Roger Tsien

Roger Tsien died in August 2016. His contributions to biochemical research were enormous. He shared the Nobel Prize for Chemistry in 2008 for work on GFP, but those who use his calcium dyes know his work is much broader than GFP. Indeed Roger was always more interested in cell dynamics than “mere stains”. Though his most recent work did focus on the latter, but with the goal of helping real time cancer surgery. Here is a partial list of “Roger’s firsts”, proving optical tools for studying cell dynamics was his main contribution:

The First Wave, synthetic chemical tools-

1. Ca-selective dye. Tsien, Biochemistry 1980. A single author paper Roger published as postdoc after his PhD (from which he did not publish a paper?) where in the synthesis of BAPTA was described and the first calcium-selective dye (quin2) was introduced. Note no reports of fluorescence appeared here and nor studies of living cells.

2. Fluorescent Ca dyes. Grynkiewicz, Poenie, Tsien, JBC 1985, 260, 3440. Surely Roger’s most important paper. The synthesis of fura-2 and indo-1, as well as their fluorescence properties for ratiometric measurements of [Ca]. Again, no live cell work.

3. Green and red fluorescent Ca dyes. Minta, Kao, Tsien, JBC 1989, 264, 8179. The “problem” with fura-2 is it required near-UV light for imaging. So Ca indicators modeled on traditional green and red dyes were called fluo-3 and rhod-2. These intensity based Ca dyes proved essential for confocal and 2-photon microscopy.

4. Fluorescent Na dye. Minta Tsien, JBC 1989, 264, 19449. As a coda to the Ca project, Roger also made a sodium dye. No very impactful compared to fura-2 and fluo-3.

5. Caged Ca. Tsien, Zucker, BJ 1986. In the middle of the “Ca indicator project” this paper appears. The first caged Ca report, two years before my own 1988 paper. The good news for me was nitr-2 was not very good (too slow and inefficient), but it still first.

6. Ratiometric video confocal. Tsien, Proc Royal Micro Soc 1990. Nikon commercialized this microscope, but I am told it was too expensive.

7. cAMP indicator. Adams, Harootunian, Buechler, Taylor, Tsien, Nature. 1991, 349, 694. Once you had made an indicator for cations, it was “obvious” that you wanted to image other things. Here they used chemistry to tag the regulatory and catalytic subunits of PKA with green and red dyes. Unfortunately this indicator had to be microinjected into cells, and was bedeviled by other problems.

8. Caged NO.  Makings, Tsien, JBC 1994, 269, 6282. There were Rh complexes that were used as caged NO, but this pure organic molecule was the first rationally designed caged compound for a gas.

9. Bhc-Glu.  The first caged Glu designed for 2P photolysis. In the same year I presented work on 2P photolysis of Glu at the SGP annual conference, this paper appears as Roger’s NAS membership paper. Fortunately for me the probe does not work (too slow, poor QY, not soluble in ACSF), and MNI-Glu does.

The second wave, the DNA era-

10. GFP. Heim, Prasher, Tsien PNAS 1994, 91, 12501. mutations made wt GFP much better and blue. Is it churlish to note that Clontech did the same thing independently?

11. cpGFP. Baird, Zachariuas, Tsien, PNAS 1999, 96, 11241. Scientifically more original than the first 2 papers?

12. GE Ca dye (Cameleon). Miyawaki, Tsien Nature. 1997 388, 882. Back to indicators, but now genetic encoding proves transformative. Note that unlike fura-2, it takes another 10 years and 100 of person years of work to start to “perfect” GECI.

13. GE cAMP dye. Zaccolo, De Giorgi, Cho, Feng, Knapp, Negulescu, Taylor, Tsien, Pozzan, Nat Cell Biol 2000, 2, 25-29. Returns to cAMP but now GE so they start to work better.

14. GE kinase dye. Ting, Kain, Klemke, Tsien, PNAS 2001, 98, 15003. The model study for all other GE probes for protein activity rather than solute concentration.

I have not mentioned AM esters, long wavelength GE dyes, TimeSTAMP, beta-lactamase indicators, the “mfruits”, using GFP as a pH indicator, voltage sensors, etc. Nor how bad FlAsH was for many labs.

In 2010 I organized the SGP annual conference on New Optical Methods in Cell Physiology. This was the third so themed by the Society, and Roger was the only person to speak at all three. At the conference he gave the first (?) public showings of two new technologies.

miniSOG. Shu, Lev-Ram, Deerinck, Qi, Ramko, Davidson, Jin, Ellisman, Tsien, Plos Biol 2011, 9, e1001041. Allows correlation of EM and fluorescence imaging with a GE probe.

PNAS 2010, 107, 4317. Nguyen, Olson, Aguilera, Jiang, Scadeng, Ellies, Tsien. Roger returned to organic chemistry with optical marking of tumors with targeted cell penetrating peptides. No clever name, but Roger said this was his most important work.