Paolo Casali, M.D.

Molecular genetics of antibody generation, epigenetics of the antibody response, in vivo antibody response in humanized mice

Mechanisms of immunoglobulin locus activation and targeting, as well as regulation of genome-wide and specific gene expression by epigenetic marks and gut microbiota, in antibody/autoantibody responses and immune memory.

The Casali lab continues to focus on the B cell mechanisms underpinning the maturation of T-dependent (CD40) or T-independent (toll-like receptor) antibody and autoantibody responses, that is, Ig locus class-switch DNA recombination (CSR)/somatic hypermutation (SHM), memory B cell and plasma cell differentiation, and their regulation. Using biochemical and molecular genetic approaches, we elucidated the mechanisms by which AID inserts staggered-end double-strand breaks in S and V(D)J DNA to initiate CSR/SHM, and identified 5’-AGCT-3’ repeats and 14-3-3 adaptors as essential elements in targeting/stabilizing AID to IgH locus. We also defined roles for translesion DNA synthesis polymerases ζ (Rev3) and Ɵ in SHM, a non-enzymatic role for DNA polymerase Rev1 in CSR and a role for the homologous recombination DNA repair Rad52 in alternative non-homologous end-joining (A-NHEJ) of CSR. We have identified HoxC4 as a critical transcription factor in Aicda activation and estrogen-ERs in activation of the HoxC4 promoter and, therefore, AID expression, as modulated by Rab7 small GTPase. Estrogen-activated HoxC4 potentiates AID expression and AID off-targeting, thereby promoting chromosomal translocations, autoimmunity and lymphomagenesis. Recently, we have tackled the role of epigenetic modifications and factors, e.g., histone posttranslational modifications, non-coding RNAs, histone deacetylases (HDACs) and DNA methylases, in regulating Aicda (AID gene) expression, targeting the CSR/SHM machinery to the IgH locus, Prdm1 (Blimp1 gene) expression and plasma cell differentiation. These studies have unveiled important roles for Zn2+-dependent Class I, II, IV HDACs and NAD+-dependent Class III Sirt1 in regulating CSR/SHM and plasma cell differentiation. Also, they indicate that some of such HDACs synergize with epigenetic factors for new outcomes. As one example, we show critical and concerted roles of the NAD+-Sirt1 histone/non-histone protein deacetylase with Tet2 DNA demethylase/histone glycosylase, in B cell-intrinsic epigenetic modulation of AID and Blimp1 in autoantibody responses. Having perfected the construction of humanized huNSG/cKitW-41J mice, we can now extend the analysis of such epigenetic modulation human antibody responses in vivo. Thus, by performing first-class research using cutting-edge technology and open communication, my laboratory continues to train next generation scientists to become future leaders in molecular immunology and epigenetics.

Related diseases: Lupus, Cancer, Allergy, Autoimmunity

Techniques: Deep Sequencing, ATAC-sequencing, humanized mice, cell sorting

• Research & Grants

  Research profile

• Publications

  Selected Publications (last 5 years)

  ·         Chupp, D.P., C.E. Rivera, Y. A. Fisher, H. Zan and P. Casali.  2022. Construction of mice with a fully human immune system mounting class-switched, hypermutated and neutralizing antibody responses.  Cell, to be submitted.

  ·         Rivera, C.E., Y. Zhou, A.D. Fisher, D.P. Chupp, H. Yan, J.R. Simon, H. Zan, Z. Xu and P. Casali.  2022.  T-independent TLR-BCR linked coengagement induces class-switched, hypermutated and neutralizing antibody responses.  Science Immunol., submitted.

  ·        Yan, H., R. Wang, M. Fernandez, C. E. Rivera, C. Cervantes, J.B. Moroney, X.-D. Li, N. Zhang, X.-Z. Meng, Z. Yin, R. Kedl, B. Min, C.A. Hunter, Y. Xiang, P. Casali and Z. Xu.  2022.  BATF3-dependent induction of IL-27 by B cells bridges the innate and adaptive stages of the antibody response. bioRxiv 2020 Jun; doi. 10.1101/2020.06.26.117010. To be submitted to Cell.

  ·         Xu, Y., H. Zhou, G. Post, H. Zan and P. Casali.   2022.  Rad52 mediates class-switch DNA recombination to IgD through microhomology-mediated alternative end-joining.  Nature Commun. 13: 980. PMID: 35190531  PMCID: PMC8861003 DOI: 10.1038/s41467-022-28576-2.

  ·         Casali, P., S. Li, G. Morales, C.C. Daw, D.P. Chupp, A.D. Fisher and H. Zan.  2021. Epigenetic modulation of class-switch DNA recombination to IgA through selective downregulation of Smad2, Smad3 and Smad4.  Front. Immunol. 12:761450. DOI: 10.3389/fimmu.2021.761450  PMID: 34868004  PMCID: PMC8635144.

