Biology subjects

Margariti, A.

Publications and source records attributed to Margariti, A..

4 recordsLinked to original sources

bioRxiv2023

A novel nested gene Aff3ir participates in vascular remodelling by enhancing endothelial cell differentiation in mice

Endothelial integrity in the vasculature is critically maintained by vascular stem/progenitor cells (SPCs) giving rise to endothelial cells (ECs). However, the genes significantly activated during differentiation remain incompletely understood. Based on mouse aorta and vein cDNA library, we unearthed a hitherto unidentified gene nested residing within intron 6 of Aff3, christened as Aff3 intron resident (Aff3ir), upregulated during laminar shear stress-induced ECs differentiation in mouse. Proteomic analysis substantiated the presence of a 45-amino acid(aa) peptide (AFF3IR-ORF1) and 109-aa or 151-aa protein (AFF3IR-ORF2) encoded from two transcript variants. During embryonic development, AFF3IR-ORF1 peaked at E14.5, while AFF3IR-ORF2 displayed a continuous increase until E19.5. In adult mice, AFF3IR-ORF1 was detected in the lung, liver, spleen, and kidney, while AFF3IR-ORF2 was most abundant in the aorta. Furthermore, Western blot and immunofluorescence analyses revealed a specific upregulation of AFF3IR-ORF2, but not AFF3IR-ORF1, three days after femoral artery injury or hindlimb ischemia in vivo. Overexpression of AFF3IR-ORF2 enhanced, while its knockdown attenuated, SPCs differentiation into ECs induced by shear stress or vascular endothelial growth factor in vitro. Notably, the upregulated AFF3IR-ORF2 hindered SPCs proliferation by sequestering minichromosome maintenance complex component 3 in the cytoplasm, thereby shifting the status of SPCs from a pro-proliferation to a pro-differentiation state. In conclusion, our discoveries unveil the novel protein-coding gene Aff3ir as a participant in ECs differentiation, providing fresh insights into the regulation of vascular endothelial integrity.

cell biology↗

bioRxiv2023

The translation of a short open reading frame product within the human TUBA1B gene regulates cancer cell proliferation by importin-β

Understanding cancer biology is crucial for improving treatment strategies. This study identified TUBA1B-sORF1, a short open reading frame product alternatively translated from the human -tubulin gene (TUBA1B), which has a completely different amino acid sequence from the -tubulin 1B chain. TUBA1B-sORF1 is highly expressed in cancer cell lines and gastric carcinoma. Both methionine-initiated canonical and leucine-initiated noncanonical translations of TUBA1B-sORF1 coexist in cancer cells, and there is a transition between sORF1 and -tubulin translations, evidenced by the TUBA1B-sORF1/-tubulinlow/- subpopulation. Knocking down TUBA1B-sORF1 reduces cancer cell proliferation and tumorigenicity. TUBA1B-sORF1 facilitates protein nuclear translocation, leading to the upregulation of proliferation-promoting genes and downregulation of proliferation-inhibiting genes. Specifically, it forms a complex with importin {beta} and {beta}-catenin, promoting {beta}-catenin nuclear translocation and target gene transcription. These findings reveal that TUBA1B is a polycistronic gene translating at least two entirely different proteins: -tubulin and TUBA1B-sORF1. The variable translation between them may regulate tumorigenesis, making TUBA1B-sORF1 a promising therapeutic target and diagnostic biomarker for cancer treatment.

cancer biology↗

bioRxiv2022

Human blood vessel organoids reveal a critical role for CTGF in maintaining microvascular integrity

The microvasculature plays a key role in tissue perfusion, transport of mediators, and exchange of gases and metabolites to and from tissues. Microvascular dysfunction has emerged as an important contributor to cardiovascular diseases. In this study we used human blood vessel organoids (BVOs) as a model of the microvasculature to delineate the mechanisms of microvascular dysfunction caused by metabolic rewiring. BVOs fully recapitulated key features of the normal human microvasculature, including reliance of mature endothelial cells (ECs) on glycolytic metabolism, as concluded from metabolic flux assays using 13C-glucose labelling and mass spectrometry-based metabolomics. Treatment of BVOs with PFK15, a pharmacological inhibitor of glycolysis, resulted in rapid tissue restructuring, vessel regression with reduced pericyte coverage and alterations in tight junction morphology. Proteomic analysis of the BVO secretome revealed remodelling of the extracellular matrix and differential expression of paracrine mediators such as CTGF. Treatment with recombinant CTGF recovered tight junction formation and increased pericyte coverage in microvessels. Our metabolic and proteomics findings demonstrate that BVOs rapidly undergo restructuring in response to metabolic changes and identify CTGF as a critical paracrine regulator of microvascular integrity.

cell biology↗

bioRxiv2022

Impaired Function in Diabetic Patient iPSCs-derived Blood Vessel Organoids Stem from a Subpopulation of Vascular Cells

The presence of both endothelial cells (ECs) and mural cells are central to the proper function of blood vessels in health and pathological changes in diseases including diabetes. Although iPSCs-derived vascular organoids (VOs) provide an appealing in vitro disease model and platform for drug screening, whether these organoids recapitulate human disease remains debatable. Here, we show human diabetic (DB)-VOs represent impaired vascular function including enhanced ROS activity, with higher mitochondrial content and activity, increased pro-inflammatory cytokines, and less regenerative potential in vivo. Using single-cell RNA sequencing, we identify all specialized types of vascular cells (artery, capillary, vein, lymphatic and tip cells, as well as pericytes and vSMCs) within vascular organoids, while demonstrating the dichotomy landscape of ECs and mural cells. Furthermore, we reveal basal heterogeneity within vascular organoids and demonstrate differences between diabetic and non-diabetic VOs. Of note, a subpopulation of ECs significantly enrich for ROS and oxidative phosphorylation hallmarks in DB-VOs, may represent early signs of aberrant angiogenesis in diabetes. This study helps to identify key biomarkers for diabetic disease progression and find signalling molecules amenable to drug intervention.

cell biology↗