Objective To screen the proteins associated with four-and-a-half LIM domains 3 (FHL3) 3’ untranslated region (3’UTR) in glioma cells.
Methods Western blot was adopted to detect the regulatory effect of poly(C)-binding protein 2 (PCBP2) on FHL3. Biotin pull-down and sliver staining were employed to screen and verify the candidate binding proteins of FHL3 3’UTR. Then liquid chromatography-tandem mass spectrometry (LC-MS/MS) and molecule annotation system were used to identify and analyze the candidate binding proteins. Immuno-precipitation was conducted to study the interaction between PCBP2 and polypyrimidine tract-binding protein 1 (PTBP1), a binding protein identified by LC-MS/MS.
Results PCBP2 could bind to FHL3 mRNA 3’UTR-A and inhibited the expression of FHL3 in T98G glioms cells. 22 candidate binding proteins were identified. Among them, there were 11 RNA binding proteins, including PCBP2. PTBP1 associated with FHL3 mRNA 3’UTR and interacted with PCBP2 protein.
Conclusion PCBP2 and PTBP1 can both associate with FHL3 mRNA 3’UTR through forming a protein complex.

An analytical method based on solid phase extraction was developed and validated for analysis of adefovir in human plasma. Adefovir-d4 was used as an internal standard and Synergi MAX RP80A (150 mm × 4.6 mm, 4μm) column provided the desired chromatographic separation of compounds followed by detection with mass spectrometry. The method used simple isocratic chromato-graphic condition and mass spectrometric detection in the positive ionization mode. The calibration curves were linear over the range of 0.50–42.47 ng/mL with the lower limit of quantitation validated at 0.50 ng/mL. Matrix effect was assessed by post-column infusion experiment to monitor phospholipids and post-extraction addition experiment was performed. The degree of matrix effect for adefovir was determined as 7.5%and ion-enhancement in five different lots of human plasma was 7.1%and had no impact on study samples analysis with 4.5 min run time. The intra- and inter-day precision values were within 7.7% and 7.8%, respectively, for adefovir at the lower limit of quantification level. Validated bioanalytical method was successfully applied to clinical sample analysis.