Lipid droplets (LDs) are the major lipid storage organelles of eukaryotic cells and a source of nutrients for intracellular pathogens. We demonstrate that mammalian LDs are endowed with a protein-mediated antimicrobial capacity, which is up-regulated by danger signals. In response to lipopolysaccharide (LPS), multiple host defense proteins, including interferon-inducible guanosine triphosphatases and the antimicrobial cathelicidin, assemble into complex clusters on LDs. LPS additionally promotes the physical and functional uncoupling of LDs from mitochondria, reducing fatty acid metabolism while increasing LD-bacterial contacts. Thus, LDs actively participate in mammalian innate immunity at two levels: They are both cell-autonomous organelles that organize and use immune proteins to kill intracellular pathogens as well as central players in the local and systemic metabolic adaptation to infection.

TTLL3 and TTLL8 are tubulin glycine ligases catalyzing posttranslational glycylation of microtubules. We show here for the first time that these enzymes are required for robust formation of primary cilia. We further discover the existence of primary cilia in colon and demonstrate that TTLL3 is the only glycylase in this organ. As a consequence, colon epithelium shows a reduced number of primary cilia accompanied by an increased rate of cell division in TTLL3-knockout mice. Strikingly, higher proliferation is compensated by faster tissue turnover in normal colon. In a mouse model for tumorigenesis, lack of TTLL3 strongly promotes tumor development. We further demonstrate that decreased levels of TTLL3 expression are linked to the development of human colorectal carcinomas. Thus, we have uncovered a novel role for tubulin glycylation in primary cilia maintenance, which controls cell proliferation of colon epithelial cells and plays an essential role in colon cancer development.

The posttranslational modification of tubulin plays an important role in regulating microtubule function. Enzymes responsible for deglutamylating tubulin are members of a family of cytosolic carboxypeptidases. By completing the functional characterization of this protein family in mammals, it is demonstrated that CCP2 and CCP3 are deglutamylases.

New C-terminally truncated α- and β-tubulin variants, both ending with an –EEEG sequence, are identified in vivo: αΔ3-tubulin, which has a specific neuronal distribution pattern (distinct from that of αΔ2-tubulin) and seems to be related to dynamic microtubules, and βΔ4-tubulin, corresponding to β2A/B-tubulin modified by truncation of four C-terminal residues, which is ubiquitously present in cells and tissues.

Tubulin is subject to a wide variety of posttranslational modifications, which, as part of the tubulin code, are involved in the regulation of microtubule functions. Glycylation has so far predominantly been found in motile cilia and flagella, and absence of this modification leads to ciliary disassembly. Here, we demonstrate that the correct functioning of connecting cilia of photoreceptors, which are nonmotile sensory cilia, is also dependent on glycylation. In contrast to many other tissues, only one glycylase, TTLL3, is expressed in retina. Ttll3−/− mice lack glycylation in photoreceptors, which results in shortening of connecting cilia and slow retinal degeneration. Moreover, absence of glycylation results in increased levels of tubulin glutamylation in photoreceptors, and inversely, the hyperglutamylation observed in the Purkinje cell degeneration ( pcd) mouse abolishes glycylation. This suggests that both posttranslational modifications compete for modification sites, and that unbalancing the glutamylation-glycylation equilibrium on axonemes of connecting cilia, regardless of the enzymatic mechanism, invariably leads to retinal degeneration.

Gold nanoparticles (17 nm) have been functionalized with the antiangiogenic monoclonal antibody drug Cetuximab at a well-defined orientation and coverage density of antibodies. Functionalization has been carried out through site-directed chemistry via the selective oxidation of the carbohydrate moiety of antibodies linked to a thiolated hydrazide. A431 tumor cells have been exposed to these conjugates for in vitro evaluation of their effects. In addition to epithelial growth factor receptor blocking, trafficking and signaling alterations were also observed. Thus, the blocking effects of Cetuximab were increased and sustained for a longer time when associated with the nanoparticles. Enhancing antibody therapy effects by decreasing the needed dose and prolonging its effect by avoiding receptor recycling may serve to obtain increased therapeutic benefits for immunotherapy.

The efficient delivery of nucleic acids into mammalian cells is a central aspect of cell biology and of medical applications, including cancer therapy and tissue engineering. Non-viral chemical methods have been received with great interest for transfecting cells. However, further development of nanocarriers that are biocompatible, efficient and suitable for clinical applications is still required. In this paper, the different material platforms for gene delivery are comparatively addressed, and the mechanisms of interaction with biological systems are discussed carefully.

Cytosolic carboxypeptidases (CCPs) constitute a new subfamily of M14 metallocarboxypeptidases associated to axonal regeneration and neuronal degeneration, among others. CCPs are deglutamylating enzymes, able to catalyze the shortening of polyglutamate side-chains and the gene-encoded C termini of tubulin, telokin, and myosin light chain kinase. The functions of these enzymes are not entirely understood, in part because of the lack of information about C-terminal protein processing in the cell and its functional implications. By means of C-terminal COFRADIC, a positional proteomics approach, we searched for cellular substrates targets of CCP1, the most relevant member of this family. We here identified seven new putative CCP1 protein substrates, including ribosomal proteins, translation factors, and high mobility group proteins. Furthermore, we showed for the first time that CCP1 processes both glutamates as well as C-terminal aspartates. The implication of these C termini in molecular interactions furthermore suggests that CCP1-mediated shortening of acidic protein tails might regulate proteinprotein and protein-DNA interactions. Molecular & Cellular