ALBERT

Description: Undergraduate programs in public health are growing rapidly. At colleges and universities throughout the United States, both the number of programs and the number of students have expanded greatly in the past decade. In response to this trend, the Council for Education of Public Health (CEPH) has begun to accredit undergraduate public health programs, with the first programs approved in 2014. Around the country programs exhibit wide variation, from concentrations in liberal arts colleges to pre-clinical foundations at doctorate-granting universities to undergraduate programs in accredited schools of public health. Faculty, both new and seasoned, are fully aware of the need to integrate undergraduate education in public health with graduate education—but the roadmaps of exactly how to do so are still nascent. The purpose of this Research Topic is to gather articles describing this variation, with the intent that the collective body of work will facilitate analysis and discussion of what makes a quality education and builds a competent workforce.

Description: Abstract 2011 Although both talin and kindlin-3 binding to the β3 cytoplasmic domain are required for agonist-induced αIIbβ3 activation in platelets, the biochemical basis for this dual requirement is not clear. Recent NMR and hydrogen-deuterium exchange studies of disulfide-stabilized complexes containing the full cytoplasmic domains of αIIb and β3 dispersed in detergent micelles or lipid bilayers revealed that the β3 cytoplasmic domain consists of three helices: a stable proximal helix contiguous with the transmembrane domain and two distal dynamic amphiphilic helices whose fluctuations allow interaction of the helices with lipid bilayers or cytoplasmic proteins. These results suggest a cooperative model for talin and kindlin-3 binding to β3 with the talin and kindlin-3 binding sites kinetically- and thermodynamically-linked. Whether there is a preferred temporal sequence for kindlin-3 versus talin binding to β3 during physiological αIIbβ3 activation in platelets is not known, but the greater mobility of the kindlin-3 binding site suggests it might have a kinetic advantage over talin, assuming both are present in appropriate forms for binding. Much is known about the structure and function of talin, but substantially less is known about kindlin-3 in part because it has not been possible to express the complete molecule in bacterial expression systems. To address this issue, we have examined kindlin-3 expression and function in human platelets. Two kindlin-3 isoforms have been identified, a long form (Mr ∼ 76 kDa; accession: NM_178443) and a short form (Mr ∼75 kDa accession: NM_031471), that differ by the presence of 4 residues (RIPR; residues 360–363) in the PH domain of the long isoform. Using highly purified platelet and leukocyte RNA and RT PCR, we found that kindlin-3 expressed in platelets and leukocytes consist almost entirely of the 663 amino acid short isoform. Kindlin-3 present in platelet extracts is functionally active and spontaneously binds to the β3 cytoplasmic domain in pull down assays. Moreover, because kindlin-3 binding is abrogated by the β3 mutations S752P and T759A, but not T759F, the in vitro binding of kindlin-3 does not appear to be phosphorylation dependent. Further, surface plasmon resonance spectroscopy suggests that the PH domain of kindlin-3 partially drives membrane binding in the presence of phospholipids. Treatment of washed human platelets with the PAR1-activating peptide TRAP-6 (SFLLRNP) resulted in the rapid incorporation of kindlin-3 present in the platelet cytosol into the platelet cytoskeleton. We also found that kindlin-3 is present in dense fractions when platelets extracts were fractionated on sucrose gradients. Likewise, immunofluorescent images of platelets adherent to fibrinogen and platelet immuno-electron microscopy detected the presence of kindlin-3 in vesicular structures. Finally, using out-dated human platelets as starting material, we purified kindlin-3 to near homogeneity by the sequential use of ion-exchange and gel-filtration chromatography. These results provide a foundation for understanding the unique role that kindlin-3 plays in regulating the activity of platelet αIIbβ3. Disclosures: No relevant conflicts of interest to declare.