Cell division marker
This application relates to a newly identified animal cell structure, the midbody scar. This structure is a remnant of the midbody that is retained by one daughter cell following cytokinesis and persists through multiple subsequent cell cycles. The midbody scar can be useful as a marker of dividing cells or of a cell's replicative age.
1. A method of identifying a dividing cell in a population of mammalian cells, the method comprising:
obtaining a population of mammalian cells comprising at least one cell suspected of being a dividing cell;
detecting a cell having one or more midbody scars by a method comprising contacting the population of mammalian cells with an antibody or an antigen-binding portion thereof that binds specifically to a polypeptide component of a midbody scar selected from the group consisting of:
mitotic kinesin-like protein 1 (MKLP1), Epsilon tubulin (ε-tubulin), Centrosomal Protein 55KDa (Cep55), and Aurora B kinase, and detecting binding of the antibody or antigen-binding portion thereof to the polypeptide component, wherein a ring structure not at a midbody or centrosome is the midbody scar; and
identifying the cell having one or more midbody scars as the dividing cell.
2. The method of claim 1 , wherein the population of cells comprises dividing cells and non-dividing cells.
3. The method of claim 1 , wherein the dividing cell is a cancerous cell.
4. The method of claim 1 , wherein the dividing cell is a stem or progenitor cell.
5. The method of claim 1 , further comprising identifying cells having a pre-selected number of midbody scars.
6. The method of claim 5 , wherein the pre-selected number is 0 to 2 midbody scars per cell.
7. The method of claim 5 , wherein the pre-selected number is 4 or more midbody scars per cell.
8. The method of claim 5 , further comprising selecting cells having the pre-selected number of midbody scars.
9. The method of claim 8 , further comprising ablating the selected cells.
10. The method of claim 8 , further comprising isolating the selected cells.
11. The method of claim 1 , wherein the detecting step comprises optically detecting the presence of a cellular structure having morphological characteristics of the midbody scar.
12. The method of claim 1 , wherein optically detecting the presence of the cellular structure comprises using phase contrast microscopy to analyze the cell.
13. The method of claim 12 , wherein the analysis is automated.
14. The method of claim 1 , wherein the antibody or antigen binding portion thereof is a detectable antibody or antigen-binding portion thereof.
15. The method of claim 14 , wherein the detection is automated.
16. The method of claim 14 , wherein the detectible antibody comprises an enzyme having a detectable enzymatic activity.
17. The method of claim 14 , wherein the detectible antibody or antigen binding portion thereof comprises a fluorescent label.
18. The method of claim 17 , wherein the detecting step comprises detecting the presence of fluorescence from the detectible antibody or antigen binding portion thereof.
19. The method of claim 18 , wherein detecting the presence of fluorescence comprises using fluorescence microscopy.
20. The method of claim 1 , wherein the population of cells is from a subject suspected of having a proliferative disorder.
21. The method of claim 20 , further comprising:
determining the percentage of cells in the sample that have a selected number of midbody scars;
comparing the percentage of cells in the sample to a reference percentage representing a sample from a subject that does not have a proliferative disorder; and
identifying a subject having an elevated percentage of dividing cells in the sample as compared to the reference percentage as having a proliferative disorder.
22. The method of claim 20 , wherein the proliferative disorder is selected from the group consisting of: atherosclerosis, rheumatoid arthritis, idiopathic pulmonary fibrosis, scleroderma, cirrhosis of the liver, lupus, vasculitis, endometriosis, uterine fibroids, prostatic hyperplasia, nephritis, skin disorders, and cancer.
23. The method of claim 1 , further comprising isolating the dividing cells.
24. The method of claim 23 , further comprising expanding the isolated dividing cells in culture.
25. The method of claim 1 , wherein the ring structure is about 2μm in diameter.
26. The method of claim 1 , wherein the ring structure is localized adjacent to the plasma membrane.
27. The method of claim 1 , wherein the ring structure is determined not to comprise γ-tubulin.
28. An isolated midbody scar from a mammalian cell, wherein the midbody scar is a ring structure not at a midbody or centrosome that comprises mitotic kinesin-like protein 1 (MKLP1), Epsilon tubulin (ε-tubulin), Centrosomal Protein 55kDa (Cep55), and Aurora B kinase, and the midbody scar is isolated by a method that comprises contacting a mammalian cell with an antibod or an antigen-binding portion thereof that binds s ecificall to one of: mitotic kinesin-like protein 1 (MKLP1), Epsilon tubulin (ε-tubulin), Centrosomal Protein 55KDa (Cep55), and Aurora B kinase.