Rina Rosin-Arbesfeld

Dysbiosis of the gut microbiota is strongly associated with a wide range of pathologies, including various types of cancer. Porphyromonas gingivalis (P. gingivalis), an oral bacterium, is implicated in the development of colorectal cancer (CRC), and although the exact mechanisms by which P. gingivalis contributes to CRC remain unclear, and emerging evidence suggests that various bacterial elements are involved in the bacterium's pathogenic effects. Here, we show that P. gingivalis secreted factors promote CRC neoplasia progression by modulating both the Wnt/β-catenin and the Hippo-YAP signaling pathways. Using specific inhibitors and P. gingivalis mutant strains, our findings demonstrate that cysteine proteases, specifically Lysin-gingipain (Kgp) and Argin-gingipain A (RgpA), as well as hydrogen sulfide (H₂S), strongly induce the expression of epithelial-mesenchymal transition (EMT) markers, leading to cell detachment and increased motility. These findings reveal a novel connection between microbial virulence and defense mechanisms, such as H₂S, and host cell transformation, suggesting a potential role for bacterial secreted factors in driving CRC neoplasia.

Wnt signaling is one of the cell’s most complex and important signal transduction pathways. This pathway, which is divided into additional sub-pathways, regulates cell growth, motility, polarity, and differentiation during embryonic development as well as stem cell regeneration. In addition, the Wnt cascades are involved in maintaining different aspects of adult homeostasis. The Wnt ligands, which normally initiate this cascade, are secreted glycoproteins that bind specific receptors and co-receptors to execute their intracellular signaling activity. The Wnt pathways have been extensively studied in anchored cells and in tissues. However, recent evidence now shows that the Wnt cascades are functional in the circulation and that these important signals can affect different circulating blood cells by traveling through the bloodstream. Wnt signaling can function in both paracrine and autocrine manner; however, in the current review, we will discuss the exocrine properties of the pathway and address the following topics: the source of Wnt ligands and their ability to travel in the bloodstream; which cell populations express Wnt signaling components; and finally, what are the physiological roles of the Wnt cascade in the different circulating blood cells.

The striatin family proteins, striatin, SG2NA, and zinedin, belong to the calmodulin-binding WD-40 repeat protein group and are components of the striatin interacting phosphatase and kinase (STRIPAK) complex. These proteins are known for their roles as scaffold proteins, facilitating various cellular pathways, and regulating cell–cell interactions and signaling mechanisms. The observation that Striatin is expressed in cell junctions, suggests a potential role in maintaining cell integrity and communication. Here, we used shRNA technology to examine the biological significance of the striatin family proteins. This approach allowed us to modulate their expression levels and observe the effects on cellular processes. Our results suggest that the striatin family members affect the Hippo signaling pathway by protecting phosphorylated YAP (pYAP) from proteasomal degradation, thus decreasing the expression of Hippo target genes. This regulation impacts key cellular processes, such as cell migration and proliferation. RNA sequencing analyses of keratinocytes and fibroblasts depleted of striatin proteins enabled the identification of novel gene sets affected by the modulation of striatin expression and provided insights into the broader impact of striatin proteins and their roles in various cellular pathways.

The β-catenin dependent canonical Wnt signaling pathway plays a crucial role in maintaining normal homeostasis. However, when dysregulated, Wnt signaling is closely associated with various pathological conditions, including inflammation and different types of cancer.Here, we show a new connection between the leukocyte inflammatory response and the Wnt signaling pathway. Specifically, we demonstrate that circulating human primary monocytes express distinct Wnt signaling components and are susceptible to stimulation by the classical Wnt ligand—Wnt-3a. Although this stimulation increased the levels of β-catenin protein, the expression of the classical Wnt-target genes was not affected. Intriguingly, treating circulating human monocytes with Wnt-3a induces the secretion of cytokines and chemokines, enhancing monocyte migration. Mechanistically, the enhanced monocyte migration in response to Wnt stimuli is mediated through CCL2, a strong monocyte-chemoattractant.To further explore the physiological relevance of these findings, we conducted ex-vivo experiments using blood samples of patients with rheumatic joint diseases (RJD) – conditions where monocytes are known to be dysfunctional. Wnt-3a generated a unique cytokine expression profile, which was significantly distinct from that observed in monocytes obtained from healthy donors.Thus, our results provide the first evidence that Wnt-3a may serve as a potent stimulator of monocyte-driven immune processes. These findings contribute to our understanding of inflammatory diseases and, more importantly, shed light on the role of a core signaling pathway in the circulation.

