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Understanding a cell part construction manager

The Hu lab has deepened our understanding of a protein, called SP1, that controls how cells build an internal part, the peroxisome, crucial for maintaining healthy plants and animals.

Dr. Jianping Hu, Professor at the PRL, says, "Peroxisomes are like food processors that break down fatty acids (fats) into smaller pieces so they can be used to produce energy, and they also help protect their hosts from environmental stresses."

The Hu lab observed that SP1, like a gatekeeper, controls the level of proteins (called PEX, for peroxins) that import the building tools into peroxisomes. SP1 breaks some of these PEX proteins down once they have performed their necessary functions.

Hu says, “SP1 does that so that protein import into the peroxisome is controlled and not overly active when not needed. It is important to maintain this balance, and SP1 facilitates it.”

Jianping Hu portrait
Dr. Jianping Hu.
By Harley J Seeley Photography

In one experiment, the Hu lab identified mutants with deficient PEX proteins – in other words, the building tools weren’t being appropriately shuttled into the peroxisome.

Then, SP1 was removed. “Without SP1, these PEX proteins could not be degraded, so they accumulated in the plant. This stabilization of the PEX proteins led to an enhanced import of the ‘building tools’, therefore rescuing some of the deficiencies of the original mutants and reinforcing the idea of SP1’s role as a ‘building regulator’.”

From ag to human medicine applications

“This is new and exciting work,” Hu says. “We already knew that SP1 helped control protein import into the chloroplast, another part of plant cells responsible for providing food and energy to most of the planet. It seems SP1 wears many hats after all.”

“And understanding how these cellular building processes are controlled could someday lead us to real-world agricultural solutions, such as molecular strategies to engineer crops with better metabolism or improved defenses against diseases.”

Hu also found that SP1 shares characteristics with a protein found in humans, opening the possibility that this family of proteins controls the construction of multiple cell parts over many different species.

“Perhaps the biomedical field will someday use this information to cure human peroxisomal disorders, which can be devastating (symptoms include poor growth, neurological dysfunctions, hearing/visual problems, liver disease, etc), as peroxisomes carry out essential functions in the human body.”


Banner of construction site by By Jakob Montrasio, CC BY 2.0;This research was funded by the National Science Foundation. The findings have been published in the journal, Proceedings of the National Academy of Sciences. Additional MSU researchers contributing to the study include: Rongui Pan and John Satkovich from the MSU-DOE Plant Research Laboratory.

 

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