Enzyme Secretion and the Incorporation of P32 Into Phospholipides of Pancreas Slices

Hokin, Mabel R.; Hokin, Lowell E.

doi:10.1016/s0021-9258(19)52367-5

Cited by 710 publications

(29 citation statements)

References 13 publications

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“…The results of a series of papers by the Hokins (7)(8)(9)(10)(11)(12)(13)(14)(15), dealing with the turnover of pancreatic phospholipids (PLP),' seem to be consistent with the latter hypothesis, since, in slices of pancreas stimulated with either cholinergic drugs (7) or pancreozymin (8), incorporation of s2 Pi into PLP was found to be greatly enhanced . Such an increment is due to the synthesis of new lipid molecules (9,10) and does not involve all PLP but is restricted to a few of them, primarily to phosphatidylinositol (PI) (9)(10)(11) .…”

mentioning

confidence: 82%

In Vitro Stimulation of Enzyme Secretion and the Synthesis of Microsomal Membranes in the Pancreas of the Guinea Pig

Meldolesi

Cova

1971

The Journal of Cell Biology

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Several mechanisms have been suggested to explain how secretory cells remove from the plasmalemma the excess membrane resulting from the insertion of granule membrane during exocytosis : intact patches of membrane may be internalized and then reutilized within the cell ; alternatively these membranes may be either disassembled to subunits or degraded . In the latter case new membranes should be synthetized at other sites of the cell, probably in the rough-surfaced endoplasmic reticulum (RER) and the Golgi complex . In the present research, membrane subfractions were obtained from rough microsomes (derived from fragmented and resealed RER cisternae) and from smooth microsomes (primarily contributed by Golgi stacks and vesicles) of the guinea pig pancreas by incubation at 4°C for 4 hr in 0 .0005 M puromycin at high ionic strength followed by mild (pH 7 .8) alkaline extraction with 0 .2 M NaHCO3 . Such treatments release the majority of nonmembrane components of both microsomal fractions (i .e., contained secretory enzymes, ribosomes, and absorbed proteins of the cell sap) and allow the membranes to be recovered by centrifugation . The effect of in vitro stimulation of enzyme secretion (brought about in pancreas slices by 0 .0001 M carbamoyl choline) on the rate of synthesis of the phospholipid (PLP) and protein of these membranes was then investigated . In agreement with previous data, we observed that in stimulated slices the synthesis of microsomal PLP was greatly increased . In contrast, the synthesis of microsomal membrane proteins was unchanged . These results suggest that exocytosis is not coupled with an increased rate of synthesis of complete ER and Golgi membranes and are, therefore, consistent with the view that excess plasma membrane is preserved and reutilized, either as discrete membrane patches or as membrane macromolecules, throughout the secretory cycle . 6It is now firmly established that, in the acinar cells of the pancreas, stimulation of secretion ultimately results in the discharge of digestive enzymes stored within zymogen granules by a process akin to exocytosis (1-5) . Such a process consists of fusion of the limiting membrane of the granule with the apical portion of the plasmalemma and therefore results, at least temporarily, in the incorporation of the first membrane into the latter. The mechanism of removal of excess membrane from the acinar lumen is still unknown . As proposed by Palade (1), intact patches of membranes may be internalized from the cell surface and reutilized in the packaging of new zymogen granules . Alternatively these membranes may be degraded as suggested originally by Fawcett (6), new membranes being synthesized at other sites in the cell .The results of a series of papers by the Hokins

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mentioning

confidence: 82%

In Vitro Stimulation of Enzyme Secretion and the Synthesis of Microsomal Membranes in the Pancreas of the Guinea Pig

Meldolesi

Cova

1971

The Journal of Cell Biology

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“…Représentative secretagogues were selected from four groups depending on their mode of action: (1) Carbamylcholine mimics the neutrotransmitter acetylcholine while resisting acetylcholine esterase [7]. It stimulâtes "'Ca outflux and increases cyclic GMP levels [8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

