22 Matching Annotations
  1. Oct 2026
    1. To study the function of GPR143, we investigated the phenotypic effect of overexpression of GPR143 in pheochromocytoma (PC12) cells treated with nerve growth factor. Overexpression of mouse GPR143 inhibited neurite outgrowth, and the effect was mitigated by l-DOPA cyclohexylester, an antagonist for l-DOPA. Furthermore, knockdown of G-protein Gα13 attenuated mouse GPR143 induced inhibition of neurite outgrowth. Human wild-type (wt) GPR143 also inhibited neurite outgrowth, but its mutants did not mimic the effect of wt GPR143. Our results provide a mechanism for axon guidance phenotype in ocular albinism 1.

      ExperimentName: GPR143 over-expression in neuroendocrine tumor cells

      NonPatientCell: CL:0000336 (adrenal medulla chromaffin cell, specifically the PC-12 cell line)

      GeneFunction: GO:0031175 (neuron projection development)

      GeneAlteration: Over-expression of GPR143 was accomplished by stable transfection of PC-12 cells with mCherry-tagged wild-type or mutant GPR143.

      FunctionalEvidence: Figure 4C indicates that GPR143 over-expression decreases the # of neurites longer than 100 microns, and that this occurs through a mechanism that is dependent on the G-protein Galpha13. Figure 5E shows that this effect of wild-type GPR143 is particularly pronounced for neurites longer than 150 microns, and is not mimicked by GPR143 missense variants reported in patients.

      FAVariants: Patient-associated variants were p.Asp78Asn (ClinVar: 98620), p.Trp133Arg (ClinVar: 10516 or 10519), p.Ile261Asn (CAID: CA411996177), and p.Trp292Gly (ClinVar: 98647).

    1. To address the function of OA1 in melanosome biogenesis, we have used siRNA inactivation and combined morphological and biochemical methods to investigate melanosome ultrastructure, melanosomal protein localization and expression in human pigmented melanocytic cells. OA1 loss of function leads to decreased pigmentation and causes formation of enlarged aberrant premelanosomes harboring disorganized fibrillar structures and displaying proteins of mature melanosomes and lysosomes at their membrane.

      ExperimentName: GPR143 silencing in melanoma cells

      NonPatientCell: CL:1000458 (melanocyte of skin, specifically the highly pigmented MNT-1 human melanoma cell line)

      GeneFunction: GO:1903232 (melanosome assembly)

      GeneAlteration: GPR143 silencing was accomplished by transient transfection of MNT-1 cells with specific siRNA, alongside a non-targeting siRNA control.

      FunctionalEvidence: siRNA-treated cells exhibited 50% reduction in mature melanosomes and melanin-containing cells by immunofluorescence (Figures 2E, 2F, 2G). This was confirmed by electron microscopy (Figures 2H, 2I, 2J, 2K). GPR143 silencing also resulted in a combination of normal sized melanosomes and enlarged macromelanosome precursors (Figures 2I, S2A). These cellular defects are an approximate match to the giant melanosomes in the melanocytes of the human patients as well as the hypopigmentation of the fundus.

      FAVariants: GPR143 disruption was siRNA-based, and patient-associated variants were not studied.

    1. In this study, we have investigated the biosynthesis and intracellular localization of this protein in transiently transfected BHK-21 cells using a CLN5-specific peptide antibody.

      ExperimentName: Intracellular localization of exogenously expressed wild-type and variant CLN5

      NonPatientCell: BKH-21 cells (fibroblast-derived cell line, EFO:0002009)

      GeneFunction: Localization to lysosome (GO:0005764)

      GeneAlteration: The variant was introduced into the construct encoding CLN5 using site-directed mutagenesis.

      FunctionalEvidence: Localization studies were performed in BHK-21 cells transiently transfected with wild-type or variant CLN5. The wild-type co-localized with lysosome and late endosome markers, while the variant co-localized with a Golgi marker (Fig. 3D–F) and showed some ER staining and vesicular-like staining. The stability of the variant following cyclohexamide treatment was also shorter than the wild-type. (Fig. 4G-4H).

      FAVariants: The variant used was NM_006493.4(CLN5):c.1028_1029del (p.Thr342_Tyr343insTer) (ClinVar:2564).

