Bombesin Receptor-Activated Protein (BRAP) Modulates NF-κB Activation in Bronchial Epithelial Cells by Enhancing HDAC Activity

SNP-based and haplotype-based genome-wide association on drug dependence in Han Chinese

BACKGROUND

Drug addiction is a serious problem worldwide and is influenced by genetic factors. The present study aimed to investigate the association between genetics and drug addiction among Han Chinese.

METHODS

A total of 1000 Chinese users of illicit drugs and 9693 healthy controls were enrolled and underwent single nucleotide polymorphism (SNP)-based and haplotype-based association analyses via whole-genome genotyping.

RESULTS

Both single-SNP and haplotype tests revealed associations between illicit drug use and several immune-related genes in the major histocompatibility complex (MHC) region (SNP association: log10BF = 15.135, p = 1.054e-18; haplotype association: log10BF = 20.925, p = 2.065e-24). These genes may affect the risk of drug addiction via modulation of the neuroimmune system. The single-SNP test exclusively reported genome-wide significant associations between rs3782886 (SNP association: log10BF = 8.726, p = 4.842e-11) in BRAP and rs671 (SNP association: log10BF = 7.406, p = 9.333e-10) in ALDH2 and drug addiction. The haplotype test exclusively reported a genome-wide significant association (haplotype association: log10BF = 7.607, p = 3.342e-11) between a region with allelic heterogeneity on chromosome 22 and drug addiction, which may be involved in the pathway of vitamin B12 transport and metabolism, indicating a causal link between lower vitamin B12 levels and methamphetamine addiction.

CONCLUSIONS

These findings provide new insights into risk-modeling and the prevention and treatment of methamphetamine and heroin dependence, which may further contribute to potential novel therapeutic approaches.

Knockout of the BRAP homolog in mice leads to abnormal tracheal cilia

Both bombesin receptor-activated protein (BRAP) and its mouse homolog have been found to be expressed in bronchial epithelia but with unclear functions. Using electron microscopy combined with histological assays, we found that BRAP homolog deficiency in mice led to abnormal tracheal cilia. Rab-3A-interacting protein (Rabin8), a protein that might play a role in cilia development, was screened by yeast two-hybrid and further verified to have interaction with human BRAP by co-immunoprecipitation and pulldown assays. The expression levels of Rabin8, together with acetylated α-tubulin, a marker of cilia, were either downregulated by knockdown of BRAP or upregulated by overexpression of BRAP in cultured immortalized human bronchial epithelial cells. These results reveal a role for BRAP in airway cilia formation.

Lack of bombesin receptor-activated protein homologous protein impairs hippocampal synaptic plasticity and promotes chronic unpredictable mild stress induced behavioral changes in mice

Bombesin receptor-activated protein (BRAP) and its homologous protein in mice, which is encoded by bc004004 gene, were expressed abundantly in brain tissues with unknown functions. We treated bc004004^-/- mice with chronic unpredictable mild stress (CUMS) to test whether those mice were more vulnerable to stress-related disorders. The results of forced swimming test, sucrose preference test, and open field test showed that after being treated with CUMS for 28 days or 35 days both bc004004^-/- and bc004004^+/+ mice exhibited behavioural changes and there was no significant difference between bc004004^+/+ and bc004004^-/-. However, behavioural changes were observed only in bc004004^-/- mice after being exposed to CUMS for 21 days, but not in bc004004^+/+ after 21-day CUMS exposure, indicating that lack of BRAP homologous protein may cause vulnerability to stress-related disorders in mice. In addition, bc004004^-/- mice showed a reduction in recognition memory as revealed by novel object recognition test. Since memory changes and stress related behavioural changes are all closely related to the hippocampus function we further analyzed the changes of dendrites and synapses of hippocampal neurons as well as expression levels of some proteins closely related to synaptic function. bc004004^-/- mice exhibited decreased dendritic lengths and increased amount of immature spines, as well as altered expression pattern of synaptic related proteins including GluN2A, synaptophysin and BDNF in the hippocampus. Those findings suggest that BRAP homologous protein may have a protective effect on the behavioural response to stress via regulating dendritic spine formation and synaptic plasticity in the hippocampus.

Bombesin receptor-activated protein exacerbates cisplatin-induced AKI by regulating the degradation of SIRT2

BACKGROUND

Acute kidney injury (AKI) is a public health problem with no specific therapies in the clinic and the underlying pathogenesis of AKI remains obscure. Bombesin receptor-activated protein (BRAP, C6ORF89 protein) was initially discovered as a ligand for a previously orphan G-protein-coupled receptor bombesin-like receptor-3. At present, accepted biological effects of BRAP include cell cycle progression, wound repair and the activation of histone deacetylases. However, its role in kidney disease is unknown. In this study we have investigated the role of BRAP and underlying mechanisms involved in cisplatin (CP)-induced AKI.

