Crk1/2 and CrkL play critical roles in maintaining podocyte morphology and function

CRK and NCK adaptors may functionally overlap in zebrafish neurodevelopment, as indicated by common binding partners and overlapping expression patterns

CRK adaptor proteins are important for signal transduction mechanisms driving cell proliferation and positioning during vertebrate central nervous system development. Zebrafish lacking both CRK family members exhibit small, disorganized retinas with 50% penetrance. The goal of this study was to determine whether another adaptor protein might functionally compensate for the loss of CRK adaptors. Expression patterns in developing zebrafish, and bioinformatic analyses of the motifs recognized by their SH2 and SH3 domains, suggest NCK adaptors are well-positioned to compensate for loss of CRK adaptors. In support of this hypothesis, proteomic analyses found CRK and NCK adaptors share overlapping interacting partners including known regulators of cell adhesion and migration, suggesting their functional intersection in neurodevelopment.

Identification of inflammatory response and alternative splicing in acute kidney injury and experimental verification of the involvement of RNA‑binding protein RBFOX1 in this disease

An increasing number of inflammatory responses and alternative splicing (AS) have been recently reported to be associated with various kidney diseases. The effect of inflammatory response on acute kidney injury (AKI) has not been fully clarified. In the present study, a mouse model of AKI induced by cisplatin and ischemia-reperfusion (IR) was established and genome-wide profiling analysis and identification of differentially expressed genes (DEGs) in kidney tissue was conducted by Gene Ontology (GO) functional analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, protein-protein interaction (PPI) network analysis and RT-qPCR. The results revealed that common DEGs in AKI induced by cisplatin and IR were enriched in the inflammatory response pathway, including hub genes CSF-1, CXCL1, CXCL10, IL-1β, IL-34, IL-6 and TLR2. AS in AKI was initially reported. Cisplatin-induced AS was enriched in the phosphorylation pathway, involving regulated AS genes CSNK1A1, PAK2, CRK, ADK and IKBKB. IR-induced AS was enriched in apoptosis and proliferation pathways, including DEGs ZDHHC16, BCL2L1 and FGF1 regulated by AS. The ability of RNA-binding proteins (RBPs) to regulate AS was coordinated with the function of context-dependent genetic mechanisms. A total of 49 common differentially expressed RBP genes were screened. RNA binding fox-1 homolog 1 (RBFOX1) was revealed to be the top downregulated gene. The relative levels of RBFOX1 in the nuclei of mouse renal tubular epithelial cells in mRNA and proteins were downregulated by cisplatin and IR. Moreover, the biological functions of RBFOX1 were investigated in human renal proximal tubular epithelial cells (HK-2 cells). Results of in vitro experiments revealed that exogenous RBFOX1 inhibited inflammation and oxidative stress to reduce hypoxia/reoxygenation-induced apoptosis of HK-2 cells. This phenomenon may be related to the inhibition of NF-κB and the activation of the NRF2/HO-1 signaling pathway. In conclusion, the inflammatory cytokines, AS and RBPs in AKI were analyzed in the present study via whole transcriptome sequencing. It was revealed that the RBP gene RBFOX1 was involved in the pathogenesis of AKI. Thus, the present study provided novel insights into the mechanism of AKI pathogenesis.

CRKL, AIFM3, AIF, BCL2, and UBASH3A during Human Kidney Development

We aimed to investigate the spatio-temporal expression of possible CAKUT candidate genes CRKL, AIFM3, and UBASH3A, as well as AIF and BCL2 during human kidney development. Human fetal kidney tissue was stained with antibodies and analyzed by fluorescence microscopy and RT-PCR. Quantification of positive cells was assessed by calculation of area percentage and counting cells in nephron structures. Results showed statistically significant differences in the temporal expression patterns of the examined markers, depending on the investigated developmental stage. Limited but strong expression of CRKL was seen in developing kidneys, with increasing expression up to the period where the majority of nephrons are formed. Results also lead us to conclude that AIFM3 and AIF are important for promoting cell survival, but only AIFM3 is considered a CAKUT candidate gene due to the lack of AIF in nephron developmental structures. Our findings imply great importance of AIFM3 in energy production in nephrogenesis and tubular maturation. UBASH3A raw scores showed greater immunoreactivity in developing structures than mature ones which would point to a meaningful role in nephrogenesis. The fact that mRNA and proteins of CRKL, UBASH3A, and AIFM3 were detected in all phases of kidney development implies their role as renal development control genes.

Crk adaptor proteins are necessary for the development of the zebrafish retina

BACKGROUND

The development of the central nervous system (CNS) requires critical cell signaling molecules to coordinate cell proliferation and migration in order to structure the adult tissue. Chicken tumor virus #10 Regulator of Kinase (CRK) and CRK-like (CRKL) are adaptor proteins with pre-metazoan ancestry and are known to be required for patterning laminated structures downstream of Reelin (RELN), such as the cerebral cortex, cerebellum, and hippocampus. CRK and CRKL also play crucial roles in a variety of other growth factor and extracellular matrix signaling cascades. The neuronal retina is another highly laminated structure within the CNS that is dependent on migration for proper development, but the cell signaling mechanisms behind neuronal positioning in the retina are only partly understood.

RESULTS

We find that crk and crkl have largely overlapping expression within the developing zebrafish nervous system. We find that their disruption results in smaller eye size and loss of retinal lamination.

CONCLUSIONS

Our data indicate that Crk adaptors are critical for proper development of the zebrafish neural retina in a crk/crkl dose-dependent manner.