Nishida, E. | bioRxiv Science

bioRxiv2026

Hyperactivation of Mincle in exacerbated apical periodontitis in an autoinflammatory mouse model for cherubism

Aims: To examine the role of Mincle, a C-type lectin (Clec) pathogen recognition receptor (PRR), in exacerbated apical periodontitis (AP) in an autoinflammatory mouse model for cherubism (CBM). Methodology: Patients with immune system dysfunction have higher prevalence of AP but the mechanism remains largely unknown. We studied a knock-in (KI) mouse model carrying a Sh3bp2 mutation for CBM. We performed pulp exposure in one lower 1st molar of 5- to 6-week-old mice to introduce pathogen-associated molecular patterns (PAMP)-induced endodontic infection. We determined the expression levels of Clec subfamily genes by qPCR. To suppress Mincle, we generated Sh3bp2+/+Mincle+/+, Sh3bp2+/KIMincle+/+, and Sh3bp2+/KIMincleKO/KO mice or injected Sh3bp2+/KI mice with a Mincle-binding DNA aptamer (AptMincle). Mice were analyzed 42 days after pulp exposure by micro-CT (mCT), qPCR and immunoblotting. Statistical analysis was performed by one-way ANOVA followed by post-hoc analysis with Tukeys test or two-way ANOVA followed by Sidak correction. p < 0.05 was considered statistically significant. Results: Expression of Clec4e (Mincle) was significantly increased in Sh3bp2 mutant mice after pulp exposure compared to WT littermates (p<0.0001). Sh3bp2+/KIMincle+/+ and Sh3bp2+/KIMincleKO/KO mice had a comparable response to pulp exposure, including the degree of bone loss and induction of inducible NOS (iNOS), IL-1b, and TNF-a. Sh3bp2+/KI mice injected with AptMincle after pulp exposure for 21 days showed significant amelioration of bone loss compared to mice with vehicle injection (p<0.0001). Conclusions: These seemingly conflicting data of suppressing Mincle by crossing with Mincle KO mice and AptMincle injection suggest that Mincle has dual functions upon PAMPs stimulation, consistent with a previous study showing that Mincle enhances tissue destruction during the inflammatory stage and is subsequently needed for inflammation resolution. Fine-tuned suppression of Mincle significantly reduces the severity of AP in Sh3bp2+/KI mice. This study suggests that patients with CBM may benefit from more frequent dental examinations and early intervention to reduce or prevent severe progressive bone loss in periapical tissues.

molecular biology↗

bioRxiv2023

Identification of FAM53C as a suppressive binding protein of a neurodevelopmental disorders-related kinase DYRK1A

The protein kinase DYRK1A encoded in human chromosome 21 is the major contributor to the multiple symptoms observed in Down syndrome patients. In addition, DYRK1A malfunction is associated with various other neurodevelopmental disorders such as autism spectrum disorder. Here we identified FAM53C with no hitherto known biological function as a novel suppressive binding partner of DYRK1A. FAM53C bound to the catalytic protein kinase domain of DYRK1A, whereas DCAF7/WDR68, the major DYRK1A-binding protein, binds to the N-terminal domain of DYRK1A. The binding of FAM53C inhibited autophosphorylation activity of DYRK1A and its kinase activity to an exogenous substrate MAPT/Tau. FAM53C did not bind directly to DCAF7/WDR68, whereas DYRK1A tethered FAM53C and DCAF7/WDR68 by binding concurrently to both of them, forming a tri-protein complex. DYRK1A possesses a nuclear localization signal and accumulates in the nucleus when overexpressed in cells. Co-expression of FAM53C induced cytoplasmic re-localization of DYRK1A, revealing the cytoplasmic anchoring function of FAM53C to DYRK1A. Moreover, the binding of FAM53C to DYRK1A suppressed the DYRK1A-dependent nuclear localization of DCAF7/WDR68. All the results show that FAM53C binds to DYRK1A, suppresses its kinase activity, and anchors it in the cytoplasm. In addition, FAM53C bound to the DYRK1A-related kinase DYRK1B with an Hsp90/Cdc37-independent manner. The results explain for the first time why endogenous DYRK1A is distributed in the cytoplasm in normal brain tissue. FAM53C-dependent regulation of the kinase activity and intracellular localization of DYRK1A may play a significant role in gene expression regulation caused by normal and aberrant levels of DYRK1A.

cell biology↗