Voraussetzungen und derzeitige Grenzen der quantitativen elektronenmikroskopischen Autoradiographie bei Kinetikstudien an Dr�senzellen

Rohr, H.P.; Seitter, Ute; Schmalbeck, J.

doi:10.1007/bf00328848

Cited by 6 publications

(1 citation statement)

References 41 publications

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“…2), but continue to accumulate in secretory granules even 100 rain after the pulse. Thus the secretory protein transport is achieved, according to the classic secretory pathway (45), at a rate comparable to that observed in various glands of mammals, such as: Brunner's gland (57), mammary gland (58), liver (2,20), parotid gland (8), endocrine pancreas (44), and prostate (19). In all these glands, the proteins are still accumulating in the secretory granules 1 h after pulse.…”

Section: Normal Intracellular Transport Of Secretory Proteinsmentioning

confidence: 52%

Microtubules and protein secretion in rat lacrimal glands: localization of short-term effects of colchicine on the secretory process.

Busson-Mabillot¹,

Chambaut-Guérin²,

Ovtracht³

et al. 1982

The Journal of Cell Biology

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ABSlRACl The pathway and kinetics of the secretory protein transport in rat lacrimal exorbital gland have been established by an in vitro time-course radioautographic study of pulse-labeled protein secretion.The colchicine-sensitive steps have been localized by using the drug at various times with respect to the pulse labeling of proteins. Colchicine (10/IM) does not block any step of the secretory protein transport, but when introduced before the pulse it decreases the transfer of labeled proteins from the rough endoplasmic reticulum to the Golgi area, suppressing their temporary accumulation in the Golgi area before any alteration of this organelle is detectable. Moreover, colchicine inhibits protein release only from the secretory granules formed in its presence because the peroxidase discharge is diminished I h after colchicine addition, and the secretion of newly synthesized proteins is strongly inhibited only when colchicine is introduced before secretory granule formation.Morphometric studies show that there is a great increase of secondary lysosomes, related to crinophagy, as early as 40-50 rain after colchicine is added. However, changes in lysosomal enzymatic activities remained biochemically undetectable.We conclude that: (a) the labile microtubular system does not seem indispensable for protein transport in the rough endoplasmic reticulum-Golgi area but may facilitate this step, perhaps by maintaining the spatial organization of this area; and (b) in the lacrimal gland, colchicine inhibits protein release not by acting on the steps of secretion following the secretory granule formation, but by acting chiefly on the steps preceding secretory granule formation, perhaps by making the secretory granules formed in its presence incapable of discharging their content.From data obtained with various secretory tissues, it appears that the microtubular system could be involved in the secretory process (62). We have previously shown in rat lacrimal #ands that colchicine inhibited the release of newly synthesized proreins by impairing their intraceUular transport (9), and simultaneously induced a disorganization of the labile microtubular system. This latter effect could result from the shift of the equilibrium between microtubules and tubulin and from the impediment of microtubule assembly due to the colchicinetubulin complex (10). The intraceUular transport alterations produced by colchicine have also been observed in other tissues that produce exportable proteins (liver: 17, 52-55; pancreas B-]FIE JOURNAL Of CELL BIOLOGY • VOtUME 95 OCTOBER 1982 105-117 @The Rockefeller University Press -0021-9525/82/10/0105/13 $1.00 cells: 36, 37; fibroblasts: 12, 14, 38; anterior pituitary: 1, 26, 48; mammary gland: 30, 41, 42; parotid gland: 46; exocrine pancreas: 61; parathyroid gland: 11, 29). Although there is no definite proof, the hypothesis that both events (i.e., inhibition of protein secretion and disruption of labile microtubules) might be related by a causal effect is favored.The aim of the present work is to lo...

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