Disease relevance of INCENP

• By using a complex of proteins expressed in baculovirus, immunoblot analysis demonstrated that the INCENP protein is a major autoantigen in this patient with GLPL syndrome [1].
• In carcinomas, Incenp mRNA correlated with T category (p = 0.0149), and Survivin (p = 0.0382) and Cyclin-D1 (p = 0.0185) were associated with tumour differentiation [2].

High impact information on INCENP

• Here we report the identification of Dasra A and Dasra B, two new components of the vertebrate chromosomal passenger complex containing Incenp, Survivin, and the kinase Aurora B, and demonstrate that this complex is required for chromatin-induced microtubule stabilization and spindle formation [3].
• Phosphorylation of two serines in the carboxyl terminus of INCENP generates the fully active kinase [4].
• This phenotype is rescued by the exogenous expression of INCENP wild type and INCENP mutated at Thr 59 to Ala (T59A), but not at Thr 388 to Ala (T388A) [5].
• The replacement of endogenous INCENP with T388A resulted in the delay of progression from metaphase to anaphase [5].
• PIASy-dependent SUMO-2-conjugated species were highly concentrated on the inner centromere, and inhibition of PIASy blocked anaphase sister chromatid segregation in egg extracts [6].

Biological context of INCENP

• INCENP centromere and spindle targeting: identification of essential conserved motifs and involvement of heterochromatin protein HP1 [7].
• To begin to understand the mechanisms of INCENP function in mitosis, we have performed a yeast two-hybrid screen for interacting proteins [7].
• Surprisingly, this interaction does not appear to be involved in targeting INCENP to the centromeric heterochromatin, but may instead have a role in its transfer from the chromosomes to the anaphase spindle [7].
• Furthermore, Aurora-C co-expressed with INCENP elicits the phosphorylation of endogenous histone H3 in mammalian cells, even though this phosphorylation is not sufficient to establish chromosome condensation in interphase cells [8].
• A nonphosphorylatable mutant (TSS893-895AAA) was a poor activator of Aurora B, demonstrating that INCENP phosphorylation is important for kinase activation [9].

Anatomical context of INCENP

• Second, INCENP and Aurora-B exist in a complex in Xenopus eggs [9] and in mammalian cultured cells [7] [10].
• When microtubules are eliminated, INCENP is dispersed across the entire cell cortex [11].
• Functional activity of the neocentromere is shown by the retention of the ring chromosome in 97% of the patient's lymphocytes and 100% of his cultured fibroblasts, as well as by the presence of key centromere binding proteins CENP-E, CENP-F, and INCENP [12].
• Although relaxing furrows contained overlapping microtubules from opposing centrosomes, they lacked microtubule bundles as well as INCENP and CHO1 [13].
• Analysis of mitotic cells with incomplete chromatid separation showed that reassembly of the nuclear membrane, deposition of INner CENtromere Protein (INCENP)/Aurora B to the spindle midzone and furrow formation occur while the two groups of daughter chromosomes are still connected by sex chromosome arms [14].

Associations of INCENP with chemical compounds

• Mutation at threonine 117 also prevented immunoprecipitation of INCENP with survivin in vivo [15].

Physical interactions of INCENP

• These data suggest that Aurora B kinase activity and the formation of the Aurora B/INCENP/survivin complex both contribute to its proper localization [9].
• INCENP binds the Aurora-related kinase AIRK2 and is required to target it to chromosomes, the central spindle and cleavage furrow [16].

Enzymatic interactions of INCENP

• We report here that human Aurora-B is phosphorylated at Thr-232 through interaction with the inner centromere protein (INCENP) in vivo [17].

Regulatory relationships of INCENP

• We show that INCENP binds and activates Aurora-C in vivo and in vitro [8].
• Using recombinant proteins, we found that Aurora B kinase activity was stimulated by INCENP and that the C-terminal region of INCENP was sufficient for activation [9].

Other interactions of INCENP

• Direct association with inner centromere protein (INCENP) activates the novel chromosomal passenger protein, Aurora-C [8].
• Furthermore, we show that INCENP is required for recruiting MKLP1 to the spindle midzone/midbody [18].
• Our data support a model where CENP-A phosphorylation is involved in regulating Aurora B, INCENP, and PP1gamma1 targeting within the cell [19].
• EVI5 protein associates with the INCENP-aurora B kinase-survivin chromosomal passenger complex and is involved in the completion of cytokinesis [20].
• TD-60 and INCENP also show identical localization in cells that exit mitosis in the presence of dihydrocytochalasin B (DCB), an inhibitor of actin assembly [21].

Analytical, diagnostic and therapeutic context of INCENP

• Immunofluorescence and live-cell imaging analyses have shown that, in addition to multiple chromosome segregation defects, cells that lacked INCENP by RNAi (RNA interference) exhibit abnormal spindle midzone/midbody formation, resulting in formation of binucleated/multinucleated cells [18].
• We have identified the human INCENP gene by library screening and reverse transcription-polymerase chain reaction (RT-PCR) and localized it to chromosomal region 11q12 [22].
• In addition, INCENP, ZWINT-1, ZW10 antisense-treated chromosome morphology was very similar to that of Roberts chromosome when analysed by atomic force microscopy [23].

References