Objective:This study tested the hypothesis that mitogen-activated protein kinase (MAPK) pathway is up-regulated during the course of pregnancy concomitant with uterine hypertrophy.
Methods:The expression and intracellular distribution of components of the MAPK cascade and the activation of MAPKs erk1 and erk2 were examined in the pregnant rat myometrium (days 10-22 of gestation). Protein expression was detected by Western analysis of myometrial subcellular fractions. Mitogen-activated protein kinase activation was studied by detection of tyrosine phosphorylation of erk1 and erk2 kinases and enzymatic activity.
Results:Mitogen-activated protein kinase activity increased from day 15 to day 20 of pregnancy. Immediately before parturition, MAPK activity, but not expression, declined sharply. During the same interval, membrane expression of the mitogenic-switching protein ras and the ras activator sos declined.
Conclusion:The shift in intracellular distribution ras and ras chaperone proteins may precede the down-regulation of membrane-dependent mitogenic signaling and uterine hypertrophy as pregnancy approaches parturition.
1. Owens GK, role of contractile agonists in growth regulation of vascular smooth muscle cells. Adv Exper Med Biol1991;308:71-79.
2.
2. Dzau VJ. The role of mechanical and humoral factors in growth regulation of vascular smooth muscle and cardiac myocytes. Curr Opin Nephrol Hypertens1993;2:27-32.
3.
3. Daifotis AG, Weir EC, Dreyer BE, Broadus AE. Stretch-induced parathyroid hormone-related peptdie gene expression in the rat uterus. J Biol Chem1992;267:23455-23458.
4.
4. Ashen MD, Hamlyn JM. Smooth muscle hypertrophy and arterial remodeling in deozycorticosterone acetate-salt hypertension. Clin Exp Hypertens1994;16:261-282.
5.
5. Lee SL, Wang WW, Lanzillo JJ, Fanburg BL. Serotonin produces both hyperplasia and hypertrophy of bovine pulmonary artery smooth muscle cells in culture. Am J Physiol1994;266:L46-L52.
6.
6. Morishita R, Gibbons GH, Ellison KE, et al. Evidence for direct local effect of angiotension in vascular hypertrophy. In vivo gene transfer of angiotension converting enzyme. J Clin Invest1994;94:978-984.
7.
7. Huwiler A, Stabel S, Fabbro D, Pfeilshifter J. Platelet-derived growth factor and angiotensin II stimulate the mitogen-activated protein kinase cascade in renal mesangial cells: comparison of hypertrophic and hyperplastic agonist. Biochem J1995;305:777-784.
8.
8. Csapo A, Erdos T, De Mattos CE, Gramss E, Moscowitz C. Stretch-induced uterine growth, protein synthesis and function. Nature1965;207:1378-1379.
9.
9. De Mattos CE, Kempson AL, Erdos T, Csapo A. Stretchinduced myometrial hypertrophy. Fertil Steril1967;18:545-556.
10.
10. Keyes LE, Moore LG, Walchak SJ, Dempsey EC. Pregnancy-stimulated growth of vascular smooth msucle cells: importance of protein kinase C-dependent synergy between estrogen and platelet-derived growth factor. J Cell Physiol1996;166:22-32.
11.
11. Hall A. A biochemical function for ras—at last. Science1994;264:1413-1414.
12.
12. Avruch J, Zhang XF, Kyriakis JM. Raf meets ras: completing the framework of a signal transduction pathway. Trends Biochem Sci1994;19:279-283.
13.
13. Carnero A, Jimenez B, Lacal JC. Progesterone but not ras requires MPF for in vitro activation of MAPK and S6 KII: MAPK is an essential conexion point of both signaling pathways. J Cell Biochem1994;55:465-476.
14.
14. Langan EM, Youkey JR, Elmore JR, Franklin DP, Singer HA. Regulation of MAP kinase activity by growth stimuli in vascular smooth muscle. J Surg Res1994;57:215-220.
15.
15. Morinelli TA, Zhang LM, Newman WH, Meier KE. Thromboxane A2/prostaglandin H2-stimulated mitogenesis of coronary artery smooth muscle cells involves activation of mitogen-activated protein kinase and S6 kinase. J Biol Chem1994;269:5693-5698.
16.
16. Blenis J. Signal transduction via the MAP kinases: proceed at your own risk. Proc Natl Acad Sci USA1993;90:5889-5892.
