Uncovering enzyme (UCE), encoded by the human NAGPA, is a trans-Golgi enzyme that adds the mannose-6- phosphate recognition tag on lysosomal enzymes destined for the lysosome. Mutations in NAGPA are known to cause stuttering, a common speech disorder with unknown etiology. The human NAGPA gene is transcribed into two different forms, probably due to alternative splicing. One of them, known as a brain isoform, is lacking exon 8 (102-bp). We performed quantitative real-time PCR for the NAGPA brain and non-brain isoforms in a cDNA panel originating from 16 human tissues and 24 sub-brain regions. According to our findings, the relative quantity of the NAGPA brain isoform in the brain was 4.7 times more than that in the control cDNA, a pooled mixture of equal amounts of cDNAs from the 16 different tissues. Further analysis using the cDNA panel originating from 24 different sub-brain regions revealed that the cerebral cortex contained the largest amount of NAGPA brain isoform. Relative quantity in the cerebral cortex was 8.6 times more than that in the control cDNA (P=0.00004). The lowest quantity of this isoform was detected in cDNA from the pituitary gland. In conclusion, findings of the current study suggest that the cerebral cortex, expressing the highest quantity of the NAGPA brain isoform, might be the region associated with speech function.

• Changsoo Kang(School of Biological Sciences and Chemistry, College of Natural Sciences, Sungshin Women’s University) Corresponding Author