Novel insight into the phenotype of microcephaly 19 in the patient with missense COPB2 mutation

COPB2 gene encodes the Coatomer Protein Complex Subunit Beta-2 that plays a crucial role in the cellular vesicle transport system and it is essential for brain development during embryogenesis. Mutations in COPB2 lead to an extremely rare genetic disease named Microcephaly type 19 with autosomal recessive inheritance. This study describes a missense pathogenic homozygous variant (NM_004766.3:c.760 C > T, p.Arg254Cys) in the COPB2 gene, which was identified by Whole-Exome sequencing and confirmed by Sanger sequencing. The proband of the present study is an eight-and-a-half-year-old Iranian female who was born to consanguineous parents. She manifests global developmental delay, intellectual disability, microcephaly, seizures, spasticity, strabismus, and failure to thrive symptoms. Moreover, she is unable to stand, walk, or speak. Here we report the second homozygous mutation (NM_004766.3:c.760 C > T, p.Arg254Cys) in the COPB2 gene in the second family in the world with MCPH19. The responsible variant (NM_004766.3:c.760 C > T, p.Arg254Cys) for the observed symptoms in the proband was identical to the identified variant in the previously reported Caucasian/Native American family. Sharing this extremely rare pathogenic variant in two families with different origins is an extraordinary event that could aid us to determine the phenotype of this disease more precisely. Eventually, we provide a case-based review of the clinical features and compared our findings to the previously reported family for a better understanding of the clinical presentation of Microcephaly type 19 disease.

Implication of COPB2 Expression on Cutaneous Squamous Cell Carcinoma Pathogenesis

Simple Summary

The present study aimed to evaluate the effect of COPB2 expression on cutaneous squamous cell carcinoma (cSCC) pathogenesis. cSCC, a common category of skin cancer, is marked by a reasonably favorable prognosis. However, there has been a steady rise in the annual incidence of cases; in particular, a subset of cases showed aggressive progression. However, the underlying molecular mechanism of cSCC pathogenesis is largely unknown. In the present study, we found that COPB2 may act as a potential oncogene and modulator of the tumor immune microenvironment in cSCC pathogenesis. Therefore, COPB2 can serve as a novel predictive prognostic biomarker and immunotherapeutic target in cSCC patients.

Abstract

The underlying molecular mechanisms of cutaneous squamous cell carcinoma (cSCC) pathogenesis are largely unknown. In the present study, we aimed to evaluate the effect of coatomer protein complex subunit beta 2 (COPB2) expression on cSCC pathogenesis. Clinicopathological significance of COPB2 in cSCC was investigated by analyzing the Gene Expression Omnibus (GEO) database and through a retrospective cohort study of 95 cSCC patients. The effect of COPB2 expression on the biological behavior of cSCC cells was investigated both in vitro and in vivo. We found that COPB2 expression was significantly higher in cSCC samples than in normal skin samples. In our cohort, a considerable association was found between COPB2 expression and indicators of tumor immune microenvironment (TIME), such as histocompatibility complex class (MHC) I, and MHC II, CD4+/ CD8+ tumor-infiltrating lymphocytes. Additionally, COPB2 expression had an independent impact on worsened recurrence-free survival in our cohort. Furthermore, decreased proliferation, invasion, tumorigenic activities, and increased apoptosis were observed after COPB2 knockdown in cSCC cells. COPB2 may act as a potential oncogene and candidate modulator of the TIME in cSCC. Therefore, it can serve as a novel predictive prognostic biomarker and candidate immunotherapeutic target in cSCC patients.

COPB2 loss of function causes a coatopathy with osteoporosis and developmental delay

