title: Role of H2-calponin in regulating macrophage motility and phagocytosis.
abstract: The actin cytoskeleton plays a major role in cell motility that is essential for the function of phagocytes. Calponin is an actin-associated regulatory protein. Here we report the finding of significant levels of the h2 isoform of calponin in peripheral blood cells of myeloid lineage. To study the functional significance, h2-calponin gene (Cnn2) interrupted mice were constructed. Germ line transmission of the Cnn2-flox-neo allele was obtained in chimeras from two independent clones of targeted embryonic stem cells. The insertion of the neo(R) cassette into intron 2 of the Cnn2 gene resulted in a significant knockdown of h2-calponin expression. Removing the frt-flanked neo(R) cassette by FLP1 recombinase rescued the knockdown effect. Cre recombinase-induced deletion of the loxP-flanked exon 2 eliminated the expression of h2-calponin protein. H2-calponin-free mice showed reduced numbers of peripheral blood neutrophils and monocytes. H2-calponin-free macrophages demonstrated a higher rate of proliferation and faster migration than that of h2-calponin-positive cells, consistent with a faster diapedesis of peripheral monocytes and neutrophils. H2-calponin-free macrophages showed reduced spreading in adhesion culture together with decreased tropomyosin in the actin cytoskeleton. The lack of h2-calponin also significantly increased macrophage phagocytotic activity, suggesting a novel mechanism to regulate phagocyte functions.
authors.affiliation: Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
authors.forename: Qi-Quan
authors.initials: QQ
authors.lastname: Huang
authors.forename: M Moazzem
authors.initials: MM
authors.lastname: Hossain
authors.forename: Kaichun
authors.initials: K
authors.lastname: Wu
authors.forename: Kakoli
authors.initials: K
authors.lastname: Parai
authors.forename: Richard M
authors.initials: RM
authors.lastname: Pope
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Jin
mesh_terms: D000199:Actins / Q000737:chemistry; D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D019070:Cell Lineage; D002465:Cell Movement; D049109:Cell Proliferation; D003599:Cytoskeleton / Q000378:metabolism; D005091:Exons; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008840:Microfilament Proteins / Q000737:chemistry / Q000502:physiology*; D008954:Models, Biological; D010587:Phagocytosis; D014335:Tropomyosin / Q000737:chemistry; D000096985:Calponins
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D014335:Tropomyosin; D000096985:Calponins