The PtK2 cell line was initiated from renal tissue excised from an adult male rat kangaroo (Potorous tridactylus), a marsupial native to Australia. PtK2 cells exhibit epithelial morphology and stain positive for the intermediate filament protein keratin.

PtK2 cells demonstrate susceptibility to an array of viruses, including herpes simplex, coxsackievirus A9, vesicular stomatitis (Ogden strain), and vaccinia. The line is known to be resistant to poliovirus 2, adenovirus 5, and coxsackievirus B5. PtK2 is a particularly popular line with scientists carrying out research on the mitotic process.

Mitosis is the part of cell division that entails the division of a cell's nucleus. The process occurs in all higher eukaryotes and generally is considered to be comprised of four distinct stages (prophase, metaphase, anaphase, and telophase). Two identical nuclei containing copies of the genetic information of the parent cell are usually produced via mitosis, and each is typically bestowed to a distinct daughter cell. Live cultured PtK2 cells, which characteristically possess a comparatively small number of large chromosomes and remain relatively flat during division, are commonly utilized as models for mitosis. When grown at 37 degrees Celsius, approximately every 2 to 3.5 hours the male rat kangaroo kidney cells undergo the mitotic process. Similar to most other epithelial lines, PtK2 cells are strongly contact inhibited.

The adherent log phase culture of PtK2 cells depicted above was treated for one hour with MitoTracker Red CMXRos in order to label the mitochondrial network, and the fixed cells were then incubated with mouse anti-cytokeratin primary antibodies followed by goat anti-mouse secondary antibodies (IgG) conjugated to fluorescein. The nuclei were counterstained with DAPI. Images were recorded in grayscale with a 12-bit digital camera coupled to either a Nikon E-600 or Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.

Rat Kangaroo Kidney Cellular Tubulin Network - In order to visualize the microtubules present in the rat kangaroo kidney cells illustrated in this section, a PtK2 culture was immunofluorescently labeled with anti-tubulin mouse monoclonal primary antibodies followed by goat anti-mouse secondary antibody fragments conjugated to Rhodamine Red-X. In addition, the cells were labeled for cell nuclei with the classic nucleic acid stain, DAPI.

Targeting Keratin Intermediate Filaments in PtK2 Epithelial Cell Cultures - After treatment for one hour with MitoTracker Red CMXRos in serum-based growth medium, an adherent culture of PtK2 cells was fixed in 50:50 methanol:acetone, permeabilized, blocked, and treated with mouse anti-cytokeratin (pan) monoclonal antibodies. The intermediate filaments were visualized with goat anti-mouse secondary antibodies (IgG) conjugated to fluorescein, and the nuclei were counterstained with DAPI.

Beta-Catenin Linking Proteins in PtK2 Cells - The technique of double immunofluorescence was employed to simultaneously label a log phase culture of PtK2 cells with mouse anti-tubulin and rabbit anti-beta-catenin primary antibodies, followed by goat anti-mouse and anti-rabbit secondary antibodies conjugated to Cy3 and Cy2, respectively. Tubulin is the basic component of microtubules and members of the catenin family of peripheral cytosolic proteins bind selectively to the highly conserved cytoplasmic tail domain of the cell-to-cell adhesion cadherin proteins.

The Microtubule Network and Nuclear DNA in Male Rat Kangaroo Kidney Cells - Immunofluorescence with mouse anti-alpha-tubulin was employed to visualize distribution of the microtubule network in the PtK2 epithelial cell culture illustrated in this section. The secondary antibody (goat anti-mouse IgG) was conjugated to Cy2. Nuclei were labeled with the classic nucleic acid stain DAPI.

PtK2 Cell Cultures with Rhodamine Red-X and DAPI - The featured rat kangaroo kidney epithelial (PtK2) cell culture was immunofluorescently labeled with anti-tubulin mouse monoclonal primary antibodies followed by goat anti-mouse secondary antibody fragments conjugated to Rhodamine Red-X in order to target the microtubule network. DAPI was utilized to counterstain DNA in the cell nucleus.

G-Actin, F-Actin, and DNA in Rat Kangaroo Kidney Cells - A culture of PtK2 epithelial cells was labeled with the enzyme DNase I conjugated to the fluorochrome Texas Red in order to reveal unpolymerized globular (G) actin, which accumulates in the center of the cell. In addition, the specimen was stained for DNA with the ultraviolet-absorbing probe DAPI, and for the cytoskeletal filamentous actin network with Alexa Fluor 488 conjugated to phalloidin.

Immunofluorescence Labeling of Tubulin in PtK2 Epithelial Cell Cultures - In order to visualize the relationship between the nucleus and the intracellular microtubule network, the culture of rat kangaroo kidney (PtK2) cells presented in this section was immunofluorescently labeled with anti-tubulin (pan) mouse monoclonal primary antibodies followed by goat anti-mouse Fab fragments conjugated to Cy3. DNA in the cell nucleus was counterstained with DAPI.

Rat Kangaroo Cells Labeled for Polymerized and Unpolymerized Actin - The featured PtK2 cells were resident in a culture fluorescently labeled with Texas Red conjugated to the enzyme DNase I, Alexa Fluor 488 conjugated to phalloidin, and DAPI, targeting globular (unpolymerized) actin, the filamentous F-actin network, and nuclei, respectively.

Intermediate Filaments and the Mitochondria Network in Adherent PtK2 Cell Cultures - The adherent log phase culture of PtK2 cells featured in this section was treated for one hour with MitoTracker Red CMXRos in order to label the mitochondrial network, and the fixed cells were then incubated with mouse anti-cytokeratin primary antibodies followed by goat anti-mouse secondary antibodies (IgG) conjugated to Cy2. The nuclei were counterstained with DAPI.

Distribution of Vimentin and Filamentous Actin in Adherent Rat Kangaroo Kidney Epithelial Cell Cultures - Mitosis is a method of cell division that consists of a series of steps in which two identical daughter cells are produced from a single parent cell. Each of the daughter cells receives a full set of chromosomes indistinguishable from the chromosomes of the cell that produced them. Living PtK2 cells are popularly used to visualize the mitotic process because they contain a relatively few number of chromosomes, and these chromosomes are quite large in size. The cells are also particularly well suited for such a purpose because they remain relatively flat during mitosis, further increasing the ease with which the stages of nuclear division can be observed.