ETV4 and ETV5 drive synovial sarcoma through cell cycle and DUX4 embryonic pathway control

Synovial sarcoma is an aggressive malignancy with no effective treatments for patients with metastasis. The synovial sarcoma fusion SS18-SSX, which recruits the SWI/SNF-BAF chromatin remodeling and polycomb repressive complexes, results in epigenetic activation of FGF receptor (FGFR) signaling. In genetic FGFR-knockout models, culture, and xenograft synovial sarcoma models treated with the FGFR inhibitor BGJ398, we show that FGFR1, FGFR2, and FGFR3 were crucial for tumor growth. Transcriptome analyses of BGJ398-treated cells and histological and expression analyses of mouse and human synovial sarcoma tumors revealed prevalent expression of two ETS factors and FGFR targets, ETV4 and ETV5. We further demonstrate that ETV4 and ETV5 acted as drivers of synovial sarcoma growth, most likely through control of the cell cycle. Upon ETV4 and ETV5 knockdown, we observed a striking upregulation of DUX4 and its transcriptional targets that activate the zygotic genome and drive the atrophy program in facioscapulohumeral dystrophy patients. In addition to demonstrating the importance of inhibiting all three FGFRs, the current findings reveal potential nodes of attack for the cancer with the discovery of ETV4 and ETV5 as appropriate biomarkers and molecular targets, and activation of the embryonic DUX4 pathway as a promising approach to block synovial sarcoma tumors.

Kainate receptors regulate development of glutamatergic synaptic circuitry in the rodent amygdala

Perturbed information processing in the amygdala has been implicated in developmentally originating neuropsychiatric disorders. However, little is known on the mechanisms that guide formation and refinement of intrinsic connections between amygdaloid nuclei. We demonstrate that in rodents the glutamatergic connection from basolateral to central amygdala (BLA-CeA) develops rapidly during the first 10 postnatal days, before external inputs underlying amygdala-dependent behaviors emerge. During this restricted period of synaptic development, kainate-type of ionotropic glutamate receptors (KARs) are highly expressed in the BLA and tonically activated to regulate glutamate release via a G-protein-dependent mechanism. Genetic manipulation of this endogenous KAR activity locally in the newborn LA perturbed development of glutamatergic input to CeA, identifying KARs as a physiological mechanism regulating formation of the glutamatergic circuitry in the amygdala.

FGF receptors 1 and 2 control chemically induced injury and compound detoxification in regenerating livers of mice

BACKGROUND & AIMS

Fibroblast growth factor receptor 4 (FGFR4) controls bile acid metabolism and protects the liver from fibrosis, but the roles of FGFR1 and FGFR2 in the adult liver are largely unknown. We investigated the functions and mechanisms of action of these receptors in liver homeostasis, regeneration, and fibrosis.

METHODS

We generated mice with hepatocytes that lack FGFR1 and FGFR2 and subjected them to acute and chronic carbon tetrachloride-induced liver injury and partial hepatectomy; mice were also injected with FGF7. We performed histology, histomorphometry, real-time reverse transcription polymerase chain reaction, and immunoblot analyses.

RESULTS

In hepatocytes, loss of FGFR1 and FGFR2 eliminated responsiveness to FGF7 and related FGF family members but did not affect toxin-induced liver injury and fibrosis. However, mortality after partial hepatectomy increased because of severe hepatocyte necrosis. These effects appeared to be mediated by a failure of hepatocytes to induce the expression of the transcriptional regulators Dbp and Tef upon liver surgery; this affected expression of their target genes, which encode detoxifying cytochrome P450 enzymes. We found that Dbp and Tef expression was directly controlled by FGFR signaling in hepatocytes. As a consequence of the reduced expression of genes that control detoxification, the liver tissue that remained after partial hepatectomy failed to efficiently metabolize endogenous compounds and the drugs applied for anesthesia/analgesia.

CONCLUSIONS

We identified a new, cytoprotective effect of FGFR1 and FGFR2 in the regenerating liver and suggest the use of recombinant FGF7 to increase survival of patients after surgical resection of large amounts of liver tissue.

Association between environmental stress and epidermal papillomatosis of roach Rutilus rutilus

We studied the association between environmental stress and epidermal papillomatosis of roach Rutilus rutilus L. in Finnish waters using a 'matched pairs' design. Populations impacted by industrial and/or sewage effluents were compared to reference populations from pristine sites. We examined both the prevalence (proportion of diseased fish) and intensity (number of scales covered by tumors) of the disease. Results of Generalized Linear Mixed Models (GLMM) indicated that the risk of papillomatosis was 7.5 times higher in males than females, and increased 1.3 times for every 10 mm increment in fish length. We controlled for the possible effects of fish size, sex and temporal variation through sampling procedures and statistical analyses. Mean prevalence of epidermal papillomatosis was 16.6 and 5.8% in impact and reference populations, respectively (10 population pairs; nfish = 1714). Results of GLMM suggested that the risk of being diseased was 2.7 times higher in the impact than reference populations. Thus, the prevalence of epidermal papillomatosis in roach can be used as an indicator of environmental stress. Results of Linear Mixed Models indicated no difference in the intensity of the disease between impact and reference populations (5 population pairs; nfish = 73; mean+/-SE 10.7+/-1.8 and 11.7+/- 2.9 scales, respectively), although prevalence was higher in impact populations in those 5 population pairs. The possible relationship between environmental stress and intensity of epidermal papillomatosis in natural roach populations remains to be demonstrated.