Fig. 1: NMNAT2 expression is highly variable across the visual system tissues and within retinal ganglion cell populations, and declines following injury.
From: NMNAT2 is a druggable target to drive neuronal NAD production
A Nmnat2 expression is highly variable between individual BXD mice (note logarithmic scales) across RGC relevant tissues (whole eye, n = 157; retina, n = 55; midbrain, n = 37 animals). It is important to note that these data are from different datasets and experiments and therefore should not be used for comparison across tissues, only within tissues. B In the retina, this variability is not related to the number of RGCs (Spearman’s rank correlation, shaded area = 95% CI) and the variance in Nmnat2 expression is significantly greater than for RGC markers Pou4f1, Rbpms, and Tubb3 (Pitman-Morgan test of variance for paired samples, two-sided). Both the founder strains (B6 and D2) are represented in these data and neither of these strains have the most upper or lower values (D2 = 10.69, B6 = 11.09, min for series = 10.23, max for series = 11.29 RMA gene level). C This variability in Nmnat2 increases with age (<200 days, n = 157 or >350 days, n = 187). D NMNAT2 expression in human retina is also highly variable between individuals (left, n = 50; right, n = 105). E Within the cell types of the retina, RGCs demonstrate the greatest average expression of NMNAT2 by single cell and single nucleus RNA-sequencing (red = highest expression, peach = lowest, dot plot scaled by % of expressing cells within types; AC amacrine cell, BP bipolar cell, HC horizontal cell, RPE retinal pigment epithelium) data from6 and47. Even within these individual RGCs, NMNAT2 expression is highly variable (n = 74 RGCs for scSeq, n = 2039 RGCs for NucSeq). F In D2 mice (a chronic, age-related mouse model of glaucoma), Nmnat2 expression declines in whole ONH at a pre/early-degenerative time point (stage 3) and in retina declines in late disease (stage 4) relative to DBA/2J-GpnmbR150X (for ONH, Group 1 (n = 8), Group 2 (n = 8), Group 3 (n = 6), Group 4 (n = 4), Group 5 (n = 4) where expression is compared to n = 5 D2-Gpnmb + ; in the retina, Group 1 (n = 8), Group 2 (n = 9), Group 3 (n = 3), Group 4 (n = 10); expression is compared to n = 8 D2-Gpnmb +). In sorted RGCs from D2 retina, this decline in Nmnat2 is detectable at an early, pre-degenerative time point in RGCs with high RNA dysregulation (Group 1 (n = 9 age-matched D2-Gpnmb+ and n = 6 D2s), Group 2 (n = 6 D2s), Group 3 (n = 10 D2s), Group 4 (n = 4 D2s). Data in F from3,8, significance as FDR). G This is replicated under the isolated glaucomatous insults of ocular hypertension (whole optic nerves from rat inducible model following 7 days of high IOP (OHT), n = 6; and normotensive controls, n = 7) and following direct RGC injury through axotomy (whole retina in retinal explant model, 12 h culture ex vivo following axotomy, n = 5; or controls, n = 5; two-sided Student’s t-test). For A–C: TPM transcripts per million, RMA robust multiarray analysis, QUANT quantile, RPKM reads per kilobase of exon per million. Data in A–F were generated through screening publicly available datasets (see Methods). *P < 0.05, **P < 0.01, ***P < 0.001, NS = non-significant (P > 0.05). For box plots, the centre hinge represents the median with upper and lower hinges representing the first and third quartiles; whiskers represent 1.5 times the interquartile range.
