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Faculty Detail    
Name JAN NOVAK
  
Campus Address BBRB 761A Zip 2170
Phone  (205) 934-4480
E-mail  jannovak@uab.edu
Other websites
     


Faculty Appointment(s)
Appointment Type Department Division Rank
Primary  Microbiology  Microbiology Professor Distinguished
Center  Center for AIDS Research  Center for AIDS Research Professor Distinguished
Center  Center for Biophysical Sciences/Engineering  Center for Biophysical Sciences/Engineering Professor Distinguished
Center  Comp Arthritis, MSK, Bone & Autoimmunity Ctr  Comp Arthritis, MSK, Bone & Autoimmunity Ctr Professor Distinguished
Center  Comprehensive Cancer Center  Comprehensive Cancer Center Professor Distinguished
Center  Ctr for Clinical & Translational Sci  Ctr for Clinical & Translational Sci Professor Distinguished
Center  Nephrology Research & Training Center  Nephrology Research & Training Center Professor Distinguished
Center  UAB Immunology Institute  UAB Immunology Institute Professor Distinguished

Graduate Biomedical Sciences Affiliations
Biochemistry and Structural Biology 
Hughes Med-Grad Fellowship Program 
Immunology 
Microbiology 

Biographical Sketch 
Dr. Jan Novak (b. 1962) is a Professor of Microbiology at UAB. He received BS and MS in Biology from the Charles University, Prague, Czech Republic and PhD in Cell and Molecular Biology from the Czech Academy of Sciences. He has been at UAB since 1992, first in the Department of Oral Biology where he studied genetics and biochemistry of bacterially produced biologically active peptides and since 1997 in the Department of Microbiology.



Research/Clinical Interest
Title
Pathogenesis and treatments of chronic diseases, infectious diseases, cancer. IgA nephropathy. Mucosal immunology. Biomarkers.
Description
Major topics are related to renal diseases and autoimmune diseases (IgA nephropathy and other chronic diseases of the kidney), cancer, and mucosal infections, including sexually transmitted diseases, such as those caused by HIV. Other interests include biologically active compounds. 1. Pathogenesis of IgA nephropathy IgA nephropathy (IgAN) is the most common cause of primary glomerulonephritis in the United States. Most patients experience progressive kidney disease, which can culminate in end-stage renal disease. Currently, there is no disease-specific treatment. Thus, improvements in the understanding of the pathogenesis of the disease are of critical importance in developing clinically relevant strategies for non-invasive diagnosis, monitoring of disease progression, and development of disease-specific therapy. IgAN is characterized by prominent mesangial deposits of IgA1, with co-deposits of C3 and IgG, IgM or both, typically associated with mesangial proliferation and expansion of the extracellular matrix. Hematuria is typical and often includes episodes of macroscopic bleeding that coincide with mucosal infections, including infections of the upper respiratory tract and digestive system. A considerable body of evidence suggests that the mesangial deposits are derived from circulating immune complexes containing IgA1. IgA1 in the circulating immune complexes and in the renal deposits exhibits galactose (Gal) deficiency in the hinge-region O-glycans unique to IgA1 (Gd-IgA1). Direct analysis of the pathogenesis has been difficult, however, due to the lack of animal models (IgA1 occurs only in certain primates), the heterogeneity of disease progression, and the mutifactorial nature of the disease which appears to involve a number of genes plus environmental triggers. Detailed analyses of the IgA1 antigen (Gd-IgA1) and the anti-Gd-IgA1 antibodies involved in the formation of the immune complexes have identified specific aberrations that are characteristic of IgAN but also indicate that when these aberrations occur alone they are not associated with clinical expression of IgAN. We have proposed the concept that a multi-hit mechanism underlies the pathophysiology and genetics of IgAN. It has been known for some time that patients with IgAN have high levels of Gd-IgA1 (Hit 1). Moreover, the circulating complexes in patients with IgAN contain Gd-IgA1and Gd-IgA1 is the predominant glycosylation variant of IgA1 in the mesangium. The occurrence of high levels of Gd-IgA1 is not, however, sufficient for the development of nephritis and several different experimental approaches indicate that Gd-IgA1 that is not incorporated into immune complexes is not pathogenic. Moreover, a high circulating load of Gd-IgA1 alone does not induce renal injury; thus, the factors that facilitate the formation of the Gd-IgA1-containing immune complexes (Hit 3) are critical for the clinical expression of IgAN. In patients with IgAN, the immune complexes containing Gd-IgA1 are formed almost exclusively by binding to IgG or IgA1 antibodies. (Hit 2). The IgG antibodies recognize GalNAc-containing epitopes on the Gal-deficient hinge region of the Gd-IgA1 and that they exhibit unique features in the complementarity-determining region 3 (CDR3) of the variable region of their heavy chains. The serum levels of IgG antibodies specific for Gd-IgA1 correlate with disease severity, as assessed by the magnitude of proteinuria. As Gd-IgA1-binding antibodies also are present in the sera of normal individuals, albeit at lower levels, these data suggest that their presence is not sufficient for induction of renal injury. Thus, the interactions of the anti-Gd-IgA1 antibodies with the Gd-IgA1 that result in immune complex formation (Hit 3) are critical for the clinical expression of IgAN. Thus, the glycosylation defects in the hinge region of Gd-IgA1 and the epitope specificity of the Gd-IgA1 autoantibodies are of critical importance in the formation of pathogenic immune complexes; however, there is evidence in the literature, which is supported by our preliminary data, that other serum factors interact with the immune complexes and contribute to their pathogenicity. Little is known regarding whether these factors are necessary for the immune complex-induced injury or alternatively act to modify the effects of the immune complexes by promoting stability, binding, or activity. Similarly, little is known concerning the molecular mechanisms that are triggered by the binding of the immune complexes to the mesangial cells. Our identification of the Gd-IgA1 defects and the IgG autoantibodies as well as the unique reagents and techniques that we have developed, including the use of engineered immune complexes, allow us to dissect the relative roles of these different components in the formation of immune complexes and to identify the characteristics of the pathogenic immune complexes in IgAN (Hit 3). Similarly, the use of the engineered immune complexes allows analysis of the mesangial deposition of the immune complexes and the mechanisms by which they promote cell activation and initiation of glomerular injury (Hit 4). Goals: 1. Identify and characterize genetic, biochemical, and immunological factors and pathways that - are involved in aberrant glycosylation of IgA1 in IgAN; - direct production of anti-glycan antibodies specific for aberrantly glycosylated IgA1; - are bound in the nephritogenic IgA1-containing complexes; - are induced in mesangial cells by the nephritogenic IgA1-containing complexes. 2. Identify and characterize markers of IgAN with diagnostic and prognostic significance. 3. Identify and characterize targets for disease-specific treatment of IgAN. 4. Extend these studies to other diseases with aberrant glycosylation and anti-glycan antibodies, such as breast cancer and other types of adenocarcinoma. 2. Cell-specific glycosylation of HIV-1 envelope glycoprotein HIV-1 envelope (Env) gp120/gp41 trimers are involved in the binding of virus to the host-cell receptor (CD4) and co-receptor(s) and the initial steps of cell entry. Approximately half of the total molecular mass of gp120 is attributed to N-glycans. Analysis of HIV-1 env nucleotide sequences suggested a close association between the V3-loop potential N-glycosylation sites (PNGS) and CCR5 usage. These studies, however, were based on amino sequences deduced from nucleotide sequences and, thus, have not assessed the effect of glycan composition on the gp120-coreceptor interactions. Furthermore, there are some limited data that V1/2, V3, and V4 glycans affect immune recognition of gp120 and also the interactions of gp120 with HIV receptors/co-receptors on target cells. Env gp120 glycans serve as epitopes for some Abs and, importantly, as a shield against most neutralizing Abs, with HIV-1 escape variants characterized by diverse env sequences present in the chronic stages of infection. These escape variants emerge due to the pressure of immune system. Molecular studies of HIV-1 transmission have identified early-transmitted “founder” viruses (TFV) and the molecular pathways of early env diversification. The variants from early and chronic stages of infection differ in the number and localization of PNGS. The new PNGS may be involved in generating a shield against neutralizing Abs (Fig. 2). Recently, It was shown that some of the PNGS were unoccupied or variably glycosylated. For example, two clade B HIV-1 gp120 sequences with two PNGS at the beginning of V3 region exhibited rather striking differences in the actual glycosylation of these sites. One sequence had both PNGS occupied by complex glycans whereas the other one had two glycosylation variants; the first variant had only the first PNGS glycosylated by a high-mannose glycan and the second variant had both PNGS occupied, with the first site having a complex glycan and the other site a high-mannose glycan. Although the biological significance of this observation could not be concluded from such a limited number of analyses, these observations clearly suggested that the glycosylation of Env, including gp120, is co-determined by the viral genome, glycan density on folded gp120 proteins, and the host cells producing the virus. Our preliminary studies, performed with recombinant (r) consensus B (Con B) gp120 trimers and using high-resolution mass spectrometry (MS), supported this conclusion and showed that gp120 glycosylation is cell specific, thus extending the earlier reports for HIV-2, and is affected by cellular metabolism. Furthermore, our studies revealed that the differential glycosylation of gp120 affects the binding of HIV-1-specific Abs. Specifically, our data indicated that gp120 expressed in T cells and muscle cells was less reactive with gp120-specific Abs compared to gp120 produced in other cells, such as 293T cells. As the T cells are the natural host cells for HIV-1 and DNA vaccines are applied intramuscularly leading to production of muscle-derived gp120, these observations may have implications for vaccine design. Apparently, certain cell-specific types of glycosylation render gp120 more resistant to Ab recognition, whereas other glycosylation patterns may be more permissive for immune recognition. It is not known how gp120 in TFV and late HIV-1 variants are glycosylated in different cell types and how these, presumably differentially glycosylated gp120 molecules are recognized by HIV-1-specific Abs from sera of HIV-1 infected patients or volunteers immunized with env DNA vaccine. Molecular analysis of glycosylation of these different gp120 molecules produced in different cells will reveal whether the glycosylation of late, escape variants can be directly linked to decreased binding by serum neutralizing Abs. These studies of HIV-1 Env glycosylation will have an impact on the understanding of basic mechanisms affecting immune recognition and immune escape of HIV-1 and could contribute to rational design of future vaccination strategies. Goals: Identify and characterize biochemical and genetic factors and pathways that 1. Regulate cell-specific pathways of Env glycosylation; 2. Affect recognition of Env and thus HIV-1 by Abs; 3. Contribute to enhanced immune responses and inform HIV/AIDS vaccine development.

Selected Publications 
Publication PUBMEDID
Renfrow, M.B., Cooper, H.J., Tomana, M., Kulhavy, R., Hiki, Y., Toma, K., Emmett, M.R., Mestecky, J., Marshall A. G., Novak, J. Determination of aberrant O-glycosylation in the IgA1 hinge region by electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry. J. Biol. Chem. 280, 19136-19145, 2005.   
Tomana, M., Novak, J., Julian, B. A., Matousovic, K., Konecny, K., Mestecky, J. Circulating immune complexes in IgA nephropathy consist of IgA1 with galactose-deficient hinge region and antiglycan antibodies. J. Clin. Invest. 104, 73-81, 1999.   
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