Cadherin rules microvilli

A cadherin in flies concentrates not on sticking cells together, say D'Alterio et al. (page 549), but on controlling the extension of microvilli.Microvilli are actin-filled apical protrusions on epithelial cells. Actin bundling and polymerizing proteins are the usual suspects regulating microvilli length. But the new results reveal that a plasma membrane protein, a cadherin family member called Cad99C, is also necessary.

Female flies lacking Cad99C had short, misshapen microvilli on their follicle cells, which secrete the material used to make egg shells. Overexpression of Cad99C, by contrast, resulted in abnormally long microvilli.

Mutations in a related vertebrate cadherin, called protocadherin 15 (PCDH15), cause deafness associated with abnormal cochlear microvilli. Scientists have generally guessed that PCDH15 links and aligns microvilli similar to the classical cadherin involvement in adherens junctions. But this might not...