Karl Tryggvason

Karolinska Institutet | KI · Department of Medical Biochemistry and Biophysics

For the goal of regenerative cardiology, cellular therapy may be used to restore injured heart muscle. The molecular mechanisms behind the engraftment and maturation of these transplanted cells, however, remain poorly understood. Thus, to obtain a comprehensive understanding of the complex transcriptional landscapes within their transplanted spatia...

Approximately 30% of steroid-resistant nephrotic syndromes are attributed to monogenic disorders that involve 27 genes. Mutations in KANK family members have also been linked to nephrotic syndrome; however, the precise mechanism remains elusive. To investigate this, podocyte-specific Kank1 knockout mice were generated to examine phenotypic changes....

Approximately 30% of steroid-resistant nephrotic syndromes are attributed to monogenic disorders that involve 27 genes. Mutations in KANK family members have also been linked to nephrotic syndrome; however, the precise mechanism remains elusive. To investigate this, podocyte-specific Kank1 knockout mice were generated to examine phenotypic changes....

Ischemic heart disease is the most prevalent cause of death globally. Regenerative cardiology using stem cell-based therapy is a potential approach to replace infarcted myocardial (MI) heart tissue. We used cardiovascular progenitors (CVPs) derived from human pluripotent embryonic stem cells differentiated to cardiomyocyte progenitors on a laminin...

Ischemic heart disease, which is often associated with irreversibly damaged heart muscle, is a major global health burden. Here, we report the potential of stem cell-derived committed cardiac progenitors (CCPs) have in regenerative cardiology. Human pluripotent embryonic stem cells were differentiated to CCPs on a laminin 521 + 221 matrix, characte...

Blindness caused by advanced stages of inherited retinal diseases and age-related macular degeneration are characterized by photoreceptor loss. Cell therapy involving replacement with functional photoreceptor-like cells generated from human pluripotent stem cells holds great promise. Here, we generated a human recombinant retina-specific laminin is...

Leukemia cutis or leukemic cell infiltration in skin is one of the common extramedullary manifestations of acute myeloid leukemia (AML) and signifies a poorer prognosis. However, its pathogenesis and maintenance remain understudied. Here, we report massive AML cell infiltration in mouse skin. These cells were retained in the skin post-chemotherapy...

Impairement of normal hmatopoiesis and leukemia progression are two well-linked processes during leukemia development and controlled by the bone marrow (BM) niche. Extracellular matrix proteins including laminin are important BM niche components. However, their role in hematopoiesis regeneration and leukemia is unknown. Laminin α4 (Lama4), a major...

Stem cell therapy could potentially replace damaged heart muscle for regenerative cardiology. We hypothesized that immature cardiovascular progenitors (CVPs) when transplanted into infarcted hearts would electrically synchronized and mature in vivo thus avoiding the occurrence of VTs. In this study, we reported the derivation and applications of hE...

Crb2 is a cell polarity-related type I transmembrane protein expressed in the apical membrane of podocytes. Knockdown of crb2 causes glomerular permeability defects in zebrafish, and its complete knockout causes embryonic lethality in mice. There are also reports of Crb2 mutations in patients with steroid-resistant nephrotic syndrome, although the...

Not only in kidney glomerular physiological function but also glomerular pathology especially in diabetic condition, glomerular podocytes play pivotal roles. Therefore, it is important to increase our knowledge about the genes and proteins expressed in podocytes. Recently, we have identified a novel podocyte-expressed gene, R3h domain containing-li...

The efficacy of islet transplantation for diabetes treatment suffers from lack of cadaver-derived islets, islet necrosis and long transfer times prior to transplantation. Here, we developed a method for culturing mouse and human islets in vitro on α5-laminins, which are natural components of islet basement membranes. Adhering islets spread to form...

Matrix metalloproteinases (MMPs) contribute to the breakdown of tissue structures such as the basement membrane, promoting tissue fibrosis. Here we developed an electrospun membrane biofunctionalized with a fragment of the laminin β1-chain to modulate the expression of MMP2 in this context. We demonstrate that interfacing of the β1-fragment with th...

Supplementary Figures.

The majority of macromolecular crystal structures are determined using the method of molecular replacement, in which known related structures are rotated and translated to provide an initial atomic model for the new structure. A theoretical understanding of the signal-to-noise ratio in likelihood-based molecular replacement searches has been develo...

