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Biology subjects

Almog, R.

Publications and source records attributed to Almog, R..

3 recordsLinked to original sources

iPSCs-derived Bronchial Airways-On-Chip for Assessment of Cytokine Secretion triggered by Volatile Organic Compounds

Air quality monitoring currently relies mostly on a combination of epidemiological data and classic experimental data. Our objective was to design an alternative approach for assessing air pollutant risk potential using a specialized platform capable of detecting long-term and indirect effects of exposure via the inhaled route. We used a Bronchial Airways-On-Chip (BOC) offering some of the physiological complexity of the human lung based on our previously developed device coupled with in-vitro differentiated bronchial epithelium derived from induced Pluripotent Stem Cells (iPSCs). This setup is capable of replicating bronchial epithelia exposure to irritants at air-liquid interface, in controlled and reproducible conditions. It comprises the first proof-of-concept design combining a BOC with iPSCs-derived bronchial epithelium as an alternative approach towards potential risk assessmnet of inhaled pollutants. As a representative pollutant we use Benzene, a Volatile Organic Compound (VOC). At low concentrations and short-term exposure it is not considered acutely harmful, but long-term exposure can result in mutagenic and carcinogenic effects. As air pollutant toxicity is known to be mediated by the respiratory epithelial lining and secretion of cytokines, we demonstrate our system to be sufficiently sensitive to capture increased cytokine secretion corresponding to increasing concentrations of Benzene. Of utmost relevance is our finding that an accumulative effect could be detected, only caused by prolonged exposure at low concentrations of Benzene, previously shown to be non-toxic in classic short-term in-vitro studies. Finally, the accumulative effect could be reversed using a commonly-used asthma medication (Montelukast), further supporting the relevance of the setup.

bioengineering↗

RNF5 Regulation of RBBP4 Defines Acute Myeloid Leukemia Growth and Susceptibility to Histone Deacetylase Inhibitors

Acute myeloid leukemia (AML) remains incurable, largely due to its resistance to conventional treatments. Here, we found that increased expression and abundance of the ubiquitin ligase RNF5 contributes to AML development and survival. High RNF5 expression in AML patients correlated with poor prognosis. RNF5 inhibition decreased AML cell growth in culture and in vivo, and blocked development of MLL-AF9-driven leukemogenesis in mice, prolonging their survival. RNF5 inhibition led to transcriptional changes that overlapped with those seen upon HDAC1 inhibition. RNF5 induced the formation of K29 ubiquitin chains on the histone-binding protein RBBP4, promoting its recruitment and subsequent epigenetic regulation of genes involved in AML development and maintenance. Correspondingly, RNF5 or RBBP4 knockdown enhanced the sensitivity of AML cells to histone deacetylase (HDAC) inhibitors. Notably, low expression of RNF5 and HDAC coincided with a favorable prognosis. Our studies identified ERAD-independent role for RNF5, demonstrating that its control of RBBP4 constitutes an epigenetic pathway that drives AML while highlighting RNF5/RBBP4 as markers to stratify patients for treatment with HDAC inhibitors.

cancer biology↗

Regulation of HDAC2-PDX1 by RNF125 defines pancreatic cancer development

There is an urgent need to define mechanisms underlying pancreatic adenocarcinoma (PDA) development. Our studies of ubiquitin ligases that may underlie PDA development led us to identify and characterize RNF125. We show that RNF125 exhibits nuclear expression in acinar cells, with reduced and largely cytosolic expression in ductal cells, PanIN and PDA specimens. We find that RNF125 interacts with histone deacetylase 2 (HDAC2) and promotes its non-canonical K63-linked ubiquitination. Inhibition of HDAC2 activity by RNF125 resulted in elevated expression of the pancreatic and duodenal homeobox 1 (PDX1). Correspondingly, inhibition of RNF125 expression enhanced organoid growth in culture and orthotopic tumor development. Conversely, restoration of PDX1 levels in human or mouse PDA cells and organoids depleted of RNF125, inhibited cell proliferation and growth, while expression of HDAC2 enhanced it. Notably, higher expression of RNF125 and PDX1 coincided with differentiated tumor phenotypes, and better outcome in PDA patients. In demonstrating the importance of RNF125 control of PDX1 expression via HDAC2 ubiquitination in PDA development, our findings highlight markers (RNF125, PDX1) and targets (HDAC2) for monitoring and possible treatment of PDA.

cancer biology↗