Sajja Ranjit ‘29
News Editor
On April 17, in Albert C. Jacobs Life Sciences Center (LSC) Room 134, students and faculty gathered to hear Assistant Professor DurreShahwar Muhammed unpack one of the cell’s most overlooked organelles: the peroxisome. Though often overshadowed by the mitochondria or chloroplasts, Muhammad’s research suggests these tiny structures may play a central role in how cells survive stress and what happens when that system breaks down.
Muhammad started the talk by highlighting her background. She earned her B.S. in biological sciences at the University of Illinois Chicago before completing her Ph.D. in plant and microbial biology at North Carolina State University and postdoctoral training at Rice University. She is now an assistant professor at University of Massachusetts Amherst, where her lab studies how cells maintain internal balance under stress.
Her journey, she emphasized, was non linear. After initially stepping away from research during and after college, she returned as a lab technician, an experience that reshaped her career path and interest in biology. She later balanced graduate school, postdoctoral research, and raising a family while earning competitive fellowship including NSF and NIH support. “Life will always happen,” Muhammed said. “But there’s always a way forward.” She encouraged students to seek out multiple research experiences and remain open to changing directions.
After outlining her background, Muhammad turned to her research on peroxisomes which are small but essential organelles responsible for processes like fatty acid breakdown and the regulation of reactive oxygen species (ROS). First identified by Chriddtian de Duve, peroxisomes are found across many organisms and play a critical role in maintaining cellular balance.
“They compartmentalize diverse enzymatic reactions,” Muhammad explained, noting that while these processes are necessary for metabolism, they generate high levels of oxidative stress. This creates a central challenge: How do peroxisomes maintain stability in such a harsh environment?
Her lab addresses this question by studying proteostasis, or the ability of cells to maintain healthy, functional proteins. Using the plant model Arabidopsis Thaliana, or Thale Cress, her team studies early plant development, when peroxisomes are critical for converting stored lipids into energy before photosynthesis begins.
“In seedlings, this pathway is really prominent early on,” she said, referring to fatty acid beta oxidation, which allows plants to convert stored lipids into energy before photosynthesis begins
At the center of this work is a protein called LON2, which helps regulate peroxisome health. When LON2 is disrupted, cells develop fewer, enlarged and dysfunctional peroxisomes. These structural changes are accompanied by clear physiological effects, including delayed germination, impaired growth and defects in protein import.
“Dysfunctional LON2 leads to impaired peroxisome function,” Muhammad said.
Her lab found that without LON2, damaged proteins accumulate inside peroxisomes and trigger excessive pexophagy, a selective autophagy process that breaks down peroxisomes. While pexophagy normally helps remove damaged organelles, too much of it reduces the number of functional peroxisomes available to the cell. Blocking this degradation process was able to restore function, suggesting that LON2 plays a protective role.
“LON2 protects peroxisomal proteins from degradation in wild type,” she explained.
The consequences extend beyond the organelle itself. Muhammad’s team found disruptions in lipid metabolism and delayed chloroplast development, demonstrating how dysfunction in one organelle can affect the entire cell.
“There are whole-cell consequences when peroxisomes are dysfunctional” she noted.
One key finding in particular involved the accumulation of lipid droplets, which normally serve as energy reserves. When fatty acid breakdown is impaired, these lipids are not efficiently metabolized, leading to delays in the plant’s transition from early growth to photosynthesis. In healthy seedlings, this transition is tightly regulated: peroxisomes dominate early metabolism, but over time, chloroplasts take over as photosynthesis begins.
“These processes have to be coordinated,” Muhammad said.
Her team’s data suggest that when peroxisomes fail, cells may redirect excess fatty acids to other organelles such as chloroplasts to prevent toxic buildup. “Free fatty acids are toxic,” Muhammad said, explaining the need for cells to carefully manage metabolic byproducts. While this compensatory mechanism may help protect the cell, it also disrupts normal development and delays chloroplast maturation.
Beyond plant biology, Muhammed emphasized the broader significance of peroxisomes. These organelles are also linked to human health, including metabolic diseases, cancer, and viral infection. “Peroxisomes interact with many other organelles and influence the whole cell,” she said. “So when they’re not functioning properly, the consequences are widespread.”
Through her research, Muhammad is helping shift scientific attention to an often overlooked organelle. By uncovering how peroxisomes maintain balance under stress, her work highlights their central role not only in plant development, but in the fundamental functioning of cells across organelles.
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