See Supplemental Information for detailed experimental procedures. Statistical analyses were performed with Prism software (Graphpad Software) using the Fisher’s exact test, one-way ANOVA

or two-way repeated-measures ANOVA with Bonferroni post hoc multicomparison test and Student’s t test for pair-wise comparisons. p < 0.05 was considered statistically significant. GFP-positive neurite densities within the PVN region were first converted to binary file then further quantified by Image J (NIH). We thank members of the Jans, Xu, and Vaisse laboratories Sorafenib at UCSF for discussions, Dr. Chris Bohlen and Xiuming Wong at UCSF for confirming the rapamycin activity, Dr. James Warne at UCSF for measuring α-MSH in tissue explants, Dr. Grant Li at UCSF for providing the Pomc-cre, Tsc1-flox, and ZeG mouse lines, and Dr. Jeffrey Friedman at Rockefeller University for providing the POMC-GFP mouse line. This work was supported by American Diabetes Association Mentor-Based Fellowship 7-06-MN-29 (to S.-B.Y.), NIDDK summer student training grant (to G.B.), and the NIH grant MH065334 (to L.Y.J.). Y.N.J. and L.Y.J. are investigators check details of the Howard Hughes Medical Institute. “
“During mammalian development, alternative splicing of pre-mRNAs plays a critical role in the extensive

remodeling of tissues throughout both embryonic and postnatal phases (Chen and Manley, 2009; Kalsotra and Cooper, 2011). The spatial and temporal expression patterns of specific protein isoforms are exquisitely controlled during each developmental window such that the unique physiological requirements of each cell type are adequately met. While >90% of human multiexon genes produce alternatively spliced transcripts, the complex network PDK4 of dynamic interactions between multiple cell types that characterizes the central nervous system (CNS) suggests

that alternative splicing regulation is particularly critical for the developing brain (Li et al., 2007; Licatalosi and Darnell, 2010; Wang et al., 2008). The importance of alternative splicing during developmental transitions has been highlighted by studies on the autosomal dominant disease myotonic dystrophy (DM) (Cooper et al., 2009; Poulos et al., 2011). CNS function is compromised in DM with hypersomnia, cognitive and behavioral abnormalities, progressive memory problems, cerebral atrophy, and, in the congenital form of the disease, mental retardation (Meola and Sansone, 2007; Weber et al., 2010). DM is caused by microsatellite CTG expansions in the DMPK gene (DM type 1 [DM1]) or CNBP CCTG expansions (DM type 2 [DM2]). Transcription of these repeats generates C(C)UG expansion [C(C)UGexp] RNAs that disrupt alternative splicing, resulting in the persistence of fetal splicing patterns in adult tissues. A current disease model suggests that splicing disruption occurs because the muscleblind-like protein 1 (MBNL1), which normally promotes adult splicing patterns, is sequestered by C(C)UGexp RNAs ( Cooper et al., 2009; Du et al.