The dynamics of the actin cytoskeleton and its regulation by Rho GTPases are essential to maintain cell shape, to allow cell motility and are also critical during cell cycle progression and mitosis. Rho GTPases and their effectors are involved in cell rounding at mitosis onset, in chromosomes alignment and are required for contraction of the actomyosin ring that separates daughter cells at the ...

The development of the nervous system requires a strict control of cell cycle entry and withdrawal. The olfactory epithelium (OE) is noticeable by its ability to yield new neurons not only during development but also continuously during adulthood. The aim of our study was to investigate, by biochemical and immunohistochemical methods, which cell cycle regulators are involved in the control of n...

Introduction The Ras family of small GTPases was originally discovered as viral oncogenes ; subsequent studies demonstrated that the cellular proto-oncogenes are mutated in a high proportion of human tumours such as colorectal and pancreatic cancer [l]. Oncogenic mutations create forms of the Ras proteins that are constitutively active because they are locked in the active GTP-bound state [2]. ...

We define a measure of coherent activity for gene regulatory networks, a property that reflects the unity of purpose between the regulatory agents with a common target. We propose that such harmonious regulatory action is desirable under a demand for energy efficiency and may be selected for under evolutionary pressures. We consider two recent models of the cell-cycle regulatory network of the ...

The expression of the flagellar master operon, flhDC, peaked in the middle of three consecutive cell cycles. The level of expression was lowest at the time of cell division. The expression of the second-level operon, flhB, peaked at cell division. The swimming speed of individual cells was also highest at the time of cell division.

Pulmonary surfactant phosphatidylcholine (PC) formation increases as alveolar type II cells mature and arrest in G0/G1 state of the cell cycle at late fetal gestation. To determine whether this G0/G1 arrest is responsible for the increase in PC synthesis, we investigated the rates of PC synthesis and the activity, phosphorylation, intracellular distribution, synthesis, and degradation of a key ...

T he mammalian brain was originally thought to birth new neurons only during development. A modern paradigm shift began in the 1960s as experimental evidence of neurogenesis in adult brain and its functional implications began to emerge. Neural stem cells have now been identified to undergo mitosis, proliferate, and differentiate into neurons, astroglia, or oligodendroglia within specialized ne...

Cellular growth, development, and differentiation are tightly controlled by a conserved biological mechanism: the cell cycle. This cycle is primarily regulated by cyclin-dependent kinase (CDK)-cyclin complexes, checkpoint kinases, and CDK inhibitors. Deregulation of the cell cycle is a hallmark of the transformation of normal cells into tumor cells. Given its importance in tumorigenesis, severa...

Angiotensin II has emerged as an important growth factor for vascular, cardiac, and renal cells. Depending on the specific cell type and presence of other growth factors, angiotensin II induces proliferation (replication of DNA with subsequent successful division of cells), hypertrophy (increase in cell size, cell protein, and mRNA content without DNA replication), apoptosis (programmed cell de...

Cell cycles in early amphibian embryos are characterized by the absence of G1 and G2 phases. The simple cycle of S phase and mitosis does show similarities with other systems, particularly in the presence of cytoplasmic components advancing nuclei into DNA synthesis and mitosis. Maturation-promoting factor induces nuclear envelope breakdown and subsequent chromosome condensation. Cytoplasmic fa...