Discovery of an O-mannosylation pathway selectively serving cadherins and protocadherins

Larsen, Ida Signe Bohse; Narimatsu, Yoshiki; Joshi, Hiren J.; Siukstaite, Lina; Harrison, O.J.; Brasch, Julia; Goodman, K.M.; Hansen, Lars; Shapiro, Lawrence; Honig, Barry; Vakhrushev, Sergey Y.; Clausen, Henrik; Halim, Adnan

doi:10.1073/pnas.1708319114

Cited by 89 publications

(130 citation statements)

References 45 publications

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“…Whereas N ‐glycosylations are found in many human proteins, there are currently only some human proteins known, which carry O ‐mannosylations at specific serine or threonine residues. However, in the last decade it was shown that especially members of the cadherin family carry O ‐mannosylations . Remarkably, Larsen et al .…”

Section: Discussionmentioning

confidence: 99%

Incorporation of desmocollin‐2 into the plasma membrane requires N‐glycosylation at multiple sites

et al. 2019

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Desmocollin‐2 (DSC2) is a desmosomal protein of the cadherin family. Desmosomes are multiprotein complexes, which are involved in cell adhesion of cardiomyocytes and of keratinocytes. The molecular structure of the complete extracellular domain (ECD) of DSC2 was recently described, revealing three disulfide bridges, four N ‐glycosylation sites, and four O ‐mannosylation sites. However, the functional relevance of these post‐translational modifications for the protein trafficking of DSC2 to the plasma membrane is still unknown. Here, we generated a set of DSC2 mutants, in which we systematically exchanged all N ‐glycosylation sites, O ‐mannosylation sites, and disulfide bridges within the ECD and investigated the resulting subcellular localization by confocal laser scanning microscopy. Of note, all single and double N ‐glycosylation‐ deficient mutants were efficiently incorporated into the plasma membrane, indicating that the absence of these glycosylation sites has a minor effect on the protein trafficking of DSC2. However, the exchange of multiple N ‐glycosylation sites resulted in intracellular accumulation. Colocalization analysis using cell compartment trackers revealed that N ‐glycosylation‐ deficient DSC2 mutants were retained within the Golgi apparatus. In contrast, elimination of the four O ‐mannosylation sites or the disulfide bridges in the ECD has no obvious effect on the intracellular protein processing of DSC2. These experiments underscore the importance of N ‐glycosylation at multiple sites of DSC2 for efficient intracellular transport to the plasma membrane.

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Section: Discussionmentioning

confidence: 99%

Incorporation of desmocollin‐2 into the plasma membrane requires N‐glycosylation at multiple sites

et al. 2019

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“…TMTC1-4 are not only implicated in the O-mannosylation of cadherins but were also found to be involved in the O-mannosylation of several ER/Golgi resident proteins, including ERp57, ERdj4 and FKBP10 (Larsen et al, 2017a). Each of these are important chaperones for protein folding of the secretory pathway aiding in disulfide bond formation, BiP activation and proline cis trans isomerization.…”

Section: Discussionmentioning

confidence: 99%

“…TMTC1-4 were discovered to contribute to the O-mannosylation proteome when a subset of substrates remained O-mannosylated in cells that lacked the known Omannosyltransferases, POMT1 and POMT2 (Larsen et al, 2017a(Larsen et al, , 2017b. A significant difference in O-mannosylation of the cadherin family of proteins was observed upon knockout of all four TMTCs in HEK293 cells (HEK293 SC/TMTC1,2,3,4 ) (Larsen et al, 2017a). Glycoproteomics was used to determine that E-cadherin was O-mannosylated at nine sites (Supplemental Fig.…”

Section: Tmtc3 Rescues O-mannosylation Of E-cadherinmentioning

confidence: 99%

“…A new putative family of O-mannosyltransferases was recently discovered in mammals (Larsen et al, 2017a(Larsen et al, , 2017b. This family is comprised of four tetratricopeptide repeat (TPR)-containing proteins that appear to be ER polytopic transmembrane proteins called TMTC1-4 (transmembrane and TPR-containing proteins 1-4) (Della-Morte et al, 2011;Racapé et al, 2011;Cao et al, 2012;Sunryd et al, 2014;Larsen et al, 2017a;Li et al, 2018). TMTC1, 2 and 4 are ER proteins involved in Ca 2+ regulation as they associate with ER Ca 2+ re-uptake pump SERCA2B (Sunryd et al, 2014;Li et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…TMTC1, 2 and 4 are ER proteins involved in Ca 2+ regulation as they associate with ER Ca 2+ re-uptake pump SERCA2B (Sunryd et al, 2014;Li et al, 2018). The knockouts of TMTC1-4 have been shown using glycoproteomics to be involved in the O-mannosylation of cadherins (Larsen et al, 2017a(Larsen et al, , 2019. TMTC1-4 contain homologous structural elements as their N-terminal halves are comprised of a number of hydrophobic domains and the C-terminal halves are predicted to be composed mainly of long stretches of TPR motifs (8-12) (Karpenahalli et al, 2007;Letunic and Bork, 2018) (Fig.…”

