Apolipoproteins in human fetal colon: immunolocalization, biogenesis, and hormonal regulation.
The present investigation aimed at defining the localization of apolipoproteins (apo) A-I, A-IV, B-48, and B-100 along the crypt-villus axis of the human fetal colon, their biogenesis during gestation, and their hormonal regulation. Using immunofluorescence, the distribution of apo A-I and A-IV appeared as a gradient, increasing from the developing crypt to the tip of the villus. On the other hand, apo B-100 staining was found in the crypt and the lower mid-villus region with varying intensities in the upper villus cells, while the 2D8 antibody which recognizes both apo B-100 and B-48, revealed uniform staining along the crypt-villus axis. Apolipoprotein synthesis, determined by [35S] methionine labeling, immunoprecipitation, and SDS-PAGE showed a predominance of apo A-IV (53%), followed by apo A-I (23.9%), apo B-48 (13.4%), and apo B-100 (9.7%). The synthesis of each apolipoprotein was significantly modulated by hydrocortisone, insulin and epidermal growth factor (EGF). Apart from a decrease in apo B-100 exerted by EGF and a reduction in apo A-I resulting from the addition of insulin, the other apolipoproteins were all enhanced. Our data confirm that the fetal colon has the capacity to synthesize apolipoprotein A-I, A-IV, B-48, and B-100 and establish that their synthesis are modulated by hormonal and growth factors known to be involved in the regulatory mechanism of the functional development of human jejunum.
Basque
J R
JR
Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Québec, Canada.
Lévy
E
E
Beaulieu
J F
JF
Ménard
D
D
D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I / Q000032:analysis / Q000096:biosynthesis; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001053:Apolipoproteins / Q000032:analysis* / Q000096:biosynthesis* / Q000276:immunology; D001054:Apolipoproteins A / Q000032:analysis / Q000096:biosynthesis; D001055:Apolipoproteins B / Q000032:analysis / Q000096:biosynthesis; D003106:Colon / Q000196:embryology* / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005865:Gestational Age; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000737:chemistry / Q000196:embryology* / Q000378:metabolism; D007583:Jejunum / Q000196:embryology / Q000378:metabolism; D009924:Organ Culture Techniques; D011233:Precipitin Tests; D014238:Trichloroacetic Acid
D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D006728:Hormones; D007328:Insulin; C022205:apolipoprotein A-IV; D014238:Trichloroacetic Acid; D004815:Epidermal Growth Factor; D006854:Hydrocortisone