Partner: Karolina Tudelska


Ostatnie publikacje
1.Tudelska K., Markiewicz J., Kochańczyk M., Czerkies M., Prus W., Korwek Z., Abdi A., Błoński S., Kaźmierczak B., Lipniacki T., Information processing in the NF-κB pathway, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-017-16166-y, Vol.7, pp.15926-15926, 2017

Streszczenie:

The NF-κB pathway is known to transmit merely 1 bit of information about stimulus level. We combined experimentation with mathematical modeling to elucidate how information about TNF concentration is turned into a binary decision. Using Kolmogorov-Smirnov distance, we quantified the cell’s ability to discern 8 TNF concentrations at each step of the NF-κB pathway, to find that input discernibility decreases as signal propagates along the pathway. Discernibility of low TNF concentrations is restricted by noise at the TNF receptor level, whereas discernibility of high TNF concentrations it is restricted by saturation/depletion of downstream signaling components. Consequently, signal discernibility is highest between 0.03 and 1 ng/ml TNF. Simultaneous exposure to TNF or LPS and a translation inhibitor, cycloheximide, leads to prolonged NF-κB activation and a marked increase of transcript levels of NF-κB inhibitors, IκBα and A20. The impact of cycloheximide becomes apparent after the first peak of nuclear NF-κB translocation, meaning that the NF-κB network not only relays 1 bit of information to coordinate the all-or-nothing expression of early genes, but also over a longer time course integrates information about other stimuli. The NF-κB system should be thus perceived as a feedback-controlled decision-making module rather than a simple information transmission channel.

Słowa kluczowe:

cellular signaling networks, innate immunity, stress signaling

Afiliacje autorów:

Tudelska K.-IPPT PAN
Markiewicz J.-IPPT PAN
Kochańczyk M.-IPPT PAN
Czerkies M.-IPPT PAN
Prus W.-IPPT PAN
Korwek Z.-IPPT PAN
Abdi A.-New Jersey Institute of Technology (US)
Błoński S.-IPPT PAN
Kaźmierczak B.-IPPT PAN
Lipniacki T.-IPPT PAN
40p.
2.Korwek Z., Tudelska K., Nałęcz-Jawecki P., Czerkies M., Prus W., Markiewicz J., Kochańczyk M., Lipniacki T., Importins promote high-frequency NF-κB oscillations increasing information channel capacity, Biology Direct, ISSN: 1745-6150, DOI: 10.1186/s13062-016-0164-z, Vol.11, No.61, pp.1-21, 2016

Streszczenie:

BACKGROUND:
Importins and exportins influence gene expression by enabling nucleocytoplasmic shuttling of transcription factors. A key transcription factor of innate immunity, NF-κB, is sequestered in the cytoplasm by its inhibitor, IκBα, which masks nuclear localization sequence of NF-κB. In response to TNFα or LPS, IκBα is degraded, which allows importins to bind NF-κB and shepherd it across nuclear pores. NF-κB nuclear activity is terminated when newly synthesized IκBα enters the nucleus, binds NF-κB and exportin which directs the complex to the cytoplasm. Although importins/exportins are known to regulate spatiotemporal kinetics of NF-κB and other transcription factors governing innate immunity, the mechanistic details of these interactions have not been elucidated and mathematically modelled.
RESULTS:
Based on our quantitative experimental data, we pursue NF-κB system modelling by explicitly including NF-κB-importin and IκBα-exportin binding to show that the competition between importins and IκBα enables NF-κB nuclear translocation despite high levels of IκBα. These interactions reduce the effective relaxation time and allow the NF-κB regulatory pathway to respond to recurrent TNFα pulses of 45-min period, which is about twice shorter than the characteristic period of NF-κB oscillations. By stochastic simulations of model dynamics we demonstrate that randomly appearing, short TNFα pulses can be converted to essentially digital pulses of NF-κB activity, provided that intervals between input pulses are not shorter than 1 h.
CONCLUSIONS:
By including interactions involving importin-α and exportin we bring the modelling of spatiotemporal kinetics of transcription factors to a more mechanistic level. Basing on the analysis of the pursued model we estimated the information transmission rate of the NF-κB pathway as 1 bit per hour.

Słowa kluczowe:

Karyopherins, Nucleocytoplasmic transport, Negative feedback, Channel information capacity, Mathematical modelling

Afiliacje autorów:

Korwek Z.-IPPT PAN
Tudelska K.-other affiliation
Nałęcz-Jawecki P.-University of Warsaw (PL)
Czerkies M.-IPPT PAN
Prus W.-IPPT PAN
Markiewicz J.-IPPT PAN
Kochańczyk M.-IPPT PAN
Lipniacki T.-IPPT PAN
35p.