Fish scale keratocytes constitute a sensitive model system for YopE mediated phenotypes in Yersinia pseudotuberculosis infections

• The bacterial pathogen Yersinia pseudotuberculosis employs a type 3 secretion system (T3SS) to deliver virulence associated effectors directly into the host cell. Four of the translocated effectors affect the actin cytoskeleton of the cell, demonstrating the importance of inducing actin rearrangements for the establishment of a successful Yersinia infection. To further examine the role of the effectors in actin targeting, we have established a novel model system using fish scale keratocytes. Fish scale keratocytes are rapidly migrating cells present on the surface of teleost skin. The keratocytes are part of the quick wound repair mechanism of fish and are also able to internalize bacteria. The cell consists of a large extended lamellipodium, a two-dimensional actin network regulated by RhoGTPases.                                         By using live cell microscopy, we identified that wild-type Y. pseudotuberculosis caused a cytotoxic effect towards the keratocytes already within 10 minutes of infection. In contrast, a bacterial strain lacking the T3SS was rapidly internalized by the keratocytes. Further, YopE was found to be the sole effector responsible for this cytotoxic effect. YopE inactivates multiple small RhoGTPases via its GAP activity (GTPase activating protein) to induce cytotoxicity in a wide variety of cell types, including HeLa cells. Several domains of YopE are important for proper GAP function. When a number of earlier isolated point mutants of YopE were examined, none of the mutants could induce cytotoxicity towards keratocytes. Thus, this finding is in sharp contrast to earlier observations in HeLa cells, where all but one mutation caused cytotoxicity. In conclusion, the keratocytes appear to be more sensitive towards YopE mediated effects than HeLa cells and would therefore constitute a relevant model system for Yersinia infections for further studies.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

Yersinia

infection

fish keratocytes

YopE

cytotoxicity

Molecular biology

Molekylärbiologi

molekylärbiologi

Molecular Biology

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)