Mouse anti-Human CNOT2 monoclonal antibody, clone 3F21

Chromosome 12q15 microdeletion syndrome is characterized by intellectual disability and dysmorphic facial features, but the associations between each of the deleted genes and the phenotypes of 12q15 microdeletion syndrome remain unclear. Recently, the smallest region of overlap in 16 previously reported patients was used to define three candidate genes for the 12q15 microdeletion syndrome: CNOT2, KCNMB4, and PTPRB. Among these three candidate genes, CNOT2 maintains the structural integrity of the carbon catabolite repressor 4 (CCR4)-negative on TATA (NOT) complex, which plays a key role in regulating global gene expression, and is essential for the enzymatic activity of the CCR4-NOT complex. Disruption of the CCR4-NOT complex results in dysregulation of global gene expression, and is associated with various human disease processes, including neuronal diseases. Therefore, CNOT2 haploinsufficiency might account for the neurological features of the 12q15 microdeletion syndrome. Herein, we document a 12-year-old female patient with mild intellectual disability and multiple structural abnormalities including cleft lip and palate and 2-3 toe syndactyly. She exhibited dysmorphic facial features such as upslanting and short palpebral fissures, micrognathia, low-set ears, and hypoplastic antihelix. A microarray analysis showed a de novo 1.32-Mb deletion within 12q15 that included CNOT2 and 14 other genes. Remapping of the 12q15 deletion region in the 16 previously reported patients together with that in the newly identified patient indicated that CNOT2 is the only gene that is commonly deleted. These findings suggest that CNOT2 is the prime candidate for the neurological phenotypes of the 12q15 microdeletion syndrome.

Eukaryotic mRNA decay is initiated by shortening of the poly (A) tail; however, neither the molecular mechanisms underlying deadenylation nor its regulation is well understood. The human CCR4-NOT complex is a major cytoplasmic deadenylase consisting of a combination of at least nine subunits, four of which have deadenylase activity. The roles of the other subunits remain obscure. Here, we show that CNOT2 depletion by siRNA induces apoptosis. We also show that CNOT2 depletion destabilizes the complex, resulting in the formation of a complex smaller than that formed in control siRNA-treated cells. The deadenylase activity of the CNOT6L subunit-containing complex prepared from CNOT2-depleted cells was less than that from control cells. Intriguingly, the formation of P-bodies, where mRNA degradation supposedly takes place, was largely suppressed in CNOT2-depleted cells. Furthermore, CNOT2 depletion enhanced CHOP mRNA levels, suggesting that endoplasmic reticulum (ER) stress was occurring, which causes apoptosis in a caspase-dependent manner. These results suggest that CNOT2 is important for controlling cell viability through the maintenance of the structural integrity and enzymatic activity of the CCR4-NOT complex.