    1. We conclude that the RPE65/D477G missense mutant has only moderately reduced isomerase activity and, furthermore, does not act as a dominant-negative mutant affecting WT protein function, but rather behaves similarly to, or even better than, other hypomorphic missense mutations of RPE65 that have been previously characterized

      ExperimentName: Exogenous expression of the RPE65 D477G variant in HEK293-F cells

      NonPatientCell: HEK293-F cell line (EFO:0001182)

      GeneFunction: all-trans-retinyl-ester hydrolase, 11-cis retinol forming activity (GO:0052885)

      GeneAlteration: A substitution equivalent to the human NM_000329.3(RPE65):c.1430A>G (p.Asp477Gly) variant was introduced by site-directed mutagenesis into canine RPE65 and transiently transfected into HEK293-F cells.

      FunctionalEvidence: The variant triggered a moderate decrease in retinoid isomerase activity / 11-cis retinol formation that appeared to be balanced out by the presence of the wild-type allele, rather than acting in a dominant negative fashion (Figure 1B). This loss of function was less dramatic than other hypomorphs known to be associated with autosomal recessive RPE65 retinopathy. Thus, loss of enzymatic function is unlikely to be the primary mechanism by which the variant contributes to autosomal dominantly inherited disease.

      FAVariants: NM_000329.3(RPE65):c.1430A>G (p.Asp477Gly) variant (ClinVar:750796)

    1. Accelerated Ca2+ Current Activation Through α1ST1354S Leads to an Increase of SR Ca2+ Release in the Presence of Caffeine

      NonPatientCell Mouse cell line, EFO:0002887 "Myotubes of the homozygous CaVα1S-null (dysgenic) mouse cell line GLT were cultured on 35-mm culture dishes as described previously (32)."

      GeneAlteration Mouse GLT line myotubes were transfected with GFP-tagged α1S cDNA constructs at the onset of myoblast fusion using FuGENE 6 transfection reagent according to the manufacturer's protocols (Roche Diagnostics).

      FunctionalEvidence Fig 3: faster voltage-gated activation than WT. Fig 6: increased release of calcium ions in the presence of caffeine vs WT.

      FAVariants NM_000069.2(CACNA1S):c.4060A>T (p.Thr1354Ser), ClinVar ID: 161208

    1. Biochemical Characterization S156C, G166C, and S181C SFD Mutations

      NonPatientCell: COS-7 cells (EFO:0001643, CLO:0002597)

      GeneFunction: GO:0008191 (metalloendopeptidase inhibitor activity), GO:0046872 (metal ion binding), GO:0002020 (protease binding), GO:0005615 (active in extracellular space), GO:0031012 (active in extracellular matrix)

      GeneAlteration: TIMP3 expression constructs encoding the "Ser181Cys", "Ser156Cys", "Gly166Cys", and "Glu139X" variants (officially referred to as the Ser204Cys, Ser179Cys, Gly189Cys, and Glu162X variants) were generated by PCR-based mutagenesis of the wild-type TIMP-3-pCI.neo construct.

      FunctionalEvidence: The TIMP3 variants were exogenously expressed in COS-7 cells alongside the wild-type control. Reverse zymography of extracellular matrix from these cells revealed the presence of dimeric species with metalloproteinase inhibitory activity in the variant-transfected conditions, but not in the wild-type control (Figure 3). These bands were confirmed to be TIMP3 by immunoblotting the extracellular matrix from these cells under non-reducing conditions, as they disappeared under reducing conditions (Figure 4). Under reducing conditions, the variant-transfected cells show higher levels of monomeric TIMP3 relative to the wild-type control (Figure 4b), but it should be noted that the wild-type control is depicted on a separate blot / exposure. The dimerized Glu162X variant is difficult to distinguish from other full-length monomeric species, but appears to be present as well (Figure 5).

      FAVariants: Variants used were equivalent to NM_000362.5(TIMP3):c.610A>T (p.Ser204Cys) (ClinVarID:12676), NM_000362.5(TIMP3):c.536C>G, (p.Ser179Cys) (ClinVarID:12678), NM_000362.5(TIMP3):c.565G>T (p.Gly189Cys) (ClinVarID:12679), and NM_000362.5(TIMP3):c.484G>T (p.Glu162X) (ClinVarID:12680).

    1. By directly measuring the turnover of TIMP-3 and SFD-TIMP-3 protein in the matrix of human RPE cells, we show that in all cases mutation induces multimerization, rendering a proportion of the SFD proteins resistant to degradation and providing a mechanism for TIMP-3 accumulation in the disease.

      NonPatientCell*: ARPE-19 (human retinal pigment epithelial) cell line (CLO:0001749, CL:0009004)

      GeneFunction: GO:0008191 (metalloendopeptidase inhibitor activity), GO:0046872 (metal ion binding), GO:0002020 (protease binding), GO:0005615 (active in extracellular space), GO:0031012 (active in extracellular matrix)

      GeneAlteration: TIMP3 expression constructs encoding the "Ser181Cys", "Ser156Cys", and "Glu139X" variants (officially referred to as the Ser204Cys, Ser179Cys, and Glu162X variants) were generated by PCR-based mutagenesis of the wild-type TIMP-3-pCI.neo construct (previously described in PMID:10854443).

