Mitochondrial clearance by the STK38 kinase supports oncogenic Ras-induced cell transformation.

Oncogenic Ras signalling occurs frequently in many human cancers. However, no effective targeted therapies are currently available to treat patients suffering from Ras-driven tumours. Therefore, it is imperative to identify downstream effectors of Ras signalling that potentially represent promising new therapeutic options. Particularly, considering that autophagy inhibition can impair the survival of Ras-transformed cells in tissue culture and mouse models, an understanding of factors regulating the balance between autophagy and apoptosis in Ras-transformed human cells is needed. Here, we report critical roles of the STK38 protein kinase in oncogenic Ras transformation. STK38 knockdown impaired anoikis resistance, anchorage-independent soft agar growth, and in vivo xenograft growth of Ras-transformed human cells. Mechanistically, STK38 supports Ras-driven transformation through promoting detachment-induced autophagy. Even more importantly, upon cell detachment STK38 is required to sustain the removal of damaged mitochondria by mitophagy, a selective autophagic process, to prevent excessive mitochondrial reactive oxygen species production that can negatively affect cancer cell survival. Significantly, knockdown of PINK1 or Parkin, two positive regulators of mitophagy, also impaired anoikis resistance and anchorage-independent growth of Ras-transformed human cells, while knockdown of USP30, a negative regulator of PINK1/Parkin-mediated mitophagy, restored anchorage-independent growth of STK38-depleted Ras-transformed human cells. Therefore, our findings collectively reveal novel molecular players that determine whether Ras-transformed human cells die or survive upon cell detachment, which potentially could be exploited for the development of novel strategies to target Ras-transformed cells

Modifying one’s hand’s trajectory when a moving target’s orientation changes

The path that the hand takes to intercept an elongated moving target depends on the target’s orientation. How quickly do people respond to changes in the moving target’s orientation? In the present study, participants were asked to intercept moving targets that sometimes abruptly changed orientation shortly after they started moving. It took the participants slightly more than 150 ms to adjust their hands’ paths to a change in target orientation. This is about 50 ms longer than it took them to respond to a 5-mm jump in the moving target’s position. It is only slightly shorter than it took them to initiate the movement. We propose that responses to changes in visually perceived orientation are not exceptionally fast, because there is no relationship between target orientation and direction of hand movement that is sufficiently general in everyday life for one to risk making an inappropriate response in order to respond faster

Knockout of the dhfr-ts Gene in Trypanosoma cruzi Generates Attenuated Parasites Able to Confer Protection against a Virulent Challenge

Chagas disease is the clinical manifestation of the infection produced by the flagellate parasite Trypanosoma cruzi and currently there is no vaccine to prevent this disease. Therefore, different approaches or alternatives are urgently needed. Vaccination with live attenuated parasites has been used effectively in mice to reduce parasitemia and histological damage. However, the use of live parasites as inmunogens is controversial due to the risk of reversion to a virulent phenotype. In this work we genetically manipulated a naturally attenuated strain of T. cruzi in order to produce parasites with impaired replication and infectivity, using the mutation as a safety device against reversion to virulence. We show that genetically modified parasites display a lower proliferation rate in vitro and induced almost undetectable levels of T. cruzi specific CD8+ T cells when injected in mice. Furthermore, the immune response induced by these live mutant parasites confers protection against a subsequent virulent infection even a year after the original immunization