Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons.

Hypoglycemia-associated autonomic failure (HAAF) is a well-established complication of diabetes. Although HAAF has serious outcomes such as recurrent morbidity, coma, and death, the mechanisms of HAAF and its pathological components are largely unknown. Our previous studies have revealed that hypoglycemia is associated with the upregulation of an immediate early gene - FOS. In addition, it is documented that glucose deprivation activates neuronal autophagic activities. Therefore, the present study aimed to identify the role of FOS and one of the core components of the autophagy pathway, Beclin-1 (encoded by the BECN1 gene), in the regulation of autophagic mechanisms in embryonic hypothalamic neurons in response to hypoglycemic conditions. Embryonic Mouse Hypothalamic Cell Line N39 (mHypoE-N39 or N39) was cultured in reduced concentrations of glucose (2000, 900, 500, and 200 mg/L). Gene and protein expression, as well as immunofluorescence studies on autophagy were conducted under different reduced glucose concentrations in N39 hypothalamic neurons with and without FOS and BECN1 gene knockdowns (KD). The outcomes of the present study have demonstrated a significant increase in autophagosome formation and subsequent lysosomal degradation in the hypothalamic neurons in response to reduced glucose concentrations. This hypoglycemic response appears to be lowered to a similar extent in the FOS KD and BECN1 KD cells, albeit insignificantly from the negative control, is indicative of the involvement of FOS in the autophagic response of hypothalamic neurons to hypoglycemia. Moreover, the KD cells exhibited a change in morphology and reduced cell viability compared with the control cells. Our findings suggest that reduced FOS expression could potentially be associated with impaired autophagic activities that are dependent on BECN1, which could lead to decreased or blunted hypothalamic activation in response to hypoglycemia, and this, in turn, may contribute to the development of HAAF.

Cryopreservation and validation of differentiated PDGFRα-positive cells for long term usage in experimentation.

OBJECTIVE: Differentiation of immortalized Mesenchymal Stromal Cells (iMSCs) into PDGFRα-positive cells under controlled growth conditions has several vital implications in functional studies concerned with the pathogenesis of Diabetic Gastroparesis (DGP). A study published previously by our research group demonstrated the importance of these cells as a novel, in-vitro model for investigating the functional role of neuronal nitric oxide synthase. The currently available methods require fresh differentiation of PDGFRα-positive cells for each round of experimentation. This leads to longer delays, higher usage of reagents, and inconsistency in reproducibility of experiments frequently. We thus aimed to establish through validation that cryopreserving and maintaining the iMSC-derived PDGFRα-positive cells for functional investigations help us to overcome these challenges. RESULTS: We demonstrated for the first time that the differentiated PDGFRα-positive cells from iMSCs can be cryopreserved and thawed to be used as per the experimental requirements with prolonged preservation of their characteristics. We assessed the viability of differentiated PDGFRα-positive cells pre- and post-freezing with the subsequent validation of their functional features using flow cytometry, qRT-PCR, and western blotting. We have been successful in demonstrating for the first time that the cryopreservation of previously differentiated PDGFRα-positive cells can be used as a feasible and cost-effective model for experimental reproducibility in functional studies of Diabetes Gastroparesis.