The Homeodomain-Interacting Protein Kinases (HIPK) are a family of serine/threonine protein kinases shown to be critical in regulation of many cellular processes including cell survival, proliferation and apoptosis. Since there are four HIPK family members in mammals that show some redundancy, functional studies of this protein family can be simplified with the nematode Caenorhabditis elegans since it expresses a single HIPK protein (HPK-1).
Both HIPKs and HPK-1 localise to nuclear speckles suggesting that they are likely to be involved in analogous cellular processes. Despite this, the first published observation of
hpk-1 mutants reported no obvious phenotypes (Raich et al., 2003). Recently
hpk-1 was reported as one of the genes necessary for the extended lifespan of
daf-2 mutants (Samuelson et al., 2007). To expand on this knowledge we performed phenotypic analyses on a worm strain carrying a deletion mutation within
hpk-1 with the global aim of discovering some of the in vivo functions of worm HPK-1. Additionally, to gain insights into molecular mechanisms of HPK-1 function, microarray analysis was performed on the
hpk-1 mutant strain. These analyses have revealed that various cellular processes may be regulated by HPK-1 including ageing, metabolism and expression of collagens.
Reference list:
Raich, W. B., Moorman, C., Lacefield, C. O., Lehrer, J., Bartsch, D., Plasterk, R. H., et al. (2003). Characterization of Caenorhabditis elegans homologs of the Down syndrome candidate gene DYRK1A. Genetics 163, 571-80.
Samuelson, A. V., Carr, C. E. &Ruvkun, G. (2007). Gene activities that mediate increased life span of C. elegans insulin-like signaling mutants. Genes Dev 21, 2976-94.