Abundance and significance of neuroligin-1 and glutamate in Hirschsprung's disease

AIM: To investigate the abundance and potential diagnostic significance of neuroligin-1 and glutamate(Glu) in Hirschsprung's disease(HSCR).METHODS: Ninety children with HSCR and 50 children without HSCR matched for similar nutritional status, age and basal metabolic index were studied. The expression and localization of neuroligin-1 and Glu were assessed using double-labeling immunofluorescence staining of longitudinal muscles with adherent myenteric plexus from the surgically excised colon of children with HSCR. Western blot analysis, quantitative real-time PCR(q RT-PCR) and immunohistochemistry were performed to evaluate the abundance of neuroligin-1 and Glu in different HSCR-affected segments(ganglionic, transitional, and aganglionic segments). Enzyme-linked immunosorbent assay(ELISA) was used to detect and compare serum Glu levels in the long-segment HSCR, short-segment HSCR and non-HSCR samples.RESULTS: Neuroligin-1 and Glu were co-expressed highest to lowest in the ganglionic, transi tional and aganglionic segments based on Western blot(neuroligin-1: 0.177 ± 0.008 vs 0.101 ± 0.006, 0.177 ± 0.008 vs 0.035 ± 0.005, and 0.101 ± 0.006 vs 0.035 ±0.005, P < 0.005; Glu: 0.198 ± 0.006 vs 0.115 ± 0.008, 0.198 ± 0.006 vs 0.040 ± 0.003, and 0.115 ± 0.008 vs 0.040 ± 0.003, P < 0.005) and q RT-PCR(neuroligin-1: 9.58 × 10-5 ± 9.94 × 10-6 vs 2.49 × 10-5 ± 1.38 × 10-6, 9.58 × 10-5 ± 9.94 × 10-6 vs 7.17 × 10-6 ± 1.12 × 10-6, and 2.49 × 10-5 ± 1.38 × 10-6 vs 7.17 × 10-6 ± 1.12 × 10-6, P < 0.005). Serum Glu level was the highest to lowest in the non-HSCR, short-type HSCR and long-type HSCR samples based on ELISA(in nmol/μL, 0.93 ± 0.31 vs 0.57 ± 0.25, 0.93 ± 0.31 vs 0.23 ± 0.16, and 0.57 ± 0.25 vs 0.23 ± 0.16, P < 0.005).CONCLUSION: Neuroligin-1 and Glu may represent new markers of ganglion cells, whose expression may correlate with the pathogenesis, diagnosis, differential diagnosis or classification of HSCR.

LRRK2G2019S Mutation Inhibits Degradation of α-Synuclein in an In Vitro Model of Parkinson's Disease

The G2019S mutation of the leucine-rich repeat kinase 2(LRRK2)is the most common genetic cause of Parkinson's disease (PD).However,the molecular mechanisms of LRRK2 mutation contributing to the onset and progression of PD have not been fully illustrated.We generated HEK293 cells stably transfected with α-synuclein and investigated the effect of LRRK2 G2019S mutation on the degradation of α-synuclein.The lysosomal activity was assessed by the protein degradation of glyceraldehyde-3-phosphate dehydrogenase and ribonuclease A.It was found that α-synuclein was mainly degraded in lysosomes.LRRK2G2019S inhibited the degradation of α-synuclein,and promoted its aggregation.LRRK2G 2019S also decreased the activities of lysosomal enzymes including cathepsin B and cathepsin L.Furthermore,the inhibitory effect of LRRK2 G2019S on lysosomal functions did not depend on its kinase activity.These findings indicated that the inhibitory effect of LRRK2 G2019S on α-synuclein degradation could underlie the pathogenesis of aberrant α-synuclein aggregation in PD with LRRK2 mutation.