In vitro expanded CNS precursors could provide a renewable source of dopamine (DA) neurons for cell therapy in Parkinson's disease. Functional DA neurons have been derived previously from early midbrain precursors. Here we demonstrate the ability of Nurr1, a nuclear orphan receptor essential for midbrain DA neuron development in vivo, to induce dopaminergic differentiation in naïve CNS precursors in vitro. Independent of gestational age or brain region of origin, Nurr1-induced precursors expressed dopaminergic markers and exhibited depolarization-evoked DA release in vitro. However, these cells were less mature and secreted lower levels of DA than those derived from mesencephalic precursors. Transplantation of Nurr1-induced DA neuron precursors resulted in limited survival and in vivo differentiation. No behavioral improvement in apomorphine-induced rotation scores was observed. These results demonstrate that Nurr1 induces dopaminergic features in naïve CNS precursors in vitro. However, additional factors will be required to achieve in vivo function and to unravel the full potential of neural precursors for cell therapy in Parkinson's disease.

The bacterial effector proteins SseK and NleB glycosylate host proteins on arginine residues, leading to reduced NF-κB-dependent responses to infection. Salmonella SseK1 and SseK2 are E. coli NleB1 orthologs that behave as NleB1-like GTs, although they differ in protein substrate specificity. Here we report that these enzymes are retaining glycosyltransferases composed of a helix-loop-helix (HLH) domain, a lid domain, and a catalytic domain. A conserved HEN motif (His-Glu-Asn) in the active site is important for enzyme catalysis and bacterial virulence. We observe differences between SseK1 and SseK2 in interactions with substrates and identify substrate residues that are critical for enzyme recognition. Long Molecular Dynamics simulations suggest that the HLH domain determines substrate specificity and the lid-domain regulates the opening of the active site. Overall, our data suggest a front-face SNi mechanism, explain differences in activities among these effectors, and have implications for future drug development against enteric pathogens.

Mitochondrial dysfunction may play a key role in the progression of steatosis to nonalcoholic steatohepatitis (NASH); however, the molecular mechanism that controls the structure and function of mitochondria in NASH is not clearly understood. Here, we demonstrated that RORα is a regulator of expression of Bnip3 and PGC-1α, and thereby enhances mitochondrial quality. First, we observed that liver-specific RORα knockout mice (RORα-LKO) were more susceptible to high-fat diet-induced NASH compared with control, probably due to mitochondrial dysfunction. Concordantly, mitochondrial fission in response to nutrient stimuli was abolished with downregulation of Bnip3 and phospho-Drp1 in the hepatocytes of RORα-LKO. RORα enhanced oxygen consumption rate and expression of genes associated with mitochondrial quality control. Finally, we observed the positive correlation of the expression levels of Bnip3 and PGC-1α with those of RORα in patients with steatohepatitis. Together, we demonstrated that RORα mediates mitochondrial quality under nutrient-overloaded conditions and propose RORα as a potential therapeutic target in treatment of NASH.

No abstract