Interaction of the Plasma Membrane Ca2+ Pump 4b/CI with the Ca2+/Calmodulin-dependent Membrane-associated Kinase CASK

Abstract

Spatial and temporal regulation of intracellular Ca 2؉ is a key event in many signaling pathways. Plasma membrane Ca 2؉ -ATPases (PMCAs) are major regulators of Ca 2؉ homeostasis and bind to PDZ (PSD-95/Dlg/ZO-1) domains via their C termini. Various membrane-associated guanylate kinase family members have been identified as interaction partners of PMCAs. In particular, SAP90/PSD95, PSD93/chapsyn-110, SAP97, and SAP102 all bind to the C-terminal tails of PMCA "b" splice variants. Additionally, it has been demonstrated that PMCA4b interacts with neuronal nitric-oxide synthase and that isoform 2b interacts with Na ؉ /H ؉ exchanger regulatory factor 2, both via a PDZ domain. CASK (calcium/calmodulin-dependent serine protein kinase) contains a calmodulin-dependent protein kinase-like domain followed by PDZ, SH3, and guanylate kinase-like domains. In adult brain CASK is located at neuronal synapses and interacts with various proteins, e.g. neurexin and Veli/LIN-7. In kidney it is localized to renal epithelia. Surprisingly, interaction with the Tbr-1 transcription factor, nuclear transport, binding to DNA Telements (in a complex with Tbr-1), and transcriptional competence has been shown. Here we show that the C terminus of PMCA4b binds to CASK and that both proteins co-precipitate from brain and kidney tissue lysates. Immunofluorescence staining revealed co-expression of PMCA, CASK, and calbindin-D-28K in distal tubuli of rat kidney sections. To test if physical interaction of both proteins results in functional consequences we constructed a T-element-dependent reporter vector and investigated luciferase activity in HEK293 lysates, previously co-transfected with PMCA4b expression and control vectors. Expression of wild-type PMCA resulted in an 80% decrease in T-element-dependent transcriptional activity, whereas co-expression of a point-mutated PMCA, with nearly eliminated Ca 2؉ pumping activity, had only a small influence on regulation of transcriptional activity. These results provide evidence of a new direct Ca 2؉ -dependent link from the plasma membrane to the nucleus. (12). In contrast to these observations, overexpression of PMCA4b in the myocardium of transgenic rats did not result in an altered regulation of contraction/relaxation cycle but in an enhanced growth response of cardiac myocytes to different stimuli (13). Additionally, it has been shown that the C termini of several PMCA variants, especially variants PMCA4b and PMCA2b, bind to PDZ domains of proteins of the MAGUK (membrane-associated guanylate kinases) family (14,15), to the PDZ domain of nitricoxide synthase I (nNOS, NOS-I (16)) and to Na ϩ /H ϩ exchanger regulatory factor (NHERF (23)). We observed that isoform PMCA4b (PMCA4CI) not only interacted physically with nitricoxide synthase I, but also down-regulated its activity in a dose-dependent manner through local Ca 2ϩ depletion (16). A compilation of interaction partners currently known is given in Table IA. Gene knock-out studies of PMCA2 have revealed balance and hearing deficits and slower gro...

Plasma Membrane Ca2+ ATPase 4 Is Required for Sperm Motility and Male Fertility

“…. ETPV), most presumably mediating specificity of binding to certain PDZ domains, as shown previously for other human PMCA b splice variants (17)(18)(19)(20)(21)32). …”

“…The subcellular distribution of PMCA4b was determined by immunofluorescence stainings. Isolated sperm were allowed to swim out from cauda epididymidis in sperm preparation buffer (MediCult, catalog number 10680060) for 15 min, and the suspension was streaked out on poly-lysine-coated slides, airdried for 10 min, and fixed and stained as described previously (21). The PMCA4-specific polyclonal antiserum was also described previously (26).…”

“…The well defined tissue-specific expression pattern of different isoforms and splice variants of the pump in various mammalian tissues (14) and the regulated expression pattern during mouse development (15) strongly suggest a specific physiological function for each isoform and splice variant (reviewed in Strehler and Zacharias (16)). The identification of physical and functional interaction partners of the Ca 2ϩ pump has given insights into the putative functions of PMCAs as regulators of Ca 2ϩ -dependent signal transduction processes (17)(18)(19)(20)(21). Interaction of PMCA2 and -4 "b" splice variants was shown to be mediated by the PDZ-(PSD-95/Dlg/ZO-1) domain of the corresponding interaction partner and the C termini of the PMCA isoform (which harbors a typical PDZ domain binding motif (17)).…”

Deletion of CASK in mice is lethal and impairs synaptic function

“…Consistent with this notion, CASK binds to neurexins and to SynCAMs, which are putative synaptic cell-adhesion molecules (3,8). In addition, CASK may traffic Ca 2ϩ channels to the synapse (9), target potassium channels (10), and/or the Ca 2ϩ pump 4b/Cl (11) to the plasma membrane, interact with liprins (12) or kinesin (13), and/or regulate transcription by interacting with transcription factors in the nucleus (14). Moreover, analysis of CASK mutations in Drosophila melanogaster and C. elegans suggested several other functions.…”

Mutation of plasma membrane Ca 2+ ATPase isoform 3 in a family with X-linked congenital cerebellar ataxia impairs Ca 2+ homeostasis

“…More than a dozen X-linked gene defects generate a cerebellar phenotype (36), with those associated with mutations in the synaptic proteins oligophrenin-1 (OPHN1) (37,38) and calcium/calmodulin-dependent serin protein kinase (CASK) (39,40) being well-characterized. The CASK syndrome is caused by the disruption of the gene for the Ca 2+ -CaM-dependent protein kinase, and it may be significant that CASK interacts through its PDZ [Post synaptic density protein (PSD95), Drosophila disc large tumor suppressor (Dlg1), and Zonula occludens-1 protein (zo-1)]-binding domain with the C terminal of the PMCA pump (41). PMCAs are part of a postsynaptic complex formed by metabotropic glutamate receptors (mGluR1), Homer (which interacts with OPHN1), and InsP 3 type 1 receptors (InsP 3 R1) (42)(43)(44).…”