Characterization of Beta Tubulin Expression During Human Foam Cell Formation and in Atherosclerotic Lesions of the Aorta
Authors: De Los Santos Andrea , Torres Adriana , Contreras‐Shannon Veronica 
Published: November 2023

Foam cells arise when monocytes accumulate lipids and as a result get larger. It is assumed that the cytoskeleton compensates for this morphological change. Beta tubulin is essential to the formation of microtubules, which are an important component of the cytoskeleton. The purpose of this research was to elucidate the expression patterns of beta tubulin isotypes 1–4 in human monocytes during foam cell formation and in vivo in mouse atherosclerotic lesions to determine what relationship exists between beta tubulin expression and 1) a monocyte's ability to undergo foam cell formation or 2) lesion development in a mouse model of atherosclerosis. We hypothesized that the distribution of and amount of at least one beta tubulin isotype changes throughout the three stages of foam cell induction and within an atherosclerotic lesion, relative to a normal aorta. Further, we expect that monocytes with manipulated levels of a certain isotype(s) of beta tubulin will exhibit differences in the uptake of low‐density lipoprotein when compared to wild‐type human monocytes. Levels of beta tubulin 1–4 were measured by western blot and immunofluorescence throughout the stages of foam cell differentiation, and several beta tubulin isotypes were manipulated by siRNA to determine the effects of diminished beta tubulin expression on foam cell formation. Additionally, we performed immunohistochemistry, using the superior portion of the heart, and qPCR, using the abdominal aortic arch; both from ApoE−/− mice fed a high cholesterol diet to induce atherosclerotic lesions. In cultured monocytes, it was found that the distribution of beta tubulin 1, 3, and 4 changes throughout the stages of foam cell induction, and manipulation of beta tubulins altered foam cell formation. Furthermore, the silencing or decreasing of beta tubulin enhanced lipid aggregation. Based on our immunohistochemical analyses, the distribution of the beta‐tubulins appears to be unique and differs between wildtype mice without lesions and ApoE knockout mice with lesions. In particular, beta‐tubulin II was less abundant and diffuse, while beta‐tubulin III appeared more abundant but diffuse. Based on initial qPCR analyses, beta‐tubulin I and III expression was highest compared to wildtype mice. Based on the qPCR data, beta‐tubulin III has the highest rate of expression thus far; we intend to analyze expression of additional genes. This study could provide further knowledge on the development of foam cell formation and atherosclerotic lesions that may be influenced by beta‐tubulin, which may provide a possible target for treatment or prevention of atherosclerosis.Support or Funding InformationSupported by a grant to Veronica Contreras‐Shannon from the Semp Russ Foundation and Lila G. and Vesey F. Taylor Fund, San Antonio Area Foundation; a summer 2015 SURF to Andrea De Los Santos from the Undergraduate Research Office, St. Mary's University; and a summer 2014 SURF to Adriana Torres from the Undergraduate Research Office, St. Mary's University