Coatomer complexes function in the sorting and trafficking of proteins between subcellular organelles. Pathogenic variants in coatomer subunits or associated factors have been reported in multi-systemic disorders, i.e., coatopathies, that can affect the skeletal and central nervous systems. We have identified loss-of-function variants in COPB2, a component of the coatomer complex I (COPI), in individuals presenting with osteoporosis, fractures, and developmental delay of variable severity. Electron microscopy of COPB2-deficient subjects' fibroblasts showed dilated endoplasmic reticulum (ER) with granular material, prominent rough ER, and vacuoles, consistent with an intracellular trafficking defect. We studied the effect of COPB2 deficiency on collagen trafficking because of the critical role of collagen secretion in bone biology. COPB2 siRNA-treated fibroblasts showed delayed collagen secretion with retention of type I collagen in the ER and Golgi and altered distribution of Golgi markers. copb2-null zebrafish embryos showed retention of type II collagen, disorganization of the ER and Golgi, and early larval lethality. Copb2+/- mice exhibited low bone mass, and consistent with the findings in human cells and zebrafish, studies in Copb2+/- mouse fibroblasts suggest ER stress and a Golgi defect. Interestingly, ascorbic acid treatment partially rescued the zebrafish developmental phenotype and the cellular phenotype in Copb2+/- mouse fibroblasts. This work identifies a form of coatopathy due to COPB2 haploinsufficiency, explores a potential therapeutic approach for this disorder, and highlights the role of the COPI complex as a regulator of skeletal homeostasis.

Effect of COPB2 expression on proliferation, migration, and invasion of gastric cancer cells

BACKGROUND

Coatomer protein complex subunit beta 2 (COPB2) is involved in the regulation of malignant biological behavior of various tumor cells. However, its expression and clinical significance in gastric cancer are still unclear.

AIM

To investigate the effects of COPB2 on the proliferation, invasion, and migration of gastric cancer cells and the possible mechanism.

METHODS

Immunohistochemical method was used to observe the expression of COPB2 in gastric cancer and adjacent tissues. Western blot was used to detect the expression of COPB2 protein in gastric cancer tissues and gastric cancer cell lines (SGC-7901, MKN45, and AGS). After transfection of COPB2-shRNA and its corresponding negative control (Con-shRNA), and pcDNA-COPB2 and its corresponding negative control (pcDNA-Con) into SGC-7901 cells, the effects of knockdown or overexpression of COPB2 on the proliferation, colony formation, migration, and invasion ability of gastric cancer cells were analyzed by CCK-8 assay, cell colony formation assay, and Transwell assay, and the effect of knockdown or overexpression of COPB2 on AKT signaling in gastric cancer cells was detected by Western blot. A tumor xenograft model was established to detect the effect of knockdown of COPB2 on tumor growth.

RESULTS

Compared with adjacent tissues and normal gastric epithelial cells (GES-1), the expression of COPB2 protein was significantly increased in gastric cancer tissues and gastric cancer cell lines (SGC-7901, MKN45, and AGS). Knockdown of COPB2 inhibited the proliferation, colony formation, migration, and invasion of SGC-7901 and the expression of p-Akt protein, while overexpression of COPB2 showed the opposite effect. In addition, knockdown of COPB2 inhibited SGC-7901 cell growth in vivo in a tumor xenograft model.

CONCLUSION

Knockdown of COPB2 expression can inhibit the proliferation, invasion, and metastasis of gastric cancer cells, and this effect may be related to the inhibition of AKT signaling activity.

COPB2: a transport protein with multifaceted roles in cancer development and progression

The Coatomer protein complex subunit beta 2 (COPB2) is involved in the formation of the COPI coatomer protein complex and is responsible for the transport of vesicles between the Golgi apparatus and the endoplasmic reticulum. It plays an important role in maintaining the integrity of these cellular organelles, as well as in maintaining cell homeostasis. More importantly, COPB2 plays key roles in embryonic development and tumor progression. COPB2 is regarded as a vital oncogene in several cancer types and has been implicated in tumor cell proliferation, survival, invasion, and metastasis. Here, we summarize the current knowledge on the roles of COPB2 in cancer development and progression in the context of the hallmarks of cancer.

Chrysin Induced Cell Apoptosis Through H19/let-7a/COPB2 Axis in Gastric Cancer Cells and Inhibited Tumor Growth

Background

Chrysin is a natural flavone that is present in honey and has exhibited anti-tumor properties. It has been widely studied as a therapeutic agent for the treatment of various types of cancers. The objectives of this present study were to elucidate how chrysin regulates non-coding RNA expression to exert anti-tumor effects in gastric cancer cells.

Methods

Through the use of RNA sequencing, we investigated the differential expression of mRNAs in gastric cancer cells treated with chrysin. Furthermore, COPB2, H19 and let-7a overexpression and knockdown were conducted. Other features, including cell growth, apoptosis, migration and invasion, were also analyzed. Knockout of the COPB2 gene was generated using the CRISPR/Cas9 system for tumor growth analysis in vivo.

