20S Proteasome inhibitors and Leptin against obesity

The World Health Organization (WHO) estimated in 2008 that 1.4 billion adults worldwide were overweight and of these 500 million were obese with risks for developing type 2 diabetes, hypertension and cardio-vascular diseases. The discovery of the adipocyte hormone, Leptin, brought to light the possibility that its anorectic effect could be harnessed for treating the epidemic of obesity. However up until now Leptin resistance has been an unsurmountable problem and the use of this adipokine for suppressing food intake has failed. In a recent issue of Cell, Junli Liu and coworkers at Harvard Medical School report that Celastrol, a natural product isolated from the Thunder God Vine (Tripterygium Wilfordi), is a powerful antiobesity agent.

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Thiostrepton: a novel lead compound against Dengue?

Dengue Virus (DenV) is transmitted by mosquito vectors. It infects 50-100 million people each year and is at the origin of Dengue Fever and the more lethal Dengue Hemorrhagic Fever (DHF) and Shock Syndrome (DSS) leading to an estimated 500,000 cases of DHF and 22 000 deaths. The World Health Organization (WHO) estimates that 40% of the world’s population is at risk of infection.

In the June issue of Journal of Biomolecular Screening, investigators at San Diego State University (Dept of Biology) and Institute Pasteur Korea (Seoul, South Korea) developed a multiplexed cell-based assay for the identification of modulators of pre-membrane processing as a target for the discovery of DenV inhibitors. (1)

The DenV pre-membrane protein (prM) is an essential chaperone for the viral envelope protein which prevents premature fusion with vesicles during viral export. Inhibition of pre-membrane protein cleavage restricts fusion and represents, thus, a novel druggable target.

The new in vitro assay developed in this study, is the first described cell-based assay that monitors DenVprM processing within the classical secretory pathway. In a pilot screen of 1,280 small molecules on that assay, Thiostrepton, a known cyclopeptide Antibiotic and FOXM1 inhibitor,  was identified as a novel positive hit in this assay (IC50=4.94 µM).

The utility of this novel assay has been proven by the identification of Thiostrepton (available at Focus Biomolecules cat. nr 10-2108) which may be a novel lead compound for the discovery of new drugs effective against Dengue Virus.

Thiostrepton Focus Biomolecules tebu-bio Catalog # 10-2108

Thiostrepton – Antibiotic and FOXM1 inhibitor. C72H85N19O18S5 – CAS No: 1393-48-2, 98% by TLC and HPLC at Focus Biomolecules.


1- Stolp Z.D. et al. “A Multiplexed Cell-Based Assay for the Identification of Modulators of Pre-Membrane Processing as a Target against Dengue Virus” (2015) J. Biomol. Screen. 20:616-626. DOI: 10.1177/1087057115571247.


High resolution structure of the TRPA1 channel protein

One of the hottest news last month was the high resolution structure of the TRPA1 ion channel protein.

Immunohistochemical staining of TRPA1 on mouse intestine with TRPA1 polyclonal antibody (Cat. nr 157PAB11992)

IHC staining on mouse intestine with TRPA1 polyclonal antibody (Cat. nr 157PAB11992). Source: Abnova | tebu-bio.

TRPA1 is a sensor for environmental noxious agents or signaling molecules produced endogenously. The structure was solved in the presence of agonist and antagonist ligands by using single-particle electron cryo-microscopy. (1)

This smart experimental method, which has revealed several unexpected TRPA1 structural features, shows that structural  information thus discovered might greatly assist Life Researchers in the design of better antagonists which will represent the next generation analgesic and anti-inflammatory agents.

Interestingly, several TRPA1-related agents are now well characterized for further in vitro characterization.

Several useful agents for studying TRPA1 channels are available:

  • TRPA1 antagonist HC-030031 inhibits the ion channel (cat. nr 21910-1065)
  • TRPA1 antagonist A-967079 is a cell permeable TRPA1 blocker  (cat. nr 21910-1055)

    Immunogen part (green) from the 4th cystoplasmic loop of the human TRPA1 used to produce human TRPA1 specific antibody (Cat. nr OSR00130W)

    Human TRPA1 modelization. The synthetic from the 4th cytoplasmic loop of human TRPA1 (highlighted in green) was used as the antigen to produce the highly specific human TRPA1 antibody (Cat. nr 214OSR00130W). Source: Osenses | tebu-bio.

  • TRPA1 antagonist AP-18 is a selective TRPA1 channel blocker (cat. nr 21910-1127)
  • TRPA1 agonist Polygodial displays analgesic activity via desensitization of sensory neurons (cat. nr 21910-1145)


Thanks to our friends from Focus Biomolecules for this post !

Mechanism of action for angiogenesis inhibitor Borrelidin discovered

Originally identified as an active molecule against the Borrelia species, Borrelidin has since been described as a selective inhibitor of threonyl tRNA synthetase (ThrRS). More recent research has found that Borrelidin (also called Treponemycin, Antibiotic U 78548 or C2989)  induces the collapse of newly formed capillary tubules, exhibits anti-bacterial, -malarial, -insecticidal activities, and displays a potent anti-VEGF induced angiogenic activity (IC50=0.8 nM).

