Sanz-Ezquerro, J. J. | Search bioRxiv

bioRxiv2022

p38γ and p38δ modulate innate immune response by regulating MEF2D activation

Evidence implicating p38{gamma} and p38{delta} (p38{gamma}/p38{delta}) in inflammation are mainly based on experiments using p38{gamma}/p38{delta} deficient (p38{gamma}/{delta}-/-) mice, which show low levels of TPL2, the kinase upstream of MKK1-ERK1/2 in myeloid cells. This could obscure p38{gamma}/p38{delta} roles, since TPL2 is essential for regulating inflammation. Here we generated a p38{gamma}D171A/D171A/p38{delta}-/- (p38{gamma}/{delta}KIKO) mouse, expressing kinase-inactive p38{gamma} and lacking p38{delta}. This mouse exhibited normal TPL2 levels, making it an excellent tool to elucidate specific p38{gamma}/p38{delta} functions. p38{gamma}/{delta}KIKO mice showed a reduced inflammatory response and less susceptibility to LPS-induced septic shock and Candida albicans infection than wild-type mice. Gene expression analyses in LPS-activated WT and p38{gamma}/{delta}KIKO macrophages revealed that p38{gamma}/p38{delta} regulated numerous genes implicated in innate immune response. Additionally, phospho-proteomic analyses and in vitro kinase assays showed that the transcription factor myocyte enhancer factor-2D (MEF2D) was phosphorylated at Ser444 via p38{gamma}/p38{delta}. Mutation of MEF2D Ser444 to the non-phosphorylatable residue Ala increased its transcriptional activity and the expression of iNOS and IL-1{beta} mRNA. These results suggest that p38{gamma}/p38{delta} govern innate immune responses by regulating MEF2D phosphorylation and transcriptional activity.

molecular biology↗

bioRxiv2021

4D reconstruction of developmental trajectories using spherical harmonics

Although the full embryonic development of species such as Drosophila and zebrafish can be 3D imaged in real time, this is not true for mammalian organs, as normal organogenesis cannot be recapitulated in vitro. Currently available 3D data is therefore ex vivo images which provide only a snap shot of development at discrete moments in time. Here we propose a computer-based approach to recreate the continuous evolution in time and space of developmental stages from 3D volumetric images. Our method uses the mathematical approach of spherical harmonics to re-map discrete shape data into a space in which facilitates a smooth interpolation over time. We tested our approach on mouse limb buds (from E10 to E12.5) and embryonic hearts (from 10 to 29 somites). A key advantage of the method is that the resulting 4D trajectory takes advantage of all the available data (i.e. it is not dominated by the choice of a few "ideal" images), while also being able to interpolate well through time intervals for which there is little or no data. This method not only provides a quantitative basis for validating predictive models, but it also increases our understanding of morphogenetic processes. We believe this is the first data-driven quantitative 4D description of limb morphogenesis.

developmental biology↗