mTOR and S6K1 drive polycystic kidney by the control of Afadin-dependent oriented cell division

mTOR activation is essential and sufficient to cause polycystic kidneys in Tuberous Sclerosis Complex (TSC) and other genetic disorders. In disease models, a sharp increase of proliferation and cyst formation correlates with a dramatic loss of oriented cell division (OCD). We find that OCD distortion is intrinsically due to S6 kinase 1 (S6K1) activation. The concomitant loss of S6K1 in Tsc1-mutant mice restores OCD but does not decrease hyperproliferation, leading to non-cystic harmonious hyper growth of kidneys. Mass spectrometry-based phosphoproteomics for S6K1 substrates revealed Afadin, a known component of cell-cell junctions required to couple intercellular adhesions and cortical cues to spindle orientation. Afadin is directly phosphorylated by S6K1 and abnormally decorates the apical surface of Tsc1-mutant cells with E-cadherin and α-catenin. Our data reveal that S6K1 hyperactivity alters centrosome positioning in mitotic cells, affecting oriented cell division and promoting kidney cysts in conditions of mTOR hyperactivity.

Visual categorization of natural and abstract items in forest monkeys and humans

A preference for novelty paradigm was used to investigate whether mangabeys (Lophocebus albigena), an arboreal non-human primate species, were able to discriminate and to categorize different visual stimuli belonging to natural (food items) and abstract (non-food items) categories. In a comparative perspective human subjects were tested with the same procedure and the same stimuli. Two out of four mangabeys and three out of the four humans showed significant preference for novelty when comparing food versus non-food items. Hence they discriminated between these two sets of items. The two mangabeys and one non-adult human subject sorted the food items in one category, showing no preference for novelty when comparing known and unknown food-items and different views of the same food items. In contrast the two adult human subjects who showed preference for novelty in the between-category, did not show preference for novelty when comparing known and unknown food-items but did show such a preference when comparing different views of the same food items. Compared to human performances, the results suggest that mangabeys are able to form at least a perceptual category of natural, ecologically relevant stimuli.

Severe portal hypertensive gastropathy and antral vascular ectasia are distinct entities in patients with cirrhosis

BACKGROUND/AIMS

Whereas severe portal hypertensive gastropathy and gastric antral vascular ectasia (GAVE) have been separately defined in patients with cirrhosis, there is much confusion in the literature because they are both characterized by red spots at endoscopy. This prospective study compared clinical, biochemical, and pathological features of these syndromes.

METHODS

Three groups of patients with cirrhosis and either GAVE (n = 14), severe portal hypertensive gastropathy (n = 14), or no gastric features at endoscopy (controls; n = 10) were included.

RESULTS

No difference was found between patients with gastropathy and controls. Patients with GAVE presented with the following significant differences compared with other patients: a higher Child-Pugh score, a lower blood level of hemoglobin and gastrin, and a higher intestinal blood loss. At pathological examination, these patients more frequently had vascular ectasia (P = 0.04), spindle cell proliferation (P < 0.01), fibrohyalinosis (P = 0.004), and Gilliam's score of > or = 2 (P < 0.05); thrombi were encountered only in patients with GAVE (P = 0.006). Using discriminant analysis, spindle cell proliferation and fibrohyalinosis were the only significant variables yielding a diagnostic accuracy of 85% for GAVE and gastropathy.

CONCLUSIONS

GAVE and severe portal hypertensive gastropathy are two distinct entities.