Figure 6

NF-M but not other pan-neuronal and synaptic protein mRNAs is derepressed in the adrenal medulla of newborn Dicer mutant mice. (A,B,C,D,E,F,G,H) ISH on transverse trunk sections from a newborn control mouse and (A’,B’,C’,D’,E’,F’,G’,H’) an animal with homozygous inactivation of floxed Dicer by DBH promoter-driven Cre recombinase. (A, A’) DBH ISH signal marks the position of the adrenal medulla (white arrowhead) and a prevertebral neuron cluster (black arrowhead). The neurons of the sympathetic ganglion display strong mRNA signals for (B) NF-M, (C) NF-L, (D) SCG10, (E) Snap25 and (F) Syt1, similar to neurons in the dorsal root ganglion and the ventral spinal cord. Abundant NF-M mRNA signal is also detected in adrenal medulla of (B’) mutant animals but not in (B) control. However, (C’) NF-L and (D’) SCG10 mRNAs do not appear upregulated in adrenal medulla. (E) Snap25 and (F) Syt1 mRNA signals are strong in neurons, and appear low in adrenal medulla of control animals. In homozygous mutants, (E’) Snap25 and (F’) Syt1 appear unaffected in adrenal medulla but reduced in prevertebral neuron clusters. (G) Syt7 mRNA signals are very low in control, and (G’) undetectable in mutant adrenal medulla and sympathetic neuron clusters. (H, H’) Rab3a mRNA signals are high in the dorsal root ganglion and the ventral spinal cord, and weakly detected in control and mutant sympathetic neuron clusters but not in adrenal medulla. Adjacent sections were used for ISH with the probes indicated, and experiments were performed to compare three mutant and three control animals for each individual probe. The panels from a representative animal are shown in this figure. Scale bar: 100 μm.