17.
17. Davis RJ. The mitogen-activated protein kinase signal transduction pathway. J Biol Chem1993;268:14553-14556.
19. Yamazaki T, Tobe K, Hoh E, et al. Mechanical loading activates mitogen-activated protein kinase and S6 peptide kinase in cultured rat cardiac myocytes. J Biol Chem1993;268:12069-12076.
20.
20. Lucchesi PA, Bell JM, Willis LS, Byron KL, Corson MA, Berk BC. Ca2_-dependent mitogen-activated protein kinase activation in spontaneously hypertensive rat vascular smooth muscle defines a hypertensive signal transduction phenotype. Circ Res1996;78:962-970.
21.
21. Thorburn J, Thorburn A. The tyrosine kinase inhibitor, genistein, prevents α-adrenergic induced carciac muscle cell hypertrophy by inhibiting activation of the Ras-MAP kinase signaling pathway. Biochem biophys Res Comm1994;202:1586-1591.
22.
22. Jamal S. Ziff E. Transactivation of c-fos and β-actin genes by raf as a step in early response to transmembrane signals. Nature1990;344:463-466.
23.
23. Ruzycky AL. Effects of 17β-estradiol and progesterone on mitogen-activated protein kinase expression and activity in rat uterine smooth muscle. Eur J Pharmacol1996;300:247-254.
24.
24. Laemmli UK. Cleavage of structural proteins during assembly of the head of bacteriophage T4. Nature1970;227:680-680.
26. Aronheim A, Engelberg D, Li N, Al-Alawi N, Schlessinger J, Karin M. Membrane targeting of the nucleotide exchange factor so is sufficient for activating the ras signaling pathyway. Cell1994;78:949-961.
27.
27. Polakis P, McCormick F. Structural requirements for the interaction of p21ras with GAP, exchange factors, and its biological effector target. J Biol Chem1993;268:9157-9160.
28.
28. Kikuchi A, Williams LT. The post-translational modification of ras p21 is important for raf-1 activation. J Biol Chem1994;269:20054-20059.
29.
29. Schlaepfer DD, Hanks SK, Hunter T, van der Geer P. Integrinmediated signal transduction linked to ras pathway by GRB2 binding to focal adhesion kinase. Nature1994;372:780-791.
30.
30. Satosh S, Rensland H, Pfitzer G. Ras proteins increase Ca2+-responsiveness of smooth muscle contraction. FEBS Lett1993;324:211-215.
31.
31. Muslin AJ, MacNichol AM, Williams LT. Raf-1 protein kinase is important for progesterone-induced Xenopus oocyte maturation and acts downstream of mos. Mol Cell Biol1993;13:4197-4202.
32.
32. Marshall CJ. Specificity of receptor tyrosine kinase signaling: transient versus sustained extracellular signal-regulated kinase activation. Cell1995;80:179-185.
33.
33. Reszka AA, Seger R, Diltz CD, Krebs EG, Fischer EH. Association of mitogen-activated protein kinase with the microtubule cytoskeleton. Proc Natl Acad Sci USA1995;92:8881-8885.
34.
34. Childs TJ, Watson MH, Sanghera JS, Campbell DL, Pelech SL, Mak AS. Phosphorylation of smooth muscle caldesmon by mitogen-activated protein (MAP) kinase and expression of MAP kinase in differentiated smooth muscle cells. J biol Chem1992;267:22853-22859.
35.
35. Khalil RA, Menice CB, Wang A, Morgan KG. Phosphotyrosine-dependent targeting of mitogen-activated protein kinase in differentiated contractile vascular cells. Circ Res1995;76:1101-1108.
36.
36. Molloy CJ, Taylor DS, Weber H. Angiotensin stimulation of rapid protein tyrosine phosphorylation and protein kinase activation in rat aortic smooth muscle cells. J Biol Chem1993;268:7338-7345.
37.
37. Rao GN, Baas AS, Glasgow WC, Eling TE, Runge MS, Alexander RW. Activation of mitogen-activated protein kinases by arachidonic acid and its metabolites in vascular smooth muscle cells. J Biol Chem1994;269:32586-32591.
38.
38. Ohmichi M, Koike K, Nohara A, et al. Oxytocin stimulates mitogen-activated protein kinase activity in cultured human pueperal uterine myometrial cells. Endocrinology1995;136:2082-2087.
