Related Experiment Videos
Developmental aspects of lipid and lipoprotein synthesis and secretion in human gut
1Department of Nutrition, Centre de Recherche, Hôpital Ste-Justine, Université de Montréal, Québec, Canada H3T 1C5.
Insights
Human fetal intestine develops early capacity for lipid absorption and lipoprotein production. Regulatory mechanisms and hormonal influences on lipoprotein assembly and secretion in the gut are key to understanding digestive health.
Area of Science:
- Gastroenterology
- Molecular Biology
- Developmental Biology
Background:
- The human fetal intestine develops villi and enterocytes by the first trimester.
- Early in development (14-20 weeks), the small intestine can absorb lipids and produce major lipoprotein classes.
- The fetal colon also synthesizes lipids and lipoproteins, but with less efficient export.
Purpose of the Study:
- To review the ontogeny and regulatory mechanisms of lipoprotein assembly and delivery in the human gut.
- To explore the molecular events governing lipoprotein synthesis and secretion in fetal intestinal cells.
- To understand how hormonal factors modulate gut lipoprotein metabolism.
Main Methods:
- Review of existing literature on human fetal gut development and lipoprotein metabolism.
- Analysis of ontogenic changes in lipid and lipoprotein synthesis pathways.
- Examination of regulatory enzymes (HMG-CoA reductase, ACAT, MGAT) involved in lipid metabolism.
- Investigation of hormonal modulation (EGF, insulin, hydrocortisone) on gut lipoprotein secretion.
Main Results:
- The small intestine demonstrates early and efficient lipid absorption and lipoprotein export.
- Lipoprotein synthesis in the fetal gut correlates with specific regulatory enzyme patterns.
- The fetal colon synthesizes lipoproteins but is less efficient in their export compared to the small intestine.
- Hormones like epidermal growth factor, insulin, and hydrocortisone differentially affect lipoprotein synthesis and secretion in the small intestine and colon.
Conclusions:
- The human fetal gut, particularly the small intestine, possesses a sophisticated system for lipoprotein production and secretion early in development.
- Understanding these complex molecular events in the fetal gut is crucial for both normal and pathological conditions.
- The human fetal gut serves as a valuable model for studying intestinal lipoprotein biogenesis and secretion.
Abstract:
This review article focuses on the ontogeny and the regulatory mechanisms involved in the modulation of the intracellular events governing the assembly and delivery of lipoproteins in human gut. The human fetal intestine organizes villi covered with well-differentiated enterocytes during the end of the first trimester in utero. One striking event is the formation of villi in the colonic mucosa similar to those of the small intestine. The small intestine exhibits very early (14-20 weeks) the capacity to absorb lipids, to elaborate most of the major lipoprotein classes (chylomicrons, very-low-density lipoproteins, low-density lipoproteins, high-density lipoproteins), and to efficiently export these lipoproteins from the intestinal cells. The ontogenic changes of lipid and lipoprotein synthesis are correlated with specific patterns of regulatory enzymes (HMG-CoA reductase, ACAT, MGAT) that are representative of key patterns such as the cholesterol pathway, cholesterol esterification, and neutral lipid pathway. The human fetal colon also has the capability to synthesize lipids, lipoproteins, and apolipoproteins. However, comapred with the small intestine, it is much less efficient at exporting these lipoproteins. Epidermal growth factor, insulin, and hydrocortisone, which are known modulators of the brush border digestive functions of the human gut, differentially modulate the synthesis and secretion of lipoproteins in the small intestine and colon. The use of human fetal gut represents a unique model to further our understanding of the complex biosynthetic molecular events essential for the formation and secretion of lipoproteins relevant to human intestine, both in normal or pathological conditions.