Biology subjects

Azar, S.

Publications and source records attributed to Azar, S..

3 recordsLinked to original sources

bioRxiv2024

Clearing method adapted to FFPE tissues for 3D imaging of nerve fibers, B cells, and tertiary lymphoid structures

Biomedical samples are commonly used for histological examination after their inclusion in paraffin (Formalin-Fixed Paraffin-Embedded (FFPE) biopsy). However, they provide minimal information about the interactions between different tissue components such as blood vessels, nerves, and cellular aggregates. Here we present a modified iDISCO tissue-clearing method that we term miDISCO+. miDISCO+ can be used for analyzing FFPE samples, requires the use of only one single FFPE sample, and allows to acquire a detailed image of the 3D tissue/organ architecture and the relevant cellular interactions. The addition of an antigen retrieval step to the protocol enables to use antibodies whose binding is sensitive to formalin fixation due to antigen masking. This method enabled us to detect CD20+ B cell follicles and to show that they are in close contact with TH+ sympathetic nerve fibers in FFPE biopsies of human palatine tonsils, and to detect CD20+ B cells in lung tumors and observe their 3D organization within tertiary lymphoid structures. Thus, miDISCO+ could be a potent tool for clinicians to refine diagnosis and to select optimal personalized treatment by giving an integrated 3D view of the tissue structures and cellular interactions in single FFPE samples.

immunology↗

bioRxiv2021

Identification of CRYAB+ KCNN3+ SOX9+ astro-like and EGFR+ PDGFRA+ OLIG1+ oligo-like tumoral cells in diffuse low-grade gliomas and implication of Notch1 signalling in their genesis

IDH1-mutated gliomas are slow growing brain tumours, which progress into high-grade gliomas. They present intra-tumoural cell heterogeneity, but no good markers are available to distinguish the different cell subtypes. The molecular mechanisms underlying the formation of this cell diversity is also ill defined. Here we report that the SOX9 and OLIG1 transcription factors, which specifically label astrocytes and oligodendrocytes in the normal brain, reveal the presence of two largely non-overlapping tumoural populations in IDH1-mutated oligodendrogliomas and astrocytomas. Astro-like SOX9+ cells additionally stain for APOE, CRYAB, ID4, KCNN3, while oligo-like OLIG1+ cells stain for ASCL1, EGFR, IDH1, PDGFRA, PTPRZ1, SOX4, and SOX8. GPR17, an oligodendrocytic marker, was expressed by both cells. These two sub-populations appear to have distinct BMP, NOTCH1, and MAPK active pathways as stainings for BMP4, HEY1, HEY2, p-SMAD1/5 and p-ERK were higher in SOX9+ cells. We used primary cultures and a new cell line to explore the influence of NOTCH1 activation and BMP treatment on low-grade glioma cell phenotype. This revealed that NOTCH1 globally reduced oligodendrocytic markers and IDH1 expression while upregulating APOE, CRYAB, HEY1/2 and an electrophysiologically Ca2+-activated apamin-sensitive K+ channel (KCNN3/SK3). This was accompanied by reduction in proliferation. Similar effects of NOTCH1 activation were observed in non-tumoural human oligodendrocytic cells, which additionally induced strong SOX9 expression. BMP treatment reduced OLIG1/2 expression and strongly upregulated CRYAB and NOGGIN, a negative regulator of BMP. The presence of astro-like SOX9+ and oligo-like OLIG1+ cells in diffuse low-grade gliomas raise new questions about their role in the pathology.

cancer biology↗

bioRxiv2020

CB1R Regulates Soluble Leptin Receptor Levels via CHOP, Contributing to Hepatic Leptin Resistance

The soluble isoform of leptin receptor (sOb-R), secreted by the liver, regulates leptin bioavailability and bioactivity. Its reduced levels in diet-induced obesity (DIO) contributes to hyperleptinemia and leptin resistance, effects that are known to be regulated by the endocannabinoid (eCB)/CB1R system. Here we show that pharmacological activation/blockade as well as genetic overexpression/deletion of hepatic CB1R modulates sOb-R levels and consequently hepatic leptin resistance. Interestingly, peripheral CB1R blockade failed to reverse DIO-induced reduction of sOb-R levels, fat mass, dyslipidemia, and hepatic steatosis in mice lacking C/EBP homologous protein (CHOP), whereas direct activation of CB1R in hepatocytes reduced sOb-R levels in a CHOP-dependent manner. Moreover, CHOP stimulation increased sOb-R expression and release via a direct regulation of its promoter, while CHOP deletion reduced leptin sensitivity. Our findings highlight a novel molecular aspect by which the hepatic eCB/CB1R system involves in the development of hepatic leptin resistance by regulating sOb-R levels via CHOP. SummaryHere we describe a novel molecular aspect by which the hepatic endocannabinoid/CB1R system contributes to hepatic leptin resistance by regulating soluble leptin receptor levels via CHOP.

molecular biology↗