scholarly journals Carbonic anhydrase-related protein CA10 is an evolutionarily conserved pan-neurexin ligand

2017 ◽  
Vol 114 (7) ◽  
pp. E1253-E1262 ◽  
Author(s):  
Fredrik H. Sterky ◽  
Justin H. Trotter ◽  
Sung-Jin Lee ◽  
Christian V. Recktenwald ◽  
Xiao Du ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Disulfide Bonds ◽  
Secretory Pathway ◽  
Surface Expression ◽  
Surface Transport ◽  
Proteomic Screen ◽  
Evolutionarily Conserved ◽  
Intermolecular Disulfide Bonds ◽  
Related Proteins ◽  
Insight Into

Establishment, specification, and validation of synaptic connections are thought to be mediated by interactions between pre- and postsynaptic cell-adhesion molecules. Arguably, the best-characterized transsynaptic interactions are formed by presynaptic neurexins, which bind to diverse postsynaptic ligands. In a proteomic screen of neurexin-1 (Nrxn1) complexes immunoisolated from mouse brain, we identified carbonic anhydrase-related proteins CA10 and CA11, two homologous, secreted glycoproteins of unknown function that are predominantly expressed in brain. We found that CA10 directly binds in a cis configuration to a conserved membrane-proximal, extracellular sequence of α- and β-neurexins. The CA10–neurexin complex is stable and stoichiometric, and results in formation of intermolecular disulfide bonds between conserved cysteine residues in neurexins and CA10. CA10 promotes surface expression of α- and β-neurexins, suggesting that CA10 may form a complex with neurexins in the secretory pathway that facilitates surface transport of neurexins. Moreover, we observed that the Nrxn1 gene expresses from an internal 3′ promoter a third isoform, Nrxn1γ, that lacks all Nrxn1 extracellular domains except for the membrane-proximal sequences and that also tightly binds to CA10. Our data expand the understanding of neurexin-based transsynaptic interaction networks by providing further insight into the interactions nucleated by neurexins at the synapse.

scholarly journals Deorphanizing FAM19A proteins as pan-neurexin ligands with an unusual biosynthetic binding mechanism

2020 ◽  
Vol 219 (9) ◽  
Author(s):  
Anna J. Khalaj ◽  
Fredrik H. Sterky ◽  
Alessandra Sclip ◽  
Jochen Schwenk ◽  
Axel T. Brunger ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Secretory Pathway ◽  
Post Translational Modification ◽  
Loop Domain ◽  
Selective Expression ◽  
Intermolecular Disulfide Bonds ◽  
Cell Type Specific ◽  
Genetic Deletion ◽  
Activity Dependent ◽  
Adjacent Sequence

Neurexins are presynaptic adhesion molecules that organize synapses by binding to diverse trans-synaptic ligands, but how neurexins are regulated is incompletely understood. Here we identify FAM19A/TAFA proteins, “orphan" cytokines, as neurexin regulators that interact with all neurexins, except for neurexin-1γ, via an unusual mechanism. Specifically, we show that FAM19A1-A4 bind to the cysteine-loop domain of neurexins by forming intermolecular disulfide bonds during transport through the secretory pathway. FAM19A-binding required both the cysteines of the cysteine-loop domain and an adjacent sequence of neurexins. Genetic deletion of neurexins suppressed FAM19A1 expression, demonstrating that FAM19As physiologically interact with neurexins. In hippocampal cultures, expression of exogenous FAM19A1 decreased neurexin O-glycosylation and suppressed its heparan sulfate modification, suggesting that FAM19As regulate the post-translational modification of neurexins. Given the selective expression of FAM19As in specific subtypes of neurons and their activity-dependent regulation, these results suggest that FAM19As serve as cell type–specific regulators of neurexin modifications.

scholarly journals IMiDs prime myeloma cells for daratumumab-mediated cytotoxicity through loss of Ikaros and Aiolos