Results

Our results identified COPB2 as a differentially expressed mRNA that is down-regulated following treatment with chrysin. Moreover, the results showed that chrysin can induce cellular apoptosis and inhibit cell migration and invasion. To further determine the underlying mechanism of COPB2 expression, we investigated the expression of the long non-coding RNA (lncRNA) H19 and microRNA let-7a. Our results showed that treatment with chrysin significantly increased let-7a expression and reduced the expression of H19 and COPB2. In addition, our results demonstrated that reduced expression of COPB2 markedly promotes cell apoptosis. Finally, in vivo data suggested that COPB2 expression is related to tumor growth.

Conclusions

This study suggests that chrysin exhibited anti-tumor effects through a H19/let-7a/COPB2 axis.

MiR-216a-3p regulates the proliferation, apoptosis, migration, and invasion of lung cancer cells via targeting COPB2

Effect of miR-216a-3p on lung cancer hasn't been investigated. Here, we explored its effects on lung cancer. MiR-216a-3p expression in lung cancer tissues and cells was detected by RT-qPCR. The target gene of miR-216a-3p was predicted by bioinformatics and confirmed by luciferase-reporter assay. After transfection, cell viability, migration, invasion, proliferation, and apoptosis were detected by MTT, scratch, transwell, colony formation, and flow cytometry. The expressions of COPB2 and apoptosis-related factors were detected by RT-qPCR or western blot. MiR-216a-3p was low-expressed and COPB2 was high-expressed in lung cancer tissues and cells. MiR-216a-3p targeted COPB2 and regulated its expression. MiR-216a-3p inhibited lung cancer cell viability, migration, invasion, and proliferation, while promoted apoptosis. Effect of miR-216a-3p on lung cancer was reversed by COPB2. MiR-216a-3p regulated proliferation, apoptosis, migration, and invasion of lung cancer cells via targeting COPB2.

SAG expression associates with COPB2-related signaling and a poorer prognosis in breast cancer

SAG is an essential RING component of the Cullin-RING ligase (CRL) E3 ubiquitin ligase complex, which regulates diverse signaling pathways and biological processes, including cell apoptosis, embryonic development, angiogenesis, and tumorigenesis. In the present study, we revealed that SAG gene expression is upregulated in breast cancer cells and that SAG overexpression is associated with significant poorer survival in breast cancer, especially the luminal A subtype. We also detected highly correlated co-overexpression of SAG and COPB2 in breast cancers. Subsequent in vitro experiments demonstrated that SAG and COPB2 act cooperatively to stimulate breast cancer cell proliferation, migration and invasion. Our findings suggest that levels of SAG and COPB2 expression may be useful prognostic indicators in breast cancers and that SAG may be involved in COPB2-related signaling during breast cancer development.

High expression of COPB2 predicts adverse outcomes: A potential therapeutic target for glioma

Aims

To evaluate the clinical significance of coatomer protein complex subunit beta 2 (COPB2) in patients with glioma using a bioinformatics analysis.

Methods

Oncomine, GEO, and The Cancer Genome Atlas databases were used to examine the COPB2 transcript levels in glioma tissues. Gene expression profiles with clinical information from low‐grade glioma and glioblastoma (GBM) projects were analyzed for associations between COPB2 expression and clinicopathologic characteristics. Kaplan‐Meier survival and Cox regression analyses were used for survival analysis. Gene set enrichment analysis (GSEA) was conducted to screen the pathways involved in COPB2 expression. Gene set variation analysis (GSVA) and correlograms were performed to verify the correlations between COPB2 and inflammatory responses. Canonical correlation analyses examined whether COPB2‐high patients have more infiltrating inflammatory and immune cells.

Results

COPB2 was highly expressed in gliomas and high COPB2 expression correlated with shorter overall survival time and several poor clinical prognostic variables. GSEA indicated that some immune‐related pathways and other signaling pathways in cancer were associated with the COPB2‐high phenotype. The GSVA and canonical correlation analysis demonstrated that COPB2 expression was closely linked to inflammatory and immune responses, and higher immune cell infiltration.

Conclusions

COPB2 may be a potential prognostic biomarker and an immunotherapeutic target for glioma.

