[Is there a double pathway for the secretion of thyroglobulin: a "short circuit" weakly glycosyl-iodinated and a "long circuit" strongly glycosyl-iodinated?].
Intact rat thyroid lobes incubated in vitro release recently synthesized thyroglobulin (Tg) into the media at a faster rate than they release thyroglobulin stored in follicular structures. Differential release of this Tg fraction cannot be explained by morphological alterations in thyroid architecture during incubation. This rapidly excreted fraction exhibits a low density on rubidium chloride gradients characteristic of poorly sialylated and poorly iodinated thyroglobulin, comigrating on rubidium chloride gradients with thyroglobulin isolated from tunicamycin treated glands. This poorly sialylated and poorly iodinated thyroglobulin is itself unaffected in its density or release into the media by tunicamycin treatment. Tg isolated from the media of tunicamycin treated glands has nearly the same low iodine and low sialic acid content as rat serum thyroglobulin and does not incorporate radiolabelled glucosamine. This fraction thus appear to duplicate properties of low glycosylated-low iodinated thyroglobulin released from thyroid cells in organisms that have no follicular structures and no follicular storage process as well as from thyroid tissue in patients with thyroid disease states, particularly thyroid tumors. Thus it is proposed a "short loop" pathway of low-glycosylated low-iodinated thyroglobulin directly into circulation, that bypasses and is not stored in the follicular lumen, the "long loop".
Monaco
F
F
Chaire d'Endocrinologie, Université G. D'Annunzio, Chieti, Italie.
Napolitano
G
G
Lio
S
S
Roche
J
J
D000818:Animals; D002499:Centrifugation, Density Gradient; D005944:Glucosamine / Q000378:metabolism; D006031:Glycosylation; D007455:Iodine / Q000032:analysis / Q000378:metabolism*; D007457:Iodine Radioisotopes; D019158:N-Acetylneuraminic Acid; D051381:Rats; D012794:Sialic Acids; D013954:Thyroglobulin / Q000032:analysis / Q000378:metabolism*; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology
D007457:Iodine Radioisotopes; D012794:Sialic Acids; D014415:Tunicamycin; D013954:Thyroglobulin; D007455:Iodine; D019158:N-Acetylneuraminic Acid; D005944:Glucosamine
Existe-t-il une double voie de sécrétion de la thyroglobuline: un "circuit court" faiblement glycosylo-iodé et un "circuit long" fortement glycosylo-iodé?