Transcription factor MafA

MAFA
Identifiers
Aliases	MAFA, RIPE3b1, hMafA, MAF bZIP transcription factor A, INSDM
External IDs	OMIM: 610303; MGI: 2673307; GeneCards: MAFA
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 4EOT
Gene location (Human) Chr. Chromosome 8 (human) Band 8q24.3 Start 143,419,182 bp End 143,430,732 bp
Gene location (Mouse) Chr. Chromosome 15 (mouse) Band 15|15 D3 Start 75,617,339 bp End 75,620,077 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in muscle of thigh gastrocnemius muscle skeletal muscle tissue gonad islet of Langerhans testicle right testis left testis body of pancreas placenta Top expressed in islet of Langerhans vastus lateralis muscle triceps brachii muscle sternocleidomastoid muscle temporal muscle ankle gastrocnemius muscle tibialis anterior muscle muscle of thigh digastric muscle More reference expression data BioGPS More reference expression data
Gene ontology Molecular function DNA-binding transcription factor activity protein heterodimerization activity DNA binding DNA-binding transcription activator activity, RNA polymerase II-specific RNA polymerase II cis-regulatory region sequence-specific DNA binding protein homodimerization activity DNA-binding transcription factor activity, RNA polymerase II-specific sequence-specific DNA binding Cellular component nucleus Biological process regulation of transcription, DNA-templated response to glucose insulin secretion transcription by RNA polymerase II positive regulation of transcription by RNA polymerase II positive regulation of transcription, DNA-templated nitric oxide mediated signal transduction transcription, DNA-templated Sources:Amigo / QuickGO
Orthologs Databases NCBI: entry; OMA: entry Species Human Mouse Entrez 389692 378435 Ensembl ENSG00000182759 ENSMUSG00000047591 UniProt Q8NHW3 Q8CF90 RefSeq (mRNA) NM_201589 NM_194350 RefSeq (protein) NP_963883 NP_919331 Location (UCSC) Chr 8: 143.42 – 143.43 Mb Chr 15: 75.62 – 75.62 Mb PubMed search
Wikidata
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Transcription factor MafA is a protein that in humans is encoded by the MAFA gene. It is a member of the Maf family of transcription factors.

Tissue distribution

In addition to its expression in pancreatic ßcells, MAFA is also expressed in specific subsets of  excitatory and inhibitory neurons. In the peripheric nervous system, it is expressed in touch mechanoreceptors.  In the central nervous system,  Mafa is expressed in sensory neurons in the spinal cord and trigeminal nucleus, as well as in the olfactory bulb. It is also present in ventral inhibitory neurons of the spinal cord (Renshaw cells) and in brainstem inhibitory neurons controlling mouse neonatal apneas.

Regulation

MAFA is phosphorylated sequentially on four serine/threonine residues by GSK-3 kinase. These phosphorylations activate MAFA transcription and trigger its degradation in the proteasome. Altering these post-translationnal modifications leads to severe pathological consequences. Mutation of these  residues  is perinatally lethal in mice, and  mutation of the Ser64Phe priming site was reported to induce familial diabetes mellitus and insulinomatosis in humans.

Function

An in vivo study on mice proved MafA binds to the promoter in an insulin gene to regulate insulin transcription in response to serum glucose levels. MafA is a β cell-specific activator, which differentiates it from other transcription factors involved with insulin gene expression. It helps regulate the β cells involved with insulin secretion primarily by maintaining β cell metabolism. The amount of MafA in the β cells is regulated by levels of glucose and oxidative stress.

Interactions

MafA has been shown to interact with NEUROD1 and Pdx1. MafA works with Pdx1 to activate the insulin gene.