The Silicon Rhodamine-like (SiR) technology has significantly contributed to the recent development of DNA and cytoskeletal analysis by live cell imaging.

In 2014, two new Silicon Rhodamine-like (SiR) fluorescent probes were released for studying actin & tubulin by live cell imaging. SiR-Actin and SiR-Tubulin are fluorescent probes compatible with most microscopes (including super-resolution settings) that directly stain actin & tubulin without the need to transfect cells with vectors expressing fluorescently labeled Actin or Tubulin. The two original dyes were successfully followed by a new SiR-DNA probe in order to visualize DNA in living cells.

The existing SiR stains have a λ_abs of 652 nm and a λ_em of 674 nm to be used with the Cy5 filter (Fig 1).

However, the continuously growing number of researchers using these stains asked us whether stains with different biophysical properties would be made available. In other words, they were asking “is there another colour to allow for double staining e.g. of Actin and Tubulin in living cells?”

There is an increasing demand for new cholesterol-lowering therapies in addition to existing treatments (e.g. targeting statins). The pharmacological inhibition of PCSK9-mediated LDLR degradation is becoming very attractive for treating cholesterol-related diseases. But which reliable in vitro assays are available to effectively study “PCSK9-LDLR” interactions ?

In this post, I’d like to take a look at the current understanding of tubulin PTMs, that include tyrosination/detyrosination, Δ2-tubulin formation, acetylation, phosphorylation, ubiquitination, glutamylation, and glycylation. This is inspired by contribution provided by Cytoskeleton Inc., who are experts in this domain.

Fig 1: TIGIT (VSTM3)/CD226 and CD28/CTLA-4 Pathway

Over the past months, we have released a number of posts introducing inhibitor screening assays intended to investigate immuno checkpoint protein interactions, such as PD-1/PD-L1/PD-L2;  B7-1/CD28, B7-1/CTLA4;  BLTA/HVEM, CD47/SIRPα; GITR/GITRL and many others – for an overview, you might like to read 9 pathway-specific screening assays in Immunotherapy.

Today, I’d like to concentrate on the TIGIT/CD226 pathway, because it acts through a novel mechanism to regulate CD8+ T cell functions within the tumour microenvironment.