Rett syndrome (RTT) is a neurodevelopmental disorder resulting from genetic mutations in the methyl CpG binding protein 2 (MeCP2) gene. Specifically, around 35% of RTT patients harbor premature termination codons (PTCs) within the MeCP2 gene due to nonsense mutations. A promising therapeutic avenue for these individuals involves the use of aminoglycosides, which stimulate translational readthrough (TR) by causing stop codons to be interpreted as sense codons. However, the effectiveness of this treatment depends on several factors, including the type of stop codon and the surrounding nucleotides, collectively referred to as the stop codon context (SCC). Here, we develop a high-content reporter system to precisely measure TR efficiency at different SCCs, assess the recovery of the full-length MeCP2 protein, and evaluate its subcellular localization. We have conducted a comprehensive investigation into the intricate relationship between SCC characteristics and TR induction, examining a total of 14 pathogenic MeCP2 nonsense mutations with the aim to advance the prospects of personalized therapy for individuals with RTT. Our results demonstrate that TR induction can successfully restore full-length MeCP2 protein, albeit to varying degrees, contingent upon the SCC and the specific position of the PTC within the MeCP2 mRNA. TR induction can lead to the re-establishment of nuclear localization of MeCP2, indicating the potential restoration of protein functionality. In summary, our findings underscore the significance of SCC-specific approaches in the development of tailored therapies for RTT. By unraveling the relationship between SCC and TR therapy, we pave the way for personalized, individualized treatment strategies that hold promise for improving the lives of individuals affected by this debilitating neurodevelopmental disorder. Key messages: The efficiency of readthrough induction at MeCP2 premature termination codons strongly depends on the stop codon context. The position of the premature termination codon on the transcript influences the readthrough inducibility. A new high-content dual reporter assay facilitates the measurement and prediction of readthrough efficiency of specific nucleotide stop contexts. Readthrough induction results in the recovery of full-length MeCP2 and its re-localization to the nucleus. MeCP2 requires only one of its annotated nuclear localization signals.

The introduction of premature termination codons (PTCs), as a result of splicing defects, insertions, deletions, or point mutations (also termed nonsense mutations), lead to numerous genetic diseases, ranging from rare neuro-metabolic disorders to relatively common inheritable cancer syndromes and muscular dystrophies. Over the years, a large number of studies have demonstrated that certain antibiotics and other synthetic molecules can act as PTC suppressors by inducing readthrough of nonsense mutations, thereby restoring the expression of full-length proteins. Unfortunately, most PTC readthrough-inducing agents are toxic, have limited effects, and cannot be used for therapeutic purposes. Thus, further efforts are required to improve the clinical outcome of nonsense mutation suppressors. Here, by focusing on enhancing readthrough of pathogenic nonsense mutations in the adenomatous polyposis coli (APC) tumor suppressor gene, we show that disturbing the protein translation initiation complex, as well as targeting other stages of the protein translation machinery, enhances both antibiotic and non-antibiotic-mediated readthrough of nonsense mutations. These findings strongly increase our understanding of the mechanisms involved in nonsense mutation readthrough and facilitate the development of novel therapeutic targets for nonsense suppression to restore protein expression from a large variety of disease-causing mutated transcripts.

