Kathryn (Katie) Kapp

All Publications

• Charge within Nt17 peptides modulates huntingtin aggregation and initial lipid binding events. Biophysical chemistry Stonebraker, A. R., Hankin, R., Kapp, K. L., Li, P., Valentine, S. J., Legleiter, J. 2023; 303: 107123

  Abstract

  Toxic aggregation of pathogenic huntingtin protein (htt) is implicated in Huntington's disease and influenced by various factors, including the first seventeen amino acids at the N-terminus (Nt17) and the presence of lipid membranes. Nt17 has a propensity to form an amphipathic alpha-helix in the presence of binding partners, which promotes alpha-helix rich oligomer formation and facilitates htt/lipid interactions. Within Nt17 are multiple sites that are subject to post-translational modification, including acetylation and phosphorylation. Acetylation can occur at lysine 6, 9, and/or 15 while phosphorylation can occur at threonine 3, serine 13, and/or serine 16. Such modifications impact aggregation and lipid binding through the alteration of various intra- and intermolecular interactions. When incubated with htt-exon1(46Q), free Nt17 peptides containing point mutations mimicking acetylation or phosphorylation reduced fibril formation and altered oligomer morphologies. Upon exposure to lipid vesicles, changes to peptide/lipid complexation were observed and peptide-containing oligomers demonstrated reduced lipid interactions.

  View details for DOI 10.1016/j.bpc.2023.107123

  View details for PubMedID 37852163

• PATHWAYS ASSOCIATED WITH POSITIVE SEPSIS SURVIVAL OUTCOMES IN AFRICAN AMERICAN/BLACK AND NON-HISPANIC WHITE PATIENTS WITH URINARY TRACT INFECTION SHOCK Kapp, K. L., Choi, M., Bai, K., Du, L., Yende, S., Kellum, J. A., Angus, D. C., Peck-Palmer, O. M., Robinson, R. S. 2023; 60 (3): 362-372

  Abstract

  Urinary tract infections (UTIs) are a common cause of sepsis worldwide. Annually, more than 60,000 US deaths can be attributed to sepsis secondary to UTIs, and African American/Black adults have higher incidence and case-fatality rates than non-Hispanic White adults. Molecular-level factors that may help partially explain differences in sepsis survival outcomes between African American/Black and Non-Hispanic White adults are not clear. In this study, patient samples (N = 166) from the Protocolized Care for Early Septic Shock cohort were analyzed using discovery-based plasma proteomics. Patients had sepsis secondary to UTIs and were stratified according to self-identified racial background and sepsis survival outcomes. Proteomics results suggest patient heterogeneity across mechanisms driving survival from sepsis secondary to UTIs. Differentially expressed proteins (n = 122, false discovery rate-adjusted P < 0.05) in Non-Hispanic White sepsis survivors were primarily in immune system pathways, while differentially expressed proteins (n = 47, false discovery rate-adjusted P < 0.05) in African American/Black patients were mostly in metabolic pathways. However, in all patients, regardless of racial background, there were 16 differentially expressed proteins in sepsis survivors involved in translation initiation and shutdown pathways. These pathways are potential targets for prognostic intervention. Overall, this study provides information about molecular factors that may help explain disparities in sepsis survival outcomes among African American/Black and Non-Hispanic White patients with primary UTIs.

  View details for DOI 10.1097/SHK.0000000000002176

  View details for Web of Science ID 001081847700005

  View details for PubMedID 37493584

  View details for PubMedCentralID PMC10527228

• Incorporation of a Virtual Proteomics Module into the Undergraduate Analytical Curriculum JOURNAL OF CHEMICAL EDUCATION Kapp, K. L., Robinson, R. S., Verberne-Sutton, S., Stepler, K. E. 2023; 100 (8): 3124-3131

  View details for DOI 10.1021/acs.jchemed.3c00067

  View details for Web of Science ID 001020628500001

• A Prospective Cohort Protocol for the Remnant Investigation in Sepsis Study Critical Care Explorations Seymour, C. W., Urbanek, K. L., Nakayama, A., Kennedy, J. N., Powell, R., Robinson, R. A., Kapp, K. L., Billiar, T. R., Vodovotz, Y., Gelhaus, S. L., Cooper, V. S., Tang, L., Mayr, F. B., Reitz, K. M., Horvat, C., Meyer, N. J., Dickson, R. P., Angus, D. C., Peck Palmer, O. M. 2023; 5 (11): e0974

