The human gC1qR/p32 gene, C1qBP. Genomic organization and promoter analysis

The C1q and gC1qR axis as a novel checkpoint inhibitor in cancer

Understanding at the molecular level of the cell biology of tumors has led to significant treatment advances in the past. Despite such advances however, development of therapy resistance and tumor recurrence are still unresolved major challenges. This therefore underscores the need to identify novel tumor targets and develop corresponding therapies to supplement existing biologic and cytotoxic approaches so that a deeper and more sustained treatment responses could be achieved. The complement system is emerging as a potential novel target for cancer therapy. Data accumulated to date show that complement proteins, and in particular C1q and its receptors cC1qR/CR and gC1qR/p33/HABP1, are overexpressed in most cancer cells and together are involved not only in shaping the inflammatory tumor microenvironment, but also in the regulation of angiogenesis, metastasis, and cell proliferation. In addition to the soluble form of C1q that is found in plasma, the C1q molecule is also found anchored on the cell membrane of monocytes, macrophages, dendritic cells, and cancer cells, via a 22aa long leader peptide found only in the A-chain. This orientation leaves its 6 globular heads exposed outwardly and thus available for high affinity binding to a wide range of molecular ligands that enhance tumor cell survival, migration, and proliferation. Similarly, the gC1qR molecule is not only overexpressed in most cancer types but is also released into the microenvironment where it has been shown to be associated with cancer cell proliferation and metastasis by activation of the complement and kinin systems. Co-culture of either T cells or cancer cells with purified C1q or anti-gC1qR has been shown to induce an anti-proliferative response. It is therefore postulated that in the tumor microenvironment, the interaction between C1q expressing cancer cells and gC1qR bearing cytotoxic T cells results in T cell suppression in a manner akin to the PD-L1 and PD-1 interaction.

Biological function of a gC1qR homolog (EcgC1qR) of Exopalaemon carinicauda in defending bacteria challenge

The gC1qR is a ubiquitously expressed cell protein that interacts with the globular heads of C1q (gC1q) and many other ligands. In this study, one gC1qR homolog gene was obtained from Exopalaemon carinicauda and named EcgC1qR. The complete nucleotide sequence of EcgC1qR contained a 774 bp open reading frame (ORF) encoding EcgC1qR precursor of 257 amino acids. The deduced amino acid sequence of EcgC1qR revealed a 55-amino-acid-long mitochondrial targeting sequence at the N-terminal and a mitochondrial acidic matrix protein of 33 kDa (MAM33) domain. The genomic organization of EcgC1qR gene showed that EcgC1qR gene contained five exons and four introns. EcgC1qR could express in all of the detected tissues and its expression was much higher in hepatopancreas and hemocytes. The expression of EcgC1qR in the hepatopancreas of prawns challenged with Vibrio parahaemolyticus and Aeromonas hydrophila changed in a time-dependent manner. The expression of EcgC1qR in prawns challenged with V. parahaemolyticus was up-regulated at 6 h (p < 0.05), and significantly up-regulated at 12 h and 24 h (p < 0.01), and then returned to the control levels at 48 h post-challenge (p > 0.05). At the same time, the expression in Aeromonas-challenged group was significantly up-regulated at 6, 12 and 24 h. The recombinant EcgC1qR could inhibit the growth of two tested bacteria. In addition, we successfully deleted EcgC1qR gene through CRISPR/Cas9 technology and it was the first time to obtain the mutant of gC1qR homolog gene in crustacean. It's a great progress to study the biological function of gC1qR in crustacean in future.

