Harold Paul Erickson
James B. Duke Distinguished Professor of Cell Biology

Cytoskeleton: It is now clear that the actin and microtubule cytoskeleton originated in bacteria. Our major research is on FtsZ, the bacterial tubulin homolog, which assembles into a contractile ring that divides the bacterium. We have studied FtsZ assembly in vitro, and found that it assembles into thin protofilaments (pfs). Dozens of these pfs are further clustered to form the contractile Z-ring in vivo. Some important discoveries in the last ten years include:

•    Reconstitution of Z rings in vitro. We provided FtsZ with a membrane tether, and found that when incorporated inside liposomes, FtsZ-mts can assemble Z rings without any other proteins.

•    These reconstituted Z rings generate a constriction force on the membranes, again without any other proteins (no motor molecules).

  • We recently developed a model to explain how treadmilling works, based on an R to T conformational change and GTP hydrolysis.
Irisin. We believe the irisin story is bunk. Irisin was proposed in 2012 as a novel myokine, secreted by muscle cells in response to exercise, it induces the transformation of white fat to brown fat. This inspired hopes of an exercise pill that might correct obesity and other metabolic disorders. We have argued that the original discovery was flawed in several respects (Erickson, Adipocyte, 2013), and that the 1,000+ published follow-up studies are based on flawed commercial antibodies (Albrecht et al, Sci Rep 2015). Our recent review (Maak et al, Endoc Rev 2021) expands these critiques, adds new ones, and suggests that gene knockouts will help resolve controversies. 

Current Research Interests

Updated June 2019. 

Cytoskeleton: It is now clear that the actin and microtubule cytoskeleton originated in bacteria. Our major research is on FtsZ, the bacterial tubulin homolog, which assembles into a contractile ring that divides the bacterium. We have studied FtsZ assembly in vitro, and found that it assembles into thin protofilaments (pfs). Dozens of these pfs are further clustered to form the contractile Z-ring in vivo. Recent work from other labs has established that the pfs are clustered in small patches that move around the circumference of the cell by a treadmilling mechanism. A major project in our lab is to generate a Monte Carlo model that can explain treadmilling and nucleation, based on conformational changes and GTP hydrolysis. (See my 2019 article on microtubule assembly from flared pfs for a preview of our treadmilling ideas, and an important implication for microtubule assembly.) We are also interested in how FtsZ generates a constriction force, and how this force constricts against turgor pressure, or how it “cheats turgor.”

Irisin. We got interested in irisin from an indirect pathway. We believe the irisin story is bunk. Irisin was proposed in 2012 as a novel myokine: secreted by muscle cells in response to exercise, it induces the transformation of white fat to brown fat. This inspired hopes of an exercise pill that might correct obesity and other metabolic disorders. We have argued that the original discovery was flawed in several respects (Erickson, Adipocyte, 2013), and that the 600+ published follow-up studies are based on flawed commercial antibodies (Albrecht et al, Sci Rep 2015). We are currently using mass spectrometry to measure plasma concentrations of irisin in humans and baboons. This  should be interesting because humans have a mutation in the start codon that should reduce its expression ~100x relative to other animals.

Current Appointments & Affiliations

Contact Information

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