Focus on Organelle Markers…

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and it is usually separately enclosed within its own lipid bilayer (wikipedia). They are often suspended in the cytosol, or attached to the plasma membrane. Organelles were historically identified through the use of some form of microscopy and by cell fractionation.

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?

 

RhoA/ROCK and F-actin modeling involved in Insulin secretion

This is the conclusion of Liu X. et al. who demonstrated, in a mouse model, that RhoA/ROCK signaling pathway modulates insulin secretion of 3D cultured islet pancreatic ß-cells. This modulation is made through the regulation of Connexin 36.

Cell-permeable C3 transferase (C3T; Cytoskeleton Inc.) and the small molecule Y-27632 ROCK inhibitor (Stemgent-Asterand) were used in these studies.

External links regarding RhoA/ROCK in insulin secretion of pancreatic ß-cells

• Liu X. et al. “Involvement of RhoA/ROCK in insulin secretion of pancreatic ß-cells in 3D
  

  Western blot detection of RhoA (cat. nr ARH03) in cell extracts (50 µg each) of rat NRK cells (lane 1), human HeLa cells (lane 2), bovine brain extract (lane 3), and human platelet cell extract (lane 4).

  culture” (2014) Cell Tissue Res. DOI: 10.1007/s00441-014-1961-2

• Cell permeable C3 transferase (cat. nr CT04), inhibits cellular Rho within 2-4h
• Selective Rho Kinase (ROCK) inhibitors and anti Human RhoA antibody (a Mouse monoclonal that only recognizes RhoA, not RhoB, RhoC, Rac1, Rac2, Rac3, Cdc42 or H-Ras).

I hope you will enjoy this new publication. Don’t hesitate to leave your comments or remarks regarding the use of bioactive small molecules in signal transduction studies.

SUMO and cellular cytoskeletal partners

In the August 2014 edition of their newsletter, Cytoskeleton Inc. bring us an overview of SUMO activation and deconjugation processes, together with their role on cytoskeletal proteins (actin, tubulin…).

For the record, SUMO (for Small Ubiquitin-like Modifiers) is a family of small proteins that is covalently attached to (or detached from) cellular proteins. Such post-translational modification (called SUMOylation) modulates cellular architecture and numerous activities, including response to stress, progression through the cell cycle, transport, mobility…

Interested in reading more about SUMOylation of cytoskeletal proteins?

Download your free copy of the review “SUMOylation: A Post-translational Modification Targeting  Cytoskeletal Protein“!

Is there a link between members of Rho family of small G proteins and reactive oxygen species?

Both ROS (Reactive Oxygen Species) and RNS (Reactive Nitrogen Species) on the one hand, and the small G proteins belonging to the Rho family on the other hand, are key regulators in various signal transduction pathways.

More recently it has been suggested that crosstalk between reactive species and Rho GTPases plays a crucial role in some of their physiological functions. Furthermore, these crosstalk events have been linked to pathological processes, e.g. lung injury and cancer.

Our partner Cytoskeleton Inc.  has summarized recent findings in the newsletter Rho GTPases and Reactive Oxygen Species: Crosstalk and Feedback. Let’s take a look at what’s available for research in this area.

Actin-Binding Proteins (ABPs) review

Actin filaments are essential for cytoskeleton functions (cell morphology, endocytosis and trafficking, contractility, motility…). In eukaryotic cells, polymerization and depolymerization of actin filaments together with their organization in higher magnitude actin-based superstructures and their complex dynamic properties are regulated by Actin-Binding Proteins (ABPs). Here, let’s review the ABPs recently released for cytoskeleton molecular modeling studies.

Lysine Acetylation by HDACs and HATs in cellular processes

Lysine acetylation is one of the major reversible eukaryotic post-translational modifications controlling cellular fate.