Effect of placental sex hormone-binding globulin single nucleotide polymorphism rs6259 on protein and function in gestational diabetes mellitus.
Sex hormone-binding globulin (SHBG) has a key role in the occurrence and development of the gestational diab-etes mellitus (GDM). Single nucleotide polymorphism (SNP) rs6259 is a functional site in SHBG gene, which is suspected to regulate the SHBG level. The present study explored the placental SHBG SNP rs6259 distribution in Chinese pregnant women and the influence on placental SHBG concentrations, to assess the relationship of SHBG rs6259 in the occurrence and development of GDM. We screened the SHBG rs6259 allele in 210 healthy and 180 GDM gravidas by PCR-RFLP and restriction enzyme and measured placental SHBG concentrations in each genotypic group with western blot analysis. The mechanisms of SHBG rs6259 function were analyzed by cell culture, recombinant lentivirus transfection, real-time PCR, and western blot analysis. We found the differences of SHBG Asn327 allele frequency and the genotype distribution in GDM and control groups were statistically significant (P<0.05). Western blot analysis results showed that the Asn327 allele group was associated with a higher placental SHBG level than the Asp327 allele homozygote group (P<0.05). In HTR8-SVneo cell transfection, the positive transfection groups (SHBG-rs6259 Asn) led to an obviously higher tendency of SHBG mRNA and protein expression than the negative control groups (SHBG-rs6259 Asp), the normal cell group, and the blank control group (blank lentivirus LV-5) (P<0.05). Our data, therefore, reflected that SHBG SNP rs6259 causes changes in placental SHBG concentration and may play a functional role in the molecular mechanisms of GDM etiology.