MicroRNA-4461 derived from bone marrow mesenchymal stem cell exosomes inhibits tumorigenesis by downregulating COPB2 expression in colorectal cancer

Colorectal cancer (CRC) is one of the main cause of cancer-related deaths. It's reported that bone marrow mesenchymal stem cells (BMSCs) affects tumor development through secreting exosomes. This study aims to investigate the function of BMSCs-derived exosome miR-4461 in CRC. The results of qRT-PCR showed that miR-4461 expression in DLD1, HCT116 and SW480 CRC cells and CRC tissues was lower than that in FHC cells and normal tissues, respectively. And COPB2 mRNA expression was negatively correlated with miR-4461. Western blot was used to detect COPB2 protein expression. Dual-luciferase reporter assay results revealed that miR-4461 targeted COPB2. Transwell assay and CCK-8 assay demonstrated that COPB2 knockdown inhibited HCT116 and SW480 cells proliferation, migration and invasion abilities. Furthermore, BMSCs-derived exosome miR-4461 downregulated COPB2 expression and inhibited HCT116 and SW480 cells migration and invasion. The findings demonstrated that miR-4461 could be a potential target for the diagnosis and treatment of colorectal cancer.

Discovery of Druggable Host Factors Critical to Plasmodium Liver-Stage Infection

Plasmodium parasites undergo an obligatory and asymptomatic developmental stage within the liver before infecting red blood cells to cause malaria. The hijacked host pathways critical to parasite infection during this hepatic phase remain poorly understood. Here, we implemented a forward genetic screen to identify over 100 host factors within the human druggable genome that are critical to P. berghei infection in hepatoma cells. Notably, we found knockdown of genes involved in protein trafficking pathways to be detrimental to parasite infection. The disruption of protein trafficking modulators, including COPB2 and GGA1, decreases P. berghei parasite size, and an immunofluorescence study suggests that these proteins are recruited to the Plasmodium parasitophorous vacuole in infected hepatocytes. These findings reveal that various host intracellular protein trafficking pathways are subverted by Plasmodium parasites during the liver stage and provide new insights into their manipulation for growth and development.

COPB2 is up-regulated in breast cancer and plays a vital role in the metastasis via N-cadherin and Vimentin

Breast cancer (BC) is a common malignant tumour for the adult female and its relative incidence has increased continuously in recent years. The primary molecular mechanisms of breast tumourigenesis remain unclear. With the sequencing technology, we found that coatomer protein complex subunit beta 2 (COPB2) gene is overexpressed in breast cancer tissues. However, the biological function of COPB2 in BC has yet to be determined. This current research demonstrates, significant up‐regulation of COPB2 in tissues of breast cancer while comparing the adjacent normal tissue both invalidated cohort and TCGA cohort. Up‐regulated expression of COPB2 was correlated with lymph node metastasis (LNM) and oestrogen receptor (ER) in the TCGA cohort and a high level of COPB2 was associated with age and lymph node metastasis in the validated cohort. Besides, logistic analysis illustrated in BC patient COPB2 expression, tumour size, age, ER and disease stage were independent high‐risk factors of LNM. Loss of function experiments revealed that down‐regulation of COPB2 could inhibit capacities of proliferation and cell invasion in MDA‐MB‐231 and BT‐549 cell lines. Moreover, underexpression of COPB2 could decrease the EMT‐related protein N‐cadherin and vimentin which may lead to cell invasion. This current research provides new shreds of evidence that COPB2 overexpression shows significant character in the progression of breast cancer. To best of our knowledge, our findings indicated that COPB2 was vital oncogene which was associated with breast cancer.

Blepharophimosis, Ptosis, Epicanthus Inversus Syndrome: New Report with a 197-kb Deletion Upstream of FOXL2 and Review of the Literature

Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES) is due to heterozygous FOXL2 intragenic mutations in about 70% of the patients, whereas total or partial gene deletions account for a minority of cases. Alteration of FOXL2 regulatory elements has been rarely described in patients with BPES. In this study, a prepubertal girl with BPES due to a 197-kb de novo deletion of the regulatory elements upstream of FOXL2 is reported. This girl presented with additional clinical features such as a soft cleft palate and microcephaly; thus, this copy number variant might have other somatic effects. The present deletion encompasses 2 coding genes (MRPS22 and COPB2), whose homozygous mutations have been associated with microcephaly. In our case, the sequences of the non-deleted allele were normal, ruling out a compound genetic defect. Normal levels of new biomarkers of ovarian reserve (anti-müllerian hormone, inhibin B) likely indicate an early diagnosis of type 2 BPES, but an evolutive gonadal damage will be excluded only by long-term follow-up. Additional reports of microdeletions upstream of FOXL2 are needed to better define the underlying genetic mechanism and the related phenotypic spectrum; the ability of the new hormonal markers to predict ovarian function in adolescence and adulthood should be confirmed.

