07/03/2025
By Danielle Fretwell

The Francis College of Engineering, Department of Biomedical Engineering, invites you to attend a Doctoral Dissertation defense by Marla J. Hilderbrand-Chae on: “Exploring STEM Identity Formation and Lived Experiences of Minoritized Students in High School Elective Internships” and “A Materials-based Approach to Investigate Response of the Inner Nuclear Membrane Protein SUN2 to Matrix Dynamics.”

Candidate Name: Marla J. Hilderbrand-Chae
Degree: Doctoral
Defense Date: Wednesday, July 9, 2025
Time: 10 a.m. - 1 p.m.
Location: UCC 490

Committee:

  • Advisor: Yanfen Li, Ph.D., Assistant Professor, Biomedical Engineering, University of Massachusetts Lowell
  • Teresa Lee, Ph.D., Assistant Professor, Department of Biology, University of Massachusetts Lowell
  • Adam St. Jean, Ph.D., Associate Professor, Department of Biomedical Engineering, University of Massachusetts Lowell
  • Hsien Yuan Hsu, Ph.D., Associate Professor, Department of Education, University of Massachusetts Lowell
  • Panagiota Athinelis, Ph.D., Greater Lawrence Technical School, Andover, Massachusetts

Abstract:
STEM programming for high school students cultivates interest in STEM careers and develops skills that can initiate or reinforce STEM identity development. Underserved individuals in STEM, including Black or African American, Hispanic or Latino/a, and American Indian or Alaska Native, Southeast Asian, economically disadvantaged students, first generation to college, and students with disabilities, achieve beneficial results as participants of these programs. However, the application processes for these programs may present barriers that disproportionately impact students from minoritized populations. Through a mixed-methods analysis, application completion, demographics, and STEM identity levels are investigated for a high school research internship, with findings suggestive that STEM identity may play a role in who successfully completes the application, and that a more inclusive, interest-based application approach could mitigate barriers for underserved learners. In a second mixed-methods study, home support and Home STEM Talk among minoritized high school students participating in the same summer research internship are examined. Findings indicate that students from multilingual homes feel less home support for their STEM pursuits and report hardship in translating STEM topics for their caregivers. However, upon completion of the program, multilingual students made larger gains in Home STEM Talk frequency with richer discourse content than their peers from English-speaking homes. These combined studies provide new avenues for program development and evaluation to positively influence long-term STEM education and career outcomes.

Cells are constantly exposed to mechanical forces in the extracellular matrix and optimal function requires that cells interpret and respond to these forces through a process called mechanotransduction. Mechanical cues are sensed by receptors in the cellular membrane and are transduced across the nucleus by the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. One protein in this complex is a highly conserved inner-nuclear membrane protein called SUN2. Partnering with KASH-domain containing Nesprin proteins to form the LINC complex, SUN2 mediates cellular adhesions, migration, nuclear positioning, mitotic duration, and, when mutated, can result in skeletal muscle disease and cardiomyopathy. To investigate SUN2’s role in mechanotransduction, we cultured C2C12 skeletal myoblasts under defined conditions of geometric confinement and substrate stiffness. We used immunofluorescence and Western blotting with
domain-specific antibodies targeting the N-terminal (total SUN2) and C-terminal (SUN2 that is not bound in active LINC complexes, or unbound SUN2) epitopes to assess SUN2 expression dynamics in response to varied mechanical cues. The data show that unbound SUN2 is mechanosensitive and the binding state of SUN2 changes in response to differences in substrate stiffness and geometry, suggesting that the response to matrix mechanobiology is driven by expression levels of unbound SUN2.