Loss of Fgf-responsive Pea3 transcription factors results in ciliopathy-associated phenotypes during early zebrafish development

FGF signaling is used reiteratively during development and elicits several different responses, such as cell proliferation, differentiation, or migration. We parsed the complex FGF intracellular response by creating triple homozygous mutants in the Pea3 subgroup of ETS transcription factors, designated 3etv mutants. The Pea3 proteins Etv4 and Etv5 are expressed in areas of FGF activity; however, their role in FGF signal transduction as either positive or negative modulators of FGF activity was unclear. Using 3etv mutants, we found these genes act redundantly and have phenotypes consistent with known FGF defects in inner ear, pectoral fin, and posterior mesoderm development. Additionally, we uncovered a novel role for the FGF/Pea3 pathway during body axis straightening. 3etv larvae develop a curly-tail up (CTU) phenotype that we linked to mis-regulation of the polycystin and urotensin pathways, which have opposing actions to ensure a straight body orientation along the dorsal-ventral axis. We find that the Etv4/5 transcription factors act as positive regulators of FGF signaling and propose a model where Etv4/5 are required for cilia function downstream of Fgf8a.Summary StatementPea3 transcription factor triple mutants reveal a role for FGF signaling in balancing polycystin and urotensin signaling to achieve a straight body axis.

Expression of 1L-myo-Inositol -1-Phosphate Synthase (EC 5.5.1.4) is Deregulated in the Cerebellum of Curly Tail Mutant Mice

Previous research, defining spatial control of inositol phosphate biosynthesis in the developing brain of CBA (normal) and CT [curly tail (ct-CT) and straight tail (st-CT)] mutant mice implicated a role for 1l-myo-inositol 1-phosphate synthase (MIP) in normal functioning of the central nervous system. Biochemical research indicated that MIP enzymatic activity, conversion of glucose 6-phosphate into inositol phosphate, is highest in the cerebellum of ct-CT and lowest in st-CT, when compared to that of CBA mice. Here, we utilized microscopic and biochemical investigations to analyze and extend previous findings of MIP expression in the cerebellum. Results of this research indicated that MIP expression correlates, well, with its enzymatic activity in the cerebellum of CBA and CT mutant mice. Statistical analyses of fluorescent micrographs detected a significant difference in fluorescence intensity between MIP from ct-CT, st-CT, and CBA mice. These data support vital links between inositol phosphate biosynthesis, MIP expression, and normal functioning of the cerebellum. Moreover, published data, identifying significant behavioral differences in the CT mutant, as well as data linking motor and non-motor cerebellar functions to abnormal levels of inositol, support the conclusion that aspects of normal cerebellar functions require temporal and spatial control of inositol phosphate biosynthesis, MIP expression.

Tail Posture as an Indicator of Tail Biting in Undocked Finishing Pigs

Tail posture (i.e., hanging or curled) has been suggested to be an indicator of tail biting, and hanging tails predisposed to damage. The aim of this study was to investigate if tail posture was feasible as a tail damage indicator in a commercial setting. The study was carried out on one batch of 459 undocked finishing pigs (30–120 kg in weight). Weekly scoring of tail posture was combined with the scoring of tail lesions. Tail posture was observed at feeding to facilitate the usage of the method in commercial settings. A curly tail was observed in 94% of the observations. Pigs with tails scored with “wound” were 4.15 (p < 0.0001) times more likely to have hanging tails, and pigs scored with “inflamed wounds” were 14.24 (p < 0.0001) times more likely to have hanging tails, compared to pigs with nondamaged tails. Tail posture correctly classified tails with “wound” or “inflamed wound” 67.5% of the time, with 55.2% sensitivity and 79.7% specificity, respectively. The method of observing the tail position at feeding seems useful as a complement to normal inspection for detecting tail biting before tail wounds are visible to the caretaker.

Polycystin-1 regulates bone development through an interaction with the transcriptional coactivator TAZ

Polycystin-1 (PC1), encoded by the PKD1 gene that is mutated in the autosomal dominant polycystic kidney disease, regulates a number of processes including bone development. Activity of the transcription factor RunX2, which controls osteoblast differentiation, is reduced in Pkd1 mutant mice but the mechanism governing PC1 activation of RunX2 is unclear. PC1 undergoes regulated cleavage that releases its C-terminal tail (CTT), which translocates to the nucleus to modulate transcriptional pathways involved in proliferation and apoptosis. We find that the cleaved CTT of PC1 (PC1-CTT) stimulates the transcriptional coactivator TAZ (Wwtr1), an essential coactivator of RunX2. PC1-CTT physically interacts with TAZ, stimulating RunX2 transcriptional activity in pre-osteoblast cells in a TAZ-dependent manner. The PC1-CTT increases the interaction between TAZ and RunX2 and enhances the recruitment of the p300 transcriptional co-regulatory protein to the TAZ/RunX2/PC1-CTT complex. Zebrafish injected with morpholinos directed against pkd1 manifest severe bone calcification defects and a curly tail phenotype. Injection of messenger RNA (mRNA) encoding the PC1-CTT into pkd1-morphant fish restores bone mineralization and reduces the severity of the curly tail phenotype. These effects are abolished by co-injection of morpholinos directed against TAZ. Injection of mRNA encoding a dominant-active TAZ construct is sufficient to rescue both the curly tail phenotype and the skeletal defects observed in pkd1-morpholino treated fish. Thus, TAZ constitutes a key mechanistic link through which PC1 mediates its physiological functions.

Like a Dog’s Curly Tail: Finding Perfection in a World of Imperfection

Jeffery Long, a Hindu theologian, explores the problem of evil as it is raised and addressed by thinkers in the Ramakrishna Vedanta tradition of Hinduism and by two separate schools of thought from contemporary Christianity. The textual sources used from the Ramakrishna tradition consist of the teachings of Sri Ramakrishna as found in the primary sources on his life, as well as the Complete Works of Swami Vivekananda. From Christianity, Long employs works of John Hick and David Ray Griffin on the topic of theodicy. Despite the fact that the latter two authors hail from the same religious tradition, Long shows that Hick and Ramakrishna are in closer agreement on this topic than either is with Griffin’s process theology. The essay offers a revised version of the Ramakrishna-Hick theodicy that takes Griffin’s objections into account.

Arl13b and the exocyst interact synergistically in ciliogenesis

Arl13b belongs to the ADP-ribosylation factor family within the Ras superfamily of regulatory GTPases. Mutations in Arl13b cause Joubert syndrome, which is characterized by congenital cerebellar ataxia, hypotonia, oculomotor apraxia, and mental retardation. Arl13b is highly enriched in cilia and is required for ciliogenesis in multiple organs. Nevertheless, the precise role of Arl13b remains elusive. Here we report that the exocyst subunits Sec8, Exo70, and Sec5 bind preferentially to the GTP-bound form of Arl13b, consistent with the exocyst being an effector of Arl13b. Moreover, we show that Arl13b binds directly to Sec8 and Sec5. In zebrafish, depletion of arl13b or the exocyst subunit sec10 causes phenotypes characteristic of defective cilia, such as curly tail up, edema, and abnormal pronephric kidney development. We explored this further and found a synergistic genetic interaction between arl13b and sec10 morphants in cilia-dependent phenotypes. Through conditional deletion of Arl13b or Sec10 in mice, we found kidney cysts and decreased ciliogenesis in cells surrounding the cysts. Moreover, we observed a decrease in Arl13b expression in the kidneys from Sec10 conditional knockout mice. Taken together, our results indicate that Arl13b and the exocyst function together in the same pathway leading to functional cilia.