      FunctionalEvidence: TIMP3 variants were exogenously expressed in ARPE-19 cells alongside wild-type and empty vector controls. The percentage of exogenously expressed wild-type TIMP3 protein remaining associated with the extracellular matrix after separation of transfected cells from ECM was 20% (after 1 day) or <1% (after 4 days). All three variants were turned over at a slower rate, with 35-50% remaining after 1 day, and 20-25% remaining after 4 days (Figure 2). On the other hand, while the Ser179Cys and Glu162X variants showed reduced ability to inhibit cell surface activation of Pro-MMP2, Ser204Cys did not (Figure 3). As a result, the key, consistent function of TIMP3 variants in SFD may be (toxic) aggregation rather than loss of inhibitory activity.

      FAVariants: Variants used were equivalent to NM_000362.5(TIMP3):c.610A>T (p.Ser204Cys) (ClinVarID:12676), NM_000362.5(TIMP3):c.536C>G, (p.Ser179Cys) (ClinVarID:12678), and NM_000362.5(TIMP3):c.484G>T (p.Glu162X) (ClinVarID:12680).

    1. In FVIII-binding assays, vWF-W19 and vWF-Q54 show maximal binding that is 79% and 75% of wt vWF, respectively (Fig 6). Maximal binding for FVIII by vWF.3 was 52% of wt vWF. Added together, the percent reduction in binding for vWF-W19 and vWF-Q54 is nearly equal to the percent reduction of binding shown by vWF.3 (46% v 48%). These mutations also show an additive effect on the concentration of FVIII at which half-maximal binding occurs.

      ExperimentName: Factor VIII binding assays for variants exogenously expressed in COS-7 cells

      NonPatientCell: COS-7 cell line (CLO:0002597, EFO:0002009)

      GeneFunction: GO:0005515 (protein binding, specifically to Factor VIII)

      GeneAlteration: Site-directed mutagenesis was used to introduce a mutation encoding "His54Gln" (corresponding to the p.His817Gln substitution from the variant) into the mature (cleaved) VWF protein.

      FunctionalEvidence: The variant did not disrupt multimer formation (Figure 5) but reduced Factor VIII binding to 75% of wild-type levels (Figure 6). In combination with another missense mutation in cis that reduced Factor VIII binding by an additional 21-23%, and a frameshift mutation in trans predicted to cause the absence of a gene product, the variant appears likely to be contributing to pathogenicity.

      FAVariants: A construct equivalent to the c.2451T>A (p.His817Gln) variant was used (ClinVar:100224), although it expressed the proteolytically processed version of the protein product and referred to the variant as "His54Gln".

    1. We demonstrate that in CLN5-depleted HeLa cells, the lysosomal sorting receptors sortilin and cation-independent mannose 6-phosphate receptor (CI-MPR) are degraded in lysosomes due to a defect in recruitment of the retromer (an endosome-to-Golgi compartment trafficking component).

      ExperimentName: Defective lysosomal sorting receptor degradation in CLN5-depleted HeLa cells

      NonPatientCell: HeLa cells (EFO:0001185)

      GeneFunction: Lysosomal organization (GO:0007040)

      GeneAlteration: CLN5 (or the CLN1 control) was depleted by transient transfection of small interfering RNA (siRNA) into HeLa cells, 48 hrs. before assays were performed.

      FunctionalEvidence: CLN5-depleted cells have reduced immunofluorescent signal (Fig. 2K) and reduced expression (Fig. 3A) of two lysosomal sorting receptors; cation-independent mannose 6-phosphate receptor (CI-MPR) and sortilin (Fig. 2K). CLN5-depleted cells also have fragmented TGN46 signal (Fig. 2Q) and increased precursor and intermediate forms of the lysosomal cargo protein cathepsin D (Fig. 3C). These findings are consistent with CI-MPR and sortilin failing to correctly recycle to the Golgi and being degraded in lysosomes instead, possibly due to a defect in a complex called retromer, which returns membrane-associated proteins from the endosome to the Golgi or other cellular compartments. Endosomal signal for the retromer subunit Vps26 is also decreased (Fig. 4E), and both Vps26 and Vps35 are increasingly cytosolic rather than membrane-bound in CLN5-depleted cells (Fig. 6A). These defects are reversed by exogenously expressing CLN5 (Fig. 7B). Rab7 recruitment to the endosome is also defective in CLN5-depleted cells (Figs. 8B,8M). Considering that CLN5 interacts with Rab5 and Rab7 (Fig. 9A), it may serve as a scaffold recruiting Rab7 and the retromer complex to the endosomal membrane, for the purpose of recycling membrane-associated receptors such as sortilin and CI-MPR out of the endosome. Thus, patients with CLN5 loss-of-function variants may have defective recruitment of the retromer complex to the lysosome / endosome and disordered trafficking of membrane proteins out of these compartments as a result.

