Injury to podocytes and their slit diaphragms typically leads to marked proteinuria. Mutations in the TRPC6 gene that codes for a slit diaphragm-associated, cation-permeable ion channel have been shown recently to co-segregate with hereditary forms of progressive kidney failure. Herein is shown that induced expression of wild-type TRPC6 is a common feature of human proteinuric kidney diseases, with highest induction observed in membranous nephropathy. Cultured podocytes that are exposed to complement upregulate TRPC6 protein. Stimulation of receptor-operated channels in puromycin aminonucleoside-treated podocytes leads to increased calcium influx in a time-and dosage-dependent manner. Mechanistically, it is shown that TRPC6 is functionally connected to the podocyte actin cytoskeleton, which is rearranged upon overexpression of TRPC6. Transient in vivo gene delivery of TRPC6 into mice leads to expression of TRPC6 protein at the slit diaphragm and causes proteinuria. These studies suggest the involvement of TRPC6 in the pathology of nongenetic forms of proteinuric disease.

Targeted inactivation of the Bmp7 gene in mouse leads to eye defects with late onset and variable penetrance (A. T. Dudley et al., 1995, Genes Dev. 9, 2795-2807; G. Luo et al., 1995, Genes Dev. 9, 2808-2820). Here we report that the expressivity of the Bmp7 mutant phenotype markedly increases in a C3H/He genetic background and that the phenotype implicates Bmp7 in the early stages of lens development. Immunolocalization experiments show that BMP7 protein is present in the head ectoderm at the time of lens placode induction. Using an in vitro culture system, we demonstrate that addition of BMP7 antagonists during the period of lens placode induction inhibits lens formation, indicating a role for BMP7 in lens placode development. Next, to integrate Bmp7 into a developmental pathway controlling formation of the lens placode, we examined the expression of several early lens placode-specific markers in Bmp7 mutant embryos. In these embryos, Pax6 head ectoderm expression is lost just prior to the time when the lens placode should appear, while in Pax6-deficient (Sey/Sey) embryos, Bmp7 expression is maintained. These results could suggest a simple linear pathway in placode induction in which Bmp7 functions upstream of Pax6 and regulates lens placode induction. At odds with this interpretation, however, is the finding that expression of secreted Frizzled Related Protein-2 (sFRP-2), a component of the Wnt signaling pathway which is expressed in prospective lens placode, is absent in Sey/Sey embryos but initially present in Bmp7 mutants. This suggests a different model in which Bmp7 function is required to maintain Pax6 expression after induction, during a preplacodal stage of lens development. We conclude that Bmp7 is a critical component of the genetic mechanism(s) controlling lens placode formation.

Despite breakthroughs achieved with cancer checkpoint blockade therapy (CBT), many patients do not respond to anti–programmed cell death-1 (PD-1) due to primary or acquired resistance. Human tumor profiling and preclinical studies in tumor models have recently uncovered transforming growth factor–β (TGFβ) signaling activity as a potential point of intervention to overcome primary resistance to CBT. However, the development of therapies targeting TGFβ signaling has been hindered by dose-limiting cardiotoxicities, possibly due to nonselective inhibition of multiple TGFβ isoforms. Analysis of mRNA expression data from The Cancer Genome Atlas revealed that TGFΒ1 is the most prevalent TGFβ isoform expressed in many types of human tumors, suggesting that TGFβ1 may be a key contributor to primary CBT resistance. To test whether selective TGFβ1 inhibition is sufficient to overcome CBT resistance, we generated a high-affinity, fully human antibody, SRK-181, that selectively binds to latent TGFβ1 and inhibits its activation. Coadministration of SRK-181-mIgG1 and an anti–PD-1 antibody in mice harboring syngeneic tumors refractory to anti–PD-1 treatment induced profound antitumor responses and survival benefit. Specific targeting of TGFβ1 was also effective in tumors expressing more than one TGFβ isoform. Combined SRK-181-mIgG1 and anti–PD-1 treatment resulted in increased intratumoral CD8+ T cells and decreased immunosuppressive myeloid cells. No cardiac valvulopathy was observed in a 4-week rat toxicology study with SRK-181, suggesting that selectively blocking TGFβ1 activation may avoid dose-limiting toxicities previously observed with pan-TGFβ inhibitors. These results establish a rationale for exploring selective TGFβ1 inhibition to overcome primary resistance to CBT.

Pax6, a member of the paired-box family of transcription factors, is critical for oculogenesis in both vertebrates and insects. Identification of potential vertebrate Pax6 targets has been guided by studies in Drosophila, where the Pax6 homologs eyeless ( ey ) and twin of eyeless ( toy ) function within a network of genes that synergistically pattern the developing fly eye. These targets, which share homology with the fly genes sine oculis, eyes absent and dachshund, exist in mice and humans as the Six, Eya and Dach gene families. Members of these gene families are present in the developing vertebrate eye, and preliminary studies suggest that they may function in a network analogous to that in the fly. Thus, despite radically different architecture, a similar molecular scaffold underlies both vertebrate and fly eye patterning, suggesting that the considerable power of Drosophila genetics can be harnessed to study mammalian ocular development.