Description:
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SH2B3, also known as LNK, is an adaptor protein that negatively regulates growth factor and cytokine signaling. The minor allele of a single nucleotide polymorphism in
<jats:italic>SH2B3</jats:italic>
(rs3184504) encodes a tryptophan (Trp) at amino acid 262 as opposed to arginine (Arg) and is strongly associated with hypertension in genome-wide association studies. Whether this variant is causal and how it impacts hypertension development and end-organ damage is unknown. We used CRISPR-Cas9 to engineer mice homozygous for the major and minor alleles of this
<jats:italic>SH2B3</jats:italic>
polymorphism, resulting in Arg/Arg and Trp/Trp mice, respectively. Trp/Trp mice exhibited increased systolic blood pressure (SBP) by radiotelemetry during weeks 3-4 of angiotensin II (Ang II) infusion compared to Arg/Arg mice (nighttime SBP 168 vs 158 mm Hg, respectively). Renal dysfunction was also exacerbated in Ang II-treated Trp/Trp compared to Arg/Arg mice, as evidenced by significantly increased urinary albumin/creatinine ratio (0.41 vs 0.17), renal perivascular fibrosis (fibrosis score 2.0 vs 1.0), and renal macrophages (8,341 vs 6,413 per kidney). In addition, renal CD8
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T cells from Ang II-treated Trp/Trp mice produced significantly more IFNγ compared to Arg/Arg controls (median fluorescence intensity 20,455 vs 14,134), and
<jats:italic>ex vivo</jats:italic>
stimulated splenic CD8
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T cells from Trp/Trp compared to Arg/Arg mice made 2.7-fold more IFNγ. To determine a mechanism for increased T cell IFNγ production, dendritic cells and naïve T cells from Trp/Trp and Arg/Arg mice were co-cultured in different combinations. The greatest increase in GM-CSF-induced IFNγ production occurred when both dendritic cells and T cells came from Trp/Trp mice (3.4-fold greater than both cell types from Arg/Arg mice). This effect appears to be due to loss of SH2B3-mediated suppression of GM-CSF signaling, as overexpression of Trp-encoding SH2B3 in HEK cells exhibited significantly less repression of GM-CSF-induced Stat5 activation compared to Arg-encoding SH2B3. Taken together, these findings suggest that the Trp encoding allele of rs3184504 is a causal variant promoting blood pressure elevation and renal dysfunction, at least in part through loss of SH2B3-mediated repression of T cell IFNγ production.
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