      FAVariants: N/A

    1. A mutant TIMP-3 in which serine 181 was changed to a cysteine, found in Sorsby's fundus dystrophy, a hereditary macular degenerative disease, was also expressed in COS-7 cells. This gave rise to an additional 48-kDa species (possibly a TIMP-3 dimer) that retained its ability to inhibit MMPs and localize to the ECM.

      NonPatientCell: COS-7 cells (EFO:0001643, CLO:0002597)

      GeneFunction: GO:0008191 (metalloendopeptidase inhibitor activity), GO:0046872 (metal ion binding), GO:0002020 (protease binding), GO:0005615 (active in extracellular space), GO:0031012 (active in extracellular matrix)

      GeneAlteration: A TIMP3 expression construct encoding the "Ser181Cys" variant (more accurately referred to as a Ser204Cys variant) was generated by PCR using a 3' primer that contained the desired substitution.

      FunctionalEvidence: The TIMP3 variant was exogenously expressed in COS-7 cells alongside a mock transfected control (not a wild-type control). Reverse zymography of extracellular matrix from these cells revealed the presence of both a monomeric and a dimeric species with metalloproteinase inhibitory activity (Figure 4). This was confirmed by immunoblotting to be TIMP3, and the dimeric species appeared under non-reducing conditions but disappeared under reducing conditions (Figure 5). This indicated that the free cysteine present in the variant may not have compromised metalloproteinase inhibitory activity, but likely facilitated an intramolecular disfulfide bonding interaction with another TIMP3 molecule. This gain-of-function interpretation of the variant effect would be consistent with the autosomal dominant mechanism of its inheritance. The wild-type control was absent from this figure. It is not clear whether a separate but similar figure showing the wild-type control was performed under reducing or non-reducing conditions.

      FAVariants: Variant used was equivalent to NM_000362.5(TIMP3):c.610A>T (p.Ser204Cys) (ClinVarID:12676). The variant is referred to in this publication as "Ser181Cys" (due to the removal of a 23-amino acid N-terminal signal peptide from the polypeptide sequence) but encodes Ser204Cys in the full/updated polypeptide sequence.

    1. Wild type and several naturally occurring type 2N VWF variants (H817Q, R854Q+T789A, R782W, and R782W+H817Q) or a hereditary persistance of propeptide (HPP) variant (Fig. 1A) were constructed and expressed transiently in human embryonic kidney 293T cells.

      ExperimentName: Transient expression of VWD type 2N variants in 293T cells

      NonPatientCell: human embryonic kidney 293T cells (EFO:0001082)

      GeneFunction: GO:0005515 (protein binding, specifically to Factor VIII)

      GeneAlteration: A mutation encoding p.His817Gln was introduced into a construct for exogenous expression of the VWF protein.

      FunctionalEvidence: The variant protein exhibited a mild defect in FVIII binding relative to the wild-type (less severe than other VWD type 2N variants) (Figure 1C). Because of the defect in FVIII interaction, the variant also exhibits mildly reduced cleavage by ADAMTS13 (Figures 1F, 1G, and 1H).

      FAVariants: A construct equivalent to the c.2451T>A (p.His817Gln) variant was used (ClinVar:100224).

    1. that the expression of the mutant TMEM43 in cells may disrupt the gap junction function, which is demonstrated by the failure to transfer small molecules and reduced cell-cell conduction.

      NonPatientCell HL-1 atrial cell line, BTO:0003264

      GeneFunction nuclear membrane organization, GO:0071763

      GeneAlteration constructs consisting of full length wild-type and mutant (p.S358L) human TMEM43 tagged at the C-terminus with GFP were used to generate stably transfected HL-1 cells.

