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.
Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Québec, Canada.
J R
JR
Basque
E
E
Lévy
J F
JF
Beaulieu
D
D
Ménard
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