Expanded alleles of the FMR1 gene are related to unexplained recurrent miscarriages

Maternal FMR1 alleles expansion in newborns during transmission: a prospective cohort study

INTRODUCTION

The CGG repeats in the 5' untranslated region of the fragile X mental retardation 1 gene (FMR1) gene shows increased instability upon maternal transmission. Maternal FMR1 intermediate (45-54 repeats) and premutation (PM: 55-<200 repeats) alleles usually expand to full mutation (>200 repeats) alleles in offspring and consequently, cause fragile X syndrome (FXS) in them.

METHODS

In a prospective cohort study, Pakistani pregnant women in prenatal care were first screened for FMR1 expanded alleles. In the follow-up, pregnancy outcomes in women carrying FMR1 expanded alleles were recorded and their newborn offspring were also screened for FXS.

RESULTS

In a total of 1950 pregnant women, 89 (4.6%) were detected carriers for FMR1 expanded alleles; however, rates of detection of expanded alleles were found significantly high in women with a history of FXS. In addition, miscarriages and birth of affected newborns with FXS were significantly more common in women carrying large size PM alleles and had a history of FXS (P = 0.0494 and P = 0.0494, respectively).

CONCLUSIONS

The current study provides the first evidence of screening Pakistani pregnant women for FMR1 expanded alleles in prenatal care. Moreover, the miscarriage was also detected as a clinical predictor for FXS.

IMPACT

Offspring would have a higher risk of developing FXS due to maternal FMR1 alleles expansions during transmission. This is the first prospective cohort study in Pakistan for finding FMR1 allelic status of pregnant women and their newborn offspring in follow-up. The robust offspring risk for FXS estimated in this study may be valuable information for genetic counseling of women carriers for FMR1 expanded alleles. The family history and miscarriage were detected as effective indicators for FXS carrier screening in Pakistani women.

Glutathione peroxidase 3 (GPX3) suppresses the growth of melanoma cells through reactive oxygen species (ROS)-dependent stabilization of hypoxia-inducible factor 1-α and 2-α

In this study, we aimed to explore the mechanism of glutathione peroxidase 3 (GPX3) in the growth of malignant melanoma (MM) cells by hypoxia-inducible factor-1α (HIF1-α) and HIF2-α regulating the metabolism through reactive oxygen species (ROS). The messenger RNA and protein expression of GPX3, HIF1-α, HIF2-α in tissues, and cell lines were measured by reverse transcription-quantitative PCR and Western blot analysis. A375 cells were transfected with GPX3 overexpression plasmid, small interfering RNA (siRNA) targeting GPX3, or siRNA targeting HIF1-α/HIF2-α to upregulate or downregulate the expression of GPX3 or HIF1-α/HIF2-α. The effects of H₂ O₂ and N-acetylcysteine (NAC) on the levels of HIF1-α and HIF2-α after overexpression of GPX3 were studied. The cell viability was detected by Cell Counting Kit-8. The levels of ROS, glucose uptake and lactic acid production, oxidative phosphorylation, and glycolysis of cells were measured for assessment of cellular metabolism. The expression of GPX3 decreased, while ROS, HIF1-α, and HIF2-α increased in MM tissues and cells. Overexpression of GPX3 inhibited the viability of MM cells and the growth of melanoma xenografts. The overexpression of GPX3 reduced the glucose uptake, extracellular lactic acid content, and extracellular acidification rate and increased the oxygen consumption rate level. Overexpression of GPX3 could reduce the levels of HIF1-α and HIF2-α, which could regulate metabolic levels. GPX3 reduced ROS level in MM to inhibit HIF1-α and HIF2-α. The addition of H₂ O₂ increased while NAC reduced the protein levels of HIF1-α and HIF2-α in the cells overexpressing GPX3. Our study demonstrates that GPX3 inhibits the growth of MM cells through its inhibitory effect on cell metabolic disorder by inhibiting HIF1-α via regulating ROS.

Effect of STOX1 on recurrent spontaneous abortion by regulating trophoblast cell proliferation and migration via the PI3K/AKT signaling pathway

STOX1 is a transcription factor that is implicated in the high prevalence of human gestational diseases. It has been studied in various types of gestational diseases using different molecular and cellular biological technologies. However, the effect and detailed mechanism of storkhead box 1 (STOX1) in recurrent spontaneous abortion (RSA) remain unknown. This study aimed to explore the effect and detailed mechanism of STOX1 in human trophoblast cells. The result showed that downregulation of STOX1 by short hairpin RNA (shRNA) led to a decrease in proliferation and migration in HTR-8/SVneo cells, while it induced the apoptosis of HTR-8/SVneo cells. Moreover, the result showed that trophoblast cells expressed lower levels of pAKT and p85 subunits after treatment with STOX1 shRNA when compared with control. However, overexpression of STOX1 obviously increased the pAKT and p85 protein expressions. Transfection of pcDNA-AKT plasmid increased cell proliferation and migration in HTR-8/SVneo cells while suppressed the apoptosis of HTR-8/SVneo cells. Furthermore, inhibition of the PI3K/Akt pathway by a specific inhibitor promoted cell apoptosis and aggravatedly suppressed cell proliferation and migration of HTR-8/SVneo cells. On the other hand, upregulation of the PI3K/Akt pathway could increase the relative expression level of Bcl-2 and decrease the relative expression levels of Bax and Bim, while inhibition of the PI3K/Akt pathway led to adverse results. Our results demonstrated that inhibition of STOX1 could suppress trophoblast cell proliferation and migration, while promote apoptosis through inhibiting the PI3K/Akt signaling pathway. These findings might provide a new fundamental mechanism for regulating RSA and could be used to prevent and treat RSA in clinic.

microRNA-802 inhibits cell proliferation and induces apoptosis in human cervical cancer by targeting serine/arginine-rich splicing factor 9

microRNAs (miRNAs) play crucial roles in cancer development and progression by targeting mRNAs for degradation and/or translational repression. microRNA-802 (miR-802) has been reported as a tumor suppressor and its deregulation is observed in various human cancers. However, the prognostic value of miR-802 and its underlying mechanisms involved in human cervical cancer are poorly investigated. The purposes of this study were to explore the role of miR-802 in cervical cancer and to clarify the regulation of serine/arginine-rich splicing factor 9 (SRSF9) by miR-802. Here, we found that miR-802 was downregulated in both cervical cancer tissues and cell lines. Transfection of a miR-802 mimic into cervical cancer cells inhibited their proliferation and colony formation, and promoted cell cycle arrest at the G0/G1 phase and cell apoptosis. In addition, we found that miR-802 could directly target the 3'-untranslated region of SRSF9 and suppress SRSF9 expression. Rescue experiments revealed that overexpression of SRSF9 partially reversed the inhibition effect of miR-802 in cervical cancer cells. Overall, these findings demonstrate that miR-802 functions as a tumor suppressor in cervical cancer by targeting SRSF9, suggesting that miR-802 might serve as a potential therapeutic target in cervical cancer.

Curvilinear Association Between Language Disfluency and FMR1 CGG Repeat Size Across the Normal, Intermediate, and Premutation Range

Historically, investigations of FMR1 have focused almost exclusively on the clinical effects of CGG expansion within the categories of the premutation (55-200 CGG repeats) and fragile X syndrome (>200 CGG repeats). However, emerging evidence suggests that CGG-dependent phenotypes may occur across allele sizes traditionally considered within the "normal" range. This study adopted an individual-differences approach to determine the association between language production ability and CGG repeat length across the full range of normal, intermediate, and premutation alleles. Participants included 61 adult women with CGG repeats within the premutation (n = 37), intermediate (i.e., 41-54 repeats; n = 2), or normal (i.e., 6-40 repeats; n = 22) ranges. All participants were the biological mothers of a child with a developmental disorder, to control for the potential effects of parenting stress. Language samples were collected and the frequency of language disfluencies (i.e., interruptions in the flow of speech) served as an index of language production skills. Verbal inhibition skills, measured with the Hayling Sentence Completion Test, were also measured and examined as a correlate of language disfluency, consistent with theoretical work linking language disfluency with inhibitory deficits (i.e., the Inhibition Deficit Hypothesis). Blood samples were collected to determine FMR1 CGG repeat size. A general linear model tested CGG repeat size of the larger allele (allele-2) as the primary predictor of language disfluency, covarying for education level, IQ, age, and CGG repeats on the other allele. A robust curvilinear association between CGG length and language disfluency was detected, where low-normal (∼ <25 repeats) and mid-premutation alleles (∼90-110 repeats) were linked with higher rates of disfluency. Disfluency was not associated with inhibition deficits, which challenges prior theoretical work and suggests that a primary language deficit could account for elevated language disfluency in FMR1-associated conditions. Findings suggest CGG-dependent variation in language production ability, which was evident across individuals with and without CGG expansions on FMR1.