Deciphering signaling outcomes from a system of complex networks.
Cellular signal transduction machinery integrates information from multiple inputs to actuate discrete cellular behaviors. Interaction complexity exists when an input modulates the output behavior that results from other inputs. To address whether this machinery is iteratively complex--that is, whether increasing numbers of inputs produce exponential increases in discrete cellular behaviors--we examined the modulated secretion of six cytokines from macrophages in response to up to five-way combinations of an agonist of Toll-like receptor 4, three cytokines, and conditions that activated the cyclic adenosine monophosphate pathway. Although all of the selected ligands showed synergy in paired combinations, few examples of nonadditive outputs were found in response to higher-order combinations. This suggests that most potential interactions are not realized and that unique cellular responses are limited to discrete subsets of ligands and pathways that enhance specific cellular functions.
Hsueh
Robert C
RC
University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA.
Natarajan
Madhusudan
M
Fraser
Iain
I
Pond
Blake
B
Liu
Jamie
J
Mumby
Susanne
S
Han
Heping
H
Jiang
Lily I
LI
Simon
Melvin I
MI
Taussig
Ronald
R
Sternweis
Paul C
PC
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D054405:Chemokine CCL3 / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D016179:Granulocyte Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism; D016899:Interferon-beta / Q000494:pharmacology; D016753:Interleukin-10 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013400:Sugar Acids / Q000494:pharmacology; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D054405:Chemokine CCL3; D018946:Chemokine CCL5; D016207:Cytokines; D015850:Interleukin-6; D012333:RNA, Messenger; D013400:Sugar Acids; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; C002532:2-keto-3-deoxyoctonate; D016753:Interleukin-10; D016179:Granulocyte Colony-Stimulating Factor; D015124:8-Bromo Cyclic Adenosine Monophosphate; D016899:Interferon-beta; D007545:Isoproterenol