ObjectiveTo observe the effect of Simiaowan on the intestinal ATP-binding cassette superfamily G （White） member 2 （ABCG2） expression and the intestinal uric acid excretion in hyperuricemia rats. MethodA total of 48 SD male rats were randomized into the normal， model， benzbromarone （4.7 mg·kg^-1）， and high-， medium-， low-dose Simiaowan groups （2 260.6， 1 130.3， 565.2 mg·kg^-1， respectively）， with 8 rats in each group. Potassium oxonate and hypoxanthine was employed to induce hyperuricemia in rats （21 days）. On the 8^th day， administration began （once a day for 14 days）. Rats were killed on the 21^st day， and serum uric acid， serum creatinine， blood urea nitrogen， and intestinal uric acid were detected. The protein expression of ABCG2 in the small intestine was detected by Western blot. The ABCG2 protein expression and localization in intestinal tissues were determined by immunohistochemistry. The ABCG2 mRNA expression in small intestine was measured by quantitative real-time PCR. ResultThe levels of serum uric acid， serum creatinine， and blood urea nitrogen in the model group were higher than those in the normal group （P<0.01）. Low level of serum uric acid in the three Simiaowan groups and benzbromarone group （P<0.01）， high level of intestinal uric acid in medium-dose and low-dose Simiaowan groups （P<0.05， P<0.01）， high level of serum creatinine in benzbromarone group （P<0.01）， and low level of blood urea nitrogen in low-dose Simiaowan group （P<0.05） were observed as compared with those in the model group. Serum uric acid showed insignificant difference between the low-dose Simiaowan group and benzbromarone group. The expression of ABCG2 protein in the model group was lower than that in the normal group （P<0.05）. The expression of ABCG2 protein in the medium-dose and low-dose Simiaowan groups （P<0.05， P<0.01）， the high-dose Simiaowan group， and benzbromarone group increased as compared with that in the model group. ABCG2 mRNA expression was insignificantly different between the model group and the normal group， while the expression in the medium-dose and low-dose Simiaowan groups was higher than that in the model group （P<0.05）. ABCG2 protein was mainly distributed in intestinal villi， and ABCG2 protein expression demonstrated no significant difference between the model group and the normal group. The ABCG2 protein expression in the three Simiaowan groups increased as compared with that in the model group （P<0.05）. ConclusionSimiaowan can significantly reduce the serum uric acid level in hyperuricemia rats. Particularly， the low-dose Simiaowan shows similar efficacy to benzbromarone in lowering uric acid and protects renal function. The mechanism is the likelihood that it up-regulates intestinal ABCG2 expression to promote intestinal excretion of uric acid.

Mutations or inactivation of parkin, an E3 ubiquitin ligase, are associated with familial form or sporadic Parkinson's disease (PD), respectively, which manifested with the selective vulnerability of neuronal cells in substantia nigra (SN) and striatum (STR) regions. However, the underlying molecular mechanism linking parkin with the etiology of PD remains elusive. Here we report that p62, a critical regulator for protein quality control, inclusion body formation, selective autophagy and diverse signaling pathways, is a new substrate of parkin. P62 levels were increased in the SN and STR regions, but not in other brain regions in parkin knockout mice. Parkin directly interacts with and ubiquitinates p62 at the K13 to promote proteasomal degradation of p62 even in the absence of ATG5. Pathogenic mutations, knockdown of parkin or mutation of p62 at K13 prevented the degradation of p62. We further showed that parkin deficiency mice have pronounced loss of tyrosine hydroxylase positive neurons and have worse performance in motor test when treated with 6-hydroxydopamine hydrochloride in aged mice. These results suggest that, in addition to their critical role in regulating autophagy, p62 are subjected to parkin mediated proteasomal degradation and implicate that the dysregulation of parkin/p62 axis may involve in the selective vulnerability of neuronal cells during the onset of PD pathogenesis.
Adaptor Proteins, Signal Transducing ; chemistry ; metabolism ; Animals ; HEK293 Cells ; Heat-Shock Proteins ; chemistry ; metabolism ; Humans ; Lysine ; metabolism ; Mice ; Neurons ; metabolism ; pathology ; Oxidopamine ; pharmacology ; Parkinson Disease ; metabolism ; pathology ; Proteasome Endopeptidase Complex ; metabolism ; Protein Stability ; Proteolysis ; drug effects ; Sequestosome-1 Protein ; Ubiquitin-Protein Ligases ; metabolism ; Ubiquitination ; drug effects