The Role of Neurophysin Proteins: Suggestions From the Study of Their Transport and Turnover*

Pickering, B. T.; Jones, Craig; Burford, G. D.; McPherson, Margaret A.; Swann, R. W.; Heap, P. F.; Morris, John F.

doi:10.1111/j.1749-6632.1975.tb34174.x

Cited by 75 publications

(20 citation statements)

References 42 publications

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“…Sachs and his colleagues (4)(5)(6)(7)(8) have hypothesized that vasopressin and its neurophysin come from a common precursor protein that is synthesized in the hypothalamus by a ribosomal mechanism. We have already presented some evidence consistent with this hypothesis (9,10 sopressin and its associated neurophysin (11,12) and hence have diabetes insipidus-to determine which of the putative precursors, intermediates, and neurophysins are related to vasopressin and which to oxytocin. MATERIALS AND METHODS Animals and Operative Procedures.…”

mentioning

confidence: 48%

Neurophysin biosynthesis in normal rats and in rats with hereditary diabetes insipidus.

Brownstein¹,

Gainer²

1977

Proc. Natl. Acad. Sci. U.S.A.

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When [35S]cysteine was injected adjacent to the supraoptic nucleus (SON) in rats, it was rapidly incorporated into proteins in the SON. The [35S]cysteine-labeled proteins extracted from the SON were separated by isoelectric focusing on polyacrylamide gels. Twenty minutes after the injection of [I Scysteine, two major labeled peaks (pI = 5.4 and 6.1) were found in the SON of normal rats; Brattleboro rats had only one major labeled peak (pI = 5.4). One hour after the injection, four major radioactive peaks were found in the SON of normal animals (pI = 5.1,5.4,5.6, and 6.1). Animals with diabetes insipidus had only two major labeled proteins (pl = 5.1 and 5.4). Twenty-four hours after normal rats were injected with l35S-cysteine, all of the labeled peaks described above, except for the one with pI = 5. Neurons in the supraoptic nucleus (SON) and paraventricular nucleus synthesize two peptide hormones (oxytocin and vasopressin) as well as their "carrier" proteins (neurophysins) (1-3). The oxytocin, vasopressin, and neurophysins are transported, in axons of the neurons that synthesize them, to the posterior pituitary via the median eminence. Sachs and his colleagues (4-8) have hypothesized that vasopressin and its neurophysin come from a common precursor protein that is synthesized in the hypothalamus by a ribosomal mechanism. We have already presented some evidence consistent with this hypothesis (9, 10).We have found that, within 1 hr, [a3S]cysteine injected adjacent to the SON is incorporated into two proteins with molecular weights (Mr) of about 20,000 and pI of 5.4 and 6.1 (9, 10). It appears that, in time, these two proteins give rise to the two neurophysins (Mr 12,000). sopressin and its associated neurophysin (11, 12) and hence have diabetes insipidus-to determine which of the putative precursors, intermediates, and neurophysins are related to vasopressin and which to oxytocin. MATERIALS AND METHODS Animals and Operative Procedures. Female OsborneMendel (225-250 g) and Brattleboro (130-150 g) rats were used in these studies. Some of the normal Osborne-Mendel rats were given 2% (wt/vol) saline to drink for 1 week prior to use in order to stimulate vasopressin and neurophysin synthesis; others were given water ad lib as were the Brattleboro animals.The animals were anesthetized with ether, their heads were fixed in a stereotaxic device (50, nose down), and a flap of bone was removed from their skulls. The 30-gauge stainless steel needles were positioned 7 mm rostral to the interauricular line (6.8 mm for Brattleboro rats), and 2.5 mm on each side of the midline (2 mm for Brattleboro animals). The needles were lowered 8.6 mm (8.2 mm for Brattleboro animals) beneath the dural surface, and 1 ,ul of a solution containing 20,Ci of I35S]cysteine (50 Ci/mmol; New England Nuclear) in 0.9% NaCl and 10 mM dithiothreitol was injected through each needle over a 4-min period. After the injection, the needles were left in place for 10 min and then removed. At various times after the injections the rats were killed by...

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mentioning

confidence: 48%

Neurophysin biosynthesis in normal rats and in rats with hereditary diabetes insipidus.

Brownstein¹,

Gainer²

1977

Proc. Natl. Acad. Sci. U.S.A.

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“…This was initially described on the basis of subcellular fractionation and NSG isolation experiments [Ginsburg and Ireland, 1966;Ginsburg, 1968;Norstrom, 1973], but these results are now contested [Pickering et at., 1975]. Immunocytochemical localization of AVP or neurophysin [Castel and Hochman, 1976;K risch, 1976;Silverman, 1976] suggests the presence of this 'extragranular pool', but some other immunocytochemical studies [Kozlowski et a i, 1977;Van Leeuven and Swaab, 1977] did not detect such an 'extragranular pool', and the axoplasmic extragranular localization of labelled antibodies against AVP or neurophysin may arise from experimental artefacts [Silverman and Zimmerman, 1975;, (2) AVP may have been carried by the well-developed network of the SER (axoplasmic reticulum) from hypothalamic nuclei into the PLH.…”

Section: Plh Ultrastructurementioning

confidence: 99%

Evolution of Vasopressin Levels in the Hypothalamo-Posthypophysial System of the Rat during Rehydration following Water Deprivation

