Topologies of the three networks

Topologies of the three networks. (A) MAPK enzymatic cascade under EGF stimulus. The feedback loop is shown in purple (see the Database of Quantitative Cellular Signaling, available at http://doqcs.ncbs.res.in/~doqcs/?&y=pathwaylist). Only the part that is activated by EGF is analyzed. (B) The cell-cycle system simulated by Tyson and Novak (). At the beginning of the cell cycle (early G1), the levels of both casein kinase I (CKI) and Cdh1, which are responsible for keeping CDK/CycB complexes inactive, are high. As the cell grows, two simultaneous processes occur. First, CycB accumulates gradually in the cell nucleus, although it is still inactivated by CKI. Second, the concentration of starter kinase (SK), responsible for CKI and Cdh1 degradation, slowly rises. In the late G1 phase, the second process accelerates dramatically because of activation of TF, which causes sharp increase in SK levels and elimination of CKI and Cdh1. As soon as the concentration of CKI drops below the concentration of total CycB, active CycB-CDK complexes trigger DNA synthesis. CDK activity persists until the cell enters the M phase. (C) Immune system network. (i) Antigen enters the system and is recognized by B cells and APCs, which internalize it and then present the antigenic peptides in the form of an MHC peptide complex. (ii) T cells recognize and bind to the MHC peptide complex on B cells and APCs. (iii) B cells are stimulated, either directly by T cell binding or indirectly through the bystander effect. Stimulated T cells also divide (not shown). (iv) Stimulated B cells produce plasma cells and memory B cells. (v) Plasma cells produce antibodies, which bind to antigen and lead to its removal.

Publication

A coherent framework for multiresolution analysis of biological networks with “memory”: Ras pathway, cell cycle, and immune system. (2005) Paolo Emilio Barbano, et al. Proc Natl Acad Sci U S A. 2005 May 3;102(18):6245-6250. Figure: F1. All organisms Drosophila melanogaster Homo sapiens

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