Blood ◽  
2018 ◽  
Vol 132 (20) ◽  
pp. 2166-2178 ◽  
Author(s):  
Pasquale L. Fedele ◽  
Simon N. Willis ◽  
Yang Liao ◽  
Michael S. Low ◽  
Jai Rautela ◽  
...  
Keyword(s):  
Cell Death ◽  
Regulatory Networks ◽  
Nk Cell ◽  
Surface Expression ◽  
Nucleosome Remodeling ◽  
Interferon Stimulated Genes ◽  
Cd38 Expression ◽  
Cycle Arrest ◽  
Transcriptional Changes ◽  
Insight Into

Abstract Recent studies have demonstrated that the immunomodulatory drugs (IMiDs) lead to the degradation of the transcription factors Ikaros and Aiolos. However, why their loss subsequently leads to multiple myeloma (MM) cell death remains unclear. Using CRISPR-Cas9 genome editing, we have deleted IKZF1/Ikaros and IKZF3/Aiolos in human MM cell lines to gain further insight into their downstream gene regulatory networks. Inactivation of either factor alone recapitulates the cell intrinsic action of the IMiDs, resulting in cell cycle arrest and induction of apoptosis. Furthermore, evaluation of the transcriptional changes resulting from their loss demonstrates striking overlap with lenalidomide treatment. This was not dependent on reduction of the IRF4-MYC “axis,” as neither protein was consistently downregulated, despite cell death occurring, and overexpression of either factor failed to rescue for Ikaros loss. Importantly, Ikaros and Aiolos repress the expression of interferon-stimulated genes (ISGs), including CD38, and their loss led to the activation of an interferon-like response, contributing to MM cell death. Ikaros/Aiolos repressed CD38 expression through interaction with the nucleosome remodeling and deacetylase complex in MM. IMiD-induced loss of Ikaros or treatment with interferon resulted in an upregulation of CD38 surface expression on MM cells, priming for daratumumab-induced NK cell-mediated antibody-dependent cellular cytotoxicity. These results give further insight into the mechanism of action of the IMiDs and provide mechanistic rationale for combination with anti-CD38 monoclonal antibodies.

Disulfide bonds in amyloidogenesis diseases related proteins

2013 ◽  
Vol 81 (11) ◽  
pp. 1862-1873 ◽  
Author(s):  
Yang Li ◽  
Juan Yan ◽  
Xin Zhang ◽  
Kun Huang
Keyword(s):  
Disulfide Bonds ◽  
Related Proteins

scholarly journals Regulation of the Expression, Oligomerisation and Signaling of the Inhibitory Receptor CLEC12A by Cysteine Residues in the Stalk Region

2021 ◽  
Vol 22 (19) ◽  
pp. 10207
Author(s):  
Julien Vitry ◽  
Guillaume Paré ◽  
Andréa Murru ◽  
Xavier Charest-Morin ◽  
Halim Maaroufi ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Activation ◽  
Secretory Pathway ◽  
Surface Expression ◽  
Site Directed Mutagenesis ◽  
Cell Surface Expression ◽  
Dependent Manner ◽  
Inhibitory Receptor ◽  
Lectin Receptors ◽  
Stalk Domain

CLEC12A is a myeloid inhibitory receptor that negatively regulates inflammation in mouse models of autoimmune and autoinflammatory arthritis. Reduced CLEC12A expression enhances myeloid cell activation and inflammation in CLEC12A knock-out mice with collagen antibody-induced or gout-like arthritis. Similarly to other C-type lectin receptors, CLEC12A harbours a stalk domain between its ligand binding and transmembrane domains. While it is presumed that the cysteines in the stalk domain have multimerisation properties, their role in CLEC12A expression and/or signaling remain unknown. We thus used site-directed mutagenesis to determine whether the stalk domain cysteines play a role in CLEC12A expression, internalisation, oligomerisation, and/or signaling. Mutation of C118 blocks CLEC12A transport through the secretory pathway diminishing its cell-surface expression. In contrast, mutating C130 does not affect CLEC12A cell-surface expression but increases its oligomerisation, inducing ligand-independent phosphorylation of the receptor. Moreover, we provide evidence that CLEC12A dimerisation is regulated in a redox-dependent manner. We also show that antibody-induced CLEC12A cross-linking induces flotillin oligomerisation in insoluble membrane domains in which CLEC12A signals. Taken together, these data indicate that the stalk cysteines in CLEC12A differentially modulate this inhibitory receptor’s expression, oligomerisation and signaling, suggestive of the regulation of CLEC12A in a redox-dependent manner during inflammation.

