Hormone-sensitive lipase is a cholesterol esterase of the intestinal mucosa.
The identity of the enzymes responsible for lipase and cholesterol esterase activities in the small intestinal mucosa is not known. Because hormone-sensitive lipase (HSL) catalyzes the hydrolysis of acylglycerols and cholesteryl esters, we sought to determine whether HSL could be involved. HSL mRNA and protein were detected in all segments of the small intestine by Northern and Western blot analyses, respectively. Immunocytochemistry experiments revealed that HSL was expressed in the differentiated enterocytes of the villi and was absent in the undifferentiated cells of the crypt. Diacylglycerol lipase and cholesterol esterase activities were found in the different segments. Analysis of gut from HSL-null mice showed that diacylglycerol lipase activity was unchanged in the duodenum and reduced in jejunum. Neutral cholesterol esterase activity was totally abolished in duodenum, jejunum, and ileum of HSL-null mice. Analysis of HSL mRNA structure showed two types of transcripts expressed in equal amounts with alternative 5'-ends transcribed from two exons. This work demonstrates that HSL is expressed in the mucosa of the small intestine. The results also reveal that the enzyme participates in acylglycerol hydrolysis in jejunal enterocytes and cholesteryl ester hydrolysis throughout the small intestine.
Grober
Jacques
J
Laboratoire de Physiologie de la Nutrition, Ecole Nationale Supérieure de Biologie Appliquée à la Nutrition et à l'Alimentation, FRE2328 CNRS/Université de Bourgogne 1, Dijon 21000, France.
Lucas
Stéphanie
S
Sörhede-Winzell
Maria
M
Zaghini
Isabelle
I
Mairal
Aline
A
Contreras
Juan-Antonio
JA
Besnard
Philippe
P
Holm
Cecilia
C
Langin
Dominique
D
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D007413:Intestinal Mucosa / Q000201:enzymology*; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D002787:Sterol Esterase / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D017931:DNA Primers; D012333:RNA, Messenger; D002787:Sterol Esterase; D008071:Lipoprotein Lipase