Dysregulation of SCARB1 Alternative Splicing Disturbs Amino Acid Metabolism in Anembryonic Pregnancy

Anembryonic pregnancy (AP) accounts for a notable proportion of all first-trimester spontaneous miscarriage. Alternative splicing has been implicated in placental development and spontaneous abortion. However, the role of alternative splicing in modulating amino acid metabolism in AP remains unclear. We employed mass spectrometry to measure the levels of amino acids and metabolites in the serum of AP patients and healthy controls. RNA-Seq and rMATS were utilized to evaluate the alternative splicing profiles of chorionic villi from the two groups. Key splicing events in PRKCD, SCARB1, and METTL2B were subsequently validated by splicing-specific PCR. An integrated analysis, incorporating transcription factor prediction and publicly available datasets, was performed to explore the potential mechanisms by which alternative splicing may contribute to the metabolic disturbances in AP. Mass spectrometry analysis confirmed dysregulated of amino acid metabolism in AP. Compared to controls, AP patients exhibited 903 differentially alternative splicing genes and 558 differentially expressed genes, with skipping exons as the predominant alternative splicing type. Notably, PRKCD, SCARB1, and METTL2B displayed the most significant splicing changes, with preferential exon inclusion in AP samples. Motif analysis predicted that SCARB1 was a potential target gene of transcription factor TEAD4. Functional studies revealed that both SCARB1 and TEAD4 were involved in metabolism regulation, including amino acid and lipid metabolism. Our study demonstrates that dysregulation of alternative splicing in SCARB1 may contribute to AP by disrupting metabolic homeostasis, particularly amino acid metabolism. These findings highlight alternative splicing-mediated metabolic reprogramming as a potential mechanistic underpinning of AP.