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Site-specific phosphorylation regulates the functions of kindlin-3 in a variety of cells.

ABSTRACT: Studies of isolated cells, mice, and humans have demonstrated the vital role of the FERM domain protein kindlin-3 in integrin activation in certain hematopoietic and non-hematopoietic cells, consequent to binding to integrin β-subunits. To explore regulatory mechanisms, we developed a monoclonal antibody that selectively recognizes the phosphorylated form of Ser484 (pS484) in kindlin-3. Activation of platelets, HEL megakaryocytic-like cells and BT549 breast cancer cells led to enhanced expression of pS484 as assessed by immunofluorescence or Western blotting. In platelets, pS484 rose rapidly and transiently upon stimulation. When a mutant form of kindlin-3, T482S484/AA kindlin-3, was transduced into mouse megakaryocytes, it failed to support activation of integrin αIIbβ3, whereas wild-type kindlin-3 did. In MDA-MB231 breast cancer cells, expression of T482S484/AA kindlin-3 suppressed cell spreading, migration, invasion, and VEGF production. Wild-type kindlin-3 expressing cells markedly increased tumor growth in vivo, whereas T482S484/AA kindlin-3 significantly blunted tumor progression. Thus, our data establish that a unique phosphorylation event in kindlin-3 regulates its cellular functions.

SUBMITTER: Bialkowska K

PROVIDER: S-EPMC7010036 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Site-specific phosphorylation regulates the functions of kindlin-3 in a variety of cells.

Bialkowska Katarzyna K Sossey-Alaoui Khalid K Pluskota Elzbieta E Izem Lahoucine L Qin Jun J Plow Edward F EF

Life science alliance 20190301 3

Studies of isolated cells, mice, and humans have demonstrated the vital role of the FERM domain protein kindlin-3 in integrin activation in certain hematopoietic and non-hematopoietic cells, consequent to binding to integrin β-subunits. To explore regulatory mechanisms, we developed a monoclonal antibody that selectively recognizes the phosphorylated form of Ser<sup>484</sup> (pS<sup>484</sup>) in kindlin-3. Activation of platelets, HEL megakaryocytic-like cells and BT549 breast cancer cells led ...[more]

PMID: 32024667

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Project description:In all organisms, chromosome replication is regulated mainly at the initiation step. Most of the knowledge about the mechanisms that regulate replication initiation in bacteria has come from studies on rod-shaped bacteria, such as Escherichia coli and Bacillus subtilisStreptomyces is a bacterial genus that is characterized by distinctive features and a complex life cycle that shares some properties with the developmental cycle of filamentous fungi. The unusual lifestyle of streptomycetes suggests that these bacteria use various mechanisms to control key cellular processes. Here, we provide the first insights into the phosphorylation of the bacterial replication initiator protein, DnaA, from Streptomyces coelicolor We suggest that phosphorylation of DnaA triggers a conformational change that increases its ATPase activity and decreases its affinity for the replication origin, thereby blocking the formation of a functional orisome. We suggest that the phosphorylation of DnaA is catalyzed by Ser/Thr kinase AfsK, which was shown to regulate the polar growth of S. coelicolor Together, our results reveal that phosphorylation of the DnaA initiator protein functions as a negative regulatory mechanism to control the initiation of chromosome replication in a manner that presumably depends on the cellular localization of the protein.IMPORTANCE This work provides insights into the phosphorylation of the DnaA initiator protein in Streptomyces coelicolor and suggests a novel bacterial regulatory mechanism for initiation of chromosome replication. Although phosphorylation of DnaA has been reported earlier, its biological role was unknown. This work shows that upon phosphorylation, the cooperative binding of the replication origin by DnaA may be disturbed. We found that AfsK kinase is responsible for phosphorylation of DnaA. Upon upregulation of AfsK, chromosome replication occurred further from the hyphal tip. Orthologs of AfsK are exclusively found in mycelial actinomycetes that are related to Streptomyces and exhibit a complex life cycle. We propose that the AfsK-mediated regulatory pathway serves as a nonessential, energy-saving mechanism in S. coelicolor.

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Site-specific phosphorylation regulates the functions of kindlin-3 in a variety of cells.

Publications

Site-specific phosphorylation regulates the functions of kindlin-3 in a variety of cells.

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