Non-equivalence of embryonic and somatic cell nuclei affecting spindle composition in clones

• Published in: Developmental biology Vol. 289; no. 1; pp. 206 - 217
• Main Authors: Miyara, Faical, Han, Zhiming, Gao, Shaorong, Vassena, Rita, Latham, Keith E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 2006
• Subjects: Animals; Calmodulin; Calmodulin - metabolism; Chromosomes - metabolism; Clone Cells - metabolism; Cloning nuclear transfer; Embryo, Mammalian - cytology; Female; Meiosis; Mice; Mitosis; Nuclear Transfer Techniques; Oocytes - metabolism; Spindle; Spindle Apparatus - metabolism; Stem Cells - metabolism; SCNT; SCC; Cloning nuclear transfer; ECNT; Spindle; Mitosis; Meiosis; pmSCC; Calmodulin
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2005.10.030

Cloning by nuclear transfer remains inefficient but is more efficient when nuclei from embryonic cells or embryonic stem cells (ECNT) are employed as compared with somatic cells (SCNT). The factors determining efficiency have not been elucidated. We find that somatic and embryonic nuclei differ in their ability to organize meiotic and mitotic spindles of normal molecular composition. Calmodulin, a component of meiotic and mitotic spindle chromosome complexes (SCCs), displays sharply reduced association with the SCC forming after SCNT but not ECNT. This defect persists in mitotic spindles at least through the second mitosis, despite abundant calmodulin expression in the cell, and correlates with slow chromosome congression. We propose that somatic cell nuclei lack factors needed to direct normal SCC formation in oocytes and early embryos. These results reveal a striking control of SCC formation by the transplanted nucleus and provide the first identified molecular correlate of donor stage-dependent restriction in nuclear potency.