Secrets of human aging discovered in plant leaves

Scientists from UC Riverside have uncovered a significant connection between a specific plant organelle and the aging process.

This unanticipated discovery is set to improve our understanding of aging in plants, and potentially in humans as well.

The research team, led by Professor Katie Dehesh, embarked on a journey to explore which parts of plant cells were instrumental in controlling responses to various stressors such as infections, excessive salt, or insufficient light. 

Golgi body, plants, and aging

In the course of the investigation, the researchers stumbled upon the Golgi body, an organelle known to scientists for over a century, and identified its critical role in plant aging.

“For us, this finding is a big deal. For the first time, we have defined the profound importance of an organelle in the cell that was not previously implicated in the process of aging,” explained Professor Dehesh.

The Golgi body is sometimes humorously described as resembling deflated balloons or dropped lasagna. It comprises a series of membrane-covered sacs responsible for sorting and dispatching various molecules within the cell. 

“Golgi are like the post office of the cell. They package and send out proteins and lipids to where they’re needed,” said study co-author Heeseung Choi. “A damaged Golgi can create confusion and trouble in the cell’s activities, affecting how the cell works and stays healthy.”

COG protein 

A crucial component of this cellular post office is the COG protein, which acts much like a postal worker, managing the movement of sacs that transport molecules around the cell. 

The COG protein also assists the Golgi bodies in a process called glycosylation — the attachment of sugars to other proteins or lipids. This process is vital for numerous biological functions, including immune response.

The experiments involved modifying some plants to lack the COG protein. Under normal conditions, these modified plants exhibited no discernable differences from their unaltered counterparts. 

However, when deprived of light, a condition that prevents plants from producing sugars necessary for growth, the COG-deficient plants displayed accelerated aging symptoms.

Their leaves turned yellow, wrinkled, and thin – signs typically seen in unmodified plants only after a longer period of darkness.

“In the dark, the COG mutants showed signs of aging that typically appear in wild, unmodified plants around day nine. But in the mutants, these signs manifested in just three days,” explained Choi.

Rapid reversal of aging

Remarkably, reintroducing the COG protein into these plants reversed the aging signs rapidly, suggesting the profound impact of this protein and the Golgi’s normal functioning in managing stress.

This discovery is particularly exciting because Golgi bodies are not exclusive to plants but are found in all eukaryotic organisms, including humans.

This means that plants could now serve as a model to further investigate the Golgi’s role in human aging.

“Not only does our research advance our knowledge about how plants age, but it could also provide crucial clues about aging in humans,” Dehesh said. 

“When the COG protein complex doesn’t work properly, it might make our cells age faster, just like what we saw in plants when they lacked light. This breakthrough could have far-reaching implications for the study of aging and age-related diseases.”

More about Golgi body and plant aging

In the bustling city of a cell, the Golgi body plays a crucial role, akin to a highly efficient post office.

As discussed above, this organelle, discovered by Camillo Golgi in 1898, is a central hub for managing, modifying, and dispatching cellular materials. It also plays a key role in plant and human aging.

Structure and location

Residing within the eukaryotic cells, the Golgi body exhibits a distinct structure. It comprises a series of flattened, membrane-bound sacs known as cisternae.

These sacs are not mere storage spaces; they are dynamic areas where the processing of proteins and lipids occurs.

The Golgi apparatus, often located near the cell nucleus and endoplasmic reticulum, operates as a critical waypoint between these structures.

Modifying and sorting cellular products

One of the primary functions of the Golgi body is to modify proteins and lipids that the endoplasmic reticulum synthesizes.

This modification process includes the addition of sugars (glycosylation), which transforms simple proteins into more complex and functional glycoproteins.

This intricate process equips the proteins with specific “postal codes,” directing them to their correct destinations within or outside the cell.

Transporting vital components

After processing, the Golgi apparatus sorts and packages these materials into vesicles. These vesicles, which are small, membrane-bound carriers, then transport the contents to various parts of the cell or to the cell surface for secretion.

This transport mechanism is vital for numerous cellular activities, including the delivery of enzymes to lysosomes, the secretion of hormones, and the formation of the cell’s plasma membrane.

Golgi body as the hub of cellular communication

The Golgi body’s role extends beyond processing and sorting. It is instrumental in cell-to-cell communication, ensuring that cells produce and secrete the right molecules in response to environmental signals.

This function is paramount in maintaining the overall health and functionality of multicellular organisms.

In summary, the Golgi body is a cornerstone of cellular function, akin to a well-oiled machine within the vast factory of the cell. Its ability to process, modify, sort, and dispatch cellular materials is crucial for maintaining the cell’s integrity and ensuring its smooth operation.

This tiny but mighty organelle continues to be a subject of fascination and study, revealing the intricate complexities of cellular life.

The study is published in the journal Nature Plants. 

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