Research at the Kesimer Laboratory
Mucins and Mucin Interactome in the Airway
Normal airway mucus is highly structured, containing five dominant mucins (MUC5AC, MUC5B, MUC1, MUC4 and MUC16) an excess of 100 proteins that form distinct protein complexes many of which are centered around these mucins.
These complexes constitute a discrete secretory entity we call the ‘mucin interactome’. Gel properties emerge from a dynamic interplay between the mucins and proteins and that these structures engender specific rheological properties of mucus that tune it to removal by cough and flow clearance. The main goals of this proposal are to understand the functional networks of mucin-protein and protein-protein interactions to generate a so-called "interactome" map in human respiratory mucus.
If the goals of this proposal achieved, they will increase our knowledge to understand the relationship of composition to function of airway secretions that is a necessary basis for informed therapeutic intervention that is currently lacking. Funding: R01 HL103940-01, Mehmet Kesimer (Principal Investigator).
Airway mucin composition and proteome in COPD: A SPIROMICS ancillary study.
At the broadest level, the major scientific goal of this proposal, using samples of mucus obtained through “Subpopulations and intermediate outcome measures in COPD study” (SPIROMICS) from smokers, and COPD patients, both at baseline and exacerbation, is to compare the mucin properties and mucin-interacting proteins over a large number of normal controls and COPD patients, and within the patient population, to enable the sub-classifications of COPD patients and discovery of biomarkers which is useful in the future as intermediate outcome measures for clinical trials. Funding: 1R01HL110906-01 Mehmet Kesimer (Principal Investigator).
The Effect of Cystic Fibrosis Post-Secretory Settings on Mucin Expansion and Maturation
Unpacking a gel forming mucins: Unpacking is a series of post-secretory processing steps that changes the mucin from a compact cross-linked form, to an expanded linear form that becomes the basis of the mucus gel.
Cystic Fibrosis in the lung is characterized by the failure of mucus clearance. Clearly mucus plays an important role in all manifestations of CF. There are some two hundred’ mainly globular proteins in human sputum, but it is the gel-forming mucins MUC5AC and MUC5B that we believe create the structural scaffold. The mechanisms underpinning the packaging of the large gel-forming mucins in granules and their subsequent expansion to mature the mucus are very poorly understood. This work is investigating the hypothesis that in the absence of CFTR, mucin expansion/mucus maturation is impaired due to different post-secretory environment in CF mucus. In testing this hypothesis, using the resolving power of the electron microscope in addition to a broad range of biochemical and biophysical techniques, we are testing: 1) To determine the factors effecting the normal maturation of the MUC5B just after secretion; 2) To test the hypothesis that the MUC5B mucin as born into the CF environment is prejudiced in its development and subsequent maturation. Role: Principal Investigator.
Funding: CF foundation (KESIME10I0)
Role of Human Airway Epithelium Derived Exosome-Like Vesicles in Innate Defense of the Lung
Exosomes are small, 50-150 nm, organelles secreted by different cell types including epithelial, haematopoietic and some tumour cells. The molecular organisation of these structures depends mainly on the cellular source from which they are derived. The detailed roles of the exosomes remain largely unexplained. We have demonstrated their presence in lung secretions and propose that they play important roles in innate lung defence, such as binding to and neutralizing the viruses. The objective of this work is to elucidate the organization of the human tracheobronchial epithelial (HTBE) exosomes and identify their cellular origin, ultimately we wish to understand their roles in airway host defense. Our preliminary data from HTBE cell culture indicate that exosomes are highly organized structures arising from different cell types to be found in the culture and that they interact with human influenza virus. Many of them have membrane tethered mucin coats that control their recognition properties. Role: Principal Investigator.
Funding: American Lung Association (RG-167538-N)
Mucus Maturation in Normal and CF Airways - MCC The major goals of this project are to understand why mucus clearance is problematic in the CF lung. DAVIS07XX0 (William C. Davis, PI). Role: Co-Investigator
SCCOR in Host Factors in Chronic Lung Disease, Project I: The Mucus Transport Apparatus: Why Two Layers?
The major goals of this project are, using a human bronchial epithelial cell line and normal and pathological sputum, to characterize the properties of the peri-ciliary gel layer and to identify the molecular mechanisms underlying the MUC5AC-rich gel and the MUC5B flowing mucus. 1 P50 HL 084934-01 (Richard Boucher, PI). Role: Co-Investigator.