Table 2.

Partial list of FMRP target mRNAs and associated molecules in fragile X syndrome or Fmr1 knock-out mice

Category of function	Molecule	mRNA	Location of altered expression studied	Expression	References
Transcriptional regulator	MeCP2	Mecp2	Cerebellum; hippocampus, cortex, diencephalon, brainstem	↑mRNA; ↓mRNA	[79]
Translational regulator	miRNA-125b	–	Hippocampus	↑miRNA	[80▪]
Translational regulator	miRNA-132	–	Hippocampus	↑miRNA	[80▪]
mGlu receptor	mGluR1/2	GαluR1/2	Hippocampus, cortex, dentate gyrus	↑mRNA, ↑protein	[81]
NMDA receptor component	NR1	Grin 1	Prefrontal cortex; PSD of neocortex, hippocampus	↓protein; ↑protein	[82▪,83]
NMDA receptor component	NR2A	Grin2A	Prefrontal cortex	↓protein	[82▪]
NMDA receptor component	NR2B	Grin2B	Prefrontal cortex; PSD of neocortex, hippocampus	↓protein; ↑protein	[82▪,83]
GABA receptor component	GABAAR δ subunit	Gaba-Aδ	Cortex, subiculum, hippocampus	↓mRNA, ↓protein	[84,85]
Glucocorticoid receptor α	GRα	NR3CI	CA1 of hippocampus	↓protein	[86]
Signal transduction (Gq)	RGS5	Rgs5	–	↑mRNA	[84]
Scaffolding protein	PSD-95	Psd95	Hippocampus, prefrontal cortex	↓mRNA, ↓protein	[81,82▪,83,87]
Scaffolding protein	SAPAP3	Sapap3/4	Prefrontal cortex	↓mRNA, ↓protein	[82▪, 83,84]
Scaffolding protein	Shankl	Shank 1	Neocortex, hippocampus	↑mRNA	[83]
Scaffolding protein	APP	App	Cortex	↑mRNA, ↓protein	[88]
Plasticity-related protein	Arc/Arg3.1	Arc	Hippocampus, cortex	↓mRNA, ↓protein	[82▪, 89]
Scaffolding protein	Gephyrin	Gphn	Cortex	↓mRNA	[90]
Cell adhesion	Neuroligin 1	Neuroligin 1	Hippocampus	↑protein	[91]
Cell adhesion	Neuroligin 2	Neuroligin 2	Hippocampus	↑protein	[91]
GABA metabolism	GABAT	Abat	Cortex	↓mRNA, ↓protein	[85]
GABA metabolism	SSADH	ALDH5A1	Cortex, cerebellum	↓mRNA, ↓protein	[85]
GABA and glutamate metabolism	GAD	Gad	Cortex, cerebellum; amygdala; whole forebrain, cortex	↓mRNA; ↓protein; ↑protein	[92]
GABA transporter	GAT	Slc6a12	Whole forebrain, cortex, cerebellum	↓mRNA, ↓protein	[85]
Neurotransmitter	GABA	–	Amygdala	↓release	[92]
Microtubule dynamics, neurite extension	MAP1B	Map 1b	–	–	[93]
Component of Big potassium channel	BK channel a subunit	KCNMA1	Cortex	↓protein	[94]
Calcium signaling	CaMK llα	CamKllα	Hippocampus	↑mRNA, ↑protein	[81]
Axonal development	Sema3A and Sema3F	Sema3A and Sema3F	–	–	[95]

APP, amyloid precursor protein; Arc, activity-regulated cytoskeleton-associated protein; CaMK llα, calcium/calmodulin-dependent protein kinases llα t; GABA-T, GABA transaminase; GAD, glutamate decarboxylase; MAPI B, microtubule-associated protein 1B; MeCP2, methyl CpG-binding protein 2; mGluR1/2, metabotropic glutamate receptor type 1/2; PI3K, phosphatidyl inositol 3-kinases; RGS5, regulator of G-protein signaling 5; Sema, semaphorin; SSADH, succinic semialdehyde dehydrogenase.