Specialized cells that sense tissue mechanics to regulate Drosophila morphogenesis

Shaping of developing organs requires dynamic regulation of force and resistance to achieve precise outcomes, but how organs monitor tissue mechanical properties is poorly understood. We show that in developing Drosophila follicles (egg chambers), a single pair of cells performs such monitoring to drive organ shaping. These anterior polar cells secrete a matrix metalloproteinase (MMP) that specifies the appropriate degree of tissue elongation, rather than hyper- or hypo-elongated organs. MMP production is negatively regulated by basement membrane (BM) mechanical properties, which are sensed through focal adhesion signaling and autonomous contractile activity; MMP then reciprocally regulates BM remodeling, particularly at the anterior region. Changing BM properties at remote locations alone is sufficient to induce a remodeling response in polar cells. We propose that this small group of cells senses both local and distant stiffness cues to produce factors that pattern the organ's BM mechanics, ensuring proper tissue shape and reproductive success.