Actomyosin contractility regulates various cell biological processes including cytokinesis, adhesion and migration. While in lower eukaryotes, a-kinases control actomyosin relaxation, a similar role for mammalian a-kinases has yet to be established. Here, we examined whether TRPM7, a cation channel fused to an a-kinase, can affect actomyosin function. We demonstrate that activation of TRPM7 by bradykinin leads to a Ca 2 þ -and kinase-dependent interaction with the actomyosin cytoskeleton. Moreover, TRPM7 phosphorylates the myosin IIA heavy chain. Accordingly, low overexpression of TRPM7 increases intracellular Ca 2 þ levels accompanied by cell spreading, adhesion and the formation of focal adhesions. Activation of TRPM7 induces the transformation of these focal adhesions into podosomes by a kinase-dependent mechanism, an effect that can be mimicked by pharmacological inhibition of myosin II. Collectively, our results demonstrate that regulation of cell adhesion by TRPM7 is the combined effect of kinase-dependent and -independent pathways on actomyosin contractility.
In 7 long-term survivors (LTS) and 8 progressors, all carrying solely non-syncytium-inducing variants, a possible correlation between in vitro virus replicative capacity, virus load, and clinical course of human immunodeficiency virus type 1 (HIV-1) infection was analyzed. Late in infection, 3 LTS and 7 progressors had a high virus load, which coincided with the presence of rapid-replicating viruses. In contrast to progressors, LTS maintained relatively high and stable CD4 T cell counts. Four LTS persistently had relatively slow-replicating viruses and a low virus load, even after 6.6-9 years of seropositive follow-up. All virus isolates from 1 of these LTS had a 4-aa deletion in nef. These results suggest a correlation between the in vitro replicative capacity of non-syncytium-inducing HIV-1 variants and virus load. The presence of HIV-1 variants with relatively low replicative capacity throughout infection may have contributed to the beneficial clinical course in half of the LTS in this study.
We studied the temporal relationship between human immunodeficiency type 1 (HIV-1) quasispecies in tissues and in peripheral blood mononuclear cells (PBMC) of infected individuals. Sequential PBMC and tissue samples from various organs obtained at autopsy from three patients who died of AIDS-related complications were available for analysis. Biological HIV-1 clones were isolated from PBMC samples, and cellular tropism and syncytium-inducing (SI) capacity were determined. Genomic DNA was isolated from 1 cm3 of organ tissue, and proviral DNA was amplified by means of PCR and cloned with the PGEM-T vector system. A 185-bp region encompassing the third variable domain of the virus envelope, known to influence HIV-1 biological properties, was sequenced. HIV-1 could be amplified from all PBMC and organ samples, except from liver tissue for two patients. Both SI and non-syncytium-inducing (NSI) genotypes could be detected in the different tissues. Tissue-specific quasispecies were observed in brain, lung, and testis. Lymphoid tissues, such as bone marrow, lymph node, and spleen, harbored several different variants similar to those detected in blood in the last PBMC samples. In general, only tissues in which macrophages are likely to be the main target cell for HIV-1 harbored NSI HIV-1 sequences that clustered separately. Both SI and NSI sequences that clustered with sequences from late-stage PBMC were present in other tissues, which may indicate that the presence of HIV-1 in those tissues is secondary to lymphocyte infiltration rather than to tissue tropism of HIV-1 itself. These data suggest that the viral reservoir may be limited, which will have important implications for the success of HIV-1 eradication.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.