      CellPhenotype HP:0011675 Arrhythmia

      CellEvidence 1.2 cm/s slower electrical conduction velocity than WT and control (40% reduction)

      FAVariants NM_024334.2(TMEM43):c.1073C>T, CA ID: 734

    1. Figure 3

      NonPatientCell UBERON:0005424, "ARPE19 cells"

      GOterm GO:0042802

      GeneAlteration HD-Ad-F3iT494M was constructed by introducing the HA-tagged PRPF3 coding sequence carrying T493M mutation, under control of the Ubiquitin C promoter and followed by the bovine growth hormone poly(A) signal, into HD-Ad-F3i.

      FunctionalEvidence T494M phosphorylates less readily than WT

      FAVariants NM_004698.3(PRPF3):c.1481C>T (p.Thr494Met), 3352

    1. The mutant protein was shown to dimerize in culture cells and retain its MMP inhibitory activity.

      NonPatientCell: ARPE-19 (human retinal pigment epithelial) cell line (CLO:0001749, CL:0009004)

      GeneFunction: GO:0008191 (metalloendopeptidase inhibitor activity), GO:0046872 (metal ion binding), GO:0002020 (protease binding), GO:0005615 (active in extracellular space), GO:0031012 (active in extracellular matrix)

      GeneAlteration: A TIMP3 expression construct encoding the Glu162Lys variant (referred to in the paper as "Glu139Lys") was generated by PCR-based mutagenesis of the wild-type pCDNA3-TIMP3.

      FunctionalEvidence: The TIMP3 variant was exogenously expressed in ARPE-19 cells alongside a mock transfected control (not a wild-type control). Immunoblotting of non-reduced samples detected both monomeric (24 kDa) and dimeric (48 kDa) forms of the variant (Figure 8). Reverse zymographs of extracellular matrix from both wild-type TIMP3- and variant TIMP3-transfected cells revealed the presence of the dimeric species for the variant but not the wild-type, and confirmed its intact metalloproteinase inhibitory activity (Figure 9). This indicated that the free cysteine present in the variant may not have compromised metalloproteinase inhibitory activity, but likely facilitated an intramolecular disfulfide bonding interaction with another TIMP3 molecule. This gain-of-function interpretation of the variant effect would be consistent with the autosomal dominant mechanism of inheritance.

      FAVariants: Variant used was NM_000362.5(TIMP3):c.484G>A (p.Glu162Lys) (CAID:CA411540222). The variant is referred to in this publication as "Glu139Lys" (due to the removal of a 23-amino acid N-terminal signal peptide from the polypeptide sequence) but encodes Glu162Lys in the full/updated polypeptide sequence.

    1. While pluripotent mesenchymal cell lines can be induced into the osteoblastic lineage, they may not reflect endogenous osteoblastic proliferation and differentiation. Consequently, we sought to determine whether the secreted form of LRP5 (LRP5ΔTM) could interfere with bone accrual in calvarial explant cultures. In three independent experiments, explants that were cultured in the presence of conditioned media from cells expressing LRP5ΔTM consistently had thinner bone, as determined by ALP staining and von Kossa staining, than did explants that were cultured in conditioned media from cells expressing wild-type LRP5 (Figure 7). Thus, LRP5ΔTM is able to inhibit bone growth, presumably by binding and interfering with secreted growth factors such as Wnts.

      ExperimentName: LRP5 inhibition using a dominant negative construct blocks bone accrual in mouse calvarial explant culture.

      NonPatientCell: CL:0001035 (bone cell, specifically mouse calvarial explant cultures)

      GeneFunction: GO:0098868 (bone growth)

      GeneAlteration: Calvarial explant cultures from mice were treated with conditioned media from cells exogenously secreting either wild-type LRP5 or dominant negative LRP5deltaTM.

      FunctionalEvidence: Bone accrual / thickness decreases significantly at multiple points in mouse calvarial (skull) explants treated with LRP5deltaTM relative to LRP5-WT (Figure 7).

      FAVariants: LRP5 function was attenuated using an artificial dominant negative mutant while a human variant was not introduced into the LRP5 gene.

    1. OPN1LW gene transcripts expressed in transiently transfected human embryonic kidney (HEK293T) cells. A: Relative expression (RE) levels of unspliced transcripts determined by qPCR across the following boundaries: exon 4 – intron 4; intron 4 – exon 5; exon 5 – intron 5; and intron 5 – exon 6. B: Relative levels of spliced OPN1LW gene transcripts, measured by qPCR, using primer sets that generate amplicons form exon 4 – exon 5 and exon 5 – exon 6. In all cases, the RE values represent OPN1LW mRNA expression normalized to the geometric mean of two internal control genes, RPL13A and EF1A1. Wild-type (WT), black; variant 1 (V1), white; variant 2 (V2), gray; variant 3 (V3), hatched. * and ** denote statistical significance at 1% and 5% probability levels, respectively.

