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Y Mizuno, Y Kanou, M Rogatcheva, T Imai, S Refetoff, H Seo, Y Murata, Genomic organization of mouse ZAKI-4 gene that encodes ZAKI-4 alpha and beta isoforms, endogenous calcineurin inhibitors, and changes in the expression of these isoforms by thyroid hormone in adult mouse brain and heart, European Journal of Endocrinology, Volume 150, Issue 3, Mar 2004, Pages 371–380, https://doi.org/10.1530/eje.0.1500371
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Abstract
ZAKI-4 was identified as a thyroid hormone-responsive gene in cultured human fibroblasts. A single ZAKI-4 gene encodes two isoforms, ZAKI-4 alpha and beta, both inhibiting calcineurin activity. ZAKI-4 alpha and beta differ at their N termini, and show distinct distribution profiles in human tissues. The aim of this study was to elucidate the organization of the mouse ZAKI-4 gene and to determine the effect of thyroid hormone on the expression of ZAKI-4 isoforms in vivo.
We cloned mouse homologues of human ZAKI-4 alpha and beta cDNA. Fluorescence in situ hybridization and bioinformatics analysis were employed to determine the gene organization. The effect of thyroid hormone on the expression of ZAKI-4 isoforms in mouse brain and heart was also studied.
Total RNA extracted from mouse cerebellum was used to clone ZAKI-4 alpha and beta cDNAs by RT-PCR followed by rapid amplification of cDNA ends. Mice were rendered hypothyroid by feeding a low iodine diet supplemented with propylthiouracil for 2 weeks. In one group (hyperthyroid) L-T(3) was injected i.p. for the last 4 days whereas another group (hypothyroid) received vehicle only. Non-treated mice were controls.
Mouse ZAKI-4 alpha and beta cDNAs were highly homologous to the human isoforms. The gene was mapped on chromosome 17qC, syntenic to human chromosome 6 where the human ZAKI-4 gene is located. As observed in human, ZAKI-4 alpha mRNA was expressed only in brain whereas beta mRNA was distributed in other tissues as well, such as heart and skeletal muscle. ZAKI-4 alpha mRNA was lower in the cerebral cortex of hypothyroid mice. Injection of L-T(3) caused an increase in ZAKI-4 beta mRNA in heart; however, expression of neither ZAKI-4 alpha nor beta mRNA was influenced by thyroid status in other tissues. These results indicate that expression of ZAKI-4 alpha and beta isoforms is regulated by thyroid hormone in vivo, and the regulation is isoform- and tissue-specific.
