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| miR-34a | |
|---|---|
| Name | miR-34a |
| Family | miR-34 family |
| Organism | Human |
| Location | Chromosome 1p36 |
| Length | ~22 nt (mature) |
| Precursor | pri-miR-34a / pre-miR-34a |
| Function | post-transcriptional gene regulation |
miR-34a is a vertebrate microRNA encoded in the human chromosome 1p36 locus that functions as a critical post-transcriptional regulator of gene expression. Discovered through genome-wide and functional screens alongside studies by groups affiliated with Harvard University, Cold Spring Harbor Laboratory, and Stanford University, miR-34a is integrated into networks governed by TP53 and other tumor suppressors, with broad impacts on apoptosis, cell cycle, senescence, and developmental programs. Its dysregulation has been implicated in cancers studied at institutions such as MD Anderson Cancer Center and Dana-Farber Cancer Institute, and it has been the subject of clinical translation efforts involving biotechnology firms and consortia.
miR-34a is a member of the miR-34 family that includes paralogs identified in comparative genomic surveys led by groups at Wellcome Trust Sanger Institute, Massachusetts Institute of Technology, and Max Planck Society. The mature ~22-nucleotide species arises from a primary transcript and exerts sequence-specific repression on target mRNAs via the RNA-induced silencing complex core components including Argonaute proteins. Early functional characterization connected miR-34a activity to the TP53 pathway, and subsequent research by teams at NIH, European Molecular Biology Laboratory, and Cold Spring Harbor Laboratory expanded its role across signaling cascades relevant to oncology and neurobiology.
The MIR34A gene resides at 1p36, a genomic region frequently altered in studies reported from Memorial Sloan Kettering Cancer Center and Karolinska Institutet. Transcription of the MIR34A locus is driven by promoters responsive to factors such as TP53, with regulatory inputs characterized by chromatin studies from Broad Institute and ENCODE Project Consortium. The primary miR-34a transcript (pri-miR-34a) is processed by the Drosha microprocessor complex and exported by Exportin-5 to be cleaved by Dicer into the pre-miRNA and mature duplex; mature strand loading into AGO2 yields the active effector. Epigenetic silencing via promoter CpG methylation, reported by groups at Johns Hopkins University and University College London, also modulates MIR34A expression in specific tissues and tumors.
miR-34a recognizes target sites in 3' untranslated regions of mRNAs, recruiting the RNA-induced silencing complex to inhibit translation and promote decay, a mechanism elucidated in biochemical work from University of California, San Francisco and Stanford University School of Medicine. Validated targets include transcripts encoding proteins such as BCL2, CDK4, CDK6, MYC, SIRT1, and MET, based on reporter assays and crosslinking-immunoprecipitation studies performed in laboratories at Yale University and University of Cambridge. Through these targets miR-34a modulates pathways governed by RAS, PI3K, and Wnt signaling nodes, as mapped in pathway analyses by teams at Institute of Cancer Research and Cold Spring Harbor Laboratory.
In vivo models developed at institutions including University of California, San Diego and Max Planck Institute for Heart and Lung Research have shown miR-34a involvement in organogenesis, neuronal differentiation, and stem cell regulation. Mouse knockout and transgenic studies reported from The Jackson Laboratory and Scripps Research indicate roles in postnatal neural plasticity, cardiac stress responses, and hematopoietic lineage decisions. Developmental functions intersect with transcriptional regulators such as NOTCH1, SOX2, and E2F family members, linking miR-34a to networks described by research teams at Cold Spring Harbor Laboratory and European Molecular Biology Laboratory.
miR-34a has been characterized as a tumor suppressor in multiple malignancies studied at Memorial Sloan Kettering Cancer Center, Mayo Clinic, and University of Texas MD Anderson Cancer Center. Loss of MIR34A via deletion, promoter methylation, or transcriptional repression correlates with progression in cancers including neuroblastoma, colorectal cancer, non-small cell lung carcinoma, breast cancer, and hepatocellular carcinoma, reported across consortia involving The Cancer Genome Atlas and International Cancer Genome Consortium. Functional restoration experiments using miR-34a mimics reduced proliferation, induced apoptosis, and sensitized cells to chemotherapeutics in preclinical models from Cold Spring Harbor Laboratory and Dana-Farber Cancer Institute, whereas oncogenic pathways mediated by MYC and MET are attenuated following miR-34a expression.
Beyond oncology, miR-34a contributes to age-related phenotypes and pathologies explored by groups at Buck Institute for Research on Aging, Harvard Medical School, and Karolinska Institutet. Elevated miR-34a levels have been linked to cardiac aging, fibrosis, neurodegeneration, and metabolic dysregulation in studies from Johns Hopkins University and Imperial College London. Mechanistically, interactions with targets such as SIRT1 implicate miR-34a in pathways connecting cellular senescence, mitochondrial function, and inflammatory signaling pathways investigated by the National Institute on Aging.
Therapeutic development of miR-34a-based agents progressed to Phase I trials led by biotechnology companies and clinical centers including Mirna Therapeutics and trial sites at MD Anderson Cancer Center and University of California, San Francisco. Delivery challenges addressed by collaborations with groups at MIT and ETH Zurich focus on lipid nanoparticles, viral vectors, and conjugate chemistries. Combination strategies pairing miR-34a restoration with checkpoint inhibitors and targeted therapies are under preclinical evaluation at Dana-Farber Cancer Institute and Stanford Cancer Institute, while epigenetic reactivation strategies are pursued by teams at University College London and Broad Institute.
Category:MicroRNA