Laminin receptor protein is implicated in hemocyte homeostasis for the whiteleg shrimp Penaeus (Litopenaeus) vannamei

Here we show that knockdown of laminin receptor (Lamr) with PvLamr dsRNA in the whiteleg shrimp Penaeus (Litopenaeus) vannamei (Pv) caused a dramatic reduction specifically in hyaline hemocytes prior to death. Since apoptosis was not detected in hemocytes or hematopoietic cells, other possible causes of hemocyte loss were investigated. Reports that suppression of crustacean hematopoietic factor (CHF)-like protein or hemocyte homeostasis-associated protein (HHAP) also reduced shrimp hemocyte counts led us to carry out yeast two-hybrid (Y2H) and co-immunoprecipitation (co-IP) assays to test for interactions between Lamr and Pv homologues to these proteins (PvCHF-like and PvHHAP). The assays revealed that Lamr bound to both these homologues, but that the homologues did not bind to each other. Subsequent RT-PCR assays confirmed that PvLamr dsRNA injection significantly reduced expression levels for both PvCHF-like and PvHHAP genes. Further work is needed to determine how interaction among these three proteins can regulate shrimp hemocyte homeostasis.