Inhibition of Hedgehog Signaling Decreases Proliferation and Clonogenicity of Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSC) have the ability to differentiate into osteoblasts, adipocytes and chondrocytes. We have previously shown that hMSC were endowed with a basal level of Hedgehog signaling that decreased after differentiation of these cells. Since hMSC differentiation is associated with growth-arrest we investigated the function of Hh signaling on cell proliferation. Here, we show that inhibition of Hh signaling, using the classical inhibitor cyclopamine, or a siRNA directed against Gli-2, leads to a decrease in hMSC proliferation. This phenomenon is not linked to apoptosis but to a block of the cells in the G0/G1 phases of the cell cycle. At the molecular level, it is associated with an increase in the active form of pRB, and a decrease in cyclin A expression and MAP kinase phosphorylation. Inhibition of Hh signaling is also associated with a decrease in the ability of the cells to form clones. By contrast, inhibition of Hh signaling during hMSC proliferation does not affect their ability to differentiate. This study demonstrates that hMSC are endowed with a basal Hedgehog signaling activity that is necessary for efficient proliferation and clonogenicity of hMSC. This observation unravels an unexpected new function for Hedgehog signaling in the regulation of human mesenchymal stem cells and highlights the critical function of this morphogen in hMSC biology

SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.

There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection

Structure activity relationship and optimization of N-(3-(2-aminothiazol-4-yl)aryl)benzenesulfonamides as anti-cancer compounds against sensitive and resistant cells

International audienceWe recently described a new family of bioactive molecules with interesting anti-cancer activities: the N-(4-(3-aminophenyl)thiazol-2-yl)acetamides. The lead compound of the series (1) displays significant anti-proliferative and cytotoxic activities against a panel of cancer cell lines, either sensitive or resistant to standard treatments. This molecule also shows a good pharmacological profile and high in vivo potency towards mice xenografts, without signs of toxicity on the animals. In the present article, we disclose the structure-activity relationships of this lead compound, which have provided clear information about the replacement of the acetamide function and the substitution pattern of the benzenesulfonamide ring. An improved high-yielding synthetic procedure towards these compounds has also been developed. Our drug design resulted in potency enhancement of 1, our new optimized lead compound being 19. These findings are of great interest to further improve this scaffold for the development of future clinical candidates

Wnt Pathway in Pancreatic Development and Pathophysiology

The pancreas is an abdominal gland that serves 2 vital purposes: assist food processing by secreting digestive enzymes and regulate blood glucose levels by releasing endocrine hormones. During embryonic development, this gland originates from epithelial buds located on opposite sites of the foregut endoderm. Pancreatic cell specification and maturation are coordinated by a complex interplay of extrinsic and intrinsic signaling events. In the recent years, the canonical Wnt/β-catenin pathway has emerged as an important player of pancreas organogenesis, regulating pancreatic epithelium specification, compartmentalization and expansion. Importantly, it has been suggested to regulate proliferation, survival and function of adult pancreatic cells, including insulin-secreting β-cells. This review summarizes recent work on the role of Wnt/β-catenin signaling in pancreas biology from early development to adulthood, emphasizing on its relevance for the development of new therapies for pancreatic diseases

Discovery and Optimization of N-(4-(3-Aminophenyl)thiazol-2-yl)acetamide as a Novel Scaffold Active against Sensitive and Resistant Cancer Cells

International audienceCancer is the second cause of deaths worldwide and is forecasted to affect more that 22 million people in 2020. Despite dramatic improvement in its care over the last two decades, the treatment of resistant forms of cancer is still an unmet challenge. Thus, innovative and efficient treatments are still needed. In this context, we report herein the synthesis and the evaluation of a new class of bioactive molecules belonging to the N-(4-(3-aminophenyl(thiazol-2-yl)acetamide family. Structure–activity relationships could be driven and resulted in the discovery of lead compound 6b. The latter display high in vitro potency against both sensitive and resistant cancer cell lines on three models: melanoma, pancreatic cancer, and chronic myeloid leukemia (CML). 6b leads to cell death by concomitant induction of apoptosis and autophagy, shows good pharmacokinetic properties, and demonstrates a significant reduction of tumor growth in vivo on A375 xenograft model in mice

The MIR34B/C genomic region contains multiple potential regulators of multiciliogenesis

International audienceThe MIR449 genomic locus encompasses several regulators of multiciliated cell (MCC) formation (multiciliogenesis). The miR-449 homologs miR-34b/c represent additional regulators of multiciliogenesis that are transcribed from another locus. Here, we characterized the expression of BTG4, LAYN, and HOATZ, located in the MIR34B/C locus using single-cell RNA-seq and super-resolution microscopy from human, mouse, or pig multiciliogenesis models. BTG4, LAYN, and HOATZ transcripts were expressed in both precursors and mature MCCs. The Layilin/LAYN protein was absent from primary cilia, but it was expressed in apical membrane regions or throughout motile cilia. LAYN silencing altered apical actin cap formation and multiciliogenesis. HOATZ protein was detected in primary cilia or throughout motile cilia. Altogether, our data suggest that the MIR34B/C locus may gather potential actors of multiciliogenesis

Compounds Triggering ER Stress Exert Anti-Melanoma Effects and Overcome BRAF Inhibitor Resistance

International audienceWe have discovered and developed a series of molecules (thiazole benzenesulfonamides). HA15, the lead compound of this series, displayed anti-cancerous activity on all melanoma cells tested, including cells isolated from patients and cells that developed resistance to BRAF inhibitors. Our molecule displayed activity against other liquid and solid tumors. HA15 also exhibited strong efficacy in xenograft mouse models with melanoma cells either sensitive or resistant to BRAF inhibitors. Transcriptomic, proteomic, and biochemical studies identified the chaperone BiP/GRP78/HSPA5 as the specific target of HA15 and demonstrated that the interaction increases ER stress, leading to melanoma cell death by concomitant induction of autophagic and apoptotic mechanisms

SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.

There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection