Alternative microexon splicing by RBFOX2 and PTBP1 is associated with metastasis in colorectal cancer

The splicing of microexons (very small exons) is frequently dysregulated in the brain of individuals with autism spectrum disorder. However, little is known of the patterns, regulatory mechanisms and roles of microexon splicing in cancer. We here examined the transcriptome-wide profile of microexon splicing in matched colorectal cancer (CRC) and normal tissue specimens. Out of 1492 microexons comprising 3 to 15 nucleotides, 21 (1%) manifested differential splicing between CRC and normal tissue. The 21 genes harboring the differentially spliced microexons were enriched in gene ontology terms related to cell adhesion and migration. RNA interference-mediated knockdown experiments identified two splicing factors, RBFOX2 and PTBP1, as regulators of microexon splicing in CRC cells. RBFOX2 and PTBP1 were found to directly bind to microexon-containing pre-mRNAs and to control their splicing in such cells. Differential microexon splicing was shown to be due, at least in part, to altered expression of RBFOX2 and PTBP1 in CRC tissue compared to matched normal tissue. Finally, we found that changes in the pattern of microexon splicing were associated with CRC metastasis. Our data thus suggest that altered expression of RBFOX2 and PTBP1 might influence CRC metastasis through the regulation of microexon splicing.

Localization of a locus responsible for the bovine chondrodysplastic dwarfism (bcd) on chromosome 6

A hereditary chondrodysplastic dwarfism caused by an autosomal recessive gene has been reported in a population of Japanese Brown cattle. Affected calves show an insufficiency of endochondral ossification at the long bones of the limbs. In the present study, we mapped the locus responsible for the disease (bcd) by linkage analysis, using microsatellite markers and a single paternal half-sib pedigree obtained from commercial herds. Linkage analysis revealed a significant linkage between the bcd locus and marker loci on the distal region of bovine Chromosome (Chr) 6. The bcd locus was mapped in the interval between microsatellite markers BM9257 and BP7 or BMS511 with a recombination fraction of 0.05 and 0.06, and a lod score of 8.6 and 10.1, respectively. A comparison of genetic maps between bovine Chr 6 and human Chr 4 or mouse Chr 5 indicates possible candidate genes including FGFR3 and BMP3 genes, which are responsible for human chondrodysplasias and associated with bone morphogenesis, respectively.

Effect on neonatal thyroid function of povidone-iodine used on mothers during perinatal period

OBJECTIVE

Our objective was to evaluate the effect on the neonatal thyroid function of povidone-iodine (PVP-I) used on mothers during the perinatal period.

METHODS

Eight consecutive-term pregnant women were randomly separated into 4 groups. Either PVP-1 or benzethonium chloride (BC) was used to disinfect both maternal skin during labor and vaginal lacerations after delivery in Group I and IV; and PVP-1 or BC was supplied to either skin or lacerations in Groups II and III. On day 5, we measured the iodide concentration in breast milk and random urine of neonates, and the levels of neonatal thyroid-stimulating hormone (TSH) and free thyroxine.

RESULTS

The TSH levels in Group I and the breast-milk iodide concentrations in Groups I and II were significantly higher than those in Group IV (p < 0.05). Dietary iodide intake from breast milk correlated significantly with urinary iodide concentrations (r = 0.52, p < 0.001). In our clinic, the recall rate at the time of screening for congenital hypothyroidism was significantly decreased by discontinuing the use of PVP-I (4.47% vs 0.74%, p < 0.001).

CONCLUSIONS

These findings suggest that the use of PVP-I on mothers is associated with transient neonatal hyperthyrotropinemia, in which breast milk might play an important role. Therefore, we recommend that the use of PVP-I be avoided during labor.

The effect of platelet activating factor on ovulation

The mechanism of ovulation has been compared to an inflammatory reaction. Platelet activating factor (PAF) is an important mediator of inflammation as it may induce the production of prostaglandins and lysosomal enzyme. We evaluated the potential role of PAF in PMSG-HCG induced ovulation using CV3988, a specific PAF receptor antagonist in a superovulated ICR mice (9-12 weeks old). CV3988 blocked the ovulation in a dose dependent manner, and the significant reduced ovulatory efficiency was observed at more than 500 micrograms dose (p less than 0.001). The ovulatory efficiency reduced by CV3988 was reversed by PAF in a dose dependent manner. In vitro fertilization (IVF) rate of follicular oocytes with treatment of CV3988 was not different from that of ovulated ova without treatment. These results suggest that PAF may be involved in the ovulation process but the presence of PAF may not be essential for the fertilization of the ova as IVF.

[Transvaginal ultrasonographic findings and hCG levels in early intrauterine pregnancies]

The correlation of transvaginal ultrasound (TVU) findings with serial hCG determinations was evaluated during early pregnancy in 60 patients. In these patients, the time of ovulation was accurately determined by ultrasonic monitoring of follicular rupture. The results were as follows. 1) A gestational sac less than 6 mm in diameter was identified in 22 of 38 cases (57.9%) in 4 weeks gestation, and the mean number of cycle days for detection of the GS was 34.1 +/- 2.5. On the other hand, fetal heart movement was detected as early as 43.0 +/- 2.8 days from the last menstrual period. 2) A good linear relationship was found between the gestational age and size of the gestational sac and size of the fetus. 3) A gestational sac was identified in one of 10 cases (10.0%) with hCG levels below 1,000 mIU/ml (1st IRP), 5 of 6 with levels of 1,000-2,000 mIU/ml, and all 15 cases with levels above 2,000 mIU/ml. These results suggested that TVU could significantly improve the detection of gestational sacs, and result in a lower hCG threshold than previously established with transabdominal sonography. Furthermore, our findings derived from patients in which the date of ovulation could be accurately determined by ultrasound should be useful in further studies of early fetal development.

[The role of platelet activating factor in ovulation]

Ovulation is associated with inflammation-like changes. Platelet activating factor (PAF) participates in the inflammatory process. We evaluated the potential role of PAF in PMSG-HCG induced ovulation with CV3988, a specific PAF receptor antagonist in hyperovulated ICR mice (9-12 weeks old). Furthermore, we investigated whether prostaglandins (PGs) interfered with the ovulation induced by PAF. CV3988 blocked the ovulation in a dose dependent manner, and the significantly reduced ovulatory efficiency was observed at a dose greater than 500 micrograms (p less than 0.001). The ovulatory efficiency reduced by CV3988 (at a dose of 500 micrograms) was recovered by PAF in a dose dependent manner. PGs production in ovary was increased in reversing the blockade of ovulation with CV3988. These results suggest that PAF may be involved in the ovulation process and PGs may not potentiate the ability of PAF to play a role in ovulation.