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Neuroregenerative effects of microtubule stabilizing Epothilone B

Epothilone B is a bioactive microtubule-stabilizing small molecule. This blood-brain barrier permeable coumpound belongs to the most popular potent cytoskeletal modeling molecules for in vitro cell based assays (see the previous post dedicated to “5 Cytoskeletal Modeling Molecules“).Epothilone B structure cat. nr 10-2133 Focus Biomolecules tebu-bio
Recently, Ruschel J. et al. have demonstrated that its delayed systemic administration in rodents promoted axonal regeneration with Central Nervous System (CNS) injuries. These findings open new therapeutic areas regarding the use of microtubule-stabilizing drug compounds, like Epothilones, in CNS recovery and neuroregeneration. [Read more…]

E3 Ligases: RING- or HECT-mediated ubiquitination?

A large number of cellular processes are regulated by the reversible conjugation of Ubiquitin (UB) proteins to substrates. UB-related research tools (including E1-, E2 and E3 Ligases) are now commercially available for further studying the role of this “Ubiquitin/Proteasome” pathway. Nevertheless, the identification of UB Ligase inhibitors remains challenging (1). Such bioactive small molecules are indeed important to further characterize the actors of this pathway, and to find new compounds for therapeutic applications.

Untill now, only a few bioactive molecules were characterized as Ub – Proteasome inhibitors. For example, TAME is known as a Ub-ligase inhibitor while Thialidomide and SMER3 specifically inhibit E3 UB ligase. (2-4) [Read more…]

The TRPV1 Pain Receptor activates T cells

The Transient Receptor Potential (TRP) ion channel family participates in numerous functions of the Nervous System. A recent publication tends to indicate that TRP might also be of interest for therapeutical strategies for controlling pro-inflammatory  CD4+ T cell reactions.

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6 good reasons (in short!) to use our blood derived cells!

HemaCare and tebu-bio distribution agreement blood cellstebu-bio signed recently a distribution agreement with HemaCare Corp. Built on a 36-year history in apheresis collection, HemaCare is a leader in cell and tissue collection and processing, providing high-quality biological material derived from normal and mobilized peripheral blood, bone marrow and cord blood that meets the unique needs of researchers, to ensure the quality research outcome they expect.

By signing this agreement with HemaCare, tebu-bio again broadens your sourcing possibilities. I am proud to say that, more than ever, our commitment to source the cell type that fits your needs is true. Really, I might hear you say? Yes, really! Let me explain why our offer is different from others. [Read more…]

5 Cytoskeletal Modeling Molecules

Cytoskeleton modeling molecules are relevant when trying to improve one’s understanding of cytoskeletal molecular modeling and associated mechanisms. Together with actin binding proteins, tubulin-based assays, small GTPase activation assays etc… these reagents are called small molecules, but they remain extremely potent in in vitro cell-based assays. Here, let’s take look at a selection of the most popular chemicals modifying actin or microtubule polymerization.

#1- Docetaxel

An antimitotic chemotherapeutic acting on the centrosome of the mitotic spindle via reversible high-affinity binding to microtubules. Docetaxel induces apoptosis in a variety of cancer cell lines.

#2- Epothilone B

A tubulin polymerization promoter inducing G2-M cell cycle arrest stabilizing microtubules and displaying potent cytotoxic activity in a variety of cell lines and mouse models.

#3- Latrunculins

Potent actin polymerization inhibitor disrupting microfilament organization.

#4- Nocodazole

A microtubule polymerization inhibitor used to induce mitotic arrest and cell synchronization. Nocodazol inhibits a number of cancer-related kinases including ABL, c-Kit, BRAF, MEK1, MEK2, and MET.

#5- Taxol

A chemotherapeutic agent for the treatment of breast, non-small cell lung and ovarian cancer. Taxol promotes tubulin polymerization, stabilizes microtubules in vitro and in vivo resulting in arrest of cells in the G2 and M phase of the cell cycle.

Many other well-qualified cytoskeleton modulators (Ansamitocin P-3, Cytochalasins, Colchicine, Vinblastine sulfate…) are available from various sources (my preference going to Focus Biomolecules for quality and price advantages!). Nevertheless, the 5 described here are among those most spontaneously cited by researchers.

What about you? Which ones would you recommend to study cytoskeleton dynamics?


Where to buy Topo inhibitors and analogs?

DNA topoisomerase I and DNA topoisomerase II (Topo I and Topo II) are nuclear enzymes which regulate the topological state of the DNA helix by transiently breaking and rejoining DNA strands. They also play a critical role in fixing DNA damage resulting from an exposure to harmful chemicals or UV rays. Topo small molecule inhibitors are well-known anticancer approaches. Today, they are coming back to the Drug discovery scene just enough to edit a post on Topo inhibitors, from their history and to their availability for in vitro R&D purposes.

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