Identification of Host Factors Involved in Human Cytomegalovirus Replication, Assembly, and Egress Using a Two-Step Small Interfering RNA Screen

As obligate intracellular parasites, viruses are completely dependent on host factors for replication. Assembly and egress of complex virus particles, such as human cytomegalovirus (HCMV), are likely to require many host factors. Despite this, relatively few have been identified and characterized. This study describes a novel high-throughput, two-step small interfering RNA (siRNA) screen, which independently measures virus replication and virus production. By combining data from replication and virus production, multiple candidate genes were identified in which knockdown resulted in substantial loss of virus production with limited effect on primary replication, suggesting roles in later stages such as virus assembly and egress. Knockdown of the top candidates, ERC1, RAB4B, COPA, and COPB2, caused profound loss of virus production. Despite COPA and COPB2 being reported to function in the same complex, knockdown of these genes produced distinct phenotypes. Furthermore, knockdown of COPA caused increased expression of viral late genes despite substantial inhibition of viral DNA replication. This suggests that efficient viral genome replication is not required for late gene expression. Finally, we show that RAB4B relocates to the viral assembly compartment following infection with HCMV and knockdown of RAB4B reduces the release of intact virion particles, suggesting that it plays a role in virion assembly and egress. This study demonstrates a powerful high-throughput screen for identification of host-virus interactions, identifies multiple host genes associated with HCMV assembly and egress, and uncovers potentially independent functions for coatomer components COPA and COPB2 during infection.

Human cytomegalovirus infection is a significant cause of disease in immunocompromised populations, individuals with heart disease, and recipients of solid organ and bone marrow transplants. HCMV is also the leading cause of infectious congenital birth defects. The majority of antivirals in clinical use target components of the virus to specifically inhibit replication. However, a major drawback of this approach is the emergence of resistance. An alternative approach is to target host factors that the virus requires for successful infection. In this study, multiple host factors were identified that were found to be essential for the production of newly infectious human cytomegalovirus. Identifying which host genes are necessary for virus replication extends our understanding of how viruses replicate and how cells function and provides potential targets for novel antivirals.

COPB2 promotes cell proliferation and tumorigenesis through up-regulating YAP1 expression in lung adenocarcinoma cells

Lung adenocarcinoma is the most common subtype of non-small cell lung cancer and responsible for more than 500,000 deaths per year worldwide. In this study, we aimed to explore the effects of COPB2 in the progression of lung adenocarcinoma and its underlying mechanism. The mRNA and protein levels of COPB2 in tumor tissues and cell lines were determined by qRT-PCR and western blotting analysis. siRNAs and over-expressed vector targeting COPB2 were used to down-regulate and up-regulate COPB2 expression in lung adenocarcinoma cell lines H1975. Cell apoptosis rate, proliferation and tumorigenesis of H1975 cells were determined by flow cytometry analysis, MTT assay and in vivo xenotransplantation assay, respectively. Western blotting and immunofluorescence assays were performed to evaluate the effects of COPB on the expression and subcellular location of YAP. Results showed COPB2 was significantly up-regulated in lung adenocarcinoma tissues and cell lines, which showed a close correlation with advanced clinical symptoms, such as tumor differentiation, TNM stage and the occurrence of lymph node metastasis and distance metastasis. Besides, the overall survival time of patients with high expression of COPB2 was shorter than that of patients with low COPB2 expression. After knockdown of COPB2, cell apoptosis rate was increased, whereas cell proliferation was decreased. Compared with that in the normal lung cell line H1688 cells, YAP1 expression was obviously increased in H1975, and over-expression of COPB2 translocated YAP1 from cytoplasm to nuclear, whereas knockdown of COPB2 showed the opposite effect. Overexpression of COPB2 enhanced cell proliferation, tumorigenesis and inhibited cell apoptosis. However, these effects were abolished when down-regulated YAP1 expression on the base of COPB2 over-expression. In conclusion, the increased expression of COPB2 was significantly correlated with the progression of lung adenocarcinoma. Up-regulation of COPB2 inhibited cell apoptosis and promoted cell growth and tumorigenesis through up-regulating YAP1 expression in lung adenocarcinoma.

