities commonly found in malnourished infants.
Nichols
B L
BL
United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
Dudley
M A
MA
Nichols
V N
VN
Putman
M
M
Avery
S E
SE
Fraley
J K
JK
Quaroni
A
A
Shiner
M
M
Carrazza
F R
FR
D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D043322:Lactase; D008297:Male; D009748:Nutrition Disorders / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis; D013393:Sucrase / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; D043322:Lactase; D001616:beta-Galactosidase; D013393:Sucrase