Post-translational processing of pro-opiomelanocortin (POMC)-derived peptides during fetal monkey pituitary development

Hatfield, Jess; Allen, Richard B.; Stack, Julianne; Rønnekleiv, Oline K.

doi:10.1016/0012-1606(88)90250-3

Cited by 21 publications

(12 citation statements)

References 18 publications

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“…After each period the medium was removed and saved, and replaced with DMEM or DMEM plus drug with a volume of 50 ltl. The samples were centrifuged to remove any debris and 30 ,ul of the supernatant was assayed for ,-endorphin immunoactivity as described by Rees, Cook, Kendall, Allen, Kramer, Ratcliffe & Knight (1971) and modified by Allen, Herbert, Hinman, Shibuya & Pert (1978) using the antiserum (Sugar) which is specific for the midportion region of the fl-endorphin molecule and cross-reacts with all forms of fl-endorphin as well as fl-lipotrophin and POMC (Hatfield, Allen, Stack & Ronnekleiv, 1988). Secretion rates were normalized using a ratio of the ,J-endorphin immunoactivity secreted during drug treatment to the ,-endorphin immunoactivity secreted during basal conditions and data are expressed as a percentage of control.…”

Section: Cell Preparationmentioning

confidence: 99%

“…Data analysis Because the major aim of this study was to make comparisons between dopamine actions on ionic currents and hormone secretion, several precautions were undertaken toward this goal: preparations used for secretion and electrophysiological experiments were identical; they were dispersed concomitantly and, except that lower density platings were used for electrophysiological recordings, were used at the same time in culture (5-7 days after dispersal). Cover-slips used for secretion and electrophysiological studies were taken at random intervals over the course of this study and subjected to ,i-endorphin immunohistochemistry (Hatfield et al 1988); in all cases (n = 8) over 95 % of cells were immunopositive.…”

Section: Cell Preparationmentioning

confidence: 99%

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Dopamine actions on calcium currents, potassium currents and hormone release in rat melanotrophs.

Stack

Surprenant

1991

The Journal of Physiology

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SUMMARY1. Intracellular and whole-cell recordings were made from primary cultures of rat intermediate pituitary cells; f8-endorphin secretion was also measured by radioimmunoassay. The effects of dopamine receptor activation on hormone secretion, calcium currents and resting potassium conductance were compared.2. Spontaneous sodium-dependent action potentials occurred in 82 % of cells recorded with intracellular microelectrodes and 64 % of cells recorded with whole-cell patch electrodes; the same proportion of cells showed spontaneous calciumdependent depolarizations in the presence of tetrodotoxin. 5. Quinpirole (1-100 nm) hyperpolarized 90 % of cells from which intracellular recordings were made and 55 % of cells recorded from with whole-cell patch pipettes. Maximum hyperpolarization of 16 + 4 mV from a resting potential of -44 + 5 mV was observed with 100 nM-quinpirole; concentration producing half-maximal effect was 3 nm. The hyperpolarization resulted from an increase in potassium conductance.6. Quinpirole (1-100 nM) decreased basal /3-endorphin secretion by 55% and abolished secretion stimulated by Bay K 8644 or isoprenaline; concentrations producing half-maximal inhibitions were 5-10 nm. Tetrodotoxin (1 ,tM), nifedipine (1 UM), nickel (500,tM) and cadmium (100/,M) did not alter basal or stimulated secretion although higher concentrations of cadmium did inhibit stimulated hormone release.7. Pertussis toxin pre-treatment prevented all actions of quinpirole. 8. Thus, concentrations of quinpirole that abolished stimulated hormone secretion did not alter calcium currents; conversely, concentrations of calcium channel MS 8792 J. STACK AND A. SURPRENANT blockers that partially or completely inhibited calcium currents did not alter basal or stimulated secretion. These results may indicate that calcium influx through the voltage-dependent calcium channels measured in these experiments does not contribute significantly to hormone release from melanotrophs.9. The same concentrations of quinpirole activated a potassium conductance and inhibited hormone release. It is concluded that membrane hyperpolarization may be the primary mechanism by which dopamine receptor activation inhibits hormone release from melanotrophs.

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Section: Cell Preparationmentioning

confidence: 99%

Section: Cell Preparationmentioning

confidence: 99%

Dopamine actions on calcium currents, potassium currents and hormone release in rat melanotrophs.

Stack

Surprenant

1991

The Journal of Physiology

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“…The ␤-endorphin and ␤-MSH RIAs have been described previously (Hatfield et al, 1988). The ␤-endorphin antiserum is specific to the mid-portion of ␤-endorphin 1-31 and cross-reacts 1:1 with all ␤-endorphins and ␤-L PH (Hatfield et al, 1988). The ␤-MSH antiserum is specific to the mid-portion of ␤-MSH and cross-reacts with the C terminus of ␥-L PH (Hatfield et al, 1988;Thorne and Thomas, 1990).…”

Section: Methodsmentioning

confidence: 99%

“…The OFQ / N antiserum is specific to the C terminus of OFQ / N1-17 and does not cross-react with ␤-endorphin or dynorphin (DYN) A. T yr14 OFQ /nociceptin was iodinated using the chloramine-T method (Quigley et al, 1998). The ␤-endorphin and ␤-MSH RIAs have been described previously (Hatfield et al, 1988). The ␤-endorphin antiserum is specific to the mid-portion of ␤-endorphin 1-31 and cross-reacts 1:1 with all ␤-endorphins and ␤-L PH (Hatfield et al, 1988).…”

