Acts as a transcriptional repressor of the GATA3 promoter. Sequence-specific DNA-binding factor that binds to the 5'-AGGTCTC-3' sequence within the negative cis-acting element intronic regulatory region (IRR) of the GATA3 gene (By similarity). Component of the little elongation complex (LEC), a complex required to regulate small nuclear RNA (snRNA) gene transcription by RNA polymerase II and III (PubMed:23932780). Induces thymocyte apoptosis when overexpressed, which may indicate a role in regulation of thymocyte homeostasis. {ECO:0000250, ECO:0000269|PubMed:12077251, ECO:0000269|PubMed:12153508, ECO:0000269|PubMed:23932780}. This is the function of Ensembl gene identifier ENSG00000144161 (ZC3H8, zinc finger CCCH-type containing 8).