Section: Introductionmentioning

confidence: 99%

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ER transmembrane protein TMTC3 contributes to O-mannosylation of E-cadherin, Cellular Adherence and Embryonic Gastrulation

Graham

Sunryd

Mathavan

et al. 2019

Preprint

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Protein glycosylation plays essential roles in protein structure, stability and activity such as cell adhesion. The cadherin superfamily of adhesion molecules carry O-linked mannose glycans at conserved sites and it was recently demonstrated that the TMTC1-4 genes contribute to the addition of these O-linked mannoses. Here, biochemical, cell biological and organismal analysis was used to determine that TMTC3 supports the Omannosylation of E-cadherin, cellular adhesion and embryonic gastrulation. Using genetically engineered cells lacking all four TMTC genes, overexpression of TMTC3 rescued O-linked glycosylation of E-cadherin and cell adherence. The knockdown of the Tmtcs in Xenopus laevis embryos caused a delay in gastrulation that was rescued by the addition of human TMTC3. Mutations in TMTC3 have been linked to neuronal cell migration diseases including Cobblestone lissencephaly. Analysis of TMTC3 mutations associated with Cobblestone lissencephaly found that three of the variants exhibit reduced stability and missence mutations were unable to complement TMTC3 rescue of gastrulation in Xenopus embryo development. Our study demonstrates that TMTC3 regulates O-linked glycosylation and cadherin-mediated adherence, providing insight into its effect on cellular adherence and migration, as well the basis of TMTC3associated Cobblestone lissencephaly.

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CircMETTL15 induces TMTC3 production by absorbing miR‐944 to promote hepatocellular carcinoma cell malignancy

Zhao,

Chen,

et al. 2023

J Biochem & Molecular Tox

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Previous data have suggested the involvement of circular RNA (circRNA) in hepatocellular carcinoma (HCC) progression. Up to now, the effect of circMETTL15 on HCC development remains unknown. This study aims to analyze the function of circMETTL15 in HCC development and the underlying mechanism. RNA expression of circMETTL15, miR‐944, and transmembrane O‐mannosyltransferase targeting cadherins 3 (TMTC3) were detected by quantitative real‐time polymerase chain reaction (qRT‐PCR). Protein expression was evaluated by Western blot analysis assay or immunohistochemistry assay. Cell proliferation was investigated by cell counting kit‐8 assay, 5‐Ethynyl‐29‐deoxyuridine (EdU) assay, and cell colony formation assay. Cell migration and invasion were assessed by wound‐healing assay and transwell assay, respectively. Angiogenic capacity was analyzed by tube formation assay. Dual‐luciferase reporter assay and RNA immunoprecipitation assay were conducted to identify the interplay between miR‐944 and circMETTL15 or TMTC3. Xenograft mouse model assay was conducted to reveal the effect of circMETTL15 on tumor formation in vivo. CircMETTL15 and TMTC3 expression were significantly upregulated, while miR‐944 expression was downregulated in HCC tissues and cells. CircMETTL15 knockdown led to decreased cell proliferation, migration, invasion, and tube formation. Besides, the inhibitors of miR‐944, a target miRNA of circMETTL15, partially restored circMETTL15 silencing‐mediated effects on the proliferation, migration, invasion, and tube formation of HCC cells. MiR‐944 overexpression also inhibited HCC cell malignancy by targeting TMTC3. Furthermore, circMETTL15 absence inhibited tumor formation by regulating miR‐944 and TMTC3 in vivo. In conclusion, circMETTL15 induced HCC development through the miR‐944/TMTC3 pathway, raising the potential of circMETTL15 as a target for HCC therapy.

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Discovery of an O-mannosylation pathway selectively serving cadherins and protocadherins

Cited by 89 publications

References 45 publications

Incorporation of desmocollin‐2 into the plasma membrane requires N‐glycosylation at multiple sites

Incorporation of desmocollin‐2 into the plasma membrane requires N‐glycosylation at multiple sites

ER transmembrane protein TMTC3 contributes to O-mannosylation of E-cadherin, Cellular Adherence and Embryonic Gastrulation

CircMETTL15 induces TMTC3 production by absorbing miR‐944 to promote hepatocellular carcinoma cell malignancy

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