      ExperimentName: OPN1LW variants identified in myopic patients were expressed exogenously in HEK293T cells and exhibited reduced expression at the mRNA level.

      NonPatientCell: HEK293T cells (EFO:0001184)

      GeneFunction: GO:0007602 (phototransduction)

      GeneAlteration: Site-directed mutagenesis was used to introduce the variants into minigenes encoding portions of the wlid-type OPN1LW gene.

      FunctionalEvidence: Three OPN1LW variants identified in myopic patients were expressed exogenously in HEK293T cells and two out of three exhibited reduced expression at the mRNA level (Figures 1A and 1B).

      FAVariants: NM_020061.6(OPN1LW):c.973A>G (p.Met325Val), CA415309107, NM_020061.6(OPN1LW):c.970T>A (p.Phe324Ile), CA415309100, NM_020061.6(OPN1LW):c.971T>A (p.Phe324Tyr), CA415309101

    1. The RetGC1 encoded by the cDNA fragment intended for the transgenic expression in the retina was first tested for Ca2+ sensitivity, apparent affinity for GCAP1, and sensitivity to inhibition by RD3, by being expressed in HEK293 cells under control of a CMV promoter (46.Peshenko I.V. Moiseyev G.P. Olshevskaya E.V. Dizhoor A.M. Factors that determine Ca2+ sensitivity of photoreceptor guanylyl cyclase: kinetic analysis of the interaction between the Ca2+-bound and the Ca2+-free guanylyl cyclase activating proteins (GCAPs) and recombinant photoreceptor guanylyl cyclase 1 (RetGC-1).Biochemistry. 2004; 43: 13796-13804Crossref PubMed Scopus (42) Google Scholar) (Fig. 1). Consistently with the original in vitro observations by Ramamurthy et al. (45.Ramamurthy V. Tucker C. Wilkie S.E. Daggett V. Hunt D.M. Hurley J.B. Interactions within the coiled-coil domain of RetGC-1 guanylyl cyclase are optimized for regulation rather than for high affinity.J. Biol. Chem. 2001; 276: 26218-26229Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar), and later by Peshenko et al. (46.Peshenko I.V. Moiseyev G.P. Olshevskaya E.V. Dizhoor A.M. Factors that determine Ca2+ sensitivity of photoreceptor guanylyl cyclase: kinetic analysis of the interaction between the Ca2+-bound and the Ca2+-free guanylyl cyclase activating proteins (GCAPs) and recombinant photoreceptor guanylyl cyclase 1 (RetGC-1).Biochemistry. 2004; 43: 13796-13804Crossref PubMed Scopus (42) Google Scholar), the half-maximal deceleration of the GCAP1-activated cyclase by calcium was shifted toward nearly 2.5-fold higher concentrations (Fig. 1A). The apparent affinity of the R838S RetGC1 for the Mg2+-liganded activator form of GCAP1 (19.Dizhoor A.M. Olshevskaya E.V. Peshenko I.V. Mg2+/Ca2+ cation binding cycle of guanylyl cyclase activating proteins (GCAPs): role in regulation of photoreceptor guanylyl cyclase.Mol. Cell Biochem. 2010; 334: 117-124Crossref PubMed Scopus (78) Google Scholar) became nearly 5-fold higher than normal (KMgGCAP1 327 ± 10 nm (S.D.) versus 1585 ± 80 nm in wild type) (Fig. 1B). In addition to its being the main reason for less effective deceleration by Ca2+ (44.Tucker C.L. Woodcock S.C. Kelsell R.E. Ramamurthy V. Hunt D.M. Hurley J.B. Biochemical analysis of a dimerization domain mutation in RetGC-1 associated with dominant cone-rod dystrophy.Proc. Natl. Acad. Sci. U.S.A. 1999; 96: 9039-9044Crossref PubMed Scopus (87) Google Scholar, 45.Ramamurthy V. Tucker C. Wilkie S.E. Daggett V. Hunt D.M. Hurley J.B. Interactions within the coiled-coil domain of RetGC-1 guanylyl cyclase are optimized for regulation rather than for high affinity.J. Biol. Chem. 2001; 276: 26218-26229Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar46.Peshenko I.V. Moiseyev G.P. Olshevskaya E.V. Dizhoor A.M. Factors that determine Ca2+ sensitivity of photoreceptor guanylyl cyclase: kinetic analysis of the interaction between the Ca2+-bound and the Ca2+-free guanylyl cyclase activating proteins (GCAPs) and recombinant photoreceptor guanylyl cyclase 1 (RetGC-1).Biochemistry. 2004; 43: 13796-13804Crossref PubMed Scopus (42) Google Scholar), observed in Fig. 1A, the higher affinity for GCAP1 proportionally correlated with a reduced sensitivity of the GCAP1-activated RetGC1 to the inhibition by RD3: the K½ RD3 rose from 2.6 ± 1.2 versus 11.4 ± 0.4 nm, respectively (p < 0.01), in the R838S RetGC1 (Fig. 1C).

