Alternative titles; symbols
HGNC Approved Gene Symbol: MIDN
Cytogenetic location: 19p13.3 Genomic coordinates (GRCh38) : 19:1,248,583-1,259,143 (from NCBI)
Using a gene trap method, Tsukahara et al. (2000) identified the mouse Midn gene. By screening an embryonic mouse cDNA library, they obtained Midn cDNA clones predicted to encode a 508-amino acid protein containing a ubiquitin-like domain. Tsukahara et al. (2000) noted that 3 different cDNAs are generated by alternative splicing. RT-PCR and whole-mount in situ hybridization analyses detected strong expression of Midn during embryogenesis in the mesencephalon from embryonic day 11.5 to 12.5. At day 12.5, weaker and more widespread expression was detected in various cell types. Northern blot analysis showed Midn expression in all adult tissues tested, with high levels in heart, lung, liver, and kidney. Tsukahara et al. (2000) localized Midn to the nucleus and nucleolus and identified a C-terminal 28-amino acid peptide important for nucleolar localization. They concluded that Midn is involved in the regulation of genes related to neurogenesis in the nucleolus.
Hofmeister-Brix et al. (2013) found that Midn was expressed in nuclei and cytoplasm, but not nucleoli, of rat and mouse insulin-secreting cell lines. Staining of pancreatic sections showed Midn expression in inlets, but only negligible expression was present in surrounding exocrine tissue. Western blot analysis of various mouse tissues and rat, mouse, and human cell lines detected MIDN at an apparent molecular mass of 50 kD. Human MIDN was also expressed as an approximately 35-kD isoform.
Using a yeast 2-hybrid assay and other protein interaction assays, Hofmeister-Brix et al. (2013) found that full-length Midn, the isolated N-terminal ubiquitin-like domain of Midn, or a Midn fragment containing the ubiquitin-like domain bound glucokinase (GCK; 138079) in rat and mouse pancreatic beta cells and cell lines. Binding was strongest at low glucose concentration, when glucokinase exists mainly in its inactive super-open-to-open conformation. Overexpression of fluorescence-tagged Midn inhibited glucokinase activity, reduced the affinity of glucokinase for glucose, and reduced glucose-induced insulin secretion in rat pancreatic MIN6 cells.
Tsukahara et al. (2000) determined that the murine Midn gene contains 9 exons.
Scott (2002) mapped the human MIDN gene to chromosome 19 based on similarity between the murine Midn sequence (GenBank AB036882) and a chromosome 19 clone (GenBank AC004221).
Hartz (2014) mapped the MIDN gene to chromosome 19p13.3 based on an alignment of the MIDN sequence (GenBank BC015089) with the genomic sequence (GRCh37).
Hartz, P. A. Personal Communication. Baltimore, Md. 6/11/2014.
Hofmeister-Brix, A., Kollmann, K., Langer, S., Schultz, J., Lenzen, S., Baltrusch, S. Identification of the ubiquitin-like domain of midnolin as a new glucokinase interaction partner. J. Biol. Chem. 288: 35824-35839, 2013. [PubMed: 24187134] [Full Text: https://doi.org/10.1074/jbc.M113.526632]
Scott, A. F. Personal Communication. Baltimore, Md. 2/20/2002.
Tsukahara, M., Suemori, H., Noguchi, S., Ji, Z.-S., Tsunoo, H. Novel nucleolar protein, midnolin, is expressed in the mesencephalon during mouse development. Gene 254: 45-55, 2000. [PubMed: 10974535] [Full Text: https://doi.org/10.1016/s0378-1119(00)00259-6]