Rougon-Rapuzzi¹,

Cau²,

Boudier³

et al. 1978

Neuroendocrinology

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Evolution of the (arginine)-vasopressin (AVP) content of the supraoptic (SON), paraventricular (PVN) and suprachiasmatic nuclei (SchN) and of the posterior lobe of the hypophysis (PLH) has been studied in rats at successive stages of rehydration after 4 days deprivation of drinking water. Particular attention has been focussed on short periods of rehydration. Evolution of the AVP content of the hypothalamo-posthypophysial system (HHS), the blood serum AVP concentration and osmolalities of serum and urine were compared. Variations of the AVP content in the different hypothalamo-hypophysial structures are parallel. A marked depletion of AVP is observed after 2 and 4 days of dehydration. The AVP content of the PLH and of the hypothalamic nuclei shows two dramatic and short increases 15 min and 3 h after the onset of rehydration; these results are discussed in relation to the known physiological regulation mechanism of the HHS. In the PLH depleted by dehydration, reloading with neurosecretory granules (NSG) begins to be noticeable only after 24 h of rehydration, so that it does not seem to account for elevations of the AVP content occurring earlier. These could be related to a marked increase of the smooth endoplasmic reticulum (SER) network taking place in axons and nerve endings before the NSG reloading.

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“…The mechanism by which these cells synthesize their peptide hormones is beginning to be characterized (2)(3)(4)(5). Briefly, the cell synthesizes a precursor that, by intragranular cleavage, gives rise to both the hormone (vasopressin or oxytocin) and its associated proteins, the neurophysins.…”

mentioning

confidence: 99%

“…In view of the possible importance of the intragranular pH (pHin) in the process of maturation and degradation of neuropeptides (3,4), we have attempted to measure the internal pH of neurohypophysial granules.…”

mentioning

confidence: 99%

Internal pH of isolated newly formed and aged neurohypophysial granules.

Scherman¹,

Nordmann²

1982

Proc. Natl. Acad. Sci. U.S.A.

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The pH gradient (ApH) across the membrane of bovine neurohypophysial granules was estimated by using the ['4C]methylamine partition technique. The granule membrane showed high permeability to sugars such as sucrose or sorbitol and to cations. Granules suspended in sucrose medium showed an acidic internal ApH that decreased with external pH from 1.0 pH unit at pH 7.5 to 0 at pH 4.5. High ionic strength of the external medium destroyed the ApH, indicating that it originated from a Donnan equilibrium. In a medium constituted to simulate cytoplasm, the ApH was =0.5 pH unit. Aged neurosecretory granules were more acidic inside than were newly formed granules. The results are discussed in relationship to the nature and the duration of maturation and degradation processes of the granule matrix.Neurohypophysial granules originate in the perikarya of neurosecretory cells located in the hypothalamus and are transported down the neurohypophysial stalk to the neurohypophysis where they release their content into the blood stream (1). The mechanism by which these cells synthesize their peptide hormones is beginning to be characterized (2-5). Briefly, the cell synthesizes a precursor that, by intragranular cleavage, gives rise to both the hormone (vasopressin or oxytocin) and its associated proteins, the neurophysins. Maturation of the peptide occurs during axonal transport of the neurosecretory granules (NSGs). This has been shown by Gainer et at (5), who injected [3S]cystein just above the magnocellular cells of rats. The radioactive marker was first incorporated into a 20,000-dalton protein that, during axonal transport, was converted to a 12,000-dalton labeled protein that crossreacted with antineurophysin antibodies. Maturation of the hormone precursor has also been suggested by the observation of Cannata and Morris (6), who showed that, after triple-aldehyde fixation, the appearance of the NSG in the perikarya is different from that in the nerve endings ofthe neural lobe. Whereas at pH 5.0 or 6.0, the granules remained dense cored in both the perikarya and the endings, at pH 8.0, a significantly greater proportion of granules retained an electron-dense core within the perikarya. Since neurophysin I (vasopressin neurophysin) and neurophysin II (oxytocin neurophysin) have pI values of 4.8 and 4.6, respectively (7), the changes in appearance of the NSG after fixation at different pH values (6, 8) suggest that the isoelectric point of the NSG content is ==5.0.Neurohypophysial granules isolated on isoosmotic gradients can be separated into two fractions, both of which contain oxytocin, vasopressin, and neurophysin (9). The two fractions differ by (i) their density (1.11 and 1.13), (ii) the mean diameter ofthe NSG at 360 mOsm (192 and 172 nm), (iii) their response to the osmotic pressure of the surrounding medium (9), and (iv) the different patterns of their protein content (10). Furthermore, we have recently shown (10) that, in mammals, the heaviest granules are the newly formed NSG (NF-NSGs) and the lightest NSG re...

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The Role of Neurophysin Proteins: Suggestions From the Study of Their Transport and Turnover*

Cited by 75 publications

References 42 publications

Neurophysin biosynthesis in normal rats and in rats with hereditary diabetes insipidus.

Neurophysin biosynthesis in normal rats and in rats with hereditary diabetes insipidus.

Evolution of Vasopressin Levels in the Hypothalamo-Posthypophysial System of the Rat during Rehydration following Water Deprivation

Internal pH of isolated newly formed and aged neurohypophysial granules.

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