      ExperimentName: Higher GUCY2D activity in the R838S variant

      NonPatientCell: HEK293 cells (EFO:0001182)

      GeneFunction: GO:0006182 (cGMP biosynthetic process)

      GeneAlteration: Site-directed mutagenesis was used to introduce the substitution encoding the R838S substitution into the gene expression construct (PMID: 15504042).

      FunctionalEvidence: The variant exhibits higher activity than the wild-type in HEK293 cells, with enhanced Ca2+ sensitivity (Figure 1A), higher GCAP1 affinity, (Figure 1B), and reduced sensitivity to RD3 inhibition (Figure 1C).

      FAVariants: NM_000180.4(GUCY2D):c.2512C>A (p.Arg838Ser) (ClinVar: 98568)

    1. We have expressed four SFD mutant TIMP-3 proteins in baby hamster kidney (BHK) cells and evaluated their characteristics alongside wild-type TIMP-3.

      ExperimentName: Functional testing of Ser179Cys, Gly190Cys, Tyr191Cys and Ser204Cys variants of TIMP3 in baby hamster kidney (BHK) cells

      NonPatientCell: Baby hamster kidney (BHK) cells, EFO:0001643 (kidney-derived cell line), CLO:0000696 (immortal hamster kidney-derived cell line), CLO:0001965 (BHK-21 cell line)

      GeneFunction: GO:0008191 (metalloendopeptidase inhibitor activity), GO:0046872 (metal ion binding), GO:0002020 (protease binding), GO:0005615 (active in extracellular space), GO:0031012 (active in extracellular matrix)

      GeneAlteration: TIMP3 expression constructs encoding the Ser179Cys, Gly190Cys, Tyr191Cys, and Ser204Cys variants (referred to in the paper as "Ser156Cys", "Gly167Cys", "Tyr166Cys", and "Ser181Cys") were generated by PCR-based mutagenesis of wild-type TIMP3 and cloned into the pNUT expression vector.

      FunctionalEvidence: BHK cells were stably transfected with each of four variants or wild-type TIMP3. All variants expressed and localized successfully to the extracellular matrix (western blotting), Both variants tested exhibited intact metalloproteinase inhibitor activity in ECM fractions (reverse zymography). All four of the variants accumulated as higher molecular weight species (Figure 1A, Figure 2), with Ser179Cys and Ser204Cys in particular accumulating to a much greater degree than the other variants or the wild-type control (Figure 2). Cell morphology and adherence were affected within the variant-expressing cells. While wild-type-transfected cells were more adherent to the ECM than the untransfected controls were, both variant-transfected cells (Ser179Cys, Ser204Cys) were even more ECM-adherent (Figure 5). Association constants were measured for TIMP3 interaction with a series of metalloproteinases, calculating their values for wild-type TIMP3 and for the Ser156Cys variant, which exhibited a 2- or 3-fold loss of reduction, depending on the substrate (Table 2).

      FAVariants: The four variants used were NM_000362.5(TIMP3):c.536C>G, p.Ser179Cys (ClinVar:12678), NM_000362.5(TIMP3):c.568G>T, p.Gly190Cys (CA411540415), NM_000362.5(TIMP3):c.572A>G, p.Tyr191Cys (ClinVar:12677), and NM_000362.5(TIMP3):c.610A>T, p.Ser204Cys (ClinVar:12676).

    1. Blocking the action of CD44 and IMPG1 in pluripotent stem cell derived retinal organoids affected the development of photoreceptors, their inner/outer segments and connecting cilia and disrupted IPM formation, with IMPG1 having an earlier and more significant impact. Together, our data suggest an important role for IMPG1 and CD44 in the development of photoreceptors and IPM formation during human retinogenesis.

      ExperimentName: Blocking IMPG1 in retinal organoids disrupts early development of IPM, photoreceptors and inner/outer segments, and connecting cilia.