Long non-coding RNA RPAIN regulates the invasion and apoptosis of trophoblast cell lines via complement protein C1q

Long non-coding RNAs (lncRNAs) are key regulatory molecules that are involved in a variety of biological processes and human diseases. Their impact on early onset preeclampsia remains unclear. In this study, we tested the expression of RPAIN (transcript variant 12 of RPA interacting protein, a non-coding RNA, NR_027683.1) in placenta tissues derived from 25 pregnant women with PE and 15 healthy pregnant women using quantitative real-time PCR. The effect of RPAIN on trophoblast proliferation, invasion, and apoptosis and the underlying mechanisms were examined in trophoblast cell lines (HTR-8/SVneo). The results showed that RPAIN expression levels were significantly increased in early onset preeclamptic placentas compared to normal controls. The proliferation and invasive abilities of the trophoblast cells were significantly inhibited, and the apoptosis abilities of the trophoblast cells were significantly promoted when RPAIN was overexpressed. In addition, the overexpression of RPAIN inhibited the expression of complement protein C1q. Furthermore, C1q overexpression rescued the decreased cell invasion and enhanced cell apoptosis in RPAIN-overexpressing trophoblast cells. Our results suggest that increased RPAIN levels may contribute to the development of preeclampsia through regulating trophoblast invasion and apoptosis via C1q. Therefore, we proposed RPAIN as a novel lncRNA molecule, which might contribute to the development of PE (preeclampsia) and might compose a potential diagnostic and therapeutic target for this disease.

Increased breast cancer risk with HABP1/p32/gC1qR genetic polymorphism rs2285747 and its upregulation in northern Chinese women

Object

Hyaluronic acid binding protein 1 (HABP1/p32/gC1qR) is overexpressed in breast cancer. However, it is unknown whether HABP1 gene polymorphisms affect breast cancer risk. This study aims to evaluate the potential association of single nucleotide polymorphisms (SNPs) of HABP1 with breast cancer in northern Chinese women.

Results

The minor allele of rs2285747 was strongly associated with breast cancer with OR of 1.553 (95% CI = 1.251–1.927). SNP rs2285747 was also associated with high HABP1 protein expression under the co-dominant and dominant model (p = 0.005, p = 0.019, respectively). For rs2472614, the patients with CG and GG were more likely to have HER2 negative tumors compared to CC (p = 0.015). For rs3786054, the patients with AG and GG were more likely to have HER2 and P53 negative breast cancer compared to AA (p = 0.024, p = 0.064, receptively).

Materials and Methods

Seven SNPs were analyzed in 505 breast cancer patients and 505 controls using SNaPshot method. The associations between SNPs and breast cancer were examined by logistic regression. The associations of SNPs with HABP1 protein expression and disease characteristics were examined by chi-square test.

Conclusions

SNP rs2285747 of HABP1 increased breast cancer risk and elevated its protein expression in northern Chinese women.

Significance of hyaluronan binding protein (HABP1/P32/gC1qR) expression in advanced serous ovarian cancer patients

BACKGROUND

To evaluate various risk factors related to the overall survival (OS) and progression free survival (PFS) in 131 patients with stage III-IV ovarian serous carcinoma.

METHODS

All patients underwent primary debulking surgery followed by a standard chemotherapeutic treatment regimen. Hyaluronan binding protein (HABP1) expression was evaluated using immunohistochemical-staining and assessed using western-immunoblotting analyses. A log-rank test was used to compare OS and PFS between cisplatin sensitive versus resistant patients. Multivariate analyses were used to identify risk factors associated with OS and PFS.

RESULTS

HABP1 over-expression was correlated to histological-differentiation, residual-tumor-size, serum CA-125 levels and International Federation of Gynecology and Obstetrics (FIGO) stage. Multivariate analyses demonstrated that increased expression of HABP1 was associated with cisplatin resistance. HABP1 low-expression resulted in an increased five-year OS and PFS. Cox proportional hazards test identified that high expression of HABP1 led to increased risk for stage III/IV serous ovarian cancer via poor OS and PFS. This was similar for cisplatin resistant patients. Thus, increased HABP1 immunoreactivity in ovarian cancer may lead to a shortening in disease-free intervals of patients.

