Integrin receptors, a large family of
adhesion receptors, are involved in the attachment of Klebsiella pneumoniae to respiratory epithelial cells, and subsequently cause the internalization of K. pneumoniae by host cells. Although a number of molecules have been reported to regulate the expression and activity of
integrin receptors in respiratory epithelial cells, the specific underlying molecular mechanisms remain largely unknown. High mobility group nucleosomal binding domain 2 (
HMGN2), a non-
histone nuclear protein, is present in eukaryotic cells as a ubiquitous
nuclear protein. Our previous studies have demonstrated that
HMGN2 affects
chromatin function and modulates the expression of antibacterial
peptide in A549 cells exposed to
lipopolysaccharide, which indicates the critical role of
HMGN2 in innate immune responses. In addition, our
cDNA microarray analysis suggested that
HMGN2 knockdown induced the enhanced expression of α5β1 integrin in A549 cells. Therefore, we hypothesized that intercellular
HMGN2 may mediate the internalization of K. pneumoniae by altering the expression of α5β1 integrin. Using the A549 cell line, we demonstrated that
HMGN2 knockdown induced the increased expression of α5β1 integrin on cell membranes, which resulted in a significant increase in K. pneumoniae internalization. Further results revealed that
HMGN2 silencing induced the expression of
talin and the activation of α5β1 integrin, which led to actin polymerization following the phosphorylation of FAK and Src. This study suggests a possible therapeutic application for bacterial internalization by targeting
HMGN2 in order to treat K. pneumoniae
infection.