      NonPatientCell: UBERON:0000966 (retina, specifically IPSC-derived retinal organoids) or CL:0009004 (retinal cell)

      GeneFunction: GO:0033165 (interphotoreceptor matrix)

      GeneAlteration: Alteration was not performed at the genetic level, but rather a blocking antibody to IMPG1 protein was added to the culture media of the developing retinal organoid at days 90 and 150 of the differentiation process. After incubation, the effects were assessed by IHC and qRT-PCR detecting key markers of differentiation (Figure 6, Figures S12-S15).

      FunctionalEvidence: Expression of RCVRN (a marker of photoreceptor and bipolar cells) and proportion of recoverin-positive cells were reduced (Figs. 6B, S12B, S14B, S14C, S15B). Expression of ARL13B (marker of photoreceptor connecting cilia) was reduced (Figs. 6B, S15B). Expression of RBP3 (marker of IPM formation) was changed only at the later time point (Figs. 6B, S12B, S15B). Expression of OPN1LW/OPN1MW (cone marker) was down-regulated (Fig. S14B). Expression of RHO (rod cell marker) and proportion of rhodopsin-positive cells were reduced, and the typical pattern of staining was replaced with a punctate pattern at the surface of the organoids (Fig. 6B, 6C). Staining for WGA (rod inner/outer segment marker) was reduced, indicating disrupted development of these structures (Fig. 6B, 6C). The authors conclude that IMPG1 is important for development of photoreceptors, inner and outer segments, connecting cilia, and IPM.

      FAVariants: No variant in IMPG1 was used, but rather an inhibitory antibody.

    1. Results

      NonPatientCell: EFO:0001182 (HEK293 Cells)

      GeneFunction: GO:0008233 (Peptidase activity)

      GeneAlteration: HEK293 cells were grown and 8 missense mutations were identified and generated by PCR-mutagenesis. The human mutant cDNAs were transfected into the cells using the calcuim-phosphate coprecipitation method and examined.

      FunctionalEvidence: When HEK293 cells were transfected with wild-type and mutant human cDNA for PHEX, the resulting cells were subject to immunoblotting to determine the protein levels in both the cell lysate and the media of cells. All the variants and the wild-type showed presence in the lysate at various levels, but C85R, G579R, G579V, S711R, and A720T were all devoid of any secreted protein in the media. Ananlysis of these cells also showed possible rescue by growing transfected cells at 26 C, thus glycosylating and maturing the proteins. The endopeptidase activity of the wild-type and variants were also compared, with D237G and Y317F mutant proteins exhibiting 50–60% of wild-type activity; E581V and S711R also displayed nearly undetectable activity. This displayed that the disease causing mechanism could be related to loss of function of peptidase activity or cellular trafficking. Evidence is found under "Results".

      FAVariant1: NM_000444.5:c.253T>C (p.Cys85Arg)

      ClinVar: 438549 https://www.ncbi.nlm.nih.gov/clinvar/variation/438549/

      FAVariant2: NM_000444.5:c.1735G>A (p.Gly579Arg)

      ClinVar: 226119 https://www.ncbi.nlm.nih.gov/clinvar/variation/226119/

      FAVariant3: NM_000444.5:c.1736G>T (p.Gly579Val)

      ClinVar: 372777 https://www.ncbi.nlm.nih.gov/clinvar/variation/372777/

      FAVariant4: NM_000444.5:c.2131A>C (p.Ser711Arg)

      CAID: CA412575294 https://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_caid?caid=CA412575294

      FAVariant5: NM_000444.5:c.2158G>A (p.Ala720Thr)

      CAID: CA412575364 https://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_caid?caid=CA412575364

    1. Figure 1

      NonPatientCell UBERON:0005424

      GOterm GO:0042802

      GeneAlteration shRNAs cloned into pCAG-mir30 vector that contained a puromycin resistance gene.

      FunctionalEvidence electron microscopy of RPE in 1-2 yo mice showed 37-48% reduced phagocytosis in mutants. (fig. 1) Assayed cryosection of mouse RPE showed mislocalization of adhesion/phagocytosis markers in RPE (fig. 4)

      FAVariants NM_004698.3(PRPF3):c.1481C>T (p.Thr494Met), 3352

    1. Fig. 2

      NonPatientCell Mouse cell line, EFO:0002887 "Myotubes generated from the homozygous dysgenic (mdg/mdg) mouse cell line GLT were cultured as described previously (44)."

      GeneAlteration GFP tagged point mutation transfected into mouse cells

      FunctionalEvidence Variant increased channel sensitivity to caffeine/voltage (fig. 2)

      FAVariants NM_000069.2(CACNA1S):c.3257G>A (p.Arg1086His), ClinVar ID: 17626

      NM_000445.4(PLEC):c.3719G>A (p.Arg1240His), ClinVar ID: 448061