Fig 2: Structure of microtubules

Recently, I issued a post about a method which allows measuring microtuble binding capabilities of proteins of interest. Today, I invite you to look at methods for measuring the dynamic polymerisation of tubulin to microtubules and to detect the impact of compounds or other variables in your experiments on this process.

Fig 1: Electron micrograph of microtubules (100,000x)

Tubulin represents one of the major cytoskeleton structures. It plays an important role in cell structure, intracellular transport, and mitosis. In eukaryotic cells, tubulin polymerizes to form structures called microtubules (MTs) (Fig. 1). When tubulin polymerizes it initially forms proto-filaments, MTs consist of 13 protofilaments and are 25nm in diameter, each um of MT length is composed of 1650 heterodimers. Microtubules are highly ordered fibers that have an intrinsic polarity, shown schematically in Figure 2. Tubulin can polymerize from both ends in vitro, however, the rate of polymerization is not equal. It has therefore become the convention to call the rapidly polymerizing end the plus-end of a microtubule and the slowly polymerizing end the minus-end. In vivo, the plus end of a microtubule is distal to the microtubule organizing center.

Montelukast is a marketed drug used for asthma treatment and to relieve symptoms of seasonal allergies. It is known to function as a leukotriene receptor antagonist.

Montelukast (Data deposited in or computed by PubChem)

In a recent study in which young and old rats were treated with Montelukast, Maschallinger et al. (1) could show that the drug reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. They could further demonstrate that some of these findings are mediated through an inhibitory effect on the GPR17 receptor.

GPR17 is an orphan G-protein-coupled receptor that is abundant in the CNS, and has been shown to play a key role in regulating oligodendrocyte differentiation and maturation although little has been known about the exact mechanism through which GPR17 influences myelination (2).

The most important result of their study is that cognitive function of old animals could be restored by the treatment with Montelukast. This could be shown in two different behavioral tests. While young rats have not been affected by the drug treatment, Montelukast significantly improved task learning in 20-month old rats. Non-cognitive behaviours such as anxiety-like behaviour, depression-like symptoms, exploration and locomotion as well as changes in body weight have not been affected by Montelukast treatment. Furthermore the authors found that Montelukast reduced microglia reactivity and restored hippocampal neurogenesis in old rats.

These findings might open the door for new potential pharmaceutic applications for Montelukast in treating dementia.

Modulators of GPR17

MDL29,951

Focus Biomolecules recently released Montelukast to facilitate GPR17 related research activities. Focus Biomolecules also offer 2 more GPR17 modulators through tebu-bio.

• Montelukast: Leukotriene antagonist and GPR17 ligand
  
• MDL29,951: MDL29,951 is a new, highly specific, small molecule activator of GPR17¹ that has been shown to be active in intact cells¹.   The ability to specifically activate GPR17 allows for the study of the exact role GPR17 plays in the maturation of
  

  Pranlukast

  oligodendrocytes and facilitates further study of this important process.

• Pranlukast: GPR17 antagonist and CysLT1 antagonist.

Interested in these modulators? Please contact us with the form below

References:

(1) J. Maschallinger et al., Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug, Nat Commun. 6, 8466 (2015)

(2) S. Hennen et al.,Decoding signaling and function of the orphan G protein-coupled receptor GPR17 with a small-molecule agonist, Sci Signal. 6, 298 (2013)

While it is likely that all Ubiquitin-Like proteins (UBLs) will be important for drug discovery because of these associations, Ubiquitin has been the most completely validated for this purpose by genetic, biological, and biochemical evidence. The enzymes of the Ubiquitin pathway are emerging as pioneer drug targets for many therapeutic areas.

The ubiquitin family of proteins is an important means of regulating protein trafficking, cell division, apoptosis, and metabolism in cells. Turnover of most cellular proteins is effected by ubiquitin tagging, which marks them for transport to the 26S proteasome for degradation.

Lysosome staining: Human fibroblasts stained with LysoLive™ SulfGreen

Visualizing fixed cells and tissues only gives snap shots of cellular processes. Over the past years, more and more cellular parameters have become measurable in living cells. For this purpose, there is a growing number of specific stains capable of entering the cell without toxic effects (which could also negatively impact the parameters to be measured).