Moleskin is essential for the formation of the myotendinous junction in Drosophila

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• 作者：Ze (Cindy)  ; Liu^a ;   ; ^b ; Erika R.  ; Geisbrecht^a ;   ; ^{geisbrechte@umkc.edu}
• 关键词：Drosophila ; Muscle development ; Moleskin ; Myotendinous junction ; MAPK
• 刊名：Developmental Biology
• 出版年：2011
• 出版时间：15 November 2011
• 年：2011
• 卷：359
• 期：2
• 页码：176-189
• 全文大小：3674 K

文摘

It is the precise connectivity between skeletal muscles and their corresponding tendon cells to form a functional myotendinous junction (MTJ) that allows for the force generation required for muscle contraction and organismal movement. The Drosophila MTJ is composed of secreted extracellular matrix (ECM) proteins deposited between integrin-mediated hemi-adherens junctions on the surface of muscle and tendon cells. In this paper, we have identified a novel, cytoplasmic role for the canonical nuclear import protein Moleskin (Msk) in Drosophila embryonic somatic muscle attachment. Msk protein is enriched at muscle attachment sites in late embryogenesis and msk mutant embryos exhibit a failure in muscle¨Ctendon cell attachment. Although the muscle¨Ctendon attachment sites are reduced in size, components of the integrin complexes and ECM proteins are properly localized in msk mutant embryos. However, msk mutants fail to localize phosphorylated focal adhesion kinase (pFAK) to the sites of muscle¨Ctendon cell junctions. In addition, the tendon cell specific proteins Stripe (Sr) and activated mitogen-activated protein kinase (MAPK) are reduced in msk mutant embryos. Our rescue experiments demonstrate that Msk is required in the muscle cell, but not in the tendon cells. Moreover, muscle attachment defects due to loss of Msk are rescued by an activated form of MAPK or the secreted epidermal growth factor receptor (Egfr) ligand Vein. Taken together, these findings provide strong evidence that Msk signals non-autonomously through the Vein-Egfr signaling pathway for late tendon cell late differentiation and/or maintenance.