title: Headpiece domain of dematin is required for the stability of the erythrocyte membrane.
abstract: Dematin is an actin-binding and bundling protein of the erythrocyte membrane skeleton. Dematin is localized to the spectrin-actin junctions, and its actin-bundling activity is regulated by phosphorylation of cAMP-dependent protein kinase. The carboxyl terminus of dematin is homologous to the "headpiece" domain of villin, an actin-bundling protein of the microvillus cytoskeleton. The headpiece domain contains an actin-binding site, a cAMP-kinase phosphorylation site, plays an essential role in dematin self-assembly, and bundles F-actin in vitro. By using homologous recombination in mouse embryonic stem cells, the headpiece domain of dematin was deleted to evaluate its function in vivo. Dematin headpiece null mice were viable and born at the expected Mendelian ratio. Hematological evaluation revealed evidence of compensated anemia and spherocytosis in the dematin headpiece null mice. The headpiece null erythrocytes were osmotically fragile, and ektacytometry/micropore filtration measurements demonstrated reduced deformability and filterability. In vitro membrane stability measurements indicated significantly greater membrane fragmentation of the dematin headpiece null erythrocytes. Finally, biochemical characterization, including the vesicle/cytoskeleton dissociation, spectrin self-association, and chemical crosslinking measurements, revealed a weakened membrane skeleton evidenced by reduced association of spectrin and actin to the plasma membrane. Together, these results provide evidence for the physiological significance of dematin and demonstrate a role for the headpiece domain in the maintenance of structural integrity and mechanical properties of erythrocytes in vivo.
authors: Department of Medicine, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA.
authors: Richie
authors: R
authors: Khanna
authors: Seon H
authors: SH
authors: Chang
authors: Shaida
authors: S
authors: Andrabi
authors: Mohammad
authors: M
authors: Azam
authors: Anthony
authors: A
authors: Kim
authors: Alicia
authors: A
authors: Rivera
authors: Carlo
authors: C
authors: Brugnara
authors: Philip S
authors: PS
authors: Low
authors: Shih-Chun
authors: SC
authors: Liu
authors: Athar H
authors: AH
authors: Chishti
mesh_terms: D000199:Actins / Q000378:metabolism; D000740:Anemia / Q000378:metabolism; D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003598:Cytoskeletal Proteins; D004910:Erythrocyte Membrane / Q000378:metabolism / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D005260:Female; D018390:Gene Targeting; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins; D013049:Spectrin / Q000378:metabolism
chemical_list: D000199:Actins; D001798:Blood Proteins; D003598:Cytoskeletal Proteins; C044805:DMTN protein, human; C489041:Dmtn protein, mouse; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D013049:Spectrin