HNRNPA2B1
Description
The HNRNPA2B1 (heterogeneous nuclear ribonucleoprotein A2/B1) is a protein-coding gene located on chromosome 7.
HNRNPA2B1 is a gene that encodes the Heterogeneous nuclear ribonucleoprotein A2/B1 protein, a member of the A/B subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs). The hnRNPs are RNA binding proteins that complex with heterogeneous nuclear RNA (hnRNA). These proteins are associated with pre-mRNAs in the nucleus and are involved in pre-mRNA processing, mRNA metabolism, and transport. HNRNPA2B1 has two repeats of quasi-RRM domains that bind to RNAs. Two alternatively spliced transcript variants are generated by this gene, encoding different isoforms. The HNRNPA2B1 gene contains 12 exons, including a B1 protein specific 36-nucleotide mini-exon. The intron/exon organization of HNRNPA2B1 is identical to that of the HNRNPA1 gene, suggesting a common origin through gene duplication.
HNRNPA2B1 is a heterogeneous nuclear ribonucleoprotein (hnRNP) that associates with nascent pre-mRNAs and packages them into hnRNP particles. The arrangement of these particles on nascent hnRNA is non-random and sequence-dependent, serving to condense and stabilize the transcripts and minimize tangling and knotting. This packaging plays a crucial role in various processes such as transcription, pre-mRNA processing, nuclear export, subcellular location, mRNA translation, and stability of mature mRNAs. HNRNPA2B1 forms hnRNP particles with at least 20 other hnRNPs and heterogeneous nuclear RNA in the nucleus. It's involved in transporting specific mRNAs to the cytoplasm in oligodendrocytes and neurons by recognizing and binding to A2RE (21 nucleotide hnRNP A2 response element) or A2RE11 (derivative 11 nucleotide oligonucleotide) sequence motifs present on some mRNAs. HNRNPA2B1 specifically binds single-stranded telomeric DNA sequences, protecting them from endonuclease digestion. It also binds to other RNA molecules, including primary miRNA (pri-miRNAs), acting as a nuclear 'reader' of the N6-methyladenosine (m6A) mark by specifically recognizing and binding a subset of nuclear m6A-containing pri-miRNAs. Binding to m6A-containing pri-miRNAs promotes their processing by enhancing the binding of DGCR8 to pri-miRNA transcripts. HNRNPA2B1 is involved in miRNA sorting into exosomes following sumoylation, possibly by binding to (m6A)-containing pre-miRNAs. It acts as a regulator of mRNA splicing efficiency, potentially by binding to m6A-containing pre-mRNAs. HNRNPA2B1 plays a role in the splicing of pyruvate kinase PKM by binding repressively to sequences flanking PKM exon 9, inhibiting exon 9 inclusion and resulting in exon 10 inclusion and production of the PKM M2 isoform. It also participates in the activation of the innate immune response by sensing the presence of viral DNA in the nucleus, homodimerizing, and being demethylated by JMJD6. This demethylation triggers translocation to the cytoplasm where it activates the TBK1-IRF3 pathway, leading to interferon alpha/beta production. HNRNPA2B1 is involved in the transport of HIV-1 genomic RNA out of the nucleus, to the microtubule organizing center (MTOC), and then to the cytoplasm. It specifically recognizes and binds the A2RE sequence motifs present on HIV-1 genomic RNA, promoting its transport. HNRNPA2B1 forms homodimers, which is necessary for nucleocytoplasmic translocation. It is found in the spliceosome C complex and in an IGF2BP1-dependent mRNP granule complex containing untranslated mRNAs. HNRNPA2B1 interacts with various proteins, including IGF2BP1, C9orf72, DGCR8, TARDBP, CKAP5, TBK1, STING1, SRC, and PPIA/CYPA.
HNRNPA2B1 is also known as HNRNPA2, HNRNPB1, HNRPA2, HNRPA2B1, HNRPB1, IBMPFD2, OPMD2, RNPA2, SNRPB1.
Associated Diseases
- Inclusion body myopathy with Paget disease of bone and frontotemporal dementia
- Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 2
- Oculopharyngeal muscular dystrophy 2