METHODS

Here we used Bc004004 (homologous of C6ORF89 in mice) knockout mice and HK2 cells to investigate the effect of BRAP on AKI in vitro and in vivo. We analyzed ChIP-Seq and RNA-Seq data to search for the upstream regulators of BRAP and downstream mediators of BRAP action in AKI. Immunostaining, real-time polymerase chain reaction (PCR), co-immunoprecipitation, a dual-luciferase reporter assay and ChIP-PCR assay were applied to reveal the upstream and downstream regulation mechanism of BRAP during cisplatin-induced AKI.

RESULTS

BRAP was downregulated in mice and human kidneys with AKI. Global Bc004004 deletion alleviated tubular cell apoptosis and necroptosis in CP-induced AKI mice, whereas local overexpression of BRAP in kidneys aggravated them. Pan-caspase inhibitor Z-VAD pretreatment attenuated CP-induced blood creatinine increase and kidney injury in wild-type mice but not in BRAP -/- mice. The activation of mixed lineage kinase like-domain was magnified by Z-VAD in CP-treated mice, especially in BRAP -/- mice. The cytoprotective effect of Z-VAD was more substantial than necrostatin-1 (Nec-1, an inhibitor of necroptosis) in CP-treated human kidney proximal tubular epithelial (HK2) cells. Furthermore, Nec-1 pretreatment reduced the CP-induced cell death in BRAP overexpression HK2 cells but did not work in cells with normal BRAP levels. We determined that CP treatment activated the nuclear factor-κB subunit P65 and inhibition of P65 increased the messenger RNA (mRNA) levels of BRAP in HK2 cells. The chromatin immunoprecipitation assay and dual-luciferase reporter gene assay verified P65 binding to the C6ORF89 promoter and reduced its mRNA expression upon CP treatment. Next we found that sirtuin 2 (SIRT2) was downregulated in CP-induced AKI and BRAP levels directly impacted the protein levels of SIRT2. Our findings further confirmed that BRAP regulates the SIRT2 protein levels by affecting SIRT2's interactions with E3 ubiquitin ligase HRD1 and subsequent proteasomal degradation.

CONCLUSIONS

Our results demonstrated that BRAP played an important role in tubular cell apoptosis and necroptosis during CP-induced AKI. Safe and efficient BRAP inhibitors might be effective therapeutic options for AKI.

Lack of bombesin receptor-activated protein attenuates bleomycin-induced pulmonary fibrosis in mice

Enhanced autophagic activity in fibroblasts due to lack of BRAP homologous protein might contribute to the resistance to pulmonary fibrosis in mice.

Bombesin receptor–activated protein (BRAP) was found to express in the interstitial cells of human fibrotic lungs with unknown function. Its homologous protein, encoded by BC004004 gene, was also present in mouse lung tissues. We used BC004004^−/− mice which lack BRAP homologous protein expression to establish a bleomycin-induced lung fibrotic model. After bleomycin treatment, BC004004^−/− mice exhibited attenuation of pulmonary injury and less pulmonary fibrosis. Fibroblasts from BC004004^−/− mice proliferated at a lower rate and produced less collagen. Autophagy-related gene 5 (ATG5) was identified as a partner interacting with human BRAP. Lacking BRAP homologous protein led to enhanced autophagy activity in mouse lung tissues as well as in isolated lung fibroblasts, indicating a negative regulatory role of this protein in autophagy via interaction with ATG5. Enhanced autophagy process in fibroblasts due to lack of BRAP homologous protein might contribute to the resistance of BC004004^−/− mice to pulmonary fibrosis.

Machine Learning Analysis of Longevity-Associated Gene Expression Landscapes in Mammals

One of the important questions in aging research is how differences in transcriptomics are associated with the longevity of various species. Unfortunately, at the level of individual genes, the links between expression in different organs and maximum lifespan (MLS) are yet to be fully understood. Analyses are complicated further by the fact that MLS is highly associated with other confounding factors (metabolic rate, gestation period, body mass, etc.) and that linear models may be limiting. Using gene expression from 41 mammalian species, across five organs, we constructed gene-centric regression models associating gene expression with MLS and other species traits. Additionally, we used SHapley Additive exPlanations and Bayesian networks to investigate the non-linear nature of the interrelations between the genes predicted to be determinants of species MLS. Our results revealed that expression patterns correlate with MLS, some across organs, and others in an organ-specific manner. The combination of methods employed revealed gene signatures formed by only a few genes that are highly predictive towards MLS, which could be used to identify novel longevity regulator candidates in mammals.

