Dataset Information

Deamidation in human islets of Langerhans

ABSTRACT: The β-cell plays a central role in the pathogenesis of T1D by neoantigen formation due to the generation of post-translational modifications, such as deamidation, being potential triggers for breaking immune tolerance. We report the detection by LC-MS/MS of 16 novel Gln and 27 novel Asn deamidations in 14 T1D-related proteins in inflammatory cytokine-stressed human islets of Langerhans. T-cell clones responsive against two Gln and three Asn deamidated peptides could be isolated from peripheral blood of T1D subjects. Ex vivo tetramer assays indicated higher T-cell frequencies in subjects with T1D compared to control subjects and a positive correlation between frequencies and insulin antibody levels at diagnosis and duration of disease for one Gln and two Asn deamidated peptides. These results highlight that inflammatory cytokine-exposed human islets are prone to both enzymatic and biochemical deamidation and suggest that both Gln and Asn deamidated peptides can promote the activation of CD4+ T cells in individuals with T1D. These findings add to the growing list of evidence that post-translational modifications undermine tolerance in T1D and may open the road for the development of new diagnostic and therapeutic applications for people living with T1D.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Endocrine Pancreas, Islet Of Langerhans

DISEASE(S): Type 1 Diabetes Mellitus

SUBMITTER: Aisha Callebaut

LAB HEAD: Chantal Mathieu

PROVIDER: PXD038758 | Pride | 2025-05-06

REPOSITORIES: Pride

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CD4+ T Cells From Individuals With Type 1 Diabetes Respond to a Novel Class of Deamidated Peptides Formed in Pancreatic Islets.

Callebaut Aïsha A Guyer Perrin P Derua Rita R Buitinga Mijke M Manganaro Anthony A Yi Xiaoyan X Sodré Fernanda Marques Câmara FMC Vig Saurabh S Suleiman Mara M Marchetti Piero P Eizirik Decio L DL Kent Sally C SC Mathieu Chantal C Mathieu Chantal C James Eddie A EA Overbergh Lut L

Diabetes 20240501 5

The β-cell plays a crucial role in the pathogenesis of type 1 diabetes, in part through the posttranslational modification of self-proteins by biochemical processes such as deamidation. These neoantigens are potential triggers for breaking immune tolerance. We report the detection by LC-MS/MS of 16 novel Gln and 27 novel Asn deamidations in 14 disease-related proteins within inflammatory cytokine-stressed human islets of Langerhans. T-cell clones responsive against one Gln- and three Asn-deamida ...[more]

PMID: 38387030

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Project description:Osteolytic lesions with suppression of osteoblastic (OB) differentiation are hallmarks of multiple myeloma (MM). Most recently, Gln availability has been found to be essential to sustain bone mass formation in murine models. On the other hand, MM cells are Gln-addicted and consume huge amounts of the amino acid, leading to a partial Gln depletion in the bone marrow (BM) plasma. We hypothesize that MM-dependent Gln depletion contributes to the defective OB differentiation characteristic of MM. Conversely, GLS (both KGA and GAC isoforms) and SLC38A2, the gene for the concentrative Gln transporter SNAT2, were induced. Consistent with this conclusion, the activity of SNAT2 was absent in undifferentiated hMSCs but well detectable after 14 days of OB differentiation, when total Gln uptake was also increased. Under the same conditions, OB differentiation markers (RUNX2, COL1A1, ALPL expression and ALPL activity or staining) were significantly induced but their expression was blunted by incubation in low-Gln (0.4 mM) medium or in the presence of the SNAT2 inhibitor MeAIB. The incubation in Gln-free D-MEM suppressed the induction of GLS and SLC38A2 along with OB differentiation, which was restored by the supplementation of Non-Essential Amino Acids (NEAA). Among NEAA, only asparagine (Asn) was able to rescue OB differentiation in the absence of Gln. The determination of intracellular amino acids with MS indicated that OB differentiation was associated with the increase of cell Asn, without significant changes of Gln, glutamate (Glu) or aspartate (Asp). Asparagine Synthetase (ASNS), the Gln-dependent enzyme that accounts for Asn synthesis, was also found induced during OB differentiation of hMSCs. Gene Expression Profiles of primary BM hMSCs and OBs from bone biopsies of both healthy donors and MM patients indicated that GLS, ASNS, and SLC38A2 are more expressed in OBs, while the expression of GLUL, the gene for GS, is higher in undifferentiated hMSCs from healthy donors. Overall, these results indicate that (1) OB differentiation of hMSCs is Gln-dependent; (2) the partial Gln depletion, imposed by Gln-addicted MM cells in the BM microenvironment, contributes to the impairment of osteoblastic differentiation of hMSCs; (3) hindrance of differentiation may depend on the limited availability of intracellular Asn derived from Gln-dependent ASNS. These results support the evidence that Gln addiction of MM cells affects bone microenvironment leading to the inhibition of OB differentiation and, consequently, to the development of MM bone disease.

			Action	DRS
	D1_CTR.msf	Msf
	D1_CTR.raw	Raw
	D1_CYT.msf	Msf
	D1_CYT.raw	Raw
	D2_CTR.msf	Msf