scholarly journals The C-terminal helix 9 motif in rat cannabinoid receptor type 1 regulates axonal trafficking and surface expression

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Alexandra Fletcher-Jones ◽  
Keri L Hildick ◽  
Ashley J Evans ◽  
Yasuko Nakamura ◽  
Kevin A Wilkinson ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Secretory Pathway ◽  
Cannabinoid Receptor ◽  
Surface Expression ◽  
Surface Polarity ◽  
Time Resolved ◽  
Surface Stability ◽  
C Terminus ◽  
Time Resolved Imaging ◽  
Dual Mechanism

Cannabinoid type one receptor (CB1R) is only stably surface expressed in axons, where it downregulates neurotransmitter release. How this tightly regulated axonal surface polarity is established and maintained is unclear. To address this question, we used time-resolved imaging to determine the trafficking of CB1R from biosynthesis to mature polarised localisation in cultured rat hippocampal neurons. We show that the secretory pathway delivery of CB1R is axonally biased and that surface expressed CB1R is more stable in axons than in dendrites. This dual mechanism is mediated by the CB1R C-terminus and involves the Helix 9 (H9) domain. Removal of the H9 domain increases secretory pathway delivery to dendrites and decreases surface stability. Furthermore, CB1RΔH9 is more sensitive to agonist-induced internalisation and less efficient at downstream signalling than CB1RWT. Together, these results shed new light on how polarity of CB1R is mediated and indicate that the C-terminal H9 domain plays key roles in this process.

scholarly journals Converging physiological roles of the anthrax toxin receptors

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1415
Author(s):  
Oksana A. Sergeeva ◽  
F. Gisou van der Goot
Keyword(s):  
Anthrax Toxin ◽  
Loss Of Function ◽  
Disease Symptoms ◽  
Hyaline Fibromatosis Syndrome ◽  
Anthrax Toxins ◽  
The Difference ◽  
Related Proteins ◽  
Tumor Endothelial Marker 8 ◽  
Insight Into ◽  
Shed Light

The anthrax toxin receptors—capillary morphogenesis gene 2 (CMG2) and tumor endothelial marker 8 (TEM8)—were identified almost 20 years ago, although few studies have moved beyond their roles as receptors for the anthrax toxins to address their physiological functions. In the last few years, insight into their endogenous roles has come from two rare diseases: hyaline fibromatosis syndrome, caused by mutations in CMG2, and growth retardation, alopecia, pseudo-anodontia, and optic atrophy (GAPO) syndrome, caused by loss-of-function mutations in TEM8. Although CMG2 and TEM8 are highly homologous at the protein level, the difference in disease symptoms points to variations in the physiological roles of the two anthrax receptors. Here, we focus on the similarities between these receptors in their ability to regulate extracellular matrix homeostasis, angiogenesis, cell migration, and skin elasticity. In this way, we shed light on how mutations in these two related proteins cause such seemingly different diseases and we highlight the existing knowledge gaps that could form the focus of future studies.

Protocadherins and diversity of the cadherin superfamily

1996 ◽  
Vol 109 (11) ◽  
pp. 2609-2611 ◽  
Author(s):  
S.T. Suzuki
Keyword(s):  
Cell Adhesion ◽  
Circumstantial Evidence ◽  
Biological Role ◽  
Classical Cadherins ◽  
Adhesion Role ◽  
Multicellular Organisms ◽  
Related Proteins ◽  
Insight Into ◽  
Cadherin Superfamily

Recent cadherin studies have revealed that many cadherins and cadherin-related proteins are expressed in various tissues of different multicellular organisms. These proteins are characterized by the multiple repeats of the cadherin motif in their extracellular domains. The members of the cadherin superfamily are divided into two groups: classical cadherin type and protocadherin type. The current cadherins appear to have evolved from a protocadherin type. Recent studies have proved the cell adhesion role of classical cadherins in embryogenesis. In contrast, the biological role of protocadherins is elusive. Circumstantial evidence, however, suggests that protocadherins are involved in a variety of cell-cell interactions. Since protocadherins, and many other new cadherins as well, have unique properties, studies of these cadherins may provide insight into the structure and biological role of the cadherin superfamily.