BRCA1-associated protein induced proliferation and migration of gastric cancer cells through MAPK pathway

BRCA1-associated protein (BRAP) was first found to bind to the nuclear localization signal motifs of BRCA1. In this study, we investigated the role of BRAP in gastric cancer. The cancer genome atlas(TCGA) data were obtained from UALCAN. We downregulated and upregulated the level of BRAP in gastric cancer cells by transfection with shRNAs and plasmids. Then, we evaluated the expression of BRAP by qRT-PCR and investigated the expression of important proteins by Western blot analysis. We conducted a microarray analysis to identify the function of BRAP in gastric cancer cells. Then, we investigated the effect of BRAP on proliferation and migration by CCK-8 assays, colony formation assays, wound healing assays and an extreme limiting dilution analysis. The analysis of TCGA data showed that BRAP was significantly overexpressed in gastric cancer tissues compared to that in normal gastric mucosal tissues (P < 0.001). A hybridization-based microarray assay was used to analyze MGC-803 cells and BRAP-downregulated MGC-803 cells. We found 22,199 protein-coding RNAs that were differentially expressed. The genes in the two groups were analyzed with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and both the focal adhesion and MAPK pathways were significantly enriched. The results of Cell Counting Kit-8(CCK-8) assays, colony formation assays, wound healing assays and the extreme limiting dilution analysis showed that the knockdown of BRAP reduced gastric cancer cell proliferation and migration and inhibited the process of epithelial-mesenehymal transition (EMT). The overexpression of BRAP induced gastric cancer cell proliferation, migration and the process of EMT. To verify the function of the mitogen-activated protein kinase (MAPK) signaling pathway, we performed a Western blot analysis. The results showed that the downregulation of BRAP decreased the levels of p-ERK and p-Raf1, thereby decreasing the activity of the MAPK signaling pathway. The use of Honokiol increased the levels of p-ERK and p-Raf1, rescuing the function of BRAP downregulation in the MAPK pathway. Xenograft tumor transplantation experiments in nude mice further confirmed the role of BRAP in gastric cancer progression and metastasis.

Research Advances in the Use of Histone Deacetylase Inhibitors for Epigenetic Targeting of Cancer

The causes and progression of cancer are controlled by epigenetic processes. The mechanisms involved in epigenetic regulation of cancer development, gene expression, and signaling pathways have been studied. Histone deacetylases (HDACs) have a major impact on chromatin remodeling and epigenetics, making their inhibitors a very interesting area of cancer research. This review comprehensively summarizes the literature regarding HDAC inhibitors (HDACis) as an anticancer treatment published in the past few years. In addition, we explain the mechanisms of their therapeutic effects on cancer. An analysis of the beneficial characteristics and drawbacks of HDACis also is presented, which will assist preclinical and clinical researchers in the design of future experiments to improve the therapeutic efficacy of these drugs and circumvent the challenges in the path of successful epigenetic therapy. Future therapeutic strategies may include a combination of HDACis and chemotherapy or other inhibitors to target multiple oncogenic signaling pathways.

Bombesin receptor-activated protein regulates neutrophil elastase-induced mucin5AC hypersecretion in human bronchial epithelial cells

Bombesin receptor-activated protein (BRAP) is highly expressed in human bronchial epithelial cells. Recent studies have shown that BRAP reduces oxidative stress, inhibits airway inflammation and suppresses nuclear factor kappaB (NF-κB) activity. Mucus overproduction is an important feature in patients with chronic inflammatory airway diseases. Neutrophil elastase (NE) is a potent inducer of mucin5AC (MUC5AC), which is considered the predominant mucin secreted by human airway epithelial cells. Here, we hypothesize that BRAP may regulate NE-induced MUC5AC hypersecretion in a bronchial epithelial cell line (HBE16). We also investigated the underlying mechanism involved in the process. In this study, we found that BRAP was present in HBE16 human bronchial epithelial cells and was significantly increased by NE. Next, we found that the up-regulation of BRAP by pEGFP-N1-BRAP caused a significant decrease in the increased levels of MUC5AC expression, NF-κB activity, and the phosphorylation of extracellular signal-regulated kinases (ERK) and epidermal growth factor receptor (EGFR) induced by NE. Meanwhile, there was a significant decrease in ROS, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels when BRAP was up-regulated by pEGFP-N1-BRAP. Moreover, when cells were transfected with pEGFP-N1-BRAP and pretreated with NF-κB, ERK or EGFR inhibitors before the NE stimulation, there were further decreased in MUC5AC expression, NF-κB activity, and the phosphorylation of ERK and EGFR. These results suggest that BRAP plays an important role in airway inflammation and its overexpression may regulate NE-induced MUC5AC hypersecretion in HBE16 cells via the EGFR/ERK/NF-κB signaling pathway.