Alteration of hedgehog signaling by chronic exposure to different pesticide formulations and unveiling the regenerative potential of recombinant sonic hedgehog in mouse model of bone marrow aplasia.

Chronic pesticide exposure-induced downregulation of hedgehog signaling and its subsequent degenerative effects on the mammalian hematopoietic system have not been investigated yet. However a number of concurrent studies have pointed out the positive correlation between chronic pesticide exposure induced bone marrow failure and immune suppression. Here, we have given an emphasis on the recapitulation of human marrow aplasia like condition in mice by chronic mixed pesticide exposures and simultaneously unravel the role of individual pesticides in the said event. Unlike the effect of mixed pesticide, individual pesticides differentially alter the hedgehog signaling in the bone marrow primitive hematopoietic compartment (Sca1 + compartment) and stromal compartment. Individually, hexaconazole disrupted hematopoietic as well as stromal hedgehog signaling activation through inhibiting SMO and facilitating PKC δ expression. On contrary, both chlorpyriphos and cypermethrin increased the sequestration and degradation of GLI1 by upregulating SU(FU) and βTrCP, respectively. However, cypermethrin-mediated inhibition of hedgehog signaling has partly shown to be circumvented by non-canonical activation of GLI1. Finally, we have tested the regenerative response of sonic hedgehog and shown that in vitro supplemented recombinant SHH protein augmented clonogenic stromal progenitors (CFU-F) as well as primitive multipotent hematopoietic clones including CFU-GEMM and CFU-GM of mixed pesticide-induced aplastic marrow. It is an indication of the marrow regeneration. Finally, our findings provide a gripping evidence that downregulated hedgehog signaling contribute to pesticide-mediated bone marrow aplasia but it could be recovered by proper supplementation of recombinant SHH along with hematopoietic base cocktail. Furthermore, SU(FU) and GLI1 can be exploited as future theradiagnostic markers for early marrow aplasia diagnosis.