  ·         Moroney, J.B., D.P. Chupp, Z. Xu, H. Zan and P. Casali. 2020. Epigenetics of the antibody and autoantibody response.  Curr. Op. Immunol. 67:75-86.  DOI: 10.1016/j.coi.2020.09.004

  ·         Moroney, A. Vasudev, A. Pertsemlidis, H. Zan and P. Casali.  2020.  Integrative transcriptome and chromatin landscape analysis reveals distinct epigenetic regulations in human memory B cells.  Nature Commun. 11:543.  DOI:10.1038/s41467-020-19242-6 PMID: 33116135 PMCID: PMC7595102.

  ·         Casali, P., T. Shen T., Y. Xu, Z. Qiu, D.P. Chupp, J. Im, Z. Xu and H. Zan. 2020. Estrogen reverses HDAC Inhibitor-mediated repression of Aicda and class-switching in antibody and autoantibody responses by downregulation of miR-26a.  Front. Immunol.11:491. DOI: 10.3389/fimmu.2020.00491.

  ·         Gan H., T. Shen, D.P. Chupp, J.R. Taylor, H.N. Sanchez, X. Li, Z. Xu, H. Zan and P. Casali. 2020.  B cell Sirt1 deacetylates histone and non-histone proteins to modulate AID expression and the antibody response. Science Adv. 6: eaay2793. PMCID: PMC7112761.

  ·         Yan, H.,  M. Fernandez, J. Wang, S. Wu, R. Wang, Z. Lou, J.B. Moroney, C.E. Rivera, J.R. Taylor, H. Gan, H. Zan, D. Kolvaskyy, D. Liu, P. Casali* and Z. Xu*.  2020.  B cell endosomal RAB7 promotes TRAF6 K63 polyubiquitination and NF-kB activation for antibody class-switching.  J. Immunol. 204: 1-15. [*equal contributors].  DOI: 10.4049/jimmunol.2000342.

  ·         Sanchez, H.N.*, J.B. Moroney*, H. Gan, T. Shen, J. Im, T. Li, J.R. Taylor, H. Zan and P. Casali.  2020.  B cell-intrinsic epigenetic modulation of antibody responses by dietary fiber-derived short-chain fatty acids.  Nature Commun. 11:60 [*equal contributors]. PMCID: PMC6940392.

  ·         Zan, H., C. Tat, Z. Qiu, J.A. Guerrero, J. R. Taylor, T. Shen and P. Casali.  2017.  Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends to modulate antibody class-switch DNA recombination.  Nature Commun. 8:14244. PMID: 28176781; PMCID: PMC5309807. DOI: 10.1038/ncomms14244.

  ·         Catalan-Dibene, J, M.I. Vazquez, V.P. S.P. Luu, Nuccio, A. Karimzadeh, J.M. Kastenschmidt, S.A. Villalta, I. Ushach, E.J. Pone, P. Casali, M. Raffatellu, M. Burkhardt, M. Hernandez-Ruiz, G. Heller, P.A. Hevezi and A. Zlotnik.  2017.  Identification of IL-40, a Novel B Cell-Associated Cytokine. J. Immunol. 199:3326-3335; DOI:10.4049/jimmunol.1700534; PMID: 28978694.

  ·         Sanchez, H.N.*, T. Shen*, D. Garcia, Z. Lai, P. Casali and H. Zan.  2017. Genome-wide analysis of HDAC inhibitor-mediated modulation of microRNAs and mRNAs in B cells induced to undergo class switch DNA recombination and plasma cell differentiation.  [*equal contributors and corresponding authors].  J. Vis. Exp., 127; PMID: 28994753; DOI:10.3791/55135.

  ·         Casali, P.  2017. DNA recombination and somatic hypermutation in the immune system. In: Lewin’s GENES XII, J.E. Krebs, E.S. Goldstein, S.T. Kilpatrick, Eds. (12th Edition), Jones & Bartlett Publishers.  Boston, Toronto, London, Singapore.  Chapter 16, pages 397-439.

  ·         Lam, T., D.V. Kulp, R. Wang, Z. Lou, J., Taylor, Q. Zhong, Z. Wang, H. Zan, D. Ivanov, G. Zhong, P. Casali* and Z. Xu*.  2016.  Small molecule inhibitor of Rab7 impairs B cell class-class switching and plasma cell survival to dampen the autoantibody response in murine lupus [*equal contributors and corresponding authors].   J. Immunol. 197:3792-3805. PMID: 27742832; PMCID: PMC5113143; DOI: 10.4049/jimmunol.1601427

  ·         Zan, H. and P. Casali.  2016.   Epigenetics of B cells and antibody responses.  Front.  Immunol. 6:656. PMID: 26793194; PMCID: PMC4707482; DOI: 10.3389/fimmu.2015.00656