  View details for DOI 10.1097/CCE.0000000000000974

• Proteomic changes associated with racial background and sepsis survival outcomes. Molecular omics Kapp, K. L., Arul, A. B., Zhang, K. C., Du, L., Yende, S., Kellum, J. A., Angus, D. C., Peck-Palmer, O. M., Robinson, R. A. 2022; 18 (10): 923-937

  Abstract

  Intra-abdominal infection is a common cause of sepsis, and intra-abdominal sepsis leads to ∼156 000 U.S. deaths annually. African American/Black adults have higher incidence and mortality rates from sepsis compared to Non-Hispanic White adults. A limited number of studies have traced survival outcomes to molecular changes; however, these studies primarily only included Non-Hispanic White adults. Our goal is to better understand molecular changes that may contribute to differences in sepsis survival in African American/Black and Non-Hispanic White adults with primary intra-abdominal infection. We employed discovery-based plasma proteomics of patient samples from the Protocolized Care for Early Septic Shock (ProCESS) cohort (N = 107). We identified 49 proteins involved in the acute phase response and complement system whose expression levels are associated with both survival outcome and racial background. Additionally, 82 proteins differentially-expressed in survivors were specific to African American/Black or Non-Hispanic White patients, suggesting molecular-level heterogeneity in sepsis patients in key inflammatory pathways. A smaller, robust set of 19 proteins were in common in African American/Black and Non-Hispanic White survivors and may represent potential universal molecular changes in sepsis. Overall, this study identifies molecular factors that may contribute to differences in survival outcomes in African American/Black patients that are not fully explained by socioeconomic or other non-biological factors.

  View details for DOI 10.1039/d2mo00171c

  View details for PubMedID 36097965

• Advancements in automation for plasma proteomics sample preparation. Molecular omics King, C. D., Kapp, K. L., Arul, A. B., Choi, M. J., Robinson, R. A. 2022; 18 (9): 828-839

  Abstract

  Automation is necessary to increase sample processing throughput for large-scale clinical analyses. Replacement of manual pipettes with robotic liquid handler systems is especially helpful in processing blood-based samples, such as plasma and serum. These samples are very heterogenous, and protein expression can vary greatly from sample-to-sample, even for healthy controls. Detection of true biological changes requires that variation from sample preparation steps and downstream analytical detection methods, such as mass spectrometry, remains low. In this mini-review, we discuss plasma proteomics protocols and the benefits of automation towards enabling detection of low abundant proteins and providing low sample error and increased sample throughput. This discussion includes considerations for automation of major sample depletion and/or enrichment strategies for plasma toward mass spectrometry detection.

  View details for DOI 10.1039/d2mo00122e

  View details for PubMedID 36048090

  View details for PubMedCentralID PMC9879274

• Lipid Membranes Influence the Ability of Small Molecules To Inhibit Huntingtin Fibrillization. Biochemistry Beasley, M., Stonebraker, A. R., Hasan, I., Kapp, K. L., Liang, B. J., Agarwal, G., Groover, S., Sedighi, F., Legleiter, J. 2019; 58 (43): 4361-4373

  Abstract

  Several diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease (HD), are associated with specific proteins aggregating and depositing within tissues and/or cellular compartments. The aggregation of these proteins is characterized by the formation of extended, β-sheet rich fibrils, termed amyloid. In addition, a variety of other aggregate species also form, including oligomers and protofibrils. Specifically, HD is caused by the aggregation of the huntingtin (htt) protein that contains an expanded polyglutamine domain. Due to the link between protein aggregation and disease, small molecule aggregation inhibitors have been pursued as potential therapeutic agents. Two such small molecules are epigallocatechin 3-gallate (EGCG) and curcumin, both of which inhibit the fibril formation of several amyloid-forming proteins. However, amyloid formation is a complex process that is strongly influenced by the protein's environment, leading to distinct aggregation pathways. Thus, changes in the protein's environment may alter the effectiveness of aggregation inhibitors. A well-known modulator of amyloid formation is lipid membranes. Here, we investigated if the presence of lipid vesicles altered the ability of EGCG or curcumin to modulate htt aggregation and influence the interaction of htt with lipid membranes. The presence of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine or total brain lipid extract vesicles prevented the curcumin from inhibiting htt fibril formation. In contrast, EGCG's inhibition of htt fibril formation persisted in the presence of lipids. Collectively, these results highlight the complexity of htt aggregation and demonstrate that the presence of lipid membranes is a key modifier of the ability of small molecules to inhibit htt fibril formation.

  View details for DOI 10.1021/acs.biochem.9b00739

  View details for PubMedID 31608620

  View details for PubMedCentralID PMC7778521