Rabbit Anti-Human CSNK1D (C-terminal) Polyclonal antibody

Circadian rhythms are intrinsic similar to 24 hour cycles that regulate diverse aspects of physiology, and in turn are regulated by interactions with the external environment. Casein kinase 1 delta (CK1 delta, CSNK1D) is a key regulator of the clock, phosphorylating both stabilizing and destabilizing sites on the PER2 protein, in a mechanism known as the phosphoswitch. CK1 delta can itself be regulated by phosphorylation on its regulatory domain, but the specific sites involved, and the role this plays in control of circadian rhythms as well as other CK1-dependent processes is not well understood. Using a sensitized PER2:: LUC reporter assay, we identified a specific phosphorylation site, T347, on CK1 delta, that regulates CK1 delta activity towards PER2. A mutant CK1 delta T347A was more active in promoting PER2 degradation. This CK1 delta regulatory site is phosphorylated in cells in trans by dinaciclib- and staurosporine-sensitive kinases, consistent with their potential regulation by cyclin dependent and other proline-directed kinases. The regulation of CK1 delta by site-specific phosphorylation via the cell cycle and other signaling pathways provides a mechanism to couple external stimuli to regulation of CK1 delta-dependent pathways including the circadian clock.

Inhibition of casein kinase 1 delta (CK1 delta) blocks primary ciliogenesis in human telomerase reverse transcriptase immortalized retinal pigmented epithelial and mouse inner medullary collecting duct cells-3. Mouse embryonic fibroblasts (MEFs) and retinal cells from Csnk1d (CK1 delta)-null mice also exhibit ciliogenesis defects. CK1 delta catalytic activity and centrosomal localization signal (CLS) are required to rescue cilia formation in MEFs(Csnk1d null). Furthermore, expression of a truncated derivative containing the CLS displaces full-length CK1 delta from the centrosome and decreases ciliary length in control MEFs, suggesting that centrosomal CK1 delta has a role in ciliogenesis. CK1 delta inhibition also alters pericentrosomal or ciliary distribution of several proteins involved in ciliary transport, including Ras-like in rat brain11A, Ras-like in rat brain-8A, centrosomal protein of 290 kDa, pericentriolar material protein 1, and polycystin-2, as well as the Golgi distribution of its binding partner, A-kinase anchor protein 450 (AKAP450). As reported for AKAP450, CK1 delta was required for microtubule nucleation at the Golgi and maintenance of Golgi integrity. Overexpression of an AKAP450 fragment containing the CK1 delta-binding site inhibits Golgi-derived microtubule nucleation, Golgi distribution of intraflagellar transport protein 20 homologue, and ciliogenesis. Our results suggest that CK1 delta mediates primary ciliogenesis by multiple mechanisms, one involving its centrosomal function and another dependent on its interaction with AKAP450 at the Golgi, where it is important for maintaining Golgi organization and polarized trafficking of multiple factors that mediate ciliary transport.