Fig. 1
miR-128 host gene conservation and ARPP21 expression during brain development. a Genomic localization of murine miR-128 within the host genes Arpp21 and R3hdm1. Two major splice isoforms of Arpp21 are depicted, as referred to in the text (Arpp21 short and long). b Domain topology of ARPP21 and R3HDM1 proteins, including major ARPP21 isoforms (Arpp21 short = ARPP21-88aa and Arpp21 long = ARPP21-807aa). c Protein sequence alignment of the core R3H motif of ARPP21 from different vertebrate species, murine R3HDM1, murine R3HDM2, and fly ENCORE using the COBALT alignment tool (NCBI). The arginine and histidine residues of the R3H motif are marked by arrows. d In situ hybridization of E15 mouse brains with probes specific for Arpp21-long and -short transcript isoforms. Expression of both isoforms is enriched in post-mitotic neurons of the cortex. The dotted line marks the lower boundary of the cortical plate. Scale bar: 100 µm. e, f Detection of ARPP21-807aa and ARPP21-88aa during brain development by western blot. e ARPP21-807aa shows a gradual increase in expression. f Expression of ARPP21-88aa is strongly increased during postnatal stages. g Immunoblot analysis of both ARPP21 protein variants in samples from different brain regions and the lymphatic system of P21 mice. ARPP21-807aa is detected in several brain regions and the thymus. ARPP21-88aa is only detected in the whole brain, cortical, striatal, and hippocampal samples. BR whole brain, CX cortex, HS hippocampus and striatum, HB hindbrain, BS brainstem, LY lymph nodes, SP spleen, TH thymus. Full western blot images are presented in Supplementary Fig. 21
