Transcriptional repressor (PubMed:12052894, PubMed:15231840). Recognizes and binds to the consensus sequence '5-[CG]NG[CG]GGGCA[CA]CC-3' (PubMed:15231840). May act as a tumor suppressor (PubMed:20154726). Involved in development of head, face, limbs and ventral body wall (By similarity). Involved in down-regulation of SIRT1 and thereby is involved in regulation of p53/TP53-dependent apoptotic DNA-damage responses (PubMed:16269335). The specific target gene promoter association seems to be depend on corepressors, such as CTBP1 or CTBP2 and MTA1 (PubMed:12052894, PubMed:20547755). In cooperation with MTA1 (indicative for an association with the NuRD complex) represses transcription from CCND1/cyclin-D1 and CDKN1C/p57Kip2 specifically in quiescent cells (PubMed:20547755). Involved in regulation of the Wnt signaling pathway probably by association with TCF7L2 and preventing TCF7L2 and CTNNB1 association with promoters of TCF-responsive genes (PubMed:16724116). Seems to repress transcription from E2F1 and ATOH1 which involves ARID1A, indicative for the participation of a distinct SWI/SNF-type chromatin-remodeling complex (PubMed:18347096, PubMed:19486893). Probably represses transcription of ACKR3, FGFBP1 and EFNA1 (PubMed:16690027, PubMed:19525223, PubMed:20154726). Self-associates (PubMed:10611298, PubMed:12052894). Interacts with HIC2 (PubMed:11554746). Interacts with CTBP1 and CTBP2 (PubMed:12052894, PubMed:16762039). Interacts with TCF7L2 and ARID1A (PubMed:16724116, PubMed:19486893). Interacts with MTA1 and MBD3; indicative for an association with the NuRD complex (PubMed:20547755). Interacts with SIRT1 (By similarity). Additional isoforms seem to exist. Ubiquitously expressed with highest levels found in lung, colon, prostate, thymus, testis and ovary. Expression is absent or decreased in many tumor cells. The BTB domain inhibits the binding to a single consensus binding site, but mediates cooperative binding to multiple binding sites. Acetylated on several residues, including Lys-333. Lys-333 is deacetylated by SIRT1. Sumoylated on Lys-333 by a PIAS family member, which enhances interaction with MTA1, positively regulates transcriptional repression activity and is enhanced by HDAC4. The HIC1 gene is frequently found epigenetically silenced or deleted in different types of solid tumors. Belongs to the krueppel C2H2-type zinc-finger protein family. Hic subfamily.