Myosin VIIA regulates microvillus morphogenesis and interacts with cadherin Cad99C in Drosophila oogenesis

Abstract

BSTRACTMicrovilli and related actin-based protrusions permit multiple interactions between cells and their environment. How the shape, length and arrangement of microvilli are determined remains largely unclear. To address this issue and explore the cooperation of the two main components of a microvillus, the central F-actin bundle and the enveloping plasma membrane, we investigated the expression and function of Myosin VIIA (Myo7A), which is encoded by crinkled (ck), and its interaction with cadherin Cad99C in the microvilli of the Drosophila follicular epithelium. Myo7A is present in the microvilli and terminal web of follicle cells, and associates with several other F-actin-rich structures in the ovary. Loss of Myo7A caused brush border defects and a reduction in the amount of the microvillus regulator Cad99C. We show that Myo7A and Cad99C form a molecular complex and that the cytoplasmic tail of Cad99C recruits Myo7A to microvilli. Our data indicate that Myo7A regulates the structure and spacing of microvilli, and interacts with Cad99C in vivo. A comparison of the mutant phenotypes suggests that Myo7A and Cad99C have co-dependent and independent functions in microvilli.

Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth

“…One could speculate that close apposition of membranes through E-Cad-dependent adhesion somehow stabilizes protrusions, possibly by allowing specific contacts between protrusions. In epithelia, intermicrovillar adhesion is assured by protocadherins (48)(49)(50), and although any requirement for microvilli remains to be demonstrated, we envisage that they reinforce RCs anchorage. This remote action of E-Cad is somewhat reminiscent of another E-Cad function during oogenesis: E-Cad clusters at the nurse cells' PM control the orientation of the filopodia-like actin cables that position nuclei during later stages of oogenesis.…”

Kibra and Merlin Activate the Hippo Pathway Spatially Distinct from and Independent of Expanded

“…To further define the specific apical domain at which these components localize, we co-stained for Merlin and three apically-localized markers - Cad99C, a marker for apical microvilli (Glowinski, et al 2014), Squash-mCherry, which localizes to the medial and junctional apical cortex, and Rab5-CFP, an early endosomal component. Serial optical sectioning of co-stained tissues revealed that the plane of maximal Merlin staining intensity coincides well with that of Cad99C (Figure S1A) and Squash (Figure S1C), but is apical to the maximal plane of Rab5-CFP (Figure S1B).…”

Listen to your gut: Using adhesion to shape the surface of functionally diverse epithelia

“…Additional evidence for a conserved apical adhesion complex comes from studies in Drosophila, which suggest that a class VII myosin (crinkled) and a cadherin (Cad99c, ortholog of PCDH15) function together to regulate microvillar growth on the surface of follicle cells during oogenesis. 37,38 The simple transporting epithelium that lines the gut arose in evolution long before the more specialized sensory epithelium of the inner ear. With this in mind, it is not surprising that hair cell stereocilia emerge from a lawn of simple microvilli during differentiation.…”