De novo mutations (DNMs) are important players in heritable diseases and evolution. Of particular interest are highly recurrent DNMs associated with congenital disorders that have been described as selfish mutations expanding in the male germline, thus becoming more frequent with age. Here, we have adapted duplex sequencing (DS), an ultradeep sequencing method that renders sequence information on both DNA strands; thus, one mutation can be reliably called in millions of sequenced bases. With DS, we examined ∼4.5 kb of the FGFR3 coding region in sperm DNA from older and younger donors. We identified sites with variant allele frequencies (VAFs) of 10−4 to 10−5, with an overall mutation frequency of the region of ∼6 × 10−7. Some of the substitutions are recurrent and are found at a higher VAF in older donors than in younger ones or are found exclusively in older donors. Also, older donors harbor more mutations associated with congenital disorders. Other mutations are present in both age groups, suggesting that these might result from a different mechanism (e.g., postzygotic mosaicism). We also observe that independent of age, the frequency and deleteriousness of the mutational spectra are more similar to COSMIC than to gnomAD variants. Our approach is an important strategy to identify mutations that could be associated with a gain of function of the receptor tyrosine kinase activity, with unexplored consequences in a society with delayed fatherhood.

Liposomes functionalized with monoclonal antibodies or their antigen-binding fragments have attracted much attention as specific drug delivery devices for treatment of various diseases including cancer. The conjugation of antibodies to liposomes is usually achieved by covalent coupling using cross-linkers in a reaction that might adversely affect the characteristics of the final product. Here we present an alternative strategy for liposome functionalization: we created a recombinant Fab antibody fragment genetically fused on its C-terminus to the hydrophobic peptide derived from pulmonary surfactant protein D, which became inserted into the liposomal bilayer during liposomal preparation and anchored the Fab onto the liposome surface. The Fab-conjugated liposomes specifically recognized antigen-positive cells and efficiently delivered their cargo, the Alexa Fluor 647 dye, into target cells in vitro and in vivo. In conclusion, our approach offers the potential for straightforward development of nanomedicines functionalized with an antibody of choice without the need of harmful cross-linkers.

Numerous publications have addressed CD147 as a tumor marker and regulator of cytoskeleton, cell growth, stress response, or immune cell function; however, the molecular functionality of CD147 remains incompletely understood. Using affinity purification, mass spectrometry, and phosphopeptide enrichment of isotope-labeled peptides, we examined the dynamic of the CD147 microenvironment and the CD147-dependent phosphoproteome in the Jurkat T cell line upon treatment with T cell stimulating agents. We identified novel dynamic interaction partners of CD147 such as CD45, CD47, GNAI2, Lck, RAP1B, and VAT1 and, furthermore, found 76 CD147-dependent phosphorylation sites on 57 proteins. Using the STRING protein network database, a network between the CD147 microenvironment and the CD147-dependent phosphoproteins was generated and led to the identification of key signaling hubs around the G proteins RAP1B and GNB1, the kinases PKCβ, PAK2, Lck, and CDK1, and the chaperone HSPA5. Gene ontology biological process term analysis revealed that wound healing-, cytoskeleton-, immune system-, stress response-, phosphorylation- and protein modification-, defense response to virus-, and TNF production-associated terms are enriched within the microenvironment and the phosphoproteins of CD147. With the generated signaling network and gene ontology biological process term grouping, we identify potential signaling routes of CD147 affecting T cell growth and function.

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Fibroblast growth factor receptors (FGFRs) initiate signal transduction via the RAS/MAPK pathway by their tyrosine-kinase activation known to determine cell-growth, tissue differentiation and apoptosis. Recently, many missense mutations have been reported for FGFR3, but we only know the functional effect for a handful of them. Some of these mutations result in aberrant FGFR3 signaling and are associated with various genetic disorders and oncogenic conditions. Here we employed micropatterned surfaces to specifically enrich fluorophore-tagged FGFR3 (mGFP-FGFR3) in certain areas of the plasma membrane of living cells. Receptor activation was then quantified via the recruitment of the downstream signal transducer GRB2 tagged with mScarlet (GRB2-mScarlet) to FGFR3 patterns. With this system, we tested the activation of FGFR3 upon ligand addition (fgf1 and fgf2) in the wildtype (WT), as well as in different FGFR3 mutants associated with congenital disorders (G380R, Y373C, K650Q, K650E). Our data showed that the addition of ligands increased GRB2 recruitment to WT FGFR3, with fgf1 having a stronger effect than fgf2. For all mutants, we found an increased basal receptor activity, and only for two of the four mutants (G380R and K650Q), activity was further increased upon ligand addition. Compared to previous reports, two mutant receptors (K650Q and K650E) had either an unexpectedly high or low activation state, respectively. This may be explained by the different receptor populations probed, since the micropatterning method specifically reports on signaling events at the plasma membrane.