Sarco(endo)plasmic reticulum ca2+ATPases (SERCA1 and 2) in human extraocular muscles
2003 (English)In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, Vol. 44, no 12, 5057-5062 p.Article in journal (Refereed) Published
PURPOSE: To investigate the composition of the fibers in human extraocular muscles (EOMs) with respect to the sarco(endo)plasmic reticulum Ca(2+)ATPases (SERCA)-1 and -2 and to investigate possible correlations between SERCA and myosin heavy chain (MyHC) composition. METHODS: EOM samples were processed for immunocytochemistry with monoclonal antibodies specific against SERCA1 (fast isoform), SERCA2 (slow isoform), or different MyHCs. A total of 1571 fibers were analyzed. Microsomal EOM fractions were analyzed with SDS-PAGE and immunoblots. RESULTS: The fast fibers, containing MyHCIIa, accounted for 79% of the fibers in the orbital layer (OL) and 74% in the global layer (GL). More than 99% of these fibers contained SERCA1, and 86% of them coexpressed SERCA1 and -2. Almost all slow fibers stained with SERCA2; 54% of those in the GL and all in the OL coexpressed SERCA1 and -2. Fifteen percent of the fibers in the GL and less than 1% in the OL were MyHCeom(pos)/MyHCIIa(neg) fibers. All these contained SERCA1 and in the OL also stained strongly with anti-SERCA2. Biochemically SERCA2 was more abundant than SERCA1. CONCLUSIONS: The human EOMs had a very complex pattern of expression of the major protein regulating fiber relaxation rate. The coexistence of SERCA1 and -2, together with complex mixtures of MyHCs in most of the fibers provide the human EOMs with a unique molecular portfolio that allows a highly specific fine-tuning regimen of contraction and relaxation.
Place, publisher, year, edition, pages
Association for Research in Vision and Ophthalmology , 2003. Vol. 44, no 12, 5057-5062 p.
IdentifiersURN: urn:nbn:se:umu:diva-3936DOI: 10.1167/iovs.03-0218PubMedID: 14638697OAI: oai:DiVA.org:umu-3936DiVA: diva2:142850