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Severe Congenital Neutropenia
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
The HAX1 (HCLS1 associated protein X-1) gene on chromosome 1q21.3 measures 3.3 kb in length, and encodes a 279 aa, 31 kDa protein (HAX1), which is an adaptor protein of the G-CSFR signaling pathway. Through interaction with hematopoietic cell-specific Lyn substrate 1 (a substrate of Src family tyrosine kinases), HAX1 participates in the clathrin-mediated endocytosis pathway, promotes GNA13-mediated cell migration, and regulates the cortical actin cytoskeleton via its interaction with KCNC3 and Arp2/3 complex.
Mucosal interactions with enteropathogenic bacteria
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Nadine Cerf-Bensussan, Pamela Schnupf, Valérie Gaboriau-Routhiau, Philippe J. Sansonetti
Finally, following their internalization, intracellular pathogens such as Listeria and Shigella can escape from the phagocytic vacuole, replicate in the cytosol, and use actin polymerization as the force to propel the bacterium within the cytosol. When bacteria reach the plasma membrane, they form protrusions into neighboring cells, which lead to secondary vacuoles, whereby the bacterium is surrounded by a double plasma membrane. These vacuoles can be lysed and the cycle repeated, allowing cell-to-cell spread and tissue dissemination. Listeria uses a pore-forming toxin called listeriolysin O to escape from the vacuole; its surface protein ActA can then bind and activate the Arp2/3 complex. Similarly, the effector IpaB permits Shigella to escape from the phagocytic vacuole. Shigella then expresses an outer membrane protein IcsA (also called VirG) that recruits N-WASP, which subsequently binds and activates the Arp2/3 complex.
Gateways of Pathogenic Bacterial Entry into Host Cells—Salmonella
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Balakrishnan Senthilkumar, Duraisamy Senbagam, Chidambaram Prahalathan, Kumarasamy Anbarasu
Besides all these well-documented entry mechanisms, some other unidentified and unfamiliar factors seems to be involved during cell invasion. Rosselin et al. (2011) demonstrated that Salmonella serovars that were not expressing the effectors like Rck, PagN, and T3SS-1 have the ability to invade different host cells by unknown mechanism. This unknown entry mechanism depends on the cell type and cell line. For example, 3T3 fibroblasts and MA104 kidney epithelial cells are most accommodating to these mechanisms to enter independently of T3SS-1, PagN, and Rck. But nonpolarized HT29 enterocytes are not prone to these unknown entry mechanisms. They stated that cytoskeletal and membrane rearrangements similar to zipper or trigger machinery system have been observed during microscopic examination of infected cell types. These factors are found to be involved in inducing the signaling cascade that mediate the Salmonella entry into human foreskin fibroblasts (Aiastui et al. 2010). Steffen et al. (2004) and Hanisch et al. (2012) described a new invasion pathway that could be independent of Arp2/3 complex, and it depends on the formation of myosin II-rich stress fiber-like structures at entry sites via the activation of RhoA/Rho kinase signaling pathway.
Dual role of ARPC1B in regulating the network between tumor-associated macrophages and tumor cells in glioblastoma
Published in OncoImmunology, 2022
Tianqi Liu, Chen Zhu, Xin Chen, Jianqi Wu, Gefei Guan, Cunyi Zou, Shuai Shen, Ling Chen, Peng Cheng, Wen Cheng, Anhua Wu
Accordingly, the aim of this study was to identify key genes associated with TAMs in GBM that are linked to tumor progression, as well as to explore the underlying mechanism. In this study, we reveal ARPC1B (actin-related protein 2/3 complex subunit 1B) as a novel regulator for GBM-TAM regulation. Actin-related protein 2/3 complex (Arp2/3) is an evolutionary conserved molecular machine that generates branched actin networks.8 Over the years, dysregulation of the Arp2/3 regulatory system in cancer has been described that excessive activation of the Arp2/3 complex commonly promotes tumor progression.9–11 ARPC1B is one of the regulatory subunits of Arp2/3 complex, which facilitates assembly and maintenance of the whole complex.12 Mutations in the ARPC1B gene have been found to result in autosomal recessive syndrome of combined immune deficiency, impaired T-cell migration and proliferation and thrombocytopenia.13–15 Meanwhile, ARPC1B is correlated with malignant phenotypes of tumors such as melanoma, osteosarcoma, and oral squamous cell carcinoma.16–18 Unfortunately, there is no comprehensive report on ARPC1B in GBM. Toward this end, we set out to describe ARPC1B function in GBM-TAM regulating network. We further evaluated the impacts and mechanism in vitro using glioma cell lines and in vivo using orthotopic/subcutaneous GBM mouse models. These findings can provide new insight into GBM progression and provide a possible therapeutic target.
Dual role of E-cadherin in cancer cells
Published in Tissue Barriers, 2022
Svetlana N. Rubtsova, Irina Y. Zhitnyak, Natalya A. Gloushankova
Actin filaments nucleate at AJs,27 but the mechanisms of actin filament polymerization at AJs are not well understood. It has been suggested that the Arp2/3 complex is involved in the nucleation of junctional actin filaments as it was shown that establishment of E-cadherin-based adhesion promotes recruitment of Arp2/3 to the AJs.28 Activators of the Arp2/3 complex, such as WAVE and N-WASP, have also been detected at epithelial AJs.22,29 Cortactin, which directly binds WAVE2 and Arp2/3 at ZA, may also regulate the junctional actin cytoskeleton.30 Formins promoting elongation of linear actin filaments may be involved in the assembly of actin filaments at AJs. It was demonstrated that RhoA effector Dia1 was essential for the formation and maintenance of linear AJs in MCF-7 cells.31 In MCF10A cells grown in Matrigel, the junctional actin assembly was mediated by Formin-like 2 downstream of Rac1.32
A porcine ligated loop model reveals new insight into the host immune response against Campylobacter jejuni
Published in Gut Microbes, 2020
Nicholas M Negretti, Yinyin Ye, Lais M Malavasi, Swechha M Pokharel, Steven Huynh, Susan Noh, Cassidy L Klima, Christopher R Gourley, Claude A Ragle, Santanu Bose, Torey Looft, Craig T Parker, Geremy Clair, Joshua N Adkins, Michael E Konkel
In addition to immune-related proteins, components of the Arp2/3 complex, which facilitate actin rearrangement, were increased in abundance in the C. jejuni-inoculated loops. One of the key requirements for C. jejuni invasion of epithelial cells is activating the actin rearrangement and adhesive machinery. While the specific cell-type producing these proteins is not known, it is known that C. jejuni relies on actin reorganization to invade epithelial cells.31 However, given the apparent abundance of neutrophil-related proteins, an increase in actin remodeling proteins could also be a result of neutrophil migration into the intestine. This influx of neutrophils, and their killing associated antimicrobial proteins, was observed at the 12 hour and 30 hour time points. Thus, we propose that neutrophils drive intestinal inflammation and the initiation of diarrhea in C. jejuni-infected individuals.