A comparative analysis of BCL-2 family

BCL-G: 20 years of research on a non-typical protein from the BCL-2 family

Proteins from the BCL-2 family control cell survival and apoptosis in health and disease, and regulate apoptosis-unrelated cellular processes. BCL-Gonad (BCL-G, also known as BCL2-like 14) is a non-typical protein of the family as its long isoform (BCL-G_L) consists of BH2 and BH3 domains without the BH1 motif. BCL-G is predominantly expressed in normal testes and different organs of the gastrointestinal tract. The complexity of regulatory mechanisms of BCL-G expression and post-translational modifications suggests that BCL-G may play distinct roles in different types of cells and disorders. While several genetic alterations of BCL2L14 have been reported, gene deletions and amplifications prevail, which is also confirmed by the analysis of sequencing data for different types of cancer. Although the studies validating the phenotypic consequences of genetic manipulations of BCL-G are limited, the role of BCL-G in apoptosis has been undermined. Recent studies using gene-perturbation approaches have revealed apoptosis-unrelated functions of BCL-G in intracellular trafficking, immunomodulation, and regulation of the mucin scaffolding network. These studies were, however, limited mainly to the role of BCL-G in the gastrointestinal tract. Therefore, further efforts using state-of-the-art methods and various types of cells are required to find out more about BCL-G activities. Deciphering the isoform-specific functions of BCL-G and the BCL-G interactome may result in the designing of novel therapeutic approaches, in which BCL-G activity will be either imitated using small-molecule BH3 mimetics or inhibited to counteract BCL-G upregulation. This review summarizes two decades of research on BCL-G.

The Role of BCL-2 and PD-1/PD-L1 Pathway in Pathogenesis of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDSs) belong to a group of clonal bone marrow malignancies. In light of the emergence of new molecules, a significant contribution to the understanding of the pathogenesis of the disease is the study of the B-cell CLL/lymphoma 2 (BCL-2) and the programmed cell death receptor 1 (PD-1) protein and its ligands. BCL-2-family proteins are involved in the regulation of the intrinsic apoptosis pathway. Disruptions in their interactions promote the progression and resistance of MDSs. They have become an important target for specific drugs. Bone marrow cytoarchitecture may prove to be a predictor of response to its use. The challenge is the observed resistance to venetoclax, for which the MCL-1 protein may be largely responsible. Molecules with the potential to break the associated resistance include S63845, S64315, chidamide and arsenic trioxide (ATO). Despite promising in vitro studies, the role of PD-1/PD-L1 pathway inhibitors has not yet been established. Knockdown of the PD-L1 gene in preclinical studies was associated with increased levels of BCL-2 and MCL-1 in lymphocytes T, which could increase their survival and promote tumor apoptosis. A trial (NCT03969446) is currently underway to combine inhibitors from both groups.

3-Pyridinylidene Derivatives of Chemically Modified Lupane and Ursane Triterpenes as Promising Anticancer Agents by Targeting Apoptosis

Cancer persists as a global challenge due to the extent to which conventional anticancer therapies pose high risks counterbalanced with their therapeutic benefit. Naturally occurring substances stand as an important safer alternative source for anticancer drug development. In the current study, a series of modified lupane and ursane derivatives was subjected to in vitro screening on the NCI-60 cancer cell line panel. Compounds 6 and 7 have been identified as highly active with GI₅₀ values ranging from 0.03 µM to 5.9 µM (compound 6) and 0.18–1.53 µM (compound 7). Thus, these two compounds were further assessed in detail in order to identify a possible antiproliferative mechanism of action. DAPI (4′,6-diamidino-2-phenylindole) staining revealed that both compounds induced nuclei condensation and overall cell morphological changes consistent with apoptotic cell death. rtPCR analysis showed that both compounds induced upregulation of proapoptotic Bak and Bad genes while downregulating Bcl-XL and Bcl-2 antiapoptotic genes. Molecular docking analysis revealed that both compounds exhibited high scores for Bcl-XL inhibition, while compound 7 showed higher in silico Bcl-XL inhibition potential as compared to the native inhibitor ATB-737, suggesting that compounds may induce apoptotic cell death through targeted antiapoptotic protein inhibition, as well.

Zebrafish BID Exerts an Antibacterial Role by Negatively Regulating p53, but in a Caspase-8-Independent Manner

Bid (BH3-interacting domain death agonist), a member of the Bcl-2 family, plays a crucial role in the initiation of apoptosis. Independent of its apoptotic function, Bid is also involved in the regulation of inflammation and innate immunity. However, the role of Bid during bacterial pathogen infection remains unclear. In the present study, Bid of zebrafish (Dario rerio) was cloned and its functions during Edwardsiella ictaluri infection were investigated. Zebrafish Bid enhances the apoptosis rate of Epithelioma papulosum cyprini (EPC) cells following E. ictaluri infection. Importantly, in vitro and in vivo bacterial invasion assays showed that overexpressed Bid could significantly inhibit the invasion and proliferation of E. ictaluri. Real-time qPCR analysis revealed that p53 gene expression was downregulated in embryos microinjected with Bid-FLAG. Further, in vitro and in vivo bacterial invasion assays showed that overexpressed p53 increased the invasion and proliferation of E. ictaluri. Moreover, the invasion and proliferation of E. ictaluri were inhibited when co-overexpressing Bid and p53 in vivo and in vitro. Further, the numbers of E. ictaluri in larvae treated with Z-IETD-FMK (caspase-8 inhibitor) were higher than those of larvae without Z-IETD-FMK treatment, while the number of E. ictaluri in larvae microinjected with bid-Flag decreased significantly, even if the larvae were treated in advance with Z-IETD-FMK. Collectively, our study demonstrated a novel antibacterial activity of fish Bid, providing evidence for understanding the function of apoptosis associated gene in pathogen infection.

The role of apoptosis in cryopreserved animal oocytes and embryos

Cryopreservation of both gametes and embryos, both for storage and for the preservation of their developmental capacity is a critical aspect of assisted reproductive technology. The survival of reproductive material following cryopreservation protocols is not only vital to clinical applications in the human in vitro fertilisation clinic, but is also important in the in vitro production of livestock embryos. The ability to routinely cryopreserve oocytes and embryos of livestock species has the potential to improve animal welfare, reduce environmental impact, and reduce the associated costs for breeding companies through the reduction of live animal transportation. Unfortunately, frozen oocytes and embryos are regularly documented to contain a higher proportion of apoptotic cells compared to their non-frozen counterparts, with freezing procedures thought to trigger apoptotic pathways of cell death. Comparisons between frozen and non-frozen samples also show changes in the gene expression of apoptotic factors such as Bcl-2 and Bax in response to cryopreservation. Apoptotic inhibition has the potential to improve cryosurvival, and how to achieve this is subject to debate. Here, we review how exposure to low temperatures during cryopreservation may be responsible for the abnormal activation of apoptotic pathways in mammalian oocytes and embryos, and discuss the ways in which they can be influenced to improve cryopreservation protocols, particularly in agriculturally important species.

The Role of Bcl-xL Protein in Viral Infections

Bcl-xL represents a family of proteins responsible for the regulation of the intrinsic apoptosis pathway. Due to its anti-apoptotic activity, Bcl-xL co-determines the viability of various virally infected cells. Their survival may determine the effectiveness of viral replication and spread, dynamics of systemic infection, and viral pathogenesis. In this paper, we have reviewed the role of Bcl-xL in the context of host infection by eight different RNA and DNA viruses: hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), influenza A virus (IAV), Epstein-Barr virus (EBV), human T-lymphotropic virus type-1 (HTLV-1), Maraba virus (MRBV), Schmallenberg virus (SBV) and coronavirus (CoV). We have described an influence of viral infection on the intracellular level of Bcl-xL and discussed the impact of Bcl-xL-dependent cell survival control on infection-accompanying pathogenic events such as tissue damage or oncogenesis. We have also presented anti-viral treatment strategies based on the pharmacological regulation of Bcl-xL expression or activity.

Integrative in silico and in vitro transcriptomics analysis revealed new lncRNAs related to intrinsic apoptotic genes in colorectal cancer

Background

Pathogenesis of colorectal cancer (CRC) is connected to deregulation of apoptosis while the effect of lncRNAs, as critical regulatory molecules, on this pathway is not clear well. The present study aimed to identify differential expression of genes and their related lncRNAs which are significantly associated with intrinsic apoptotic pathway in CRC.

Methods

The connection between CRC and apoptosis was investigated by literature reviews and the genes were enriched by using Enrichr. At the next step, differential expression of enriched genes were evaluated between normal and tumor populations in data sets and were downloaded from GEO. Then, meta-analysis and probe re-annotation were performed. For lncRNAs selection through the highest expression correlation with each of candidate genes, mRNA-lncRNA interaction of screened genes and all of lncRNAs were visualized using Cytoscape. Identified differential expression genes and lncRNAs were validated using TCGA-COAD and the obtained data were confirmed by in vitro studies in the presence of Ag@Glu-TSC nanoparticle as an apoptotic inducer. Cytotoxicity and apoptosis induction effect of Ag@Glu-TSC on Caco-2 cells was determined via MTT and Annexin V/PI, respectively. The expression of genes and lncRNAs were assayed in presence of mentioned nanoparticle. Finally, the expression level of desired genes and lncRNAs were proven in CRC tissues compared to adjacent normal tissues.

Results

After detection of 48 genes associated with intrinsic apoptosis in CRC according to literature, Enrichr screened 12 common genes involved in this pathway. Among them, 6 genes including BCL2, BCL2L11, BAD, CASP7, CASP9, and CYCS expression reduced in tumor tissue compared to normal according to meta-analysis studies and RNA-seq TCGA data. Afterwards, association of 8 lncRNAs comprising CDKN2B-AS1, LOC102724156, HAGLR, ABCC13, LOC101929340, LINC00675, FAM120AOS, PDCD4-AS1 with more than 5 candidate genes were identified. In vitro studies revealed that four selected lncRNAs including, CDKN2B-AS1, LOC102724156, HAGLR and FAM120AOS were significantly increased in the presence of in optimum concentration of Ag@Glu/TSC and decreased in tumor tissues versus adjacent normal tissues.

Conclusion

This study developed a new data mining method to screen differentially expressed lncRNAs which are involved in regulation of intrinsic apoptosis pathway in CRC quickly using published gene expression profiling microarrays. Moreover, we could validate a number of these regulators in the cellular and laboratory disease models.

Regulation of Cell Death by Mitochondrial Transport Systems of Calcium and Bcl-2 Proteins

Mitochondria represent the fundamental system for cellular energy metabolism, by not only supplying energy in the form of ATP, but also by affecting physiology and cell death via the regulation of calcium homeostasis and the activity of Bcl-2 proteins. A lot of research has recently been devoted to understanding the interplay between Bcl-2 proteins, the regulation of these interactions within the cell, and how these interactions lead to the changes in calcium homeostasis. However, the role of Bcl-2 proteins in the mediation of mitochondrial calcium homeostasis, and therefore the induction of cell death pathways, remain underestimated and are still not well understood. In this review, we first summarize our knowledge about calcium transport systems in mitochondria, which, when miss-regulated, can induce necrosis. We continue by reviewing and analyzing the functions of Bcl-2 proteins in apoptosis. Finally, we link these two regulatory mechanisms together, exploring the interactions between the mitochondrial Ca2+ transport systems and Bcl-2 proteins, both capable of inducing cell death, with the potential to determine the cell death pathway-either the apoptotic or the necrotic one.

The Regulatory Role of Mitochondrial MicroRNAs (MitomiRs) in Breast Cancer: Translational Implications Present and Future

Simple Summary

Mitochondrial microRNAs (mitomiRs) are an emerging field of study in a wide range of tumours including breast cancer. By targeting mitochondrial, or non-mitochondrial products, mitomiRs are able to regulate the functions of this organelle, thus controlling multiple carcinogenic processes. The knowledge of this system may provide a novel approach for targeted therapies, as potential biomarkers or helping in the diagnosis of such a complex malignancy.

Abstract

Breast cancer is the most prevalent and incident female neoplasm worldwide. Although survival rates have considerably improved, it is still the leading cause of cancer-related mortality in women. MicroRNAs are small non-coding RNA molecules that regulate the posttranscriptional expression of a wide variety of genes. Although it is usually located in the cytoplasm, several studies have detected a regulatory role of microRNAs in other cell compartments such as the nucleus or mitochondrion, known as “mitomiRs”. MitomiRs are essential modulators of mitochondrion tasks and their abnormal expression has been linked to the aetiology of several human diseases related to mitochondrial dysfunction, including breast cancer. This review aims to examine basic knowledge of the role of mitomiRs in breast cancer and discusses their prospects as biomarkers or therapeutic targets.