Function of Hsp27 protein in Plasmodium berghei okinetes

Efficiency in infecting the mosquito’s intestine is critical for the transmission of malaria parasites. When mosquitoes feed on the blood of an infected host, the sexual stages of Plasmodium in the food bolus develop into motile ookinetes, which cross the peritrophic matrix membrane of the vector intestine, invade epithelial cells with subsequent migration to the basal lamina to form oocysts, within which sporozoites, the infective forms of the parasite, are generated. The movement of the ookinete is dependent on actin and myosin, among other conserved molecules that constitute the motor of the parasite, conserved in the genus Apicomplexa. Although the regulation of the molecular motor is still not fully understood, some of the mechanisms involved include calcium-dependent signaling cascades, cGMP, guanylate cyclases and phosphatases. In previous studies, a small molecular weight heat shock protein of 20 kDa, HSP20, is expressed exclusively in Plasmodium berghei sporozoites and ookinetes. This chaperone can modulate the speed and targeting of sporozoites, impairing natural transmission. Furthermore, ookinetes move substantially more slowly in the absence of the Hsp20 protein. Interestingly, this deficiency did not hinder the establishment of the infection and the development of the parasite inside the mosquito. Another 27 kDa chaperone (Hsp27) has recently been identified which appears to be expressed exclusively in ookinetes. Different types of eukaryotic cells express Hsp27. In these systems, the protein has been identified as a potent cytoskeletal regulator. This property would be dependent on phosphorylation, on its structural organization and on the activation of different signaling mechanisms.

Project details

Basic Science

May 2016 — Mar 2018

Brazil