Significance It is now possible to make an accurate prediction of whether or not a molecular replacement solution of a macromolecular crystal structure will succeed, given the quality of the model, its size, and the resolution of the diffraction data. This understanding allows the development of powerful structure-solution strategies, and leads to...

Altered expression of nephrin underlies the pathophysiology of proteinuria in both congenital and acquired nephrotic syndrome. However, the epigenetic mechanisms of nephrin gene regulation remain elusive. Here, we show that Wolf-Hirschhorn syndrome candidate 1-like 1 long form (WHSC1L1-L) is a novel epigenetic modifier of nephrin gene regulation. W...

A major hurdle for in vitro culturing of primary endothelial cells (ECs) is that they readily dedifferentiate, hampering their use for therapeutic applications. Human embryonic stem cells (hESCs) may provide an unlimited cell source; however, most current protocols deriving endothelial progenitor cells (EPCs) from hESCs use direct differentiation a...

Alport syndrome is caused by mutations in the genes encoding α3, α4, or α5 (IV) chains. Unlike X-linked Alport mice, α5 and α6 (IV) chains are detected in the glomerular basement membrane of autosomal recessive Alport mice, however, the significance of this finding remains to be investigated. We therefore generated mice lacking both α3 and α6 (IV)...

Kidney diseases including diabetic nephropathy have become huge medical problems, although its precise mechanisms are still far from understood. In order to increase our knowledge about the patho-physiology of kidney, we have previously identified >300 kidney glomerulus-enriched transcripts through large-scale sequencing and microarray profiling of...

The intrinsic regenerative capacity of human fetal cardiac mesenchymal stromal cells (MSCs) has not been fully characterized. Here we demonstrate that we can expand cells with characteristics of cardiovascular progenitor cells from the MSC population of human fetal hearts. Cells cultured on cardiac muscle laminin (LN)-based substrata in combination...

Movie S1. A Spontaneously Beating fluo-4 Pre-loaded Cardiomyocyte Derived from Fetal Cardiac MSCs

Podocytes are highly specialized epithelial cells located at the outer aspects of the glomerular capillary tuft and critical components of the kidney filtration barrier. To maintain their unique features podocytes express a number of proteins that are only sparsely found elsewhere in the body. In this study, we have identified four (Tmem234, Znf185...

The establishment of permanent human embryonic stem cell lines (hESCs) was first reported in 1998. Due to their pluripotent nature and ability to differentiate to all cell types in the body, they have been considered as a cell source for regenerative medicine. Since then, intensive studies have been carried out regarding factors regulating pluripot...

Podocyte loss is central to the progression of proteinuric kidney diseases leading to end-stage kidney disease (ESKD), requiring renal replacement therapy, such as dialysis. Despite modern tools and techniques, the 5-year mortality of some patients requiring dialysis remains at about 70% to 80%. Thus, there is a great unmet need for podocyte-specif...

Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases. By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot proces...

The present disclosure is directed to the development of compositions, such as extracellular matrices, and processes for using the same, that both maintain stem cells in vitro pluripotency and enable self-renewal. In this regard, it has been discovered that when pluripotent mouse and human embryonic stem cells are cultured on plates coated with rec...

Alport syndrome (AS) is a hereditary nephritis caused by mutations in COL4A3, COL4A4 or COL4A5 encoding the type IV collagen α3, α4, and α5 chains, which are major components of the glomerular basement membrane. About 20 years have passed since COL4A3, COL4A4, and COL4A5 were identified and the first Alport mouse model was developed using a knockou...

Obesity is a global epidemic that contributes to the increasing medical burdens related to type 2 diabetes, cardiovascular disease and cancer. A better understanding of the mechanisms regulating adipose tissue expansion could lead to therapeutics that eliminate or reduce obesity-associated morbidity and mortality. The extracellular matrix (ECM) has...

Human embryonic stem cells have been considered the gold standard as a cell source for regenerative medicine since they were first cultured in 1998. They are pluripotent and can form principally all the cells types in the body. They are obtained from supernumerary human in vitro fertilization embryos that cannot be used for infertility treatment. F...

A robust method for culturing human pluripotent stem (hPS) cells under chemically defined and xeno-free conditions is an important tool for stem cell research and for the development of regenerative medicine. Here, we describe a protocol for monolayer culturing of Oct-4-positive hPS cells on a specific laminin-521 (LN-521) isoform, under xeno-free...

The transmembrane proteins Neph1 and nephrin form a complex in the slit diaphragm (SD) of podocytes. As recent studies indicate an involvement of this complex in the polymerization of the actin cytoskeleton and proteinuria, we wanted to study the subcellular localization of Neph1 in the normal human kidney and its expression in focal segmental glom...

