Testing the role of arylphorin during midgut healing in response to Cry1Ac intoxication

Epithelial integrity in the lepidopteran larval midgut is preserved by tissue healing mechanisms mediated by stem cell proliferation and differentiation.  In the insect midgut epithelium, this healing process is only active during molting or following injury.  While a limited number of midgut growth factors have been identified from hemolymph and fat body extracts, the factors involved in regulation of the midgut healing response are not known.  Our work is focused on the regenerative response elicited in the midgut of Heliothis virescens (tobacco budworm) larvae after challenge with the Cry1Ac toxin from the bacterium Bacillus thuringiensis.  Through a differential proteomic analysis using primary midgut cell cultures we have identified arylphorin as a significantly up-regulated protein in response to Cry1Ac intoxication.  In the current work we analyzed expression of arylphorin genes in response to Cry1Ac intoxication in H. virescens larvae and use functional assays to test the role of arylphorin in activating the insect midgut healing response.