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. 2023 Jun 28;24(13):10749. doi: 10.3390/ijms241310749

Figure 3.

Figure 3

Receptors that contribute to NAD+ synthesis pathways in T cells and how NAD+ affects IL-2 and IL-17 production. NAD+ synthesis pathways shown are: (1) de novo pathway, (2) Preiss–Handler pathway, (3) nucleoside pathway, and (4) salvage pathway. The kynurenine transported by System L amino acid transporters, which are heterodimers of CD98 and LAT1 contribute to the de novo pathway. CD73 has dual enzymatic functions, (1) cleaving NAD+ to NMN and (2) hydrolyzing NMN to NR, which both contribute to the nucleoside pathway after being imported into the cell by the nicotinamide mononucleotide transporter, Slc12a8 and equilibrative nucleoside transporter (ENT), respectively. CD38 and CD157 are ADP-ribosyl cyclases, converting NAD+ into cADPR and hydrolyzing cADPR to form ADPR. The NAD-dependent histone deacetylases, sirtuins, and their effects on IL-2 and IL-17 production are shown. Red arrows, increased in SLE T cells. Blue arrows, decreased in SLE T cells.