Rhophilin-1 is a Rho GTPase-interacting protein, the biologic function of which is largely unknown. Here, we identify and describe the functional role of Rhophilin-1 as a novel podocyte-specific protein of the kidney glomerulus. Rhophilin-1 knockout mice were phenotypically normal at birth but developed albuminuria at about 2 weeks of age. Kidneys...

Inducible systems for gene expression emerge as a new class of artificial vectors offering temporal and spatial exogenous control of gene expression. However, most inducible systems are less efficient in vivo and lack the target-organ specificity. In the present study, we have developed and optimized an oligonucleotide-based inducible system for th...

Background Perlecan is a heparan sulfate proteoglycan (HSPG) constituent of the extracellular matrix with roles in cell growth, differentiation and angiogenesis. The role of the HS-side chains in regulating in vivo angiogenesis following hind-limb ischemia is unknown. Methods Heparan sulfate deficient perlecan (Hspg2δ3/δ3, n=35) mice, containing n...

AIMS/HYPOTHESIS: Diabetic nephropathy is a major diabetic complication, and diabetes is the leading cause of end-stage renal disease (ESRD). Family studies suggest a hereditary component for diabetic nephropathy. However, only a few genes have been associated with diabetic nephropathy or ESRD in diabetic patients. Our aim was to detect novel geneti...

Background: Perlecan is a proteoglycan composed of a 470 kDa core protein linked to three heparan sulfate (HS) glycosaminoglycan chains. The intact proteoglycan inhibits the smooth muscle cell (SMC) response to vascular injury. Hspg2(Δ3/Δ3) (MΔ3/Δ3) mice produce a mutant perlecan lacking the HS side chains. The objective of this study was to determ...

Podocin is a key protein of the kidney podocyte slit diaphragm protein complex, an important part of the glomerular filtration barrier. Mutations in the human podocin gene NPHS2 cause familial or sporadic forms of renal disease owing to the disruption of filtration barrier integrity. The exclusive expression of NPHS2 in podocytes reflects its uniqu...

An abnormal urinary albumin excretion rate (AER) is often the first clinically detectable manifestation of diabetic nephropathy. Our aim was to estimate the heritability and to detect genetic variation associated with elevated AER in patients with type 1 diabetes. The discovery phase genome-wide association study (GWAS) included 1,925 patients with...

Lack of robust methods for establishment and expansion of pluripotent human embryonic stem (hES) cells still hampers development of cell therapy. Laminins (LN) are a family of highly cell-type specific basement membrane proteins important for cell adhesion, differentiation, migration and phenotype stability. Here we produce and isolate a human reco...

The glomerular filtration barrier is made up of three layers: the slit diaphragm that bridges the interlocking secondary processes of the podocytes, the glomerular basement membrane, and fenestrated endothelial cells. The filtration barrier is permselective to plasma macromolecules based on size, shape, and charge. The molecular makeup of the diffe...

Glomerular podocyte cells are critical for the function of the renal ultrafiltration barrier. Especially, the highly specialized cell-cell junction of podocytes, the slit diaphragm, has a central role in the filtration barrier. This is highlighted by the fact that mutations in molecular components of the slit diaphragm, including nephrin and Cd2-as...

Sex and genetic variation influence the risk of developing diabetic nephropathy and ESRD in patients with type 1 diabetes. We performed a genome-wide association study in a cohort of 3652 patients from the Finnish Diabetic Nephropathy (FinnDiane) Study with type 1 diabetes to determine whether sex-specific genetic risk factors for ESRD exist. A com...

Podocytes serve as an important constituent of the glomerular filtration barrier. Recently, we and others identified Myo1e as a key molecular component of the podocyte cytoskeleton. Myo1e mRNA and protein was expressed in human and mouse kidney sections as determined by Northern blot and reverse transcriptase PCR, and its expression was more eviden...

Myo1e expression in Heart (A), Liver (B) and Spleen (C) tissues (scale bar 100μm). D. For negative control by adding secondary antibody only in Myo1e staining in glomerular samples. (JPG)

Glomerular diseases represent major diagnostic and therapeutic challenges with classification of these diseases largely relying on clinical and histological findings. Elucidation of molecular mechanisms of progressive glomerular disease could facilitate quicker development. High-throughput expression profiling reveals all genes and proteins express...

