SCF-FBXO24 regulates cell proliferation by mediating ubiquitination and degradation of PRMT6.

The protein arginine methyltransferase 6 (PRMT6) is a coregulator of gene expression by methylation of the histone H3 on arginine 2 (H3R2), H4R3 and H2AR3 [1,2]. PRMT6 is aberrantly expressed in various types of human cancer, and abnormal methylation in cancers caused by overexpression of PRMT6 is considered to correlate with poor recovery prognosis [3,4]. However, mechanisms that regulate PRMT6 protein stability in cells remain largely unknown. Here we identified that an orphan F-box protein, FBXO24, that binds to 270 to 275 amino acid residues of PRMT6 to cause polyubiquitination of lysine at position 369 of PRMT6, which mediates its degradation via the ubiquitin-proteasome pathway. Overexpression of FBXO24 or knockout of PRMT6 was found to inhibit cell proliferation, migration, and invasion in H1299 cells. PRMT6 K369R mutant became resistant to degradation. Overexpression of PRMT6 K369R caused cell cycle progression, resulting in cell proliferation. Thus, our data confirm that FBXO24 regulates cell proliferation by mediating ubiquitin-dependent proteasomal degradation of PRMT6.

Mechanical, water resistance and environmental benefits of magnesium oxychloride cement incorporating rice husk ash.

Magnesium oxychloride cement (MOC) has received extensive attention as an eco-friendly cement, but its poor water resistance limits its engineering applications. In this study, MOC mixture (MOCM) was modified with 10-50 % rice husk ash (RHA) (wt% of MgO), and the development of their fresh properties, mechanical strength and microstructure was investigated. The results show that the incorporation of RHA to MOCM increases the setting time of the mixture and reduces its flowability. Due to the fine particle size and high reactivity of RHA, the incorporation of an appropriate amount of RHA to MOCM improves the matrix compactness, thereby enhancing the compressive strength of the samples. Although the microstructure of MOCM deteriorates and the strength decreases after immersion in water, the strength retention coefficient of MOCM with 50 % RHA increases by 24.57 % compared with that of plain MOCM. The incorporation of RHA not only reduces the relative content of magnesium oxide in MOCM, but also generates Mg-Cl-Si-H gel, which is beneficial to improve the water resistance of MOCM. Meanwhile, with the increase of RHA content, the carbon emission of MOCM also decreases. Compared with other modification methods, RHA-modified MOCM performs better in terms of water resistance, environmental benefits and strength enhancement.