Details for: CL0000751

Cell ID: CL0000751

Cell Name: rod bipolar cell

Description: A bipolar neuron found in the retina that is synapsed by rod photoreceptor cells but not by cone photoreceptor cells. These neurons depolarize in response to light.

Selected Context(s): Overall

Gene Significance Landscape

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Genes

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Cell Significance Index (CSI) is uniquely calculated to reveal cell-specific gene markers. More info here

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for rod bipolar cell within the selected context(s).

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for rod bipolar cell. Higher scores indicate a stronger, more significant difference in expression.
(Previously described as "Fold Change", but now represents Cliff's Delta × –log10(p).)

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for rod bipolar cell. Higher scores indicate a stronger, more significant difference in expression.
Average CSI: csi sum / gene count
Cell network configuration

This network visualizes key genes for rod bipolar cell. It primarily includes:
1. Top genes highly significant for this cell (Num. Top Cell Genes - based on the 'Min. CSI' setting).
2. Any additional specific 'Context Genes' you add below.
The final network is a combined view. Choose an Interaction Source (pathways or protein interactions) and optionally compare CSI scores with a Baseline Cell Type.

Maximum number of selected genes.
Select a context for the baseline cell.
Select a context for the target cell.
Target Cell for CSI:  rod bipolar cell (CL0000751)

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Nodes (Genes):
 Query Gene
Node size also reflects Target Cell CSI magnitude.
Node Color (Target Cell CSI in specific network):
 Very High
 High
 Medium
 Low
 Very Low
 N/A or Not Sig.
Edges (Interactions):
 STRING (Protein-Protein)
 ONTOLOGY (Shared Pathway)
 Colors vary by pathway category; default arrow applies.