In vitro lipid metabolism in the rat pancreas II. Effects of secretagogues on fatty acid metabolism, net lipolysis and ATP levels

Calderon

Furnelle

Cristophe

1979

Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metaboli

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1. The concentration of carbamylcholine, bombesin, pancreozymin, pentagastrin and secretin evoking a similar 4--5-fold maximal increase in amylase secretion from rat pancreatic fragments were 3.10(-6), 10(-7), 10(-8), 3.10(-6), and 3.10(-6) M, respectively. The maximal concentration of vasoactive intestinal peptide tested (3.10(-6) M) increased amylase secretion by 250%. The six secretagogues could be separated into two groups according to their effects on lipid metabolism and ATP levels. 2. When used at their optimal concentrations, carbamylcholine, bombesin, pancreozymin, and pentagastrin lowered pancreatic ATP levels by 18-26% and increased net release of free fatty acids by 68-105%. 3. The effects of 3.10(-6) M carbamylcholine and 10(-8) M pancreozymin on the metabolism of 3H2O, D-[U-14C]glucose and [1-14C]acetate were similar; the incorporation of radioactivity in the fatty acid moiety of glycerolipids decreased by 20--50% whereas the incorporation of 3H from 3H2O and of 14C from [U-14C]glucose increased by 20--35% in the glycerol moiety. In addition, the oxidation of [U-14C]glucose, [1-14C]acetate and [1-14C]palmitate to 14CO2 increased by 15--32% while the esterification of [1-14C]palmitate, [1-14C]-linoleate, and [1-14C]arachidonate was inhibited by 14--23%. The spectrum of fatty acids labeled with [1-14C]acetate indicated an inhibition of the malonic acid pathway whereas the elongation of polyenoic fatty acids was unaltered.

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“…The group soon noticed that crude extracts of phospholipids from brains, rather than pure lipids, were the most effective at activating PKC and set out to uncover the nature of the 'impurity' that activated PKC. The activating component was diacylglycerol (10), leading Nishizuka to make the conceptual breakthrough that PKC might be the target for one of the products of the lipid hydrolysis pathway (11) discovered by Hokin & Hokin (1953).…”

Section: Discovery Of Calcium-activated Phospholipid-dependent Protein Kinase (Protein Kinase C Pkc)mentioning

confidence: 99%

Yasutomi Nishizuka. 12 July 1932 — 4 November 2004

Yamamura

Nakamura²

2006

Biogr. Mems Fell. R. Soc.

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Yasutomi Nizhizuka was born in Seido Village, Muko–gun (now City of Ashiya), Hyogo–Prefecture, on 12 July 1932, as the second son of Yasunobu and Nobuko Nishizuka. His elder brother, Yasuaki (1922–95, pathologist, President of Aichi Cancer Center), was 10 years old, his eldest sister, Hiroko, was aged 8, his elder sister, Fumiko, was 5, and he was a heterozygotic twin with his sister Junko. His mother, Nobuko, was from the Ijichi family, a huge landlord, which traced its roots back to a powerful family of the Heian Era (eleventh century). When Yasutomi was an infant, he was so weak that his parents were not sure that he would survive to adulthood. He had intussusception (ileus) when he was six months old. He barely survived after emergency surgery at Daido Hospital in Osaka. Since then, he frequently suffered from diseases associated with stomach ache. He was always weak and ailing.

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Enzyme Secretion and the Incorporation of P32 Into Phospholipides of Pancreas Slices

Cited by 710 publications

References 13 publications

In Vitro Stimulation of Enzyme Secretion and the Synthesis of Microsomal Membranes in the Pancreas of the Guinea Pig

In Vitro Stimulation of Enzyme Secretion and the Synthesis of Microsomal Membranes in the Pancreas of the Guinea Pig

In vitro lipid metabolism in the rat pancreas II. Effects of secretagogues on fatty acid metabolism, net lipolysis and ATP levels

Yasutomi Nishizuka. 12 July 1932 — 4 November 2004

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