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Distribution of actin in mesangial cell of rat glomerulus
Abstract:
The localization of actin in the renal glomerulus of normal and streptozotocin (SZ) or aminonucleoside (AN) administered rats was studied by immunofluorescent and electron microscopy. The immunofluorescence (IF) for actin in normal rats showed a fine granular mesangial pattern, but the intensity was weak. An increase in positivity and an enlargement of the distribution of IF were observed in both SZ and AN administered rats, and the pattern of staining was still mesangial. Under an electron microscope, the mesangial cells showed an increase in number of microfilaments of 5 nm in diameter as well as in other cellular organelles, such as rERs and free ribosomes. These results suggest that the IF-positive substance for actin in the mesangium and the microfilaments observed in the mesangial cells by electron microscopy are identical with each other, i.e. actin filaments. Further, the mesangial cells may react by stimulation from injurious agents, such as SZ or AN, to increase the amount of actin as well as the number of other cellular organelles.
Insights
Kidney mesangial cells increase actin filaments in response to injury. This study used immunofluorescence and electron microscopy to observe actin localization in normal and diseased rat kidneys, revealing cellular changes in response to streptozotocin (SZ) or aminonucleoside (AN).
Area of Science:
- Nephrology
- Cell Biology
- Immunofluorescence Microscopy
- Electron Microscopy
Background:
- Actin is a key cytoskeletal protein involved in cellular structure and function.
- The role of actin in glomerular mesangial cells under pathological conditions is not fully understood.
- Streptozotocin (SZ) and aminonucleoside (AN) are common agents used to induce experimental kidney injury.
Purpose of the Study:
- To investigate the localization and changes in actin within the renal glomerulus.
- To compare actin distribution in normal rats versus rats treated with SZ or AN.
- To correlate immunofluorescence findings with ultrastructural observations of mesangial cells.
Main Methods:
- Immunofluorescence (IF) microscopy was employed to detect actin.
- Electron microscopy was used to examine the ultrastructure of mesangial cells.
- Rats were administered streptozotocin (SZ) or aminonucleoside (AN) to induce glomerular injury.
Main Results:
- Normal rat glomeruli showed weak, granular mesangial staining for actin.
- SZ- and AN-treated rats exhibited increased actin immunofluorescence intensity and distribution in the mesangium.
- Electron microscopy revealed an increased number of 5 nm microfilaments (actin filaments) and organelles in mesangial cells of treated rats.
Conclusions:
- The immunofluorescence-detectable actin in the mesangium corresponds to actin filaments observed ultrastructurally.
- Mesangial cells respond to injurious agents (SZ, AN) by increasing actin filament production.
- These findings highlight the dynamic role of actin in mesangial cell response to injury.