Dataset Information

Fer kinase limits neutrophil chemotaxis toward end target chemoattractants.

ABSTRACT: Neutrophil recruitment and directional movement toward chemotactic stimuli are important processes in innate immune responses. This study examines the role of Fer kinase in neutrophil recruitment and chemotaxis to various chemoattractants in vitro and in vivo. Mice targeted with a kinase-inactivating mutation (Fer(DR/DR)) or wild type (WT) were studied using time-lapse intravital microscopy to examine leukocyte recruitment and chemotaxis in vivo. In response to keratinocyte-derived cytokine, no difference in leukocyte chemotaxis was observed between WT and Fer(DR/DR) mice. However, in response to the chemotactic peptide WKYMVm, a selective agonist of the formyl peptide receptor, a 2-fold increase in leukocyte emigration was noted in Fer(DR/DR) mice (p < 0.05). To determine whether these defects were due to Fer signaling in the endothelium or other nonhematopoietic cells, bone marrow chimeras were generated. WKYMVm-induced leukocyte recruitment in chimeric mice (WT bone marrow to Fer(DR/DR) recipients or vice versa) was similar to WT mice, suggesting that Fer kinase signaling in both leukocytes and endothelial cells serves to limit chemotaxis. Purified Fer(DR/DR) neutrophils demonstrated enhanced chemotaxis toward end target chemoattractants (WKYMVm and C5a) compared with WT using an under-agarose gel chemotaxis assay. These defects were not observed in response to intermediate chemoattractants (keratinocyte-derived cytokine, MIP-2, or LTB(4)). Increased WKYMVm-induced chemotaxis of Fer(DR/DR) neutrophils correlated with sustained PI3K activity and reduced reliance on the p38 MAPK pathway compared with WT neutrophils. Together, these data identify Fer as a novel inhibitory kinase for neutrophil chemotaxis toward end target chemoattractants through modulation of PI3K activity.

SUBMITTER: Khajah M

PROVIDER: S-EPMC3575564 | biostudies-other | 2013 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:In bacterial chemotaxis, chemoreceptors in signaling complexes modulate the activity of two-component histidine kinase CheA in response to chemical stimuli. CheA catalyzes phosphoryl transfer from ATP to a histidinyl residue of its P1 domain. That phosphoryl group is transferred to two response regulators. Receptor control is almost exclusively at autophosphorylation, but the aspect of enzyme action on which that control acts is unclear. We investigated this by a kinetic analysis of activated kinase in signaling complexes. We found that phosphoryl transfer from ATP to P1 is an ordered sequential reaction in which the binding of ATP to CheA is the necessary first step; the second substrate, the CheA P1 domain, binds only to an ATP-occupied enzyme; and phosphorylated P1 is released prior to the second product, namely, ADP. We confirmed the crucial features of this kinetically deduced ordered mechanism by assaying P1 binding to the enzyme. In the absence of a bound nucleotide, there was no physiologically significant binding, but the enzyme occupied with a nonhydrolyzable ATP analog bound P1. Previous structural and computational analyses indicated that ATP binding creates the P1-binding site by ordering the "ATP lid." This process identifies the structural basis for the ordered kinetic mechanism. Recent mathematical modeling of kinetic data identified ATP binding as a focus of receptor-mediated kinase control. The ordered kinetic mechanism provides the biochemical logic of that control. We conclude that chemoreceptors modulate kinase by controlling ATP binding. Structural similarities among two-component kinases, particularly the ATP lid, suggest that ordered mechanisms and control of ATP binding are general features of two-component signaling.IMPORTANCE Our work provides important new insights into the action of the chemotaxis signaling kinase CheA by identifying the kinetic mechanism of its autophosphorylation as an ordered sequential reaction, in which the required first step is binding of ATP. These insights provide a framework for integrating previous kinetic, mathematical modeling, structural, simulation, and docking observations to conclude that chemoreceptors control the activity of the chemotaxis kinase by regulating binding of the autophosphorylation substrate ATP. Previously observed conformational changes in the ATP lid of the enzyme active site provide a structural basis for the ordered mechanism. Such lids are characteristic of two-component histidine kinases in general, suggesting that ordered sequential mechanisms and regulation by controlling ATP binding are common features of these kinases.

Project description:Inputs to signaling pathways can have complex statistics that depend on the environment and on the behavioral response to previous stimuli. Such behavioral feedback is particularly important in navigation. Successful navigation relies on proper coupling between sensors, which gather information during motion, and actuators, which control behavior. Because reorientation conditions future inputs, behavioral feedback can place sensors and actuators in an operational regime different from the resting state. How then can organisms maintain proper information transfer through the pathway while navigating diverse environments? In bacterial chemotaxis, robust performance is often attributed to the zero integral feedback control of the sensor, which guarantees that activity returns to resting state when the input remains constant. While this property provides sensitivity over a wide range of signal intensities, it remains unclear how other parameters such as adaptation rate and adapted activity affect chemotactic performance, especially when considering that the swimming behavior of the cell determines the input signal. We examine this issue using analytical models and simulations that incorporate recent experimental evidences about behavioral feedback and flagellar motor adaptation. By focusing on how sensory information carried by the response regulator is best utilized by the motor, we identify an operational regime that maximizes drift velocity along chemical concentration gradients for a wide range of environments and sensor adaptation rates. This optimal regime is outside the dynamic range of the motor response, but maximizes the contrast between run duration up and down gradients. In steep gradients, the feedback from chemotactic drift can push the system through a bifurcation. This creates a non-chemotactic state that traps cells unless the motor is allowed to adapt. Although motor adaptation helps, we find that as the strength of the feedback increases individual phenotypes cannot maintain the optimal operational regime in all environments, suggesting that diversity could be beneficial.

Dataset Information

Fer kinase limits neutrophil chemotaxis toward end target chemoattractants.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets