The VDAC1-based R-Tf-D-LP4 Peptide as a Potential Treatment for Diabetes Mellitus

Diabetes mellitus is a metabolic disorder approaching epidemic proportions. Non-alcoholic fatty liver disease (NAFLD) regularly coexists with metabolic disorders, including type 2 diabetes, obesity, and cardiovascular disease. Recently, we demonstrated that the voltage-dependent anion channel 1 (VDAC1) is involved in NAFLD. VDAC1 is an outer mitochondria membrane protein that serves as a mitochondrial gatekeeper, controlling metabolic and energy homeostasis, as well as crosstalk between the mitochondria and the rest of the cell. It is also involved in mitochondria-mediated apoptosis. Here, we demonstrate that the VDAC1-based peptide, R-Tf-D-LP4, affects several parameters of a NAFLD mouse model in which administration of streptozotocin (STZ) and high-fat diet 32 (STZ/HFD-32) led to both type 2 diabetes (T2D) and NAFLD phenotypes. We focused on diabetes, showing that R-Tf-D-LP4 peptide treatment of STZ/HFD-32 fed mice restored the elevated blood glucose back to close to normal levels, and increased the number and average size of islets and their insulin content as compared to untreated controls. Similar results were obtained when staining the islets for glucose transporter type 2. In addition, the R-Tf-D-LP4 peptide decreased the elevated glucose levels in a mouse displaying obese, diabetic, and metabolic symptoms due to a mutation in the obese (ob) gene. To explore the cause of the peptide-induced improvement in the endocrine pancreas phenotype, we analyzed the expression levels of the proliferation marker, Ki-67, and found it to be increased in the islets of STZ/HFD-32 fed mice treated with the R-Tf-D-LP4 peptide. Moreover, peptide treatment of STZ/HFD-32 fed mice caused an increase in the expression of β-cell maturation and differentiation PDX1 transcription factor that enhances the expression of the insulin-encoding gene, and is essential for islet development, function, proliferation, and maintenance of glucose homeostasis in the pancreas. This increase occurred mainly in the β-cells, suggesting that the source of their increased number after R-Tf-D-LP4 peptide treatment was most likely due to β-cell proliferation. These results suggest that the VDAC1-based R-Tf-D-LP4 peptide has potential as a treatment for diabetes.

Asgard ESCRT-III and VPS4 reveal conserved chromatin binding properties of the ESCRT machinery

The archaeal Asgard superphylum currently stands as the most promising prokaryotic candidate, from which eukaryotic cells emerged. This unique superphylum encodes for eukaryotic signature proteins (ESP) that could shed light on the origin of eukaryotes, but the properties and function of these proteins is largely unresolved. Here, we set to understand the function of an Asgard archaeal protein family, namely the ESCRT machinery, that is conserved across all domains of life and executes basic cellular eukaryotic functions, including membrane constriction during cell division. We find that ESCRT proteins encoded in Loki archaea, express in mammalian and yeast cells, and that the Loki ESCRT-III protein, CHMP4-7, resides in the eukaryotic nucleus in both organisms. Moreover, Loki ESCRT-III proteins associated with chromatin, recruited their AAA-ATPase VPS4 counterpart to organize in discrete foci in the mammalian nucleus, and directly bind DNA. The human ESCRT-III protein, CHMP1B, exhibited similar nuclear properties and recruited both human and Asgard VPS4s to nuclear foci, indicating interspecies interactions. Mutation analysis revealed a role for the N terminal region of ESCRT-III in mediating these phenotypes in both human and Asgard ESCRTs. These findings suggest that ESCRT proteins hold chromatin binding properties that were highly preserved through the billion years of evolution separating Asgard archaea and humans. The conserved chromatin binding properties of the ESCRT membrane remodeling machinery, reported here, may have important implications for the origin of eukaryogenesis.

The Asgard archaeal ESCRT-III system forms helical filaments and remodels eukaryotic-like membranes

The ESCRT machinery mediates membrane remodeling in numerous processes in cells including cell division and nuclear membrane reformation. The identification of ESCRT homologs in Asgard archaea, currently considered the closest prokaryotic relative of eukaryotes, implies a role for ESCRTs in the membrane remodeling processes that occurred during eukaryogenesis. Yet, the function of these distant ESCRT homologs is mostly unresolved. Here we show that Asgard ESCRT-III proteins of the Lokiarcheota self-assemble into helical filaments, a hallmark of the ESCRT system. We determined the cryo-EM structure of the filaments at 3.6 Å resolution and found that they share features of bacterial and eukaryotic ESCRT-III assemblies. Markedly, Asgard ESCRT-III filaments bound and deformed eukaryotic-like membrane vesicles. Oligonucleotides facilitated the assembly of ESCRT-III filaments and tuned the extent of membrane remodeling. The ability of Asgard archaeal ESCRTs to remodel eukaryotic-like membranes, which are fundamentally different from archaeal membranes, and the structural properties of these proteins places them at the junction between prokaryotes and eukaryotes.