Section: Methodsmentioning

confidence: 99%

Altered Processing of Pro-Orphanin FQ/Nociceptin and Pro-Opiomelanocortin-Derived Peptides in the Brains of Mice Expressing Defective Prohormone Convertase 2

Allen¹,

Peng²,

Pellegrino³

et al. 2001

J. Neurosci.

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The bioactivity of neuropeptides can be regulated by a variety of post-translational modifications, including proteolytic processing. Here, gene-targeted mice producing defective prohormone convertase 2 (PC2) were used to examine the posttranslational processing of two neuroendocrine prohormones, pro-opiomelanocortin (POMC) and pro-orphanin FQ (pOFQ)/ nociceptin (N), in the brain. Reversed-phase HPLC and gelexclusion chromatography were combined with specific radioimmunoassays to analyze the processing patterns of these two prohormones in the hypothalamus and the amygdala. In the case of POMC, the lack of PC2 activity completely prevented carboxy-shortening of ␤-endorphins and greatly diminished conversion of ␤-lipotropin to ␥-lipotropin and ␤-endorphin. Although conversion of ␤-lipotropin to ␤-endorphin decreased, the lack of PC2 activity caused an increase in ␤-lipotropin and ␤-endorphin levels in the mutant animals, but no increases in POMC or biosynthetic intermediates were seen. The extent of OFQ/N production was significantly lower in PC2-deficient mice and there was an accumulation of relatively large amounts of pOFQ/N and biosynthetic intermediates. These results demonstrate that PC2 is directly involved in the biogenesis of two brain neuropeptides in vivo and suggest that the specific prohormone and cellular context influences neuropeptide processing by PCs.

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“…Radioimmunoassay-␤-endorphin immunoassays were performed as described previously (62), using an antiserum that is specific for ␤-endorphin residues 15-26. Synthetic acetyl-␤-endorphin 1-27 was used as tracer and standard, and a 12-point standard curve was assayed with each group of samples.…”

mentioning

confidence: 99%

Analysis of the Role of Calmodulin Binding and Sequestration in Neuromodulin (GAP-43) Function

Gamby

Waage

Allen

et al. 1996

Journal of Biological Chemistry

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We demonstrated previously that forced expression of the neuronal phosphoprotein neuromodulin (also known as GAP-43, F1, B-50, and p57) in mouse anterior pituitary AtT-20 cells enhances depolarization-mediated secretion and alters cellular morphology. Here we analyze the role of calmodulin binding by neuromodulin in these responses. In cells expressing wild-type neuromodulin, a complex with calmodulin that is sensitive to intracellular calcium and phosphorylation is localized to the plasma membrane. Transfection of several mutant forms of neuromodulin shows that the effects of this protein on secretion are dependent on both calmodulin binding and association with the plasma membrane. In contrast, the morphological changes depend only on membrane association. Thus, the multitude of effects of neuromodulin noted in previous studies may result from divergent properties of this protein.The neuronal growth-associated protein neuromodulin (also designated GAP-43, B-50, and F1) is a membrane-bound phosphoprotein expressed at a high level during neuronal development and regeneration (reviewed in Refs. 1 and 2). Neuromodulin is a rapidly transported axonal protein (3-10) that is concentrated in the growth cone of elongating axons (8,(11)(12)(13)(14)(15)(16)(17). Additionally, overexpression of neuromodulin in the nervous system of transgenic mice causes spontaneous nerve sprouting at the neuromuscular junction and potentiates lesion-induced nerve sprouting and terminal arborization during re-innervation (18). Taken together, these results suggest that neuromodulin plays an important role in axon elongation. Further support for this notion has been derived from studies of several cell culture model systems (19 -28).However, a line of PC12 cells in which neuromodulin expression is nearly undetectable is nevertheless capable of robust neurite elongation in response to nerve growth factor (29). Additionally, cultured neurons derived from mice in which the neuromodulin gene has been disrupted by gene targeting extend axons to the same extent as cells that express this protein.Further analysis of the neuromodulin (Ϫ) embryos revealed that retinal axons appear incapable of crossing the midline decision point in the optic chiasm, implying that their growth cones fail to respond to environmental guidance cues (30).These results suggest that neuromodulin is perhaps not essential for axon elongation, but rather might function as a mediator of signal transduction pathways in the growth cone that serve to modulate the rate, extent, and trajectory of axonal growth.In the adult nervous system, neuromodulin expression persists in pre-synaptic terminals in those regions where the synaptic modifications associated with learning and memory are thought to occur (31-36). Additionally, the correlation of PKC 1 -mediated neuromodulin phosphorylation with long term potentiation of synaptic transmission in the hippocampus (37-40) and neurotransmitter release in vitro (41) suggest a role for neuromodulin in neuronal plasticity, possibly via modul...

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Post-translational processing of pro-opiomelanocortin (POMC)-derived peptides during fetal monkey pituitary development

Cited by 21 publications

References 18 publications

Dopamine actions on calcium currents, potassium currents and hormone release in rat melanotrophs.

Dopamine actions on calcium currents, potassium currents and hormone release in rat melanotrophs.

Altered Processing of Pro-Orphanin FQ/Nociceptin and Pro-Opiomelanocortin-Derived Peptides in the Brains of Mice Expressing Defective Prohormone Convertase 2

Analysis of the Role of Calmodulin Binding and Sequestration in Neuromodulin (GAP-43) Function

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