Transporting cells over several days without dry-ice

This paper describes a simple, hazard-free and inexpensive procedure that allows researchers to send cultured cells across the globe at ambient temperatures. The method enables transit of up to 2 weeks without compromising cell recovery. Its use will assist collaborators in distant laboratories to exchange cells without using dry-ice

Phosphorylation of survivin at threonine 34 inhibits its mitotic function and enhances its cytoprotective activity

Survivin is an essential chromosomal passenger protein required for mitotic progression. It is also an inhibitor of apoptosis and can prevent caspase-mediated cell death. In addition, survivin levels are elevated in cancer cells where its presence correlates with increased resistance to chemo- and radio-therapy, which makes it an attractive target for novel anti-cancer strategies. Interestingly, survivin is phosphorylated by the mitotic kinase, cdk1, and a non-phosphorylatable form, survivin(T34A), cannot inhibit apoptosis. Here we rigorously test the ability of survivin(T34A) and its corresponding phosphomimetic, survivin(T34E), to promote cell viability through survivin's dual roles. The effects of these mutations are diametrically opposed: survivin(T34A) accelerates cell proliferation and promotes apoptosis, whereas survivin(T34E) retards growth and promotes survival. Thus the phosphorylation status of survivin at T34 is pivotal to a cell's decision to live or die

The functional repertoire of survivin's tails

Survivin is a multitasking protein that can inhibit cell death and that is essential for mitosis. Due to these prosurvival activities and the correlation of its expression with tumour resistance to conventional cancer treatments, survivin has received much attention as a potential oncotherapeutic target. Nevertheless, many questions regarding its exact role at the molecular level remain to be elucidated. In this study we ask whether the extreme C- and NH2 termini of survivin are required for it to carry out its cytoprotective and mitotic duties. When assayed for their ability to act as a cytoprotectant, both survivin1-120 and survivin11-142 were able to protect cells against TRAIL-mediated apoptosis, but when challenged with irradiation cells expressing survivin11-142 had no survival advantage. During mitosis, however, removing the NH2 terminal 10 amino acids (survivin11-142) had no apparent effect but truncating 22 amino acids from the C-terminus (survivin1-120) prevented survivin from transferring to the midzone microtubules during anaphase. Collectively the data herein presented suggest that the C-terminus is required for cell division, and that the NH2 terminus is dispensable for apoptosis and mitosis but required for protection from irradiation

Survivin at a glance

Survivin (also known as BIRC5) is an evolutionarily conserved eukaryotic protein that is essential for cell division and can inhibit cell death. Normally it is only expressed in actively proliferating cells, but is upregulated in most, if not all cancers; consequently, it has received significant attention as a potential oncotherapeutic target. In this Cell Science at a Glance article and accompanying poster, we summarise our knowledge of survivin 21 years on from its initial discovery. We describe the structure, expression and function of survivin, highlight its interactome and conclude by describing anti-survivin strategies being trialled

Mitochondrial survivin reduces oxidative phosphorylation in cancer cells by inhibiting mitophagy

Survivin is a cancer-associated protein that is pivotal for cellular life and death: it is an essential mitotic protein and an inhibitor of apoptosis. In cancer cells, a small pool of survivin localises to the mitochondria, the function of which remains to be elucidated. Here, we report that mitochondrial survivin inhibits the selective form of autophagy, called “mitophagy”, causing an accumulation of respiratory defective mitochondria. Mechanistically the data reveal that survivin prevents recruitment of the E3-ubiquitin ligase Parkin to mitochondria and their subsequent recognition by the autophagosome. The data also demonstrate that as a consequence of this blockade cells expressing high levels of survivin have an increased dependency on anaerobic glycolysis. As these effects were found exclusively in cancer cells they suggest that the primary act of mitochondrial survivin is to force cells to implement the “Warburg Effect” by inhibiting mitochondrial turnover, which gives them a survival advantage

Mitotic activity of survivin is regulated by acetylation at K129

Survivin is a cancer-associated protein regulated by multiple factors, including acetylation at K129 within its C-terminal alpha-helical tail. Acetylation of survivin is being pursued as a potential prognostic marker in breast cancer. This modification at K129 may cause nuclear accumulation of survivin in interphase cells; however, whether this affects its essential role during mitosis has not been addressed. We posited whether mimicking acetylation of survivin at K129 alters its activity during mitosis. Fluorescence microscopy and time-lapse imaging showed that, mutating this site to an alanine to act as a constitutive acetyl mimetic, K129A, causes defects in chromosome segregation and cytokinesis. As a non-acetylatable version, K129R, also has difficulty during mitotic exit, we conclude that cyclical acetylation and deacetylation is required for fully functional survivin during mitosis

The N-terminus of survivin is a mitochondrial-targeting sequence and Src regulator

Survivin is a cancer-associated protein that exists in several locations in the cell. Its cytoplasmic residence in interphase cells is governed by CRM1-mediated nuclear exportation, and its localisation during mitosis to the centromeres and midzone microtubules is that of a canonical chromosomal passenger protein. In addition to these well-established locations, survivin is also a mitochondrial protein, but how it gets there and its function therein is presently unclear. Here we show that the first 10 amino acids at the NH2 terminus of survivin are sufficient to target GFP to the mitochondria in vivo, and ectopic expression of this decapeptide decreases cell adhesion and accelerates proliferation. The data support a signalling mechanism in which mitochondrial survivin activates the tyrosine kinase, C-Src, leading to reduced focal adhesion plaques and disruption of F-actin organisation. This strongly suggests that the NH2 terminus of survivin is a mitochondrial targeting sequence that regulates C-Src, and that survivin acts in concert with C-Src to promote tumorigenesis

The use of decellularised animal tissue to study disseminating cancer cells

Since the establishment of cell culture, common practice has been to grow adherent cells in 2D monolayers. Although cells behave completely differently when grown under these artificial conditions, the ease of 2D culturing has meant that this practice still prevails, and adopting conditions that more closely reflect the natural microenvironment has been met with substantial inertia. The alternative, animal models that mimic natural human physiology, are less accessible, strictly regulated and require licences and expensive facilities. Although transition from 2D to 3D cell culturing is gathering momentum, there is a clear need for alternative culturing methods that more closely resemble in vivo conditions. Here, we show that decellularised organs gleaned from discarded animal carcasses are ideal biomimetic scaffolds to support secondary tumour initiation in vitro. Further, we describe how to decellularise tissue and perform basic histochemistry and immunofluorescence procedures for cell and matrix detection. Cancer cell behaviour on this matrix is followed by way of an example. Because integration into the traditional work flow is easy and inexpensive, we hope this article will encourage other researchers to adopt this approach