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Published on: September 1, 2015
Calcium ameliorates renal cyst growth in metanephric organ culture: a morphological study
Nidhi Mahajan1, Tarundeep Kaur, Veena Puri
1Department of Biochemistry, Panjab University, Chandigarh, India.
Abstract:
Polycystic kidney disease (PKD) is associated with alterations in developmental processes that severely affect kidney integrity, often leading to fatal consequences. It has been suggested that dysfunctional calcium (Ca2+) regulation associated with the PKD phenotype is consequent to mutations affecting the pkd1 gene. Previously, it has been observed that blocking calcium along with cAMP allowed tubular epithelial cells to enter the proliferative phase that culminated in a cyst-like phenotype. In this regard, mouse metanephroi, (embryonic day 13.5, E13.5) were used to study morphological and ultrastructural effects of calcium replenishment on 8-bromocyclic 3'5'cyclic adenosine monophosphate (8-Br-cAMP)-induced cyst-like tubular dilations. Phase contrast microscopy of 8-Br-cAMP-treated metanephroi exhibited numerous dilated tubules that continued to increase in size for 4 days in culture. The effects of 8-Br-cAMP on renal tubular epithelia were assessed by histopathological and electron microscopic analyses. Transmission electron microscopy revealed changes such as increased vacuolation, swollen mitochondria, chromatin condensation, and disrupted cell membrane in tubular epithelia of 8-Br-cAMP-treated metanephroi. Concurrent treatments with calcium-channel agonists (calcium ionophore A23187 and phorbol-12-myristate-13-acetate) and 8-Br-cAMP abolished cAMP-induced morphometric and ultrastructural alterations. Calcium replenishment rescued tubular epithelial cells from mitogenic effects of cAMP and restored normal morphology at cellular and sub-cellular levels as verified by histopathological and ultrastructural examinations.
Insights
Calcium replenishment prevents cyst formation in polycystic kidney disease (PKD) models. Restoring calcium levels in tubular epithelial cells normalizes kidney cell structure and halts abnormal proliferation, offering a potential therapeutic strategy for PKD.
Area of Science:
- Nephrology
- Developmental Biology
- Cell Biology
Background:
- Polycystic kidney disease (PKD) involves developmental alterations impacting kidney integrity and function.
- Dysfunctional calcium (Ca2+) regulation is linked to the PKD phenotype, potentially due to pkd1 gene mutations.
- Previous studies suggest blocking calcium and cAMP promotes tubular epithelial cell proliferation, leading to cyst-like structures.
Purpose of the Study:
- To investigate the morphological and ultrastructural effects of calcium replenishment on 8-bromocyclic 3'5'cyclic adenosine monophosphate (8-Br-cAMP)-induced cyst-like tubular dilations in mouse metanephroi.
- To assess whether calcium replenishment can reverse or prevent the cellular changes associated with cAMP-induced kidney cyst formation.
Main Methods:
- Mouse metanephroi (embryonic day 13.5) were cultured and treated with 8-Br-cAMP to induce cyst-like dilations.
- Morphological changes were observed using phase contrast microscopy.
- Ultrastructural and histopathological analyses were performed using transmission electron microscopy.
- Concurrent treatments involved calcium-channel agonists (calcium ionophore A23187, phorbol-12-myristate-13-acetate) alongside 8-Br-cAMP.
Main Results:
- 8-Br-cAMP treatment led to numerous dilated tubules in metanephroi, with continuous size increase over 4 days.
- Ultrastructural analysis revealed increased vacuolation, swollen mitochondria, chromatin condensation, and disrupted cell membranes in tubular epithelia.
- Concurrent administration of calcium agonists with 8-Br-cAMP abolished the observed morphometric and ultrastructural alterations.
- Calcium replenishment effectively rescued tubular epithelial cells from the mitogenic effects of cAMP.
Conclusions:
- Calcium replenishment restores normal morphology at cellular and sub-cellular levels in metanephroi exposed to cAMP.
- Restoring calcium regulation prevents the proliferative effects of cAMP on renal tubular epithelia, mitigating cyst-like dilations.
- This suggests that modulating calcium levels could be a therapeutic approach for polycystic kidney disease.
