Figure 2. Asprosin, the C-Terminal Cleavage Product of Profibrillin, Is a Fasting-Responsive Plasma Protein.

(A) Asprosin immunoblot on six individual human plasma samples (lanes 2–7). Bacterially expressed recombinant asprosin was used as a positive control (lane 8). The molecular weight marker is shown in lane 1.

(B) Asprosin sandwich ELISA standard curve.

(C) Sandwich ELISA was used to measure plasma asprosin levels in overnight fasted humans, mice, and rats (n = 7 in each group).

(D) Sandwich ELISA was used to measure plasma asprosin levels in unaffected control subjects (WT), two patients with heterozygous FBN1 frameshift mutations 5′ to the threshold for mRNA nonsense-mediated decay (c.6769-6773del5, c.1328-23_c.1339del35insTTATTTTATT) (proximal truncation 1&2), and two NPS patients (distal truncation 1&2).

(E) Sandwich ELISA was used to measure plasma asprosin every 4 hr from circadian C57Bl/6 mice entrained to total darkness (n = 5). The period of feeding is shaded.

(F) Sandwich ELISA was used to measure plasma asprosin levels in ad libitum fed or overnight fasted humans, mice, and rats (n = 7 in each group).

(G) FBN1 expression across all human tissues using the GTEx human RNaseq database.

(H) Various WT C57Bl/6 mouse organs were assessed for Fbn1 mRNA expression by qPCR.

(I) Plasma asprosin was assessed using sandwich ELISA on plasma from 13-week-old, 6-hr fasted male WT and Bscl2-null mice.

(J) PPARg2 mRNA expression by qPCR and media asprosin by sandwich ELISA were assessed on cultured 3T3-L1 cells with or without exposure to an adipogenic cocktail for 7 days. Cells were washed with PBS and then exposed to glucose-free, serum-free media for 24 hr for assessment of secretion.

(K) C3H10T1/2 cells were subjected to the same analysis as in (J).

Data are represented as the mean ± SEM. See also Figures S1, S2, and S3.