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## Summary The [rod bipolar cell](/details-cell/CL0000751) is a specialized neuron within the retina, defined by its role in receiving synaptic input exclusively from rod photoreceptor cells and depolarizing in response to light. The gene significance profile for this cell type strongly underscores its identity as a highly specialized signaling hub for scotopic (low-light) vision. **Overall**, the top marker genes are dominated by components of ion channels, neurotransmitter receptors, and calcium signaling pathways, highlighting a cellular machinery exquisitely tuned for transducing and processing visual signals. Key markers like [TRPM1](/details-gene/4308), [GRM5](/details-gene/2915), and [CALM1](/details-gene/801) suggest that the cell's defining characteristic is its capacity for precise and sensitive signal transduction at the second stage of the visual pathway. ## Key Characteristics and Function The functional identity of the [rod bipolar cell](/details-cell/CL0000751) is articulated by several distinct clusters of highly specific genes. * **Neurotransmitter Signaling and Ion Channel Activity:** The most prominent feature of this cell is its extensive machinery for receiving and propagating neural signals. The high specificity score (`csi_z`: 41.27) for [TRPM1](/details-gene/4308), a transient receptor potential cation channel, is a hallmark of ON-bipolar cells and is essential for the light-evoked depolarization cascade. This is complemented by the metabotropic glutamate receptor [GRM5](/details-gene/2915), which detects the glutamate released from rod photoreceptors in the dark. Furthermore, the presence of GABA receptor subunits [GABBR2](/details-gene/9568) and [GABRB2](/details-gene/2561) as specific markers indicates that the cell is also integrated into inhibitory circuits, likely receiving feedback from amacrine cells. Ion homeostasis and excitability are further managed by proteins such as the potassium channel-interacting protein [KCNIP4](/details-gene/80333) and the P-type calcium transporter [ATP2B2](/details-gene/491). * **Calcium-Mediated Signal Transduction:** Central to its signaling function is a reliance on calcium dynamics. [CALM1](/details-gene/801), encoding the calcium-binding protein calmodulin, is the top-ranked marker gene (`csi_z`: 53.75), suggesting that calcium-dependent signaling is a uniquely critical process in this cell. This is consistent with its role in modulating ion channels and neurotransmitter release in response to the initial light signal. * **Neuronal Structure, Adhesion, and Transport:** The cell's structural integrity and synaptic organization are maintained by a suite of specific genes. These include [DOK6](/details-gene/220164), which is involved in neurite outgrowth ([Link](https://doi.org/10.1074/jbc.m403726200)), the cell adhesion molecule [OPCML](/details-gene/4978), and the metalloproteinase [ADAM23](/details-gene/8745), which can mediate cell-cell interactions. The high specificity of the kinesin motor protein [KIF5C](/details-gene/3800) points to the importance of active axonal transport for delivering synaptic vesicles and other essential components to its terminals in the inner plexiform layer. Additionally, the presence of [RTN4](/details-gene/57142), an inhibitor of neurite outgrowth, may suggest a role in maintaining synaptic stability in the mature retinal circuit. * **Anti-Markers:** The set of genes with the lowest expression specificity provides valuable insight into what the [rod bipolar cell](/details-cell/CL0000751) is *not* defined by. This list is populated by ubiquitously expressed housekeeping genes involved in core cellular processes such as protein degradation ([UBB](/details-gene/7314)), mitochondrial respiration ([ATP5F1E](/details-gene/514), [COX6C](/details-gene/1345)), and general RNA processing ([HNRNPA1](/details-gene/3178), [PABPC1](/details-gene/26986)). Their low specificity scores indicate that while these functions are necessary for cell survival, they are not the specialized features that distinguish rod bipolar cells from other cell types. The cell's identity is thus rooted in its specialized signaling and structural components, not its basal metabolic activity. ## Clinical Significance and Contextual Roles **Overall**, the gene profile of the [rod bipolar cell](/details-cell/CL0000751) directly implicates it in human visual disorders. The most striking example is [TRPM1](/details-gene/4308), mutations in which are a leading cause of autosomal recessive congenital stationary night blindness (CSNB). This condition is characterized by a non-progressive inability to see in low-light conditions, precisely the function mediated by the rod photoreceptor to [rod bipolar cell](/details-cell/CL0000751) pathway. The essential role of [TRPM1](/details-gene/4308) in these cells, as highlighted by its high specificity score, provides a clear molecular basis for this disease. Beyond monogenic disorders, other key markers suggest broader relevance. [GRM5](/details-gene/2915) is a target for research in a variety of neurological conditions, and its specific function in the retina is critical for the primary visual signal cascade. The neuregulin [NRG3](/details-gene/10718), another specific marker, has been associated with schizophrenia in genetic studies ([Link](https://doi.org/10.1073/pnas.94.18.9562)). While its role in the retina is not fully elucidated, its high specificity suggests that alterations in retinal processing, potentially mediated by [NRG3](/details-gene/10718) signaling, could be a peripheral manifestation or contributing factor to complex central nervous system disorders. The [rod bipolar cell](/details-cell/CL0000751), therefore, represents a critical node where genetic defects can lead to specific visual impairments or potentially reflect broader neurological vulnerabilities. ## Potential Mechanisms and Research Directions 1. **Hypothesis:** The highly specific expression of the neurite outgrowth inhibitor [RTN4](/details-gene/57142) (Nogo) in mature [rod bipolar cells](/details-cell/CL0000751) serves an active role in maintaining the precise and stable synaptic architecture of the inner plexiform layer. Rather than being a developmental remnant, it may function as a "boundary" molecule that prevents aberrant synaptic sprouting and preserves the fidelity of the established visual circuit. * **Surprising Findings:** It is counterintuitive for a potent growth inhibitor to be a defining marker of a functionally stable, post-mitotic neuron. This suggests that synaptic stability is not a passive state but an actively maintained process, where inhibitory signals are just as important as structural ones. * **Testable Questions:** In an adult mouse model, does the conditional knockout of [RTN4](/details-gene/57142) specifically in [rod bipolar cells](/details-cell/CL0000751) lead to morphological changes, such as neurite sprouting or the formation of ectopic synapses with amacrine or ganglion cells? Furthermore, does this structural change correlate with a functional deficit in scotopic vision as measured by electroretinography? 2. **Hypothesis:** The neuregulin [NRG3](/details-gene/10718), alongside its cognate receptor ErbB4, functions as a key neuromodulatory pathway within the [rod bipolar cell](/details-cell/CL0000751), dynamically adjusting the cell's response gain to both glutamatergic input from photoreceptors and GABAergic inhibition from amacrine cells. This pathway may represent a mechanism for fine-tuning retinal sensitivity and contributing to longer-term light/dark adaptation. * **Surprising Findings:** The identification of a growth factor-like signaling molecule, [NRG3](/details-gene/10718), as a highly specific marker for this cell type points towards a layer of local, tonic regulation that is distinct from the primary, fast synaptic transmission mediated by glutamate and GABA. * **Testable Questions:** Using patch-clamp electrophysiology on retinal slices, does the exogenous application of NRG3 protein alter the frequency or amplitude of spontaneous or light-evoked excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs) in [rod bipolar cells](/details-cell/CL0000751)? Does knocking down the ErbB4 receptor in these cells alter their response properties or the process of dark adaptation?