Abstract
The species-specific, as well as organ-specific expression of regulated necrosis (RN)-related molecules, is not known. We determined the expression levels of tumour necrosis factor receptor-1 (TNFR1), receptor activated protein kinase (RIPK)1, RIPK3, mixed lineage kinase domain-like (MLKL), CASP8, Fas-associated protein with death domain (FADD), cellular inhibitor of apoptosis protein (CIAP)1, CIAP2, glutathione peroxidase-4 (GPX4), cyclophilin D (CYPD), CASP1, NLRP3 and poly(ADP-ribose) polymerase-1 (PARP1) in human and mouse solid organs. We observed significant differences in expression of these molecules between human and mice. In addition, we characterized their expression profiles in acute as well as persistent tissue injury and chronic tissue remodelling using acute and chronic kidney injury models. We observed that the degree and pattern of induction of RN-related molecules were highly dependent on the trigger and disease pathogenesis. Furthermore, we studied their expression patterns in mice with lupus-like systemic autoimmunity, which revealed that the expression of MLKL, GPX4 and PARP1 significantly increased in the spleen along disease progression and CASP1, RIPK1, RIPK3 and CYPD were higher at the earlier stages but were significantly decreased in the later stages. In contrast, in the kidney, the expression of genes involved in pyroptosis, e.g. NLRP3 and CASP1 were significantly increased and TNFR1, RIPK1, RIPK3, CIAP1/2 and GPX4 were significantly decreased along the progression of lupus nephritis (LN). Thus, the organ- and species-specific expression of RN-related molecules should be considered during designing experiments, interpreting the results as well as extrapolating the conclusions from one species or organ to another species or organ respectively.
Highlights
For almost two decades apoptosis was considered to be the only programmed form of cell death and necrosis was felt to be an ‘accidental’ cell death passively induced by physiochemical insults [1]
Regulated necrosis-related molecule mRNA expression in adult human tissues We quantified the mRNA expression levels of regulated necrosis (RN)-related molecules involved in necroptosis, e.g. Tumour necrosis factor receptor-1 (TNFR1), RIPK1, RIPK3, mixed lineage kinase domain-like (MLKL), CASP8, Fas-associated protein with death domain (FADD) and CIAP1 and CIAP2; ferroptosis, e.g. glutathione peroxidase-4 (GPX4); mitochondria permeability transition (MPT)-RN, e.g. cyclophilin D (CYPD); pyroptosis, e.g. CASP1, nod-like receptor family pyrin domain containing 3 (NLRP3); parthanatos, e.g. poly(ADP-ribose) polymerase-1 (PARP1) using quantitavie real time polymerase chain reaction (qRT-PCR) in healthy human organs
GPX4 and CYPD expressions were higher in testis, whereas expression of CIAP1 and CIAP2 was higher in the thymus but all remained low in any other solid organs tested
Summary
For almost two decades apoptosis was considered to be the only programmed form of cell death and necrosis was felt to be an ‘accidental’ cell death passively induced by physiochemical insults [1]. Necroptosis Necroptosis is triggered by death receptors and requires the receptor activated protein kinase (RIPK)3-dependent. M. Honarpisheh and others phosphorylation of mixed lineage kinase domain-like (MLKL) inducing plasma membrane pore formation [4,5]. Tumour necrosis factor receptor-1 (TNFR1)-mediated necroptosis is considered a prototype form of RN. TNFR1 stimulation recruits RIPK1, which possesses important kinase-dependent and scaffolding functions that either inhibit or trigger necroptosis and apoptosis [6]. TNFR1 activation may lead to apoptosis; the deficiency of caspase-8 [7], a Fas-associated protein with death domain (FADD) [8], FLICE-like inhibitory protein [9] and cellular inhibitor of apoptosis proteins (CIAPs) 1 and 2 [10] induce necroptosis. Distinct stimuli involve the necroptosis pathway into NET formation-related neutrophil death, known as ‘suicidal NETosis’ [13,14]
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