1. Search for new synthetic immunosuppressants II. Tetrazole analogues of hymenistatin I
P Zubrzak, K Kociołek, M Smoluch, J Silberring, M L Kowalski, B Szkudlińska, J Zabrocki Acta Biochim Pol. 2001;48(4):1151-4.
Linear and cyclic hymenistatin I (HS I) analogues with dipeptide segments Ile2-Pro3 Pro3-Pro4 and Val6-Pro7 replaced by their tetrazole analogues Ile2-psi[CN4]-Ala3', Pro3-psi[CN4]-Ala4 and Val6-psi[CN4]-Ala7 were synthesized by the solid phase peptide synthesis method and cyclized with the TBTU and/or HATU reagent. The peptides were examined for their immunosuppressive activity in the lymphocyte proliferation test (LPT).
2. Immunosuppressive activity of hymenistatin I
M Cebrat, Z Wieczorek, I Z Siemion Peptides. 1996;17(2):191-6. doi: 10.1016/0196-9781(95)02123-x.
Hymenistatin I (HS-I), a cyclic octapeptide [c-(-Pro-Pro-Tyr-Val-Pro-Leu-Ile-Ile-)], was synthesized by the solid-phase peptide synthesis method and examined for its immunosuppressive activity in the humoral and cellular immune responses. The peptide activity was tested on cell lines producing various cytokines. The results are compared with the activity of the well-known immunosuppressive agent cyclosporin A (CsA). It was found that hymenistatin I exerts immunosuppressive effect (both in the humoral and cellular immune responses) comparable with that of CsA. Comparison of the influence of HS-I and CsA on cytokines production suggests that the mechanisms of the interaction with the immunological system are substantially different for the two compounds tested.
3. Calcineurin role in porcine oocyte activation
L Tůmová, E Chmelíková, T Žalmanová, V Kučerová-Chrpová, R Romar, M Dvořáková, K Hošková, J Petr Animal. 2016 Dec;10(12):1998-2007. doi: 10.1017/S1751731116000884. Epub 2016 May 10.
Calcineurin is required for oocyte exit from meiotic block in metaphase II (MII) stage in invertebrates and also in lower vertebrates. However, the role of calcineurin in mammalian oocyte activation is still unclear. The aim of this study was to determine whether calcineurin is involved in the processes regulating porcine oocyte activation. Indirect immunofluorescence demonstrated localization of both calcineurin subunits, CnA and CnB, especially in the cortex area of MII oocytes, in vitro fertilized and also parthenogenetically activated oocytes. After activation, the fluorescence intensity of the protein in the cortex area of oocytes remains unchanged; the protein calcineurin in the cytoplasm was recorded mainly around the pronuclei. Treatment of matured oocytes with calcineurin inhibitors, cyclosporin A (CsA) and hymenistatin I (HS-I), followed by activation with calcium ionophore A23187, significantly decreased the rate of activated oocytes compared to oocytes that were treated only with calcium ionophore (Ca-Io), (CsA+Ca-Io 25.0% v. Ca-Io 83.3%; HS-I+Ca-Io 32.5% v. Ca-Io 85.0%). Compared to the control, CsA treatment of matured oocytes followed by activation with Ca-Io did not affect the activity level of metaphase-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) in activated oocytes evaluated by kinase activity assay. Simultaneous staining of calcineurin and cortical granule content in matured oocytes showed that calcineurin distributed in the cortical area of the oocyte has not been colocalized with cortical granules content. On the other hand, the calcineurin inhibition before parthenogenetic activation leads to a reduction of the cortical reaction level compared to oocytes that were not treated with CsA (complete exocytosis: CsA+Ca-Io 2.6% v. Ca-Io 83.9%; sum of cortical granule brightness: CsA + Ca-Io 0.69 v. Ca-Io 0.15). Our results showed that calcineurin is involved in the process of pig oocyte activation and cortical granule exocytosis; however this regulation seems to be MPF and MAPK independent.