Several studies have demonstrated that curcumin can cause the regression of polyps in familial adenomatous polyposis (FAP), while others have shown negative results. Wholistic turmeric (WT) containing curcumin and additional bioactive compounds may contribute to this effect. We performed a double-blinded, randomized, controlled trial to assess the efficacy of WT in FAP patients. Ten FAP patients were randomly assigned to receive either WT or placebo for 6 months. Colonoscopies were performed at baseline and after 6 months. The polyp number and size, as well as the cumulative polyp burden, were assessed. No differences were noted between the groups in terms of changes from the baseline’s polyp number, size, or burden. However, stratifying the data according to the right vs. left colon indicated a decrease in the median polyp number (from 5.5 to 1.5, p = 0.06) and polyp burden (from 24.25 mm to 11.5 mm, p = 0.028) in the left colon of the patients in the WT group. The adjusted left polyp number and burden in the WT arm were lower by 5.39 (p = 0.034) and 14.68 mm (p = 0.059), respectively. Whether WT can be used to reduce the polyp burden of patients with predominantly left-sided polyps remains to be seen; thus, further larger prospective trials are required.

Coronavirus disease-19 (COVID-19) patients are prone to thrombotic complications that may increase morbidity and mortality. These complications are thought to be driven by endothelial activation and tissue damage promoted by the systemic hyperinflammation associated with COVID-19. However, the exact mechanisms contributing to these complications are still unknown. To identify additional mechanisms contributing to the aberrant clotting observed in COVID-19 patients, we analyzed platelets from COVID-19 patients compared to those from controls using mass spectrometry. We identified increased serum amyloid A (SAA) levels, an acute-phase protein, on COVID-19 patients’ platelets. In addition, using an in vitro adhesion assay, we showed that healthy platelets adhered more strongly to wells coated with COVID-19 patient serum than to wells coated with control serum. Furthermore, inhibitors of integrin aIIbβ3 receptors, a mediator of platelet–SAA binding, reduced platelet adhesion to recombinant SAA and to wells coated with COVID-19 patient serum. Our results suggest that SAA may contribute to the increased platelet adhesion observed in serum from COVID-19 patients. Thus, reducing SAA levels by decreasing inflammation or inhibiting SAA platelet-binding activity might be a valid approach to abrogate COVID-19-associated thrombotic complications.

A large number of human genetic diseases result from premature termination codons (PTCs) caused by splicing defects, insertions, deletions or point mutations also termed nonsense mutations. Nonsense mutations are the source of various genetic diseases, ranging from rare neuro-metabolic disorders to relatively common inheritable cancer syndromes and muscular dystrophies. Over the years, a wide spectrum of studies has shown that certain antibiotics and other synthetic molecules can act as nonsense mutation suppressors, by inducing readthrough of the stop-codon leading to the expression of a full-length protein. Unfortunately, most readthrough-inducing agents have limited effects and are toxic. Thus, efforts are made to improve the clinical outcome of nonsense mutation suppressors. Here we show that the mTOR pathway is involved in antibiotic-mediated readthrough of nonsense mutations at the level of protein translation initiation. We demonstrate that inhibition of the mTOR translation-initiation-controlling eIF4E branch induces antibiotic-mediated nonsense mutation readthrough, paving the way to the development of a novel therapeutic strategy for enhancing the restoration of these disease-causing mutated transcripts.

Transplantation of B cells engineered ex vivo to secrete broadly neutralizing antibodies (bNAbs) has shown efficacy in disease models. However, clinical translation of this approach would require specialized medical centers, technically demanding protocols and major histocompatibility complex compatibility of donor cells and recipients. Here we report in vivo B cell engineering using two adeno-associated viral vectors, with one coding for Staphylococcus aureus Cas9 (saCas9) and the other for 3BNC117, an anti-HIV bNAb. After intravenously injecting the vectors into mice, we observe successful editing of B cells leading to memory retention and bNAb secretion at neutralizing titers of up to 6.8 µg ml⁻¹. We observed minimal clustered regularly interspaced palindromic repeats (CRISPR)–Cas9 off-target cleavage as detected by unbiased CHANGE-sequencing analysis, whereas on-target cleavage in undesired tissues is reduced by expressing saCas9 from a B cell-specific promoter. In vivo B cell engineering to express therapeutic antibodies is a safe, potent and scalable method, which may be applicable not only to infectious diseases but also in the treatment of noncommunicable conditions, such as cancer and autoimmune disease.