title: Lupus Nephritis IgG Induction of Calcium/Calmodulin-Dependent Protein Kinase IV Expression in Podocytes and Alteration of Their Function.
abstract: OBJECTIVE
  Kidney podocytes and their slit diaphragms prevent urinary protein loss. T cells from patients with systemic lupus erythematosus display increased expression of calcium/calmodulin-dependent protein kinase IV (CaMKIV). The present study was undertaken to investigate the role of CaMKIV in podocyte function in lupus nephritis (LN).
  
  
  METHODS
  We treated kidney podocytes with IgG derived from healthy individuals or patients with LN and then analyzed gene expression using a DNA microarray. The localization of IgG in podocytes was analyzed by immunofluorescence staining, with or without silencing of neonatal Fc receptor (FcRn). In addition, we silenced CAMK4 in podocytes and analyzed the expression of selected genes. We also examined the expression of CD86 in kidney podocytes from MRL/lpr, MRL/lpr.camkiv(-/-), and MRL/MPJ mice by in situ hybridization.
  
  
  RESULTS
  We found that exposure of podocytes to IgG resulted in entry of IgG into the cytoplasm. IgG entered podocytes via the FcRn because less IgG was found in the cytoplasm of podocytes treated with FcRn small interfering RNA. DNA microarray studies of podocytes exposed to LN-derived IgG revealed up-regulation of genes related to the activation of immune cells or podocyte damage. Interestingly, CD86 expression decreased after silencing CAMK4 in podocytes. Also, in situ hybridization experiments showed that the expression of CD86 was reduced in podocytes from MRL/lpr.camkiv(-/-) mice.
  
  
  CONCLUSIONS
  LN-derived IgG enters podocytes and up-regulates CAMK4, which is followed by increased expression of genes known to be linked to podocyte damage and T cell activation. Targeted inhibition of CAMK4 in podocytes may prove to be clinically useful in patients with LN.
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan, and Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Ichinose
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ushigusa
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nishino
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Yosikazu
authors.initials: Y
authors.lastname: Nakashima
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Horai
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan, and Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Koga
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Shin-ya
authors.initials: SY
authors.lastname: Kawashiri
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Iwamoto
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Tamai
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Arima
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Obata
authors.affiliation: Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Origuchi
authors.affiliation: Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nishino
authors.affiliation: Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kawakami
authors.affiliation: Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: George C
authors.initials: GC
authors.lastname: Tsokos
mesh_terms: D000328:Adult; D000818:Animals; D051940:B7-2 Antigen / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology*; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000378:metabolism; D008181:Lupus Nephritis / Q000276:immunology* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D019463:Mice, Inbred MRL lpr; D018345:Mice, Knockout; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism; D011961:Receptors, Fc / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects; D055815:Young Adult
chemical_list: D051940:B7-2 Antigen; D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D008565:Membrane Proteins; D011961:Receptors, Fc; C113267:nephrin; C517683:CAMK4 protein, human; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; C517685:Camk4 protein, mouse; C100688:Fc receptor, neonatal