CONCLUSION

HAPBP1 over-expression in primary ovarian carcinomas is related to a decrease in OS and PFS and may be utilized as a prognostic marker for stage III/IV patients.

The molecular identity of the mitochondrial Ca2+ sequestration system

There is ample evidence to suggest that a dramatic decrease in mitochondrial Ca(2+) retention may contribute to the cell death associated with stroke, excitotoxicity, ischemia and reperfusion, and neurodegenerative diseases. Mitochondria from all studied tissues can accumulate and store Ca(2+) , but the maximum Ca(2+) storage capacity varies widely and exhibits striking tissue specificity. There is currently no explanation for this fact. Precipitation of Ca(2+) and phosphate in the mitochondrial matrix has been suggested to be the major form of storage of accumulated Ca(2+) in mitochondria. How this precipitate is formed is not known. The molecular identity of almost all proteins involved in Ca(2+) transport, storage and formation of the permeability transition pore is also unknown. This review summarizes studies aimed at identifying these proteins, and describes the properties of a known mitochondrial protein that may be involved in Ca(2+) transport and the structure of the permeability transition pore.

Computational analysis of base composition pattern and promoter elements in the putative promoter regions in relation to expression profiles of 682 human genes on chromosome 22

Abstract The base composition pattern (BCP) in the putative promoter region (PPRs) up to 5 Kb lengths of 682 human genes on Chromosome 22 (Chr22) was examined. Two-dimensional (2D) and three-dimensional (3D) functions were designed to delineate the DNA base composition, with four major patterns identified. It is found that 17.6% genes include TATA box, 28.0% GC box, 18.9% CAAT box and 38.4% CpG islands, and approximately 10% genes have one of four putative initiator (Inr) motifs. The occurrence of the promoter elements is tightly associated with the base composition features in the promoter regions, and the associations of the base composition features with occurrence of the promoter elements in the promoter regions mediate tissue-wide expression of the genes in human. The occurrence of two or more promoter elements in the promoter regions is required for the medium- and wide-range expression profiles of the human genes on Chr22. Thus, the reported data shed light on the characteristics of the PPRs of the human genes on Chr22, which may improve our understanding of regulatory roles of the PPRs with occurrence of the promoter elements in gene expression.

The contribution of gC1qR/p33 in infection and inflammation

Human gC1qR/p33 is a multi-compartmental and multi-functional cellular protein expressed on a wide range of tissues and cell types including lymphocytes, endothelial cells, dendritic cells, and platelets. Although originally isolated as a receptor for C1q by virtue of its affinity (K(d)=15-50 nM), and specificity for the globular heads of this molecule, a large body of evidence has now been accumulated which shows that in addition to C1q, gC1qR can serve as a receptor for diverse proinflammatory ligands including proteins of the plasma kinin-forming system, most notably high molecular weight kininogen (HK; K(d)=9 nM). In addition, gC1qR has been reported to recognize and bind a number of functional antigens of viral and bacterial origin. It is its ability to interact with microbial antigens and its potential to serve as a cellular protein for bacterial attachment and/or entry that has been the focus of our laboratory in the past few years. On the surface of activated platelets, gC1qR has been shown to serve as a binding site for Staphylococcus aureus and this binding is mediated by protein A. Since the binding of S. aureus to platelets is postulated to play a major role in the pathogenesis of endocarditis, gC1qR may provide a suitable surface for the initial adhesion of the bacterium. Recent data also demonstrate that the exosporium of Bacillus cereus, a member of a genus of aerobic, Gram-positive, spore-forming rod-like bacilli, which includes the deadly Bacillus anthracis, contains a binding site for gC1qR. Therefore, by virtue of its ability to recognize plasma proteins such as C1q and HK, as well as bacterial and viral antigens, cell-surface gC1qR not only is able to generate proinflammatory byproducts from the complement and kinin/kallikrein systems, but also can be an efficient vehicle and platform for a plethora of pathogenic microorganisms.