Mixed lineage kinase 2 (MLK2) is a protein kinase that signals in the stress-activated Jun N-terminal kinase signal transduction pathway. We used immunoprecipitation and mass spectrometric analysis to identify MLK2-binding proteins in cell lines with inducible expression of green fluorescent protein-tagged MLK2. Here we report the identification of clathrin as a binding partner for MLK2 in both cultured cells and mammalian brain. We demonstrate that clathrin binding requires a motif (LLDMD) located near the MLK2 C terminus, which is similar to "clathrin box" motifs important for binding of clathrin coat assembly and accessory proteins to the clathrin heavy chain. A C-terminal fragment of MLK2 containing this motif binds strongly to clathrin, and mutation of the LLDMD sequence to LAAAD completely abrogates clathrin binding. We isolated clathrin-coated vesicles from green fluorescent protein-MLK2-expressing cells and from mouse brain lysates and found that MLK2 is enriched along with clathrin in these vesicles. In addition, we demonstrated that endogenous MLK2 co-immunoprecipitates with clathrin heavy chain from the vesicle-enriched fraction of mouse brain lysate. Furthermore, overexpression of MLK2 in cultured cells inhibits accumulation of labeled transferrin in recycling endosomes during receptor-mediated endocytosis. These findings suggest a role for MLK2 and the stress-signaling pathway at sites of clathrin activity in vesicle formation or trafficking.
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http://dx.doi.org/10.1074/jbc.M204626200 | DOI Listing |
Cell Mol Life Sci
January 2025
School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong.
C1orf115 has been identified in high-throughput screens as a regulator of multidrug resistance possibly mediated through an interaction with ATP-dependent membrane transporter ABCB1. Here we show that C1orf115 not only shares structural similarities with FACI/C11orf86 to interact with clathrin adaptors to undergo endocytosis, but also induces ABCA1 transcription to promote cholesterol efflux. C1orf115 consists of an N-terminal intrinsically disordered region and a C-terminal α-helix.
View Article and Find Full Text PDFBiomark Med
January 2025
Department of Clinical Laboratory, Gansu Provincial Clinical Research Center for Laboratory Medicine, Lanzhou, China.
Raftlin (raft-linking) protein is an essential component of the lipid raft structure and plays a crucial role in B and T cell signaling pathways. It facilitates B cell receptor (BCR) signaling by promoting calcium mobilization and tyrosine phosphorylation in the cells while colocalizing with BCR on the cell membrane. Interestingly, Raftlin is internalized in lipopolysaccharide-stimulated T cells by colocalization with Toll-like receptor 4 (TLR4), wherein it exerts a similar role as in B cells.
View Article and Find Full Text PDFJ Virol
January 2025
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
Porcine epidemic diarrhea virus (PEDV), as a type of Alphacoronavirus causing acute diarrhea and high death rate among sucking piglets, poses great financial damage to the swine industry. Nevertheless, the molecular mechanism whereby PEDV enters host cells is unclear, limiting the development of PED vaccines and anti-PEDV agents. The present study found that the host protein ribonuclease kappa (RNASEK) was regulated by USF2, a transcription factor, and facilitated the PEDV replication.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Molecular Biochemistry and Clinical Investigation, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
The poor prognosis of pancreatic cancer is often attributed to difficulties of early detection due to a lack of appropriate risk factors. Previously, we demonstrated the presence of Enterococcus faecalis (E. faecalis) in pancreatic juice and tissues obtained from patients with cancers of the duodeno-pancreato-biliary region, suggesting the possible involvement of this bacterial species in chronic and malignant pancreatic diseases.
View Article and Find Full Text PDFVet Res
January 2025
Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
Porcine deltacoronavirus (PDCoV), also known as HKU15, is a swine enteropathogenic virus that is believed to have originated in birds. PDCoV belongs to the genus Deltacoronavirus (DCoV), the members of which have mostly been identified in diverse avian species. We recently reported that chicken or porcine aminopeptidase N (APN), the major cellular receptor for PDCoV, can mediate cellular entry via three pseudotyped retroviruses displaying spike proteins from three avian DCoVs (HKU11, HKU13, and HKU17).
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