A highly evolutionarily conserved mitochondrial protein is structurally related to the protein encoded by the Escherichia coli groEL gene

1988 ◽  
Vol 8 (1) ◽  
pp. 371-380
Author(s):  
T W McMullin ◽  
R L Hallberg
Keyword(s):  
Escherichia Coli ◽  
Tetrahymena Thermophila ◽  
Mitochondrial Protein ◽  
Cross Reactivity ◽  
Macromolecular Complexes ◽  
E Coli ◽  
Groel Gene ◽  
Evolutionarily Conserved ◽  
Associated Proteins ◽  
Related Proteins

We recently reported that a Tetrahymena thermophila 58-kilodalton (kDa) mitochondrial protein (hsp58) was selectively synthesized during heat shock. In this study, we show that hsp58 displayed antigenic similarity with mitochondrially associated proteins from Saccharomyces cerevisiae (64 kDa), Xenopus laevis (60 kDa), Zea mays (62 kDa), and human cells (59 kDa). Furthermore, a 58-kDa protein from Escherichia coli also exhibited antigenic cross-reactivity to an antiserum directed against the T. thermophila mitochondrial protein. The proteins from S. cerevisiae and E. coli antigenically related to hsp58 were studied in detail and found to share several other characteristics with hsp58, including heat inducibility and the property of associating into distinct oligomeric complexes. The T. thermophila, S. cerevisiae, and E. coli macromolecular complexes containing these related proteins had similar sedimentation characteristics and virtually identical morphologies as seen with the electron microscope. The distinctive properties of the E. coli homolog to T. thermophila hsp58 indicate that it is most likely the product of the groEL gene.

scholarly journals The cytoplasmic tail of human mannosidase Man1b1 contributes to catalysis-independent quality control of misfolded alpha1-antitrypsin

2020 ◽  
Vol 117 (40) ◽  
pp. 24825-24836 ◽  
Author(s):  
Ashlee H. Sun ◽  
John R. Collette ◽  
Richard N. Sifers
Keyword(s):  
Secretory Pathway ◽  
Cytoplasmic Tail ◽  
Cellular Functions ◽  
Independent Manner ◽  
Accelerated Degradation ◽  
Naturally Occurring ◽  
Regulatory Capacity ◽  
Alpha1 Antitrypsin ◽  
Catalytic Removal ◽  
Insight Into

The failure of polypeptides to achieve conformational maturation following biosynthesis can result in the formation of protein aggregates capable of disrupting essential cellular functions. In the secretory pathway, misfolded asparagine (N)-linked glycoproteins are selectively sorted for endoplasmic reticulum-associated degradation (ERAD) in response to the catalytic removal of terminal alpha-linked mannose units. Remarkably, ER mannosidase I/Man1b1, the first alpha-mannosidase implicated in this conventional N-glycan-mediated process, can also contribute to ERAD in an unconventional, catalysis-independent manner. To interrogate this functional dichotomy, the intracellular fates of two naturally occurring misfolded N-glycosylated variants of human alpha1-antitrypsin (AAT), Null Hong Kong (NHK), and Z (ATZ), in Man1b1 knockout HEK293T cells were monitored in response to mutated or truncated forms of transfected Man1b1. As expected, the conventional catalytic system requires an intact active site in the Man1b1 luminal domain. In contrast, the unconventional system is under the control of an evolutionarily extended N-terminal cytoplasmic tail. Also, N-glycans attached to misfolded AAT are not required for accelerated degradation mediated by the unconventional system, further demonstrating its catalysis-independent nature. We also established that both systems accelerate the proteasomal degradation of NHK in metabolic pulse-chase labeling studies. Taken together, these results have identified the previously unrecognized regulatory capacity of the Man1b1 cytoplasmic tail and provided insight into the functional dichotomy of Man1b1 as a component in the mammalian proteostasis network.

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