Jichuan Liu

The human cationic antimicrobial protein LL-37 is a multifunctional host defense peptide with a wide range of immunomodulatory activities. Previous work has shown that LL-37 exerts both pro- and anti-inflammatory effects. The role of mitochondria in the skin inflammatory effects of LL-37 has not been well studied. Therefore, our aim was to investigate the immunomodulatory effect of LL-37 in HaCaT cells and to delineate the underlying mechanisms related to mitochondrial function. Immunohistochemistry results from tissue microarrays showed strong cytoplasmic LL-37 staining in inflammatory cells in chronic dermatic inflammation. Using exogenous LL-37 stimulation and LL-37 knockdown and overexpression, LL-37 was demonstrated to dramatically reduce the mRNA levels and protein secretion of inflammatory cytokines including IL-6, IL-8, IL-1α and tumor necrosis factor-α, which are induced by lipopolysaccharides. The anti-inflammatory effects of LL-37 are dependent upon its ability to increase mitochondrial biogenesis and to maintain mitochondrial homeostasis. Furthermore, we observed that LL-37 enhances the LPS-induced phosphorylation of extracellular signal-regulated kinase and mammalian target of rapamycin. The mTOR inhibitor rapamycin can neutralize the protective effects of LL-37 on mitochondria. In conclusion, these results suggest that high LL-37 expression levels correlate with chronic skin inflammation; mitochondrial dysfunction occurs in HaCaT cells during inflammation; and LL-37 attenuates inflammatory impairment by stimulating mitochondrial biogenesis and protecting mitochondrial function, which are dependent upon mTOR signaling. These findings provide new insights into targeting mitochondria with LL-37 to prevent skin inflammatory reactions. © 2014 Elsevier Ltd.

OBJECTIVE: To evaluate the association of nicotinic acetylcholine receptor single nucleotide polymorphism with 7-day point prevalence abstinence in randomized clinical trials of smoking cessation therapies in individuals grouped by pharmacotherapy randomization to inform the development of personalized smoking cessation therapy. MATERIALS AND METHODS: We quantified association of four SNPs at three nAChRs with abstinence in eight randomized clinical trials. Participants were 2633 outpatient treatment-seeking, self-identified European ancestry individuals smoking at least 10 cigarettes/day, recruited through advertisement, prescribed pharmacotherapy, and provided with behavioral therapy. Interventions included nicotine replacement therapy, bupropion, varenicline, placebo, or combined NRT and bupropion, and five modes of group and individual behavioral therapy. Outcome measures tested in multivariate logistic regression were end of treatment and 6 month abstinence, with demographic, behavioral, and genetic covariates. RESULTS: 'Risk' alleles previously associated with smoking heaviness were significantly associated with reduced abstinence in the PLA pharmacotherapy group at 6MO [for rs588765, odds ratio 0.41 ], and at end of treatment and at 6MO [for rs1051730, 0.42 and 0.31 ], and with increased abstinence in the NRT PG at 6MO [for rs588765, 2.07 and for rs1051730, 2.54 ]. We observed significant heterogeneity in rs1051730 effects between PGs. CONCLUSION: chr15q25.1 nAChR SNP risk alleles for smoking heaviness significantly increase relapse with PLA treatment and significantly increase abstinence with NRT. These SNP-PG associations require replication in independent samples for validation, and testing in larger sample sizes to evaluate whether similar effects occur in other PGs. © 2013 Wolters Kluwer Health | Lippincott Williams &Wilkins.

We utilized a cohort of 828 treatment-seeking self-identified white cigarette smokers to rank candidate gene single nucleotide polymorphisms associated with the Fagerström Test for Nicotine Dependence, a measure of nicotine dependence which assesses quantity of cigarettes smoked and time- and place-dependent characteristics of the respondent's smoking behavior. A total of 1123 SNPs at 55 autosomal candidate genes, nicotinic acetylcholine receptors and genes involved in dopaminergic function, were tested for association to baseline FTND scores adjusted for age, depression, education, sex, and study site. SNP P-values were adjusted for the number of transmission models, the number of SNPs tested per candidate gene, and their intragenic correlation. DRD2, SLC6A3, and NR4A2 SNPs with adjusted P-values <0.10 were considered sufficiently noteworthy to justify further genetic, bioinformatic, and literature analyses. Each independent signal among the top-ranked SNPs accounted for ∼1% of the FTND variance in this sample. The DRD2 SNP appears to represent a novel association with nicotine dependence. The SLC6A3 SNPs have previously been shown to be associated with SLC6A3 transcription or dopamine transporter density in vitro, in vivo, and ex vivo. Analysis of SLC6A3 and NR4A2 SNPs identified a statistically significant gene-gene interaction, consistent with in vitro evidence that the NR4A2 protein product regulates SLC6A3 transcription. A community cohort of N=175 multiplex ever-smoking pedigrees provided nominal evidence for association with the FTND at these top ranked SNPs, uncorrected for multiple comparisons. © 2009 Nature Publishing Group All rights reserved.

Although the efficacy of pharmacotherapy for tobacco dependence has been previously demonstrated, there is substantial variability among individuals in treatment response. We performed a systems-based candidate gene study of 1295 single nucleotide polymorphisms in 58 genes within the neuronal nicotinic receptor and dopamine systems to investigate their role in smoking cessation in a bupropion placebo-controlled randomized clinical trial. Putative functional variants were supplemented with tagSNPs within each gene. We used global tests of main effects and treatment interactions, adjusting the P-values for multiple correlated tests. An SNP in the 3′ UTR region of the β2 nicotinic acetylcholine receptor subunit has an impact on abstinence rates at the end of treatment and after a 6-month follow-up period. This latter P-value is also significant with adjustment for the number of genes tested. Independent of treatment at 6-month follow-up, individuals carrying the minor allele have substantially decreased the odds of quitting. Effect of estimates indicate that the treatment is more effective for individuals with the wild-type compared with individuals carrying the minor allele, although this difference is only suggestive. Furthermore, this SNP demonstrated a role in the time to relapse and an impact on withdrawal symptoms at target quit date. Overall, while our results indicate strong evidence for CHRNB2 in ability to quit smoking, these results require replication in an independent sample. © 2008 The Author.

Knowledge of three-dimensional structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins' functions; but their structures are difficult to determine. Electron tomography provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral control algorithm. The validations by both negative staining and cryo-electron microscopy suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.