Published in Cancer Detection and Prevention 2000; 24(Supplement 1).

Identification and molecular characterization of casein kinase I alpha L splice variants for the potential use as a molecular marker for dividing cancer cells

TJK Yong MSc, KH Patel MSc 1, JW Sentry PhD 2, BH Toh MBBS DSc 2, LH Gan PhD 1, YY Gan PhD 1

1 School of Science, Nanyang Technological University, Singapore, Republic of Singapore, 2 Dept Pathology and Immunology, Monash Medical School, Melbourne, Australia,

AIM: Casein kinase I alpha is an ubiquitous protein kinase and localizes to mitotic spindles and centrosomes in dividing cells. In human, CKIα, CKI&alphaS and CKIαLS have been reported. METHODS: A HeLa cDNA library was screened for cDNAs encoding the splice variants. Northern hybridizations were performed to detect mRNA transcripts encoding the splice variants. mRNA destabilization studies were performed to determine the biological function of AT-rich elements (AREs) encoded by the cDNAs. RESULTS: A novel human CKI alpha L splice variant (CKIαL) and the previously reported CKI alpha S splice variant (CKIαS) were identified. Northern hybridization with DNA probes specific to the splice variants detected two mRNA transcripts of 2.4kb and 4.2kb. The 4.2kb transcript encoded six AREs compared to one ARE encoded by the 2.4kb transcript. There was significant degradation of the 4.2kb transcript when compared to the 2.4kb transcript. CONCLUSION: This is the first report on the identification of the human CKI alpha L splice variant. The four splice variants were encoded by the 2.4kb and the 4.2kb mRNA transcripts. The presence of AREs appeared to play a significant role in the degradation of CKI alpha mRNA transcripts. The significance of this finding suggested that the 4.2kb transcript encoding CKI alpha might be transcribed in a cell-cycle dependent manner which would be consistent with the intense localization of CKI alpha to mitotic spindle and centrosomes in dividing cells. The characteristics of these cell-cycle-dependent proteins could be utilized and applied in the detection of dividing cells in cancerous tissues.

KEY WORDS: AT-rich elements (AREs), cell-cycle.

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Paper presented at the International Symposium on Impact of Biotechnology on Cancer Diagnostic & Prognostic Indicators; Geneva, Switzerland; October 28 - 31, 2000; in the section on genetic risk assessment.