Localization of the actin-binding protein fesselin in chicken smooth muscle

Abstract

This report compares cellular localization of fesselin in chicken smooth, skeletal and cardiac muscle tissues using affinity purified polyclonal fesselin antibodies. Western blot analyses revealed large amounts of fesselin in gizzard smooth muscle with lower amounts in skeletal and cardiac muscle. In gizzard, fesselin was detected by immunofluorescence as discrete cytoplasmic structures. Fesselin did not co-localize with talin, vinculin or caveolin indicating that fesselin is not associated with dense bands or caveolar regions of the cell membrane. Immunoelectron microscopy established localization of fesselin within dense bodies. Since dense bodies function as anchorage points for actin and desmin in smooth muscle cells, fesselin may be involved in establishing cytoskeletal structure in this tissue. In skeletal muscle, fesselin was associated with desmin in regularly space bands distributed along the length of muscle fibers suggesting localization to the Z-line. Infrequently, this banding pattern was observed in heart tissues as well. Localization at the Z-line of skeletal and cardiac muscle suggests a role in contraction of these tissues.

Synaptopodin family of natively unfolded, actin binding proteins: physical properties and potential biological functions

“…Synaptopodin 2 and α-actinin are co-localized in dense bodies and Z-lines (Renegar et al 2009), while synaptopodin and α-actinin colocalize in kidney podocytes and the hippocampus (Asanuma et al 2005). Synaptopodin family members might be involved in the organization and anchoring of actin in the cell and might be necessary for the correct localization of α-actinin.…”

The actin binding protein, fesselin, is a member of the synaptopodin family

“…filaments and bind to other actin associated proteins suggest a role of fesselin in organizing cellular actin. This hypothesis is supported by evidence that fesselin is localized in smooth muscle dense bodies [7].…”

Avian Synaptopodin 2 (Fesselin) Stabilizes Myosin Filaments and Actomyosin in the Presence of ATP

“…There is no available evidence of fesselin binding to cellular myosin. However, staining of gizzard muscle with anti-fesselin IgG showed diffuse background staining in additional to intense staining of dense bodies (7). That diffuse staining may have been due to the association of fesselin with smooth muscle myosin.…”

“…Fesselin is localized primarily in the dense bodies of smooth muscle (7) and Z-lines of striated muscle (5). Synaptopodin 2 has been identified in several cell lines where it appears to shuttle between the nucleus and cytoplasm (5).…”