Question

Macrophages are motile cells that migrate into ischemic areas to repair damaged tissue. Which cytoskeletal filaments are most likely to alter their conformation during movement into the brain? Briefly explain your answer.

Answer 1

Macrophages are best known for their protective search and destroy functions against invading micro-organisms. These processes are commonly known as chemotaxis and phagocytosis. Both of these processes require actin cytoskeletal remodeling to produce distinct F-actin rich membrane structures called lamellipodia and phagocytic cups.
Macrophages are resident cells in tissues including lung (alveolar)liver (Kuppfer cells), brain (microglia), and bone (osteoclast), originating from either primitive myeloid progenitors
Both migration and phagocytosis involve two processes: first the sensing of external cues (chemoattractants or phagocytic targets), and second the controlled generation of mechanical forces which will lead to conspicuous deformation of the cell body. These changes in cell morphology are dependent on Arp2/3 triggered actin polymerization .

Transendothelial and interstitial motility is an essential aspect of their function as they must be able to move to specific sites upon demand. primary macrophages and CSF-1 dependent macrophage cell lines, it is evident that CSF-1 is not only a mononuclear phagocyte lineage growth factor but is an important regulator of macrophage motility
Motility is a complex and integrated process that has typically been broken down into five components: (1) cell polarization or breaking of symmetry upon designation of the leading edge, (2) actin polymerization-driven protrusion of the leading edge, (3) integrin-mediated adhesion of the extended protrusion to underlying extracellular matrix proteins to provide the necessary traction for (4) actomyosin contractility-based forward translocation of the cell body, (5) de-adhesion of the trailing edge to complete the cycle