Parkin is associated with cellular vesicles

We recently identified a novel gene, parkin, as a pathogenic gene for autosomal recessive juvenile parkinsonism. Parkin encodes a 52-kDa protein with a ubiquitin-like domain and two RING-finger motifs. To provide a insight into the function of parkin, we have examined its intracellular distribution in cultured cells. We found that parkin was localized in the trans-Golgi network and the secretory vesicles in U-373MG or SH-SY5Y cells by immunocytochemical analyses. In the subsequent subcellular fractionation studies of rat brain, we showed that parkin was copurified with the synaptic vesicles (SVs) when we used low ionic conditions throughout the procedure. An immunoelectromicroscopic analysis indicated that parkin was present on the SV membrane. Parkin was readily released from SVs into the soluble phase by increasing ionic strength at neutral pH, but not by a non-ionic detergent. To elucidate its responsible region for membrane association, we transfected with green fluorescent protein-tagged deletion mutants of parkin into COS-1 cells followed by subcellular fractionation. We demonstrated the ability of parkin to bind to the membranes through a broad region except for the ubiquitin-like domain. The significance of SV localization of parkin is discussed.

Two attacin antibacterial genes of Drosophila melanogaster

Insects express a battery of potent antimicrobial proteins in response to injury and infection. Recent work from several laboratories has demonstrated that this response is neither stereotypic nor completely nonspecific, and that different pathways are responsible for inducing the expression of antifungal and antibacterial peptides. Here we report the cloning of two closely linked attacin genes from Drosophila melanogaster. We compare their protein coding sequences and find the amino acid sequences to be more highly conserved than the nucleotide sequences, suggesting that both genes are expressed. Like other antimicrobial peptides, attacin expression is strongly induced in infected and injured flies. Unlike others, attacin transcription is uniquely sensitive to mutations in the 18-Wheeler receptor protein, and thus may be regulated by a distinct signaling pathway. The number and organization of binding sites for kappaB and other transcription factors in the promoter regions of both attacin genes are consistent with strong and rapid immune induction. We demonstrate that these promoter regions are sufficient to direct beta-galactosidase expression in transformed Drosophila third-instar larval fat body in a bacterially inducible manner. We present a comparison of the promoter regions of the two attacin genes to those cloned from other antimicrobial peptide genes to assist a better understanding of how antimicrobial genes are differentially regulated.

A lipid lowering drug (bezafibrate) has a favorable effect on liver enzymes (Al-P and gamma-GTP)

We administered 400 mg of bezafibrate daily to 27 patients with hyperlipidemia for seven moths. Most biochemical parameters remained unchanged, whereas levels of alkaline phosphatase (Al-P)and gamma-glutamyl transpeptidase (gamma-GTP), which are the hepatobiliary enzymes, were significantly decreased. Blood lipid levels were improved. Al-P levels decreased significantly from the baseline level of 174.5 IU/l to 116.7 IU/l (-26.5%) and gamma-GTP levels also decreased from 64.4 IU/l to 34.4 IU/l (-29.5%) (p < 0.001). When we compared the changes in serum lipid levels with those in Al-P and gamma-GTP levels following bezafibrate therapy, we found a slight degree of correlation between changes in gamma-GTP and triglyceride (T-G) levels, but no correlation at all between the changes of Al-P and total-cholesterol (T-cho), T-G or high density lipoprotein cholesterol (HDL-C). A close correlation was observed between both Al-P and gamma-GTP (r = 0.81, p < 0.001). From these results it was suggested that bezafibrate has not only a lipid lowering effect but has a favorable efficacy on the hepatobiliary enzymes.