Abstract-In this work we implement an automatic videobased online cell tracking system for TNFα treated cells in the transcription factor NF-kB pathway, with the aim to provide p65 measurement approximation with time and individual cell resolution. The video used to test our proposed tracking system consists on cells transfected with fluorescent p65 protein. Such protein switches its location within the cell, among the nucleus and cytoplasm over time, causing important changes on its apparent morphology. This represents a major challenge for an automatic cell tracking system. Additionally, images in the tested microscopy footage present noise and contrast variations. For noise reduction, we modified the deceived bilateral filter (DBF), a denoising and edge sharpening non linear filter. The proposed modification of the DBF consists in an adaptive border enhancement. We tested the cell tracking algorithm with different preprocessing configurations achieving a maximum tracking accuracy improvement of 28%, with the use of the modified DBF.Keywords-Online tracking, DBF, automatic cell activity analysis, NF-kB pathway, transcription factors.
I INTRODUCTIONTranscription factors (TF) tightly regulate gene expression and are involved in many cellular processes, like cell cycle, adaptability, and metabolism. In the case of transcription factor NF-kB, it is known to be altered in numerous diseases, including cancer [1]. Hence, this pathway has been an interesting target for investigating such diseases.NF-kB is regulated through a proteic inhibitor named Inhibitor of Kappa B (IkB), which binds to NF-kB and covers its nuclear localization signal, thus keeping NF-kB in the cytoplasm. When the NF-kB pathway is activated, IkB is marked for degradation, thus freeing NF-kB nuclear localization signal and allowing it to get translocated to the nucleus, where it can act as a TF for several genes involved in proliferation, survival, metastasis, angiogenesis and inflammation [1]. Since its activity depends upon which cellular compartment it is occupying, and it fluctuates over time, video analysis with single-cell, compartment (nucleus and cytoplasm) and time resolution is necessary. The resulting quantitative data, as p65 concentration (an active subunit of NF-kB), enables proper study of this and many other TF's alterations, with more precision in contrast of typical qualitative data analysis.Time lapse fluorescence microscopy is a non-invasive method for studying TF's location, since it allows molecular biologists to locate proteins within cell's compartments in time, with individual cell resolution. In the case of this study, cells transfected with NF-kB-GFP were treated with TNFα, and the cell's individual nucleus and cytoplasmatic concentrations of p65 were observed over time.Usually nuclei are used to track the cell as a primary structure, since it is less prone to shape changes over time and occlusion, unlike cell's cytoplasm. Hence, nuclei staining is usual. However, most of nuclear dyes used for staining can cause cellular ...