[Phenotyping of angiotensin-converting enzyme in the prostate in patients with prostate cancer and benign prostatic hyperplasia]

BACKGROUND

Angiotensin-converting enzyme (ACE) is expressed by all epithelial cells of the human body. Although the main proportion of ACE is synthesized by the lungs, in men, ACE is also secreted by the testes (testicular form), seminal vesicles and the prostate. In semen, the level of ACE is up to 50 times higher than in blood plasma. The substitution of highly specific epithelial cells of the prostate by tumor cells causes a dramatic decrease in ACE production by the prostate cells.

AIM

To assess the possibility of using prostatic ACE as a new marker of prostate cancer (PCa).

MATERIALS AND METHODS

ACE phenotyping in prostate of patients with PCa and benign prostatic hyperplasia (BPH) included measurement of the activity of two ACE substrates (HHL and ZPHL); calculation of the ratio of their hydrolysis rates (ZPHL/HHL ratio); quantitative assessment of the ACE immunoreactive protein, the ratio of the immunoreactive protein to the ACE activity, as well as the conformation of ACE using a panel of monoclonal antibodies (mAb) to different epitopes of ACE.

RESULTS

ACE activity in tumor cells was markedly reduced and the ratio of immunoreactive ACE to its activity increased. The ratio of the hydrolysis rates of two substrates (ZPHL/HHL ratio) in patients with PCa increased compared to control group, while it was not observed in the vast majority of patients with BPH. There were several tissue samples with a histological diagnosis of BPH, but ACE phenotype was typical for PCa.

DISCUSSION

Since a decrease in ACE activity was found in all patients with PCa, we suggest that it may serve as a reliable and early marker of the tumor development. Changes in the ACE phenotype, which are typical for PCa, but found in patients with BPH, may indicate earlier malignant changes in prostate cells, which are not visible on routine prostate biopsy.

CONCLUSIONS

ACE activity and its conformation in prostatic biopsies has the potential to be an early biomarker or a differential criterion for PCa. In PCa, the ACE activity in the prostate is significantly reduced, and the ZPHL/HHL ratio is markedly increased in comparison to control group. However, there were no such changes in patients with BPH. In hyperplastic processes of the prostate (BPH, PCa), there is a change in ACE sialylation, which is accompanied by an increase in the binding of ACE to mAb 3F10 compared to the control group. Patients with negative biopsy result, but properties of prostate ACE, which are typical for PCa, require close follow-up, since they may have an increased risk of subsequent developing PCa. However, due to a small sample of patients, the diagnostic potential of prostate ACE for PCa and BPH requires to be validated in a larger number of patients to confirm its predictive accuracy.

Correction: Pittala et al. The VDAC1-based R-Tf-D-LP4 Peptide as a Potential Treatment for Diabetes Mellitus. Cells 2020, 9, 481

In the original publication [...].

Mitochondrial VDAC1 Silencing in Urethane-Induced Lung Cancer Inhibits Tumor Growth and Alters Cancer Oncogenic Properties

Alterations in cellular metabolism are vital for cancer cell growth and motility. Here, we focused on metabolic reprogramming and changes in tumor hallmarks in lung cancer by silencing the expression of the mitochondrial gatekeeper VDAC1. To better mimic the clinical situation of lung cancer, we induced lung cancer in A/J mice using the carcinogen urethane and examined the effectiveness of si-m/hVDAC1-B encapsulated in PLGA-PEI nanoparticles. si-m/hVDAC1-B, given intravenously, induced metabolism reprogramming and inhibited tumor growth as monitored using MRI. Mice treated with non-targeted (NT) PLGA-PEI-si-NT showed many large size tumors in the lungs, while in PLGA-PEI-si-m/hVDAC-B-treated mice, lung tumor number and area were markedly decreased. Immunofluorescence staining showed decreased expression of VDAC1 and metabolism-related proteins and altered expression of cancer stem cell markers. Morphological analysis showed two types of tumors differing in their morphology; cell size and organization within the tumor. Based on specific markers, the two tumor types were identified as small cell (SCLC) and non-small cell (NSCLC) lung cancer. These two types of tumors were found only in control tumors, suggesting that PLGA-PEI-si-m/hVDAC1-B also targeted SCLC. Indeed, using a xenograft mouse model of human-derived SCLC H69 cells, si-m/hVDAC1-B inhibited tumor growth and reduced the expression of VDAC1 and energy- and metabolism-related enzymes, and of cancer stem cells in the established xenograft. Additionally, intravenous treatment of urethane-induced lung cancer mice with the VDAC1-based peptide, Retro-Tf-D-LP4, showed inhibition of tumor growth, and decreased expression levels of metabolism- and cancer stem cells-related proteins. Thus, silencing VDAC1 targeting both NSCLC and SCLC points to si-VDAC1 as a possible therapeutic tool to treat these lung cancer types. This is important as target NSCLC tumors undergo transformation to SCLC.