LIN28B cDNA Clone – Protein Lin-28 Homolog B

The protein encoded by this gene belongs to the lin-28 family, which is characterized by the presence of a cold-shock domain and a pair of CCHC zinc finger domains. This gene is highly expressed in testis, fetal liver, placenta, and in primary human tumors and cancer cell lines. It is negatively regulated by microRNAs that target sites in the 3' UTR, and overexpression of this gene in primary tumors is linked to the repression of let-7 family of microRNAs and derepression of let-7 targets, which facilitates cellular transformation. [provided by RefSeq, Jun 2012]

LIN28B: Acts as a suppressor of microRNA (miRNA) biogenesis by specifically binding the precursor let-7 (pre-let-7), a miRNA precursor. Acts by binding pre-let-7 and recruiting ZCCHC11/TUT4 uridylyltransferase, leading to the terminal uridylation of pre- let-7. Uridylated pre-let-7 miRNAs fail to be processed by Dicer and undergo degradation. Specifically recognizes the 5'-GGAG-3' motif in the terminal loop of pre-let-7. Also recognizes and binds non pre-let-7 pre-miRNAs that contain the 5'-GGAG-3' motif in the terminal loop, leading to their terminal uridylation and subsequent degradation. Mediates MYC-mediated let-7 repression. Isoform 1, when overexpressed, stimulates growth of the breast adenocarcinoma cell line MCF-7. Isoform 2 has no effect on cell growth. Interacts with ZCCHC11/TUT4. Might be negatively regulated by the microRNA let-7b. High expression in testis, fetal liver, placenta and in hepatocellular carcinoma (HCC). Isoform 1 is only detected in moderately and poorly differentiated HCC tissues and placenta. Isoform 2 is detected in fetal liver, non-tumor liver tissues, as well as well-differentiated tumor tissues. Belongs to the lin-28 family. 2 isoforms of the human protein are produced by alternative splicing.

Protein type: Unknown function

Chromosomal Location of Human Ortholog: 6q21

Cellular Component: nucleoplasm; mitochondrion; cytoplasm; nucleolus; nucleus

Molecular Function: protein binding; DNA binding; zinc ion binding; RNA binding

Biological Process: regulation of transcription, DNA-dependent; pre-microRNA processing; RNA 3'-end processing