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Thyrotropin-releasing hormone downregulates pyroglutamyl peptidase II activity in adenohypophyseal cells


, : Thyrotropin-releasing hormone downregulates pyroglutamyl peptidase II activity in adenohypophyseal cells. Neuroendocrinology 60(3): 323-330

Pyroglutamyl peptidase II (PPII) is a thyrotropin-releasing hormone (TRH) hydrolyzing ectoenzyme with a narrow specificity. In the adenohypophysis, it is present on lactotropes. This study was undertaken in order to determine whether TRH itself regulates PPII activity in the adenohypophysis. After 5 days in culture, dispersed cells from female pituitaries expressed detectable levels of PPII activity when 10-8, M 3,3',5'-triiodo-L-thyronine was present throughout the culture. 10-6 M TRH decreased PPII activity with a maximal effect (down to 46% of initial values) at 16 h and an ED-50 Of 10-9 M. (3MeHis-2)TRH, a potent agonist of the TRH receptor was effective at lower concentrations (ED-50: 1.6 times 10-10 M). Phorbol-12-myristate-13-acetate (PMA; 10-6 M), a protein kinase C (PKC) activator, diminished PPII activity to 61% or initial values with an ED-50 of 2.2 times 10-8 M. Maximal effects of PMA and TRH were not additive. Neither PMA nor TRH effects were reversed by inhibitors of protein kinases (1-(5-isoquinolinesulfonyl)-2-methyl-piperazine or sphingosine or staurosporine); TRH-induced downregulation of the enzyme was not modified by PMA pretreatment. TRH had no effect on two other ectopeptidases, endopeptidase 24.11 and dipeptidyl aminopeptidase IV. These data demonstrate that TRH specifically downregulates PPII activity in adenohypophyseal cells through TRH receptor activation and suggest that the activation of a presumably calcium-independent PKC mimics the TRH effect. TRH regulation of PPII activity may contribute to adjust lactotrope responsiveness to TRH.

US$29.90

PMID: 7969791


Other references

Anonymous, 1980: From the JCC: Complaints on clinical judgment. British Medical Journal 280(6210): 342-346

Groszkowski J., 1969: Symposium ii of the polish genetics society section on animal genetics and breeding wroclaw poland september 19 21 1968. Genetica Polonica 10(3-4): 147-213

Hooker, G.; Ellner, S.P.; Roditi, L.De.Vargas.; Earn, D.J.D., 2011: Parameterizing state-space models for infectious disease dynamics by generalized profiling: measles in Ontario. Parameter estimation for infectious disease models is important for basic understanding (e.g. to identify major transmission pathways), for forecasting emerging epidemics, and for designing control measures. Differential equation models are often...

Guichard, S.; Delord, J.P.erre; Mery, E.; Hennebelle, I.; Bugat, R.; Canal, P., 2002: Therapeutic efficacy of TrastuzumAb in a mouse model of minimal residual ovarian cancer. Proceedings of the American Association for Cancer Research Annual Meeting 43: 1064, March

Hill, Y.R.; Child, N.; Hanson, B.; Wallman, M.; Coronel, R.; Plank, G.; Rinaldi, C.A.; Gill, J.; Smith, N.P.; Taggart, P.; Bishop, M.J., 2016: Investigating a Novel Activation-Repolarisation Time Metric to Predict Localised Vulnerability to Reentry Using Computational Modelling. Exit sites associated with scar-related reentrant arrhythmias represent important targets for catheter ablation therapy. However, their accurate location in a safe and robust manner remains a significant clinical challenge. We recently proposed a...

Holland P.; Herscovics A., 1986: The effect of inhibitors of glycoprotein processing on myoblast fusion. Journal of Cell Biology 103(5 PART 2): 122A

Bean, E.W., 1965: Selection for seed retention in S48 and S51 timothy. Seed shedding was studied in 50 clones each of S51 and S48 timothy during 1961-3. Some clones retained on average during 2 or 3 seasons from 80-90% of their maximum seed weight until 42 days after peak anthesis; this was up to 28% above the variet...

Aqrawi Adnan A.M.; Sadooni Fadhil N., 1987: Recent ooids from Mesopotamian shallow shelf, Northwest Arabian Gulf. AAPG Bulletin 71(5): 526

Abe, T.; Matsumoto, T., 1979: Studies on the distribution and ecological role of termites in a lowland rain forest of west Malaysia. 3. Distribution and abundance of termites in Pasoh Forest Reserve. The distribution and abundance of termites were studied in a lowland rain forest (Pasoh Forest Reserve) of West Malaysia. Fifty-two species were found in a 1 ha plot, 14 spp. in a 16 m2 area and 10 spp. in a 2 m2 area. Density and biomass of the e...

Zakhariev B.; Robev R.M., 1980: Experience in dividing forest landscapes into districts. Gorskostopanska Nauka 17(2): 3-16