The present disclosure related to isolated laminin-521, methods for making recombinant laminin-521, host cells that express recombinant laminin-521, and compositions containing laminin-521. Laminin-521 can maintain stem cells in vitro pluripotency, enable self-renewal, and enable single cell survival of human embryonic stem cells. When pluripotent...

Scavenger receptor A5 (SCARA5) is a member of the class A scavenger receptors, with most similarity to SCARA1 (SR-A) and SCARA2 (MARCO), which are primarily expressed by macrophages and dendritic cells, in which they participate in clearance of various polyanionic macromolecules, pollution particles, and pathogens. The biological role of SCARA5 has...

We have previously reported genetic association of a single nucleotide polymorphism (SNP), rs1866813, at 3q locus with increased risk of diabetic nephropathy (DN). The SNP is located approximately 70 kb downstream of a cluster of four genes. This raises a question how the remote noncoding polymorphism affects the risk of DN. In this study, we teste...

Abnormal splicing of LMNA gene or aberrant pro-cessing of prelamin A results in progeroid syndrome. Here we show that lamin A interacts with and acti-vates SIRT1. SIRT1 exhibits reduced association with nuclear matrix (NM) and decreased deacetylase activity in the presence of progerin or prelamin A, leading to rapid depletion of adult stem cells (A...

Laminins are a large family of conserved, multidomain trimeric basement membrane proteins that contribute to the structure of extracellular matrix and influence the behavior of associated cells, such as adhesion, differentiation, migration, phenotype stability, and resistance to anoikis. In lower organisms such as Hydra there is only one isoform of...

The establishment of stable recombinant protein-producing mammalian cell lines is an expensive, time-consuming, tedious procedure. In some cases, expressed recombinant proteins have adverse effects on host cell function, including cell adhesion. Based on the adhesive properties of SCARA5, a scavenger receptor (SR) of the class A SR family, we devel...

Box and whisker plots of normalized ERBB4 expression intensities in glomerulus (A,B) and tubulointerstitium (C,D) by genotype showing eQTL associations in tubulointerstitium. Both SNPs show significant eQTL associations in tubulointerstitial kidney biopsies of Pima Indians with type 2 diabetes and DN (P = 0.018 for rs1718640, P = 0.024 for rs174188...

Longitudinal analyses in FinnDiane for rs7583877 (AFF3) and rs12437854 (chromosome 15q26). Analyses assume an additive model of the SNP effects. The plotted survival curves have been truncated at the point at which fewer than five participants remained with the corresponding genotype. The genotype legend in each figure indicates the number of sampl...

Top ranked SNPs selected for DN, ESRD vs. non ESRD, and ESRD vs. normoalbuminuria phenotypes. (DOC)

Clinical characteristics and information on genotyping of the phase two cohorts. (XLS)

Gene expression in early DN versus living donor kidney biopsies. All genes within a 2 Mb window (1 Mb upstream and downstream) of the three main signals (rs7583877/AFF3, rs12437854/15q26, rs7588550/ERBB4) were studied. (DOC)

P-value for association with DN related traits for the main signals after combined meta-analysis of DN and ESRD phenotypes. A1 is associated with increasing risk of ESRD/DN. (DOC)

Manhattan and QQ-plots for DN and ESRD phenotypes. Manhattan plots (panels A and C) highlighting P values from the discovery meta-analysis where dotted horizontal lines represent the threshold for follow up, P<1×10−5, and the solid horizontal lines indicate the threshold for genome-wide significance, P<5×10−8. The nearest genes are indicated above...

Rooted Principal Component Analysis of the discovery cohorts. Two first principal components (PC1 and PC2) are shown for (A) UK-ROI, (B) FinnDiane and (C) GoKinD US. Principal Component Analysis was calculated with EIGENSTRAT software including CEU, YRI and CBT from HapMap II as reference samples. (TIF)

Gene ontology analysis of all genes within ±1 Mbp of top GWAS signals: rs7583877/AFF3; rs12437854/15q26; rs7588550/ERBB4. (DOC)

Significantly enriched pathways (Genomatix Pathway System) for the ERBB4-correlated genes in early diabetic nephropathy. (DOC)

GENIE GWAS associations for SNPs that have been previously associated with T1D or chronic kidney disease. (DOC)

Quality control and filtering for the discovery GWAS data. (DOC)

Physicians and nurses participating in the collection of the FinnDiane study subjects. (DOC)

Additional kidney phenotype analysis results for the three main loci. (DOC)