BRCA1/BRCA2‐containing complex subunit 3 controls oligodendrocyte differentiation by dynamically regulating lysine 63‐linked ubiquitination

Abstract

Oligodendrocytes (OLs) provide the myelin sheath surrounding axons that propagates action potentials in the central nervous system (CNS). The metabolism of myelinated membranes and proteins is strictly regulated in the OLs and is closely associated with OL differentiation and maturation. The ubiquitination‐associated proteasome and endosomal system have not yet been well studied during OL differentiation and maturation. Here, we determined the functions of the Lys63‐linked ubiquitination (K63Ub) and K63‐specific deubiquitination (DUB) systems regulated by BRCA1/BRCA2‐containing complex subunit 3 (BRCC3) during OL differentiation. The competitive inhibition of K63Ub by overexpression of mutant ubiquitin (K63R) in oligodendrocyte precursor cells (OPCs) indicated that the two major CNS myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP), were upregulated in OLs derived from K63R OPCs. In contrast, the knockdown of BRCC3 (BRCC3‐KD) through the application of lentivirus‐mediated shRNA delivery system into OPCs suppressed OL differentiation by decreasing MBP expression and PLP production. Further immunoprecipitation assays revealed higher levels of sphingolipid GalC, MBP, and PLP, which were associated with K63Ub‐immunoprecipitants and detected in endosome/lysosomal compartments, in BRCC3‐KD OLs than those in OLs transfected with the scrambled shRNA (scramble OLs). The differentiation of OLs from BRCC3‐KD OPCs was impaired in the demyelinating corpus callosum of rats receiving a cuprizone‐containing diet. In the demyelinating tissues from human patients suffering from multiple sclerosis, we detected a decreased number of BRCC3‐expressing OLs at the lesion site, accompanied by a greater number of OLs expressing EEA1 and K63Ub at high levels. Altogether, the counterbalance of the K63Ub machinery and BRCC3‐triggered DUB machinery are important for the cellular trafficking of myelin proteins and OL differentiation.

Neuroglial transmitophagy and Parkinson's disease

“…Parkin normally exists in an inactive auto‐inhibited conformation which changes when its serine 65 is phosphorylated by the action of the autophosphorylated PINK1 (Chin & Li, 2016; Pickrell & Youle, 2015; Singh et al, 2018). The spheroids showed high parkin immunoreactivity, a fact also found for ubiquitin, a protein which links covalently to other proteins (ubiquitination) and works as a “kiss of death” signal for mitophagy (Chin & Li, 2016; de Rivero Vaccari et al, 2012; Rogov, Dotsch, Johansen, & Kirkin, 2014; C. Y. Wang, Deneen, & Tzeng, 2019). The polyclonal antibody used here has a higher affinity for ubiquitin‐protein conjugates than for free ubiquitin (Haas & Bright, 1985), which suggests that the high ubiquitin immunoreactivity found in the spheroids is generated by the ubiquitination of mitochondria.…”

SOX4 Mediates ATRA-Induced Differentiation in Neuroblastoma Cells

“…SOX9 has been reported to be one of the important regulators in neural crest cell development [ 27 ], ATP7A plays important roles in neuronal differentiation [ 28 ] and glial differentiation [ 29 ], CTSB promotes the differentiation of preadipocytes [ 30 ], RET has been reported regulate the differentiation of NB cells [ 31 ], CYP26A1 and CYP26B1 are retinoic acid catabolic enzymes [ 32 , 33 ], DDAH2 is a biomarker for neural stem cell differentiation [ 34 ], LTBP3 regulates the differentiation of mesenchymal stem cells [ 35 , 36 ], and MEIS1 regulates cell proliferation and differentiation during cell fate commitment in different neoplasms [ 37 ]. FHL2 has been reported to play important roles in different cells’ differentiation, including neuronal cells, gastric and colon cancer cells, and limb mesodermal progenitors [ 38 , 39 , 40 ], and BRCA2 regulates the differentiation of both normal tissues and different cancers [ 41 , 42 , 43 , 44 ]. These indicate that the overlapping up- and downregulated DEGs from the four GEO datasets may have essential roles in RA-induced cell differentiation.…”

A potential association of RNF219‐AS1 with ADHD: Evidence from categorical analysis of clinical phenotypes and from quantitative exploration of executive function and white matter microstructure endophenotypes

“…The ubiquitin‐proteasome system, regulating numerous cellular processes in eukaryotes including cell cycle and protein quality control, plays a pivotal role in the central nervous system and has linked to various psychiatry disorders such as SZ, 43 ASD 44 and depression 45 . The dynamic change of the ubiquitination‐associated proteasome, from ubiquitination to deubiquitination, could affect the myelin proteins in cellular trafficking and the oligodendrocytes differentiation and are implicated in the demyelinating disease of central nervous system (CNS) such as multiple sclerosis 46 . In addition, the ubiquitin signal could interact with autophagy and then cause the mitochondria damage and degradation 47 .…”