The possible role of pancreatic proteases in the turnover of intestinal brush border proteins

Alpers, David H.; Tedesco, Francis J.

doi:10.1016/0005-2736(75)90338-7

Cited by 165 publications

(71 citation statements)

References 24 publications

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“…The chain of events identified in the present work provides therefore a more detailed picture to the concept, already put forward earlier (see e.g. 53,54), that in the processing of pro-LPH pancreatic proteases do play a role, but a fairly limited one.…”

Section: Furin Cleaves Human Prolactasesupporting

confidence: 62%

Processing of Human Intestinal Prolactase to an Intermediate Form by Furin or by a Furin-like Proprotein Convertase

Mesonero

Gloor

Semenza³

1998

Journal of Biological Chemistry

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Human lactase-phlorizin hydrolase (human-LPH) is synthesized as a large precursor (prepro-LPH), then cleaved to a pro-LPH of 220 kDa which is further cut to a "mature-like LPH" of a size close to that of mature LPH, i.e. about 150 kDa (in the processing of rabbit pro-LPH the intermediate has a mass of approximately 180 kDa). By coexpression of human prepro-LPH with furin in COS-7 cells we show that furin generates a mature-like LPH. Radioactive amino acid sequence analysis reveals that furin recognizes the motif R-T-P-R 832 , a protein convertase consensus, to generate a NH 2 terminus located 36 amino acids upstream of the NH 2 terminal found in vivo at Ala 869 . This intermediate is ultimately cleaved to the mature LPH form by other proteases including the pancreatic ones. These data demonstrate that human pro-LPH, like the rabbit enzyme, is processed to the mature enzyme by furin or furin-like enzymes through at least an intermediate form that has, however, an apparent mass close to that of the mature enzyme.

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Section: Furin Cleaves Human Prolactasesupporting

confidence: 62%

Processing of Human Intestinal Prolactase to an Intermediate Form by Furin or by a Furin-like Proprotein Convertase

Mesonero

Gloor

Semenza³

1998

Journal of Biological Chemistry

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“…Another possibility is that the positive surfactant barrier secreted by the enterocyte in response to prostaglandin administration (28) may protect these brush border membrane-bound enzymes from proteolysis by luminal proteases. These are known to hydrolyze intestinal brush border disaccharidases as demonstrated in previous studies in pancreatic-deficient animals (30). Further studies are required to elucidate the mechanism of this prostaglandin-initiated stimulation of disaccharidase activity in the mammalian small intestine.…”

Section: Discussionmentioning

confidence: 80%

Comparative Effects of Glucocorticoids and Prostaglandins on Small Intestine of Infant Rats

1986

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ABSTRACT. Previous studies have suggested similarities between the effects of exogenously administered glucocorticoids and prostaglandins in the developing rat small intestine. In this study the effects of exogenously administered glucocorticoids and prostaglandins were compared. In addition, the effects of prostaglandins in adrenalectomized rats were evaluated. Members of both classes of compounds stimulate small intestinal disaccharidase activities, and increase RNA to DNA ratio and brush border membrane protein synthesis. Hydrocortisone accelerates enterocyte turnover, whereas prostacyclin does not. Enteral administration of 16,16-dimethyl prostaglandinEz stimulates disaccharidase activities in intact as well as shamoperated and adrenalectomized animals. The data suggest that certain prostaglandins may play a role in small intestinal metabolism which is similar to that of the glucocorticoids but is independent of the adrenal-intestinal axis. Glucocorticoids are known to play a significant role in the development of small intestinal biochemical function. These hormones appear to mediate a series of enzymatic changes in the small intestine of rats during the 3rd wk of postnatal life (I-3). Administration of hydrocortisone or ACTH during the 2nd postnatal wk causes precocious appearance of sucrase activity (4), whereas adrenalectomy at this time markedly slows the usual increase of sucrase activity (5). In adult rats, sucrase activity is independent of glucocorticoids (6).In a previous study by our group (7), prostaglandins were administered to suckling rats to determine their effects on growth and development. Analysis of small intestinal hydrolase activities demonstrated effects similar to those of the glucocorticoids. Other than this, little information is available regarding the physiological role of prostaglandins in the gastrointestinal tract of the developing fetus and neonate. More recent studies by Koelz (q a/. (8) have demonstrated that an enterally administered prostaglandin analog, 16,l 6-DMPGE2, will stimulate disaccharidase activity in the small intestine of suckling but not adult rats.Since the stimulation of the enzyme activities by the glucocorticoids and prostaglandins are similar in many respects, we decided to investigate further the comparative effects of these two classes of compounds. The purpose of these studies was

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“…Because the aminopep tidase is embedded within the brush border membrane and most of its domains including the active site are exterior to the cell surface, it is possible that the activity is influenced by some luminal factors, such as pancreatic proteases and bile acids . Other enzymes in the intestinal brush border membrane are known to be influenced by the luminal factors (4)(5)(6)(7)(8)(9)(10)(11).…”

Section: Discussionmentioning

confidence: 99%

Cholestyramine and Bile Diversion Lower the Aminopeptidase Activity in the Intestinal Brush Border Membrane of Rats.

Sonoyama

Kiriyama

Niki

1993

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryTo examine the effect of bile acids on the activity of intestinal aminopeptidase in vivo, we measured the activity of aminopepti dase in the intestinal mucosa from rats fed the diet containing cholestyr amine which sequesters luminal bile acids (experiment 1) and from bile diverted rats (experiment 2). After 32h fasting, rats were refed for 16h either of a standard diet (25% casein diets), the same diet containing cholestyramine, or the fat-free diet in experiment 1. In the intestinal washing, the content of total bile acids was markedly decreased with feeding Cholestyramine and activities of trypsin and chymotrypsin were also lowered with cholestyramine. Cholestyramine feeding decreased the specific activity of aminopeptidase in the homogenate of intestinal mucosa but increased the specific activities of sucrase and alkaline phosphatase. All these parameters were not modified by the fat-free diet. In experiment 2, bile diverted and sham operated rats were refed the standard diet for 16 h with prior 32h fasting. Bile diversion, like cholestyramine feeding, lowered the content of total bile acids, the activities of pancreatic hydro lases in the intestinal washings, and the specific activity of aminopeptidase in the intestinal mucosa. The specific activity of sucrase in the intestinal mucosa was higher in bile diverted rats but the activity of alkaline phosphatase was not changed. These data indicate that the decreased abundance of intraluminal bile acid affects the activity of intestinal aminopeptidase not through the decreased absorption of dietary lipid. We propose that the intraluminal bile acids may be important for maintaining the activity of aminopeptidase while the degradation of sucrase by the pancreatic proteinases may be accelerated by the bile acids.

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The possible role of pancreatic proteases in the turnover of intestinal brush border proteins

Cited by 165 publications

References 24 publications

Processing of Human Intestinal Prolactase to an Intermediate Form by Furin or by a Furin-like Proprotein Convertase

Processing of Human Intestinal Prolactase to an Intermediate Form by Furin or by a Furin-like Proprotein Convertase

Comparative Effects of Glucocorticoids and Prostaglandins on Small Intestine of Infant Rats

Cholestyramine and Bile Diversion Lower the Aminopeptidase Activity in the Intestinal Brush Border Membrane of Rats.

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