Localization and expression of CaBP1/caldendrin in the mouse brain

Abstract

Ca2+ binding protein 1 (CaBP1) and caldendrin are alternatively spliced variants of a subfamily of Ca2+ binding proteins with high homology to calmodulin. Although CaBP1 and caldendrin regulate effectors including plasma membrane and intracellular Ca2+ channels in heterologous expression systems, little is known about their functions in vivo. Therefore, we generated mice deficient in CaBP1/ caldendrin expression (C-KO) and analyzed the expression and cellular localization of CaBP1 and caldendrin in the mouse brain. Immunoperoxidase labeling with antibodies recognizing both CaBP1 and caldendrin was absent in the brain of C-KO mice, but was intense in multiple brain regions of wild-type mice. By western blot, the antibodies detected two proteins that were absent in the C-KO mouse and consistent in size with caldendrin variants originating from alternative translation initiation sites. By quantitative PCR, caldendrin transcript levels were far greater than those for CaBP1 particularly in the cerebral cortex and hippocampus. In the frontal cortex but not in the hippocampus, caldendrin expression increased steadily from birth. By double-label immunofluorescence, CaBP1/caldendrin was localized in principal neurons and parvalbumin-positive interneurons. In the cerebellum, CaBP1/caldendrin antibodies labeled interneurons in the molecular layer and in basket cell terminals surrounding the soma and axon initial segment of Purkinje neurons, but immunolabeling was absent in Purkinje neurons. We conclude that CaBP1/ caldendrin is localized both pre- and postsynaptically where it may regulate Ca2+ signaling and excitability in select groups of excitatory and inhibitory neurons.

CaBP1 regulates Cav1 L-type Ca2+ channels and their coupling to neurite growth and gene transcription in mouse spiral ganglion neurons

“…In analyses of cortical neurons in culture, mutation of a CaM binding site (IQ-domain) in the proximal C-terminal domain of Ca v 1.2 reduces activity-dependent phosphorylation of CREB independent of any changes in Ca v 1-mediated Ca 2+ signals (Dolmetsch et al, 2001). Mutations in the Ca v 1.2 IQ domain also disrupt CaBP1 binding (Zhou et al, 2005), and CaBP1 is highly expressed in cortical neurons (Kim et al, 2014). Thus, CaBP1 rather than CaM binding to the IQ-domain may be required for excitation-transcription coupling in neurons.…”

“…The procedures used in this study are not expected to produce pain or suffering in the animals. Generation of C-KO mice (RRID: MGI: 5780462) was described previously (Kim et al, 2014). Mice were maintained on a C57BL/6 (Envigo) background and housed in groups on a standard 12:12 hour light: dark cycle, with food and water provided ad libitum.…”

“…Alternative splicing gives rise to three CaBP1 variants (CaBP1-S, CaBP1-L, and caldendrin), of which caldendrin is the most abundant in the cochlea (Yang et al, 2016). To elucidate the cellular functions of CaBP1, we analyzed the properties of Ca v 1 channels and Ca v 1 signaling pathways in SGNs of mice lacking all three variants (C-KO; (Kim et al, 2014)). Our results indicate that CaBP1 suppresses CDI of Ca v 1 channels in SGNs and is necessary for the contribution of Ca v 1 channels to excitation-transcription coupling and the activity-dependent repression of neurite outgrowth.…”

The EF-hand Ca2+-binding protein super-family: A genome-wide analysis of gene expression patterns in the adult mouse brain

“…For 22 genes, expression and localization studies have been performed by in-situ hybridization or immunohistochemistry (numbered in column 1). 1 (Kim et al, 2014), 2 (Vasiljevic et al, 2012) 3 (Konig et al, 2003), 4 (Blazejczyk et al, 2009), 5 (Dixon et al, 1997), 6 (Bohm et al, 2008), 7 (Yang et al, 2009), 8 (Masuda et al, 2014), 9 (Saitoh et al, 1993, 10 (Xiong et al, 2004), 11 (Bhat et al, 1994), 12 (Zhang et al, 2014), 13 (Sugita et al, 2002), 14 (Kanemaru et al, 2010), 15 (Meyer, 2014), 16 (Kuwajima et al, 1992), 17 (Sah et al, 1993), 18 (Sturchler et al, 2006), 19 (Vives et al, 2003), 20 (Mulder et al, 2010), 21 (Skibinska-Kijek et al, 2009), 22 (Saitoh et al, 1994) Gene name ISH Nr The results for the 135 genes clearly expressed in the 326 brain are presented in Table 2 Abbreviations: CA1/2/3: hippocampal fields; so: stratum oriens; sp: stratum pyramidale; sr: stratum radiatum; slm: stratum lacosum moleculare; DG: dentate gyrus; sg: granule cell layer; po: polymorph layer; hf: hippocampal fissure. ISH images for 17 genes, listed in alphabetical order, and presenting a characteristic expression pattern in the hippocampus, were taken from the ABA database.…”

Intermotif Communication Induces Hierarchical Ca2+ Filling of Caldendrin

“…3,4 The protein has a unique bipartite structure with a basic and prolinerich N-terminus, and a C-terminus that it shares with two shorter splice isoforms, S-CaBP1 and L-CaBP1 (Supplementary Figure S1), which are much less abundant in brain. [3][4][5][6][7] The structural information of CDD is not known, however, based on the structure of S-CaBP1, the C-terminus resembles the structure of CaM with four EF-hand motifs, but in contrast to CaM, the first EFhand motif can probably bind both Mg 2+ and Ca 2+ , while the second EF-hand motif is cryptic. 6,8,9 Over the years, a larger CDD interactome has been identified, 1 but still very little is known how CDD operates as a Ca 2+ sensor that accommodates different binding partners.…”