Knockdown of mortalin within the medial prefrontal cortex impairs normal sensorimotor gating

Human blood analysis reveals differences in gene expression of catecholamine-regulated protein 40 (CRP40) in schizophrenia

Heat shock proteins (HSPs) are important players in neurodegeneration and psychiatric disorders. We previously reported significant reductions of a 40-kDa Catecholamine Regulated Protein (CRP40) in schizophrenia post-mortem brain specimens. This study investigated whether gene expression of CRP40 is altered in living subjects with schizophrenia. CRP40 mRNA was analyzed in white blood cells of first episode and chronic/treated schizophrenia subjects compared to healthy controls. Significant reductions in CRP40 mRNA were found among first episode schizophrenia subjects and chronic schizophrenia subjects compared to healthy controls (p<0.05 for both). These results suggest a possible functional role of CRP40 in the pathogenesis of schizophrenia.

Nuclear GRP75 binds retinoic acid receptors to promote neuronal differentiation of neuroblastoma

Retinoic acid (RA) has been approved for the differentiation therapy of neuroblastoma (NB). Previous work revealed a correlation between glucose-regulated protein 75 (GRP75) and the RA-elicited neuronal differentiation of NB cells. The present study further demonstrated that GRP75 translocates into the nucleus and physically interacts with retinoid receptors (RARα and RXRα) to augment RA-elicited neuronal differentiation. GRP75 was required for RARα/RXRα-mediated transcriptional regulation and was shown to reduce the proteasome-mediated degradation of RARα/RXRαin a RA-dependent manner. More intriguingly, the level of GRP75/RARα/RXRα tripartite complexes was tightly associated with the RA-induced suppression of tumor growth in animals and the histological grade of differentiation in human NB tumors. The formation of GRP75/RARα/RXRα complexes was intimately correlated with a normal MYCN copy number of NB tumors, possibly implicating a favorable prognosis of NB tumors. The present findings reveal a novel function of nucleus-localized GRP75 in actively promoting neuronal differentiation, delineating the mode of action for the differentiation therapy of NB by RA.