The posibility of ultrasensitivity and bistable activation of + PLS (Plasmin) and UPA (Urokinase-type plasminogen activator) in + the presence of substrate competition is explained here using a + mathematical model.
+This model is described in the article:
+ + +Abstract:
+Plasmin (PLS) and urokinase-type plasminogen activator (UPA) + are ubiquitous proteases that regulate the extracellular + environment. Although they are secreted in inactive forms, they + can activate each other through proteolytic cleavage. This + mutual interplay creates the potential for complex dynamics, + which we investigated using mathematical modeling and in vitro + experiments. We constructed ordinary differential equations to + model the conversion of precursor plasminogen into active PLS, + and precursor urokinase (scUPA) into active urokinase (tcUPA). + Although neither PLS nor UPA exhibits allosteric cooperativity, + modeling showed that cooperativity occurred at the system level + because of substrate competition. Computational simulations and + bifurcation analysis predicted that the system would be + bistable over a range of parameters for cooperativity and + positive feedback. Cell-free experiments with recombinant + proteins tested key predictions of the model. PLS activation in + response to scUPA stimulus was found to be cooperative in + vitro. Finally, bistability was demonstrated in vitro by the + presence of two significantly different steady-state levels of + PLS activation for the same levels of stimulus. We conclude + that ultrasensitive, bistable activation of UPA-PLS is possible + in the presence of substrate competition. An ultrasensitive + threshold for activation of PLS and UPA would have + ramifications for normal and disease processes, including + angiogenesis, metastasis, wound healing, and fibrosis.
+The cooperativity parameter "ci" was missing in the original + model. The parameter "ci" has been added to the added.
+This model is hosted on + BioModels Database + and identified by: + BIOMD0000000630.
+To cite BioModels Database, please use: + BioModels Database: + An enhanced, curated and annotated resource for published + quantitative kinetic models.
+To the extent possible under law, all copyright and related or + neighbouring rights to this encoded model have been dedicated to + the public domain worldwide. Please refer to + CC0 + Public Domain Dedication for more information.
+Exported by VCell 7.3
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---|---|---|---|---|---|---|---|---|---|---|---|---|---|
name | \n", - "\n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " | \n", - " |
T | \n", - "compartment | \n", - "reactions | \n", - "mmol/ml | \n", - "1.0 | \n", - "6.022141e+20 | \n", - "\n", - " | \n", - " | 1.0 | \n", - "6.022141e+20 | \n", - "0.179997 | \n", - "1.083967e+20 | \n", - "Metabolite_0 | \n", - "T | \n", - "
E | \n", - "compartment | \n", - "reactions | \n", - "mmol/ml | \n", - "1.0 | \n", - "6.022141e+20 | \n", - "\n", - " | \n", - " | 1.0 | \n", - "6.022141e+20 | \n", - "-0.010000 | \n", - "-6.022137e+18 | \n", - "Metabolite_1 | \n", - "E | \n", - "
I | \n", - "compartment | \n", - "reactions | \n", - "mmol/ml | \n", - "1.0 | \n", - "6.022141e+20 | \n", - "\n", - " | \n", - " | 1.0 | \n", - "6.022141e+20 | \n", - "-9.999512 | \n", - "-6.021847e+21 | \n", - "Metabolite_2 | \n", - "I | \n", - "