COPB2 promotes cell proliferation and tumorigenesis through up-regulating YAP1 expression in lung adenocarcinoma cells

Lung adenocarcinoma is the most common subtype of non-small cell lung cancer and responsible for more than 500,000 deaths per year worldwide. In this study, we aimed to explore the effects of COPB2 in the progression of lung adenocarcinoma and its underlying mechanism. The mRNA and protein levels of COPB2 in tumor tissues and cell lines were determined by qRT-PCR and western blotting analysis. siRNAs and over-expressed vector targeting COPB2 were used to down-regulate and up-regulate COPB2 expression in lung adenocarcinoma cell lines H1975. Cell apoptosis rate, proliferation and tumorigenesis of H1975 cells were determined by flow cytometry analysis, MTT assay and in vivo xenotransplantation assay, respectively. Western blotting and immunofluorescence assays were performed to evaluate the effects of COPB on the expression and subcellular location of YAP. Results showed COPB2 was significantly up-regulated in lung adenocarcinoma tissues and cell lines, which showed a close correlation with advanced clinical symptoms, such as tumor differentiation, TNM stage and the occurrence of lymph node metastasis and distance metastasis. Besides, the overall survival time of patients with high expression of COPB2 was shorter than that of patients with low COPB2 expression. After knockdown of COPB2, cell apoptosis rate was increased, whereas cell proliferation was decreased. Compared with that in the normal lung cell line H1688 cells, YAP1 expression was obviously increased in H1975, and over-expression of COPB2 translocated YAP1 from cytoplasm to nuclear, whereas knockdown of COPB2 showed the opposite effect. Overexpression of COPB2 enhanced cell proliferation, tumorigenesis and inhibited cell apoptosis. However, these effects were abolished when down-regulated YAP1 expression on the base of COPB2 over-expression. In conclusion, the increased expression of COPB2 was significantly correlated with the progression of lung adenocarcinoma. Up-regulation of COPB2 inhibited cell apoptosis and promoted cell growth and tumorigenesis through up-regulating YAP1 expression in lung adenocarcinoma.

COPB2 Is Upregulated in Prostate Cancer and Regulates PC-3 Cell Proliferation, Cell Cycle, and Apoptosis

BACKGROUND AND AIMS

Transport of membranes and proteins in eukaryotic cells is mediated by vesicular carriers. Coatomer complex I (COPI)-coated vesicles are involved in the transport between endoplasmic reticulum (ER) and Golgi complex. Several studies indicated that some subunits of COPI were correlated with the cell proliferation of malignant tumors. The present study focused on the function of coatomer protein complex subunit β 2 (COPB2), one of seven proteins in COPI, in prostate cancer (PCa).

METHODS

COPB2 gene expression was first analyzed by immunohistochemistry (IHC) in 15 paired PCa and carcinoma adjacent normal tissue from patients. To investigate the role of COPB2 in PCa, we used lentivirus-mediated small interfering RNA (siRNA) to knockdown COPB2 expression in human PCa cell line PC-3 and assessed it by RT-qPCR. Cellomics ArrayScan VTI imaging and colony formation were conducted to evaluate cell proliferation. Cell cycle phase arrest and apoptosis were assayed by flow cytometry.

RESULTS

COPB2 gene was upregulated in the PCa tissue. Cell proliferation was significantly inhibited in COPB2-silenced PC-3 cells using both Cellomics ArrayScan VTI imaging and colony formation assays. S-phase cell counts were significantly decreased; G1- and G2-phase cell counts were significantly increased in COPB2-siRNA group than the control group. Apoptosis was significantly increased in COPB2-siRNA cells.

CONCLUSIONS

COPB2 significantly promoted PC-3 cell proliferation and colony formation through the cell cycle and apoptosis pathway. Moreover, COPB2 showed a clinical correlation and may serve as a biomarker for the detection for PCa.