INVASION INHIBITORY PROTEIN, 45-KD

Alternative titles; symbols

• IIP45

HGNC Approved Gene Symbol: MIIP

Cytogenetic location: 1p36.22 Genomic coordinates (GRCh38): 1:12,019,465-12,032,044 (from NCBI)

▼ Cloning and Expression

Using IGFBP2 (146731) as bait in a yeast 2-hybrid screen of a fetal brain cDNA library, followed by RT-PCR of total fetal brain mRNA, Song et al. (2003) cloned IIP45. The deduced 291-amino acid protein has 3 SEG (segments of low compositional complexity) domains, an RGD motif, and several potential phosphorylation sites. Northern blot analysis detected ubiquitous expression of 1.6- and 2.4-kb transcripts. Western blot analysis detected IIP45 at an apparent molecular mass of 45 kD in all normal adult brains and anaplastic gliomas tested and in 85% of glioblastoma multiforme (GBM) tissues tested. A slow motility band was also detected in 73% of the GBMs.

▼ Gene Function

Song et al. (2003) confirmed direct interaction between IIP45 and IGFBP2 using a number of protein interaction assays. Using truncation constructs, they showed that the 77-amino acid C-terminal region of IGFBP2 interacts with a central 44-amino acid sequence of IIP45. Functional studies in a human GBM cell line showed that IIP45 inhibited GBM invasion both in vitro and in a xenograft model. IIP45 consistently inhibited expression of cell invasion-associated genes, such as NFKB (see 164011) and its downstream target gene, ICAM1 (147840).

▼ Gene Structure

Song et al. (2003) determined that the IIP45 gene contains 9 exons.

▼ Mapping

By genomic sequence analysis, Song et